AeroElectric-List Digest Archive

Tue 01/25/11


Total Messages Posted: 43



Today's Message Index:
----------------------
 
     1. 12:43 AM - Re: Odyssey PC680 Battery load tests (Jef Vervoort)
     2. 03:21 AM - Re: Comm Antenna & SWR Reading -- Too High? (tomcostanza)
     3. 04:50 AM - "Emacs!" in Response ()
     4. 05:12 AM - Re: Flush Cutting Cable Ties (Harley)
     5. 05:45 AM - Starter motors (Jan de Jong)
     6. 06:50 AM - Re: "Emacs!" in Response (user9253)
     7. 07:13 AM - Re: Re: "Emacs!" in Response (John Morgensen)
     8. 07:26 AM - Re: Odyssey PC680 Battery load tests (Robert L. Nuckolls, III)
     9. 08:11 AM - Re: Re: Comm Antenna & SWR Reading -- Too High? (Robert L. Nuckolls, III)
    10. 08:16 AM - VOMs again. . . (paul wilson)
    11. 09:01 AM - Re: VOMs again. . . (Mike Welch)
    12. 09:23 AM - Re: VOMs again. . . (Marvin Haught)
    13. 09:43 AM - Re: Comm Antenna & SWR Reading (Noel Loveys)
    14. 09:58 AM - Re: cable ties (Noel Loveys)
    15. 10:02 AM - Re: Comm Antenna & SWR Reading: Additional Info (Noel Loveys)
    16. 10:50 AM - Re: Re: Comm Antenna & SWR Reading -- Too High? (Robert L. Nuckolls, III)
    17. 11:10 AM - vor antenna (dlicheri)
    18. 11:14 AM - Re: VOMs again. . . (paul wilson)
    19. 11:16 AM - Re: cable ties (Stein Bruch)
    20. 11:18 AM - Re: VOMs again. . . (Robert L. Nuckolls, III)
    21. 11:25 AM - Re: cable ties (Robert L. Nuckolls, III)
    22. 11:42 AM - Re: "Emacs!" in Response (Noel Loveys)
    23. 11:42 AM - Re: VOMs again. . . (Mike Welch)
    24. 11:42 AM - Re: Comm Antenna & SWR Reading (Robert L. Nuckolls, III)
    25. 11:46 AM - Re: Re: "Emacs!" in Response (Dan Morrow)
    26. 11:54 AM - Re: vor antenna (Robert L. Nuckolls, III)
    27. 11:56 AM - Re: "Emacs!" in Response (Robert L. Nuckolls, III)
    28. 11:58 AM - Re: Comm Antenna & SWR Reading (Robert L. Nuckolls, III)
    29. 12:27 PM - Re: cable ties (Harley)
    30. 12:42 PM - Re: cable ties (Noel Loveys)
    31. 12:44 PM - Re: Comm Antenna & SWR Reading (Noel Loveys)
    32. 12:48 PM - Re: "Emacs!" in Response (Noel Loveys)
    33. 12:58 PM - Re: vor antenna (Noel Loveys)
    34. 01:05 PM - Re: Comm Antenna & SWR Reading (Robert L. Nuckolls, III)
    35. 01:12 PM - Re: vor antenna (Robert L. Nuckolls, III)
    36. 01:42 PM - Re: cable ties (Robert Borger)
    37. 01:50 PM - Re: vor antenna (Jared Yates)
    38. 02:50 PM - Re: VOMs again. . . (Robert L. Nuckolls, III)
    39. 03:17 PM - Re: VOMs again. . . (paul wilson)
    40. 05:22 PM - Low resistance measurement adapter. (Robert L. Nuckolls, III)
    41. 05:39 PM - Re: Low resistance measurement adapter. (Robert Borger)
    42. 07:55 PM - Re: Comm Antenna & SWR Reading (Noel Loveys)
    43. 08:14 PM - Re: vor antenna (Noel Loveys)
 
 
 


Message 1


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    Time: 12:43:05 AM PST US
    From: "Jef Vervoort" <jef.vervoortw@telenet.be>
    Subject: Odyssey PC680 Battery load tests
    Would that mean that that Panasonic battery is also a good choice for our RV ? Thanks Jef 91031 Belgium, almost there. _____ Van: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] Namens Mickey Coggins Verzonden: woensdag 19 januari 2011 19:40 Aan: aeroelectric-list@matronics.com Onderwerp: Re: AeroElectric-List: Odyssey PC680 Battery load tests Hi Bob, All three batteries were just sitting on a shelf - not connected to anything. I didn't do any charging to them during these years, which makes me wonder if perhaps they are now "damaged". The two Odyssey batteries had very low voltages - can't recall exactly, but it was low single digits, and they could not trigger a battery contactor. The Panasonic still had about 12 volts and worked fine. Exact same treatment for all three batteries. You mentioned that the battery tender is not meant as a charger. I also have a "dumb" charger that just dumps in either 2.5 or 5 amps - I forgot to check the voltage it puts out. Do you think that this charger would be better at recovering these batteries than the battery tender? Thanks, Mickey On Tue, Jan 18, 2011 at 23:50, Robert L. Nuckolls, III <nuckolls.bob@aeroelectric.com> wrote: <nuckolls.bob@aeroelectric.com> I used the West Mountain Radio CBA to test some batteries that I had hoped to use in my aircraft. =C2 Unfortunately the PC680 batteries have been laying around for about 6 years, and had became quite discharged. What kind of maintenance did you do on the batteries while stored? The Battery Tender and Battery Minders are not intended to be 'chargers' so much as 'maintainers'. When you have 12v batteries on storage, it's a good idea to clip them all together in parallel and have some sort of sophisticated maintainer supporting the lot. I use the Schumacher 1562 or a Battery Tender to support my test batteries. Some are pushing 7 years old with better than 80% of new capacity. I really thought that the Odyssey batteries would hold a charge better than a "standard" Panasonic. =C2 Also, the fact that the Panasonic is giving me double the capacity is quite surprising. Were all three stored under the same conditions? =C2 I have not yet tried my desulfator, but that's my next step. =C2 I've only tested one of my two Odyssey batteries, going to test the other "soon". We'll be interested to hear what you discover. Bob . . . -- Mickey Coggins


    Message 2


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    Time: 03:21:50 AM PST US
    Subject: Re: Comm Antenna & SWR Reading -- Too High?
    From: "tomcostanza" <Tom@CostanzaAndAssociates.com>
    Bob, In a previous life, I was a seat-of-the-pants, self-taught technician. I was told that the length of the coax didn't affect the SWR. But intuition, and more importantly, your test clearly shows that it does. Extrapolating from this, it seems it would be possible to reduce the SWR to near zero by varying the length of the coax. But would this affect performance? Your response seems to indicate that SWR is not a defacto predictor of performance. So why bother measuring it, unless it's to rule out an open or short, for which there are much easier measuring techniques? Also, the Comant specs for 2:1/3:1 probably assume an aluminum airplane. Would the fact that this is installed on a glass plane not make a difference? Last question: since I started studying antennas and transmission lines as a kid, it has always seemed like they were more art than science. Can you point me to some study material that someone with less than a PhD in physics can understand? As always, thanks for everything. Tom Costanza -------- Clear Skies, Tom Costanza Read this topic online here: http://forums.matronics.com/viewtopic.php?p=328378#328378


    Message 3


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    Time: 04:50:19 AM PST US
    From: <bakerocb@cox.net>
    Subject: "Emacs!" in Response
    1/25/2011 Hello Bob Falstad, You wrote (see copied below): "However, your response had three"Emacs!" in it that appear to refer to graphics that I can't view." I have the same problem with Bob Nuckolls' postings, but here is a solution for me: a) Go to the Matronics forum web site. http://forums.matronics.com/ b) Click on the aeroelectric list. http://forums.matronics.com/viewforum.php?f=3 c) Click on the original subject of the email(s) in question. (Comm Antenna & SWR Reading -- Too High?) http://forums.matronics.com/viewtopic.php?t=78934 d) Scroll down to the posted email in question and you should be able to see any attached graphics or photos. Please let me / us know how this works for you. 'OC' Baker Says: "The best investment we can make is the time and effort to gather and understand knowledge." PS to all: Bob, Bob, Who has got the Bob? Or which Bob? It is pretty important to me (and I am sure many others) to know which Bob author that they are reading or which Bob is being addressed. Would all posters please identify in each case by last name which Bob they are addressing and which Bob is writing by last name in each instance? Many thanks. ===================================================================== Time: 10:38:42 AM PST US From: Bob Falstad <bobair@me.com> Subject: AeroElectric-List: Re: "Emacs!" in Response: Was Comm Antenna & SWR Reading Bob, Many thanks for your quick and detailed response. However, your response had three "Emacs!" in it that appear to refer to graphics that I can't view. I searched the AeroElectric lists archives and the most detailed message re "Emacs!" was yours dated July 31, 2009. I couldn't find any other relevant messages on how to view your graphics/photos. I'm using a Macbook with OS 10.4.6 (Snow Leopard) that also has a full install of Windows XP in it. I opened your reply in three different browsers -- Safari, Firefox and Internet Explorer 8 but no joy. Any thoughts on how I can retrieve/view your "Emacs!" graphical inserts? Best regards, Bob Falstad


    Message 4


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    Time: 05:12:26 AM PST US
    From: Harley <harley@AgelessWings.com>
    Subject: Re: Flush Cutting Cable Ties
    YEARS ago, when I was still working for a living, I wrapped, tensioned and cut off thousands of cable ties over the years with this little gem. www.tnb.com/fulltilt/pdf/WT1TB.pdf I still have it, and on finding it and trying it a few minutes ago, it still works great. Tensions the tie and then with a quarter turn twist, cuts it low enough that the cut end is usually not a problem (once you get used to doing it...even the first time, it leaves only a small twisted tip). The only problem with it is if you try to put too much tension on the tie, the gripper will cut the tie off about a half inch long. You can usually regrip it and then twist. I was surprised that it is still being sold after over 30 years since I first got mine! Here it is at Newark...that's where I got mine from 30 years ago. I didn't do any further searching and, as usual with Newark's prices (I dealt with Newark all the time at work because I had a crush on my local sales rep!), you may get it cheaper elsewhere. Harley Dixon ----------------------------------------------------------------- On 1/24/2011 10:14 PM, Dennis Johnson wrote: > For cutting nylon cable ties, I've had good luck with these > cheap flush cutters from Harbor Freight: > http://www.harborfreight.com/micro-flush-cutter-90708.html > They cut the loose end of a plastic cable tie flush and don't > leave a sharp edge. Buy a few because they are cheap and > don't last forever. But if you don't try to cut anything other > than plastic cable ties or copper wire, they'll last for most > of an airplane project. > Dennis > * > *


    Message 5


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    Time: 05:45:34 AM PST US
    From: Jan de Jong <jan_de_jong@casema.nl>
    Subject: Starter motors
    Having educated myself somewhat on 12V starter motors and having looked at 13 starter motors rated from 0.85kW to 4.2kW in more or less detail I am sharing some generalized results: 1. voltage (12V) and power rating (in kW) are the only values on the nameplate 2. the power rating indicates mechanical output power (torque times rpm) 3. a power rating is determined in a circuit with a certain lead-acid battery and a fixed resistance, not with a fixed supply voltage as one might expect; this an industry protocol: - 'largest battery allowed for this motor' Bosch says (the protocol requires a certain minimum voltage drop I suspect) - battery at 80% charge and at -20 degrees C - with 1 mOhm in series a 'performance curve' is produced, and in some cases made public (fortunately) 4. at stall (rpm=0): output power is 0, input power is at maximum, about 2.7 to 3.5 times the rated power at 5.5 to 7V the stall current (in A) is about half the power rating (in W) (the internal motor resistance is 11/power rating to 14/power rating (in Ohm)) 5. at maximum rpm (torque=0): output power is 0, input power is at minimum, 0.7 to 1.0 times rated power at about 12V the idle current (in A) is 6 to 8% of the power rating (in W) 6. maximum output power (rated power) occurs at half of maximum rpm and about 45% of stall current the input power is twice the output power or a little more 7. the normal start sequence of a 1.5kW (1hp) starter motor: 7.1. stall current buildup in a few tens of ms to 750A at 5.5 to 7V 7.2. speedup to maximum output power in several hundreds of ms, the current drops to 350A at 9 or 10V 7.3. speedup to equilibrium rpm where output power generated meets power required, the current drops to a value not much above 100A at 11V, depending on the load 8. during initial speedup the power required may soon rise faster than the output power generated, the motor will then turn in semi-stalled condition at very high current - bad causes are: excessive load, battery internal resistance, circuit resistance 9. battery CA (cranking amps) rating to allow the motor to make its rated power: 45% of half the power rating (units of A and W respectively) -> not less than power rating / 5 (this is also a known rule of thumb) Some starter motor sizes: Micron: 0.5kW Rotax 912: 0.6kW (option 0.9kW) Jabiru: 1.0kW (option Bosch 1.5kW) Ulpower: 1.1kW Largest seen: Kelly 2.8kW Cheers, Jan de Jong


    Message 6


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    Time: 06:50:08 AM PST US
    Subject: Re: "Emacs!" in Response
    From: "user9253" <fran4sew@banyanol.com>
    I agree with Bakerocb. It seems that pictures have been removed from the daily email digest and replaced with Emacs! If I want to see the pictures, I go to http://forums.matronics.com/viewforum.php?f=3 to view them. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=328404#328404


    Message 7


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    Time: 07:13:49 AM PST US
    From: John Morgensen <john@morgensen.com>
    Subject: Re: "Emacs!" in Response
    No problem here. I get the individual emails. Is the problem only on the digest? John On 1/25/2011 6:45 AM, user9253 wrote: > --> AeroElectric-List message posted by: "user9253"<fran4sew@banyanol.com> > > I agree with Bakerocb. It seems that pictures have been removed from the daily email digest and replaced with Emacs! If I want to see the pictures, I go to http://forums.matronics.com/viewforum.php?f=3 to view them. > Joe > > -------- > Joe Gores > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=328404#328404 > >


    Message 8


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    Time: 07:26:41 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Odyssey PC680 Battery load tests
    At 03:17 AM 1/25/2011, you wrote: >Would that mean that that Panasonic battery is also a good choice for our RV ? > >Thanks >Jef 91031 Belgium, almost there. Check out the various threads and articles on about batteries at http://aeroelectric.com using the search feature. Also check out the chapter on batteries in The AeroElectric Connection. Over the years, I've come to understand that there are few batteries not of good value . . . it's a sort of get what you pay for idea . . . pretty fundamental to an honorable free-market economy. We've also discovered that the selling price for any product must include amortization of promotional costs. This is why many products (like alkaline cells) are often made by the same factory to be sold under a variety of brands but with wide range of pricing for exactly the same product. One is certainly justified in being skeptical of any new kid on the block for a battery of any brand or price. Without special knowledge of where that battery is made, for how many other brands and for how long deprives you of data useful for the reduction of risk. Having said that mouth full, understand that batteries suitable for service in our airplanes are more influenced by what our design goals are. MOST airplane drivers are 'happy' with a battery that cranked the engine today so he could go flying. Just like in our cars. HOWEVER . . . if your design goals include DEPENDING on a battery for an alternative SOURCE of power in case of alternator failure, it's incumbent on you to KNOW mow much power you NEED to support your ENDURANCE loads and then CONFIRM that your battery is capable of that task before you launch into the HIGHER RISK environment. This takes homework on your part along with knowledge of how to craft and maintain a failure tolerant system to your design goals ("I want to be able to fly battery- only for X.X hours") You CAN do this with a Hawker, Panasonic, Yuasa, etc. etc. Success will be based on your own knowledge of what you expect. Relying on your hangar mate's assertion that "Panasonics are fine batteries for airplanes" is not a substitute for that knowledge. If your forecasted dependence on a battery is for day/vfr/pleasure flying, then perhaps you can treat the battery like 99% of the light aircraft drivers and virtually all car drivers treat theirs. Run it till it gasps and dies. If your expectations and goals that go beyond that, you'll have to educate yourself in the processes that go to meeting those goals. If the battery of interest bears a well established branding, it's likely that you'll pretty much get your money's worth. Its a very competitive business. Anyone who has been at it for 20 years or more has probably earned their place in the market. But if the battery is some new product being offered by a bunch of folks who marketed donuts and bagels in an earlier life, then exercise due caution. Bob . . .


    Message 9


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    Time: 08:11:37 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Comm Antenna & SWR Reading -- Too High?
    At 06:18 AM 1/25/2011, you wrote: ><Tom@CostanzaAndAssociates.com> > >Bob, > >In a previous life, I was a seat-of-the-pants, self-taught >technician. I was told that the length of the coax didn't affect >the SWR. But intuition, and more importantly, your test clearly >shows that it does. Yeah but your teachers were right and so are you. The length of the coax between signal source and the load has losses. From a practical perspective, those losses are not significant in setting performance. In other words, we pick a coax that has an acceptably low loss for the system we're building. In the wild and wooly world of RF and transmission lines, most investigations are carried out with transmission lines of very low loss such that while the number is not zero, it's so small as to be ignored. > Extrapolating from this, it seems it would be possible to reduce > the SWR to near zero by varying the length of the coax. I think you missed an important point in the data. Yes, SWR varied with frequency because the load on the far end of the transmission line waves around in the frequency spectrum. Adding coax MIGHT make SWR appear better but only if there are losses in the coax. Losses reduce the magnitude of energy that makes it to the far end where it suffers reflection due to mis-match. The same losses reduce magnitude of energy reflected back to the observer's instrument at the input end. Yeah, the SWR 'appears' to improve while in fact, losses have served only to mask the truth from an otherwise reliable measurement system. Check out this tutorial on Smith charts: http://www.microwaves101.com/encyclopedia/Smithchart.cfm As a practical matter, while investigating of any generator/ transmission line/load combination the observer can ignore the effects of losses because the transmission lines are short (less than 360 electrical degrees or one wavelength). When you plot the characteristics for any combination of hardware on the Smith chart, they form a circle of constant SWR. There's an infinite number of resistance/reactance values represented by points on that circle . . . but for any given frequency, the SWR is constant for any length of transmission line. When you investigate a range of frequencies, then the circle explodes and you can get some really curious graphic art forms. That's because the antenna at the far end is optimal at one frequency only. But an size dummy load at the far end and SWR is zero only when load matches the line. When the load does not match the line, you get SWR circles other than 1:1 but they are still smooth circles and they do not change magnitude or shape by adjusting line length. The data I offered supports this. Yes, SWR did appear to become lower by adding coax but the real SWR value for the two conditions were identical. >But would this affect performance? Your response seems to indicate >that SWR is not a defacto predictor of performance. So why bother >measuring it, unless it's to rule out an open or short, for which >there are much easier measuring techniques? Yes, it affects performance . . . but probably not in observable ways. One reader noted that an SWR value on the order of 6:1 implied loss of 50% of radiated energy. That's a 3db drop of signal strength at the receiving site. The guy listening to that signal would be unlikely to hear any difference. At the same time, we COULD put 100' of coax on the antenna being investigated. The SWR would get MUCH BETTER but the power situation would get worse. Not only is REAL SWR unchanged, we've added losses to the system that mask real SWR and further reduce power delivered to the antenna. There WAS a time when practitioners of the arts and sciences of aircraft antennas counseled cutting coax cables to some specific length to maximize performance. They cited experiments with a field strength meter to support their assertions. You could not argue with their demonstrated success. You could argue their lack of understanding of what was going on. In these cases, SWR values in the system had to be high. Once a piece of transmission line becomes mis-matched, it becomes part of the impedance transformation system that attaches the power generator (tube or transistor) to the antenna's feedpoint. By fiddling with the length of a poorly matched feedline, they were in effect "tuning" the combination of reactances that participated in that power transfer. If they put a dummy load on the antenna end of the transmission line, length would have no effect on SWR or the transmitter's ability to deliver power into that transmission line. >Also, the Comant specs for 2:1/3:1 probably assume an aluminum >airplane. Would the fact that this is installed on a glass plane >not make a difference? You bet. Not only do we need to satisfy minimal RF requirements for size and geometry of ground plane, achieving a good RF bond to that ground plane is important. He cited a 2' x 3' ground plane. That's the size I used in my experiment. While not "ideal" (1/4-wave radius disk), it was certainly adequate to the task. I would not expect there to be observable difference in performance between infinite ground plane, aluminum structure, or glass structure backed up by 6 square feet of aluminum sheet. >Last question: since I started studying antennas and transmission >lines as a kid, it has always seemed like they were more art than >science. Can you point me to some study material that someone with >less than a PhD in physics can understand? They are VERY much science. The experiments have been repeated many times with great consistency. There is also an art of making sure we understand and minimize the conditions that affect the science. I'm sure that's what we're dealing with here. There ARE good reasons why we both got the measurements reported. The goal is to figure out their veracity and significance. That's the art of sifting simple-ideas for answers that define the results. >As always, thanks for everything. You're most welcome . . . and thanks for asking! Bob . . .


    Message 10


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    Time: 08:16:38 AM PST US
    From: paul wilson <pwmac@sisna.com>
    Subject: VOMs again. . .
    Sure Lots of message for good meters. And the HF $4 unit is great for checking voltages and continuity. What about a low cost meter that can be used for low resistance measurements? No need to go down to less than ~2 ohms. But a 20k lower scale dosen't do much for my needs and I have to drag out my ancient VTVM to see the resistance. I sure would be nice to have a handy VOM that gets some low R values. Any suggestions? Like to measure sensors on my truck that are supposed to be 3 ohm. and the truck is 1000 miles from the VTVM because I only carry the cheepy VOM and leave the VTVM home. - Sigh. PaulW


    Message 11


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    Time: 09:01:45 AM PST US
    From: Mike Welch <mdnanwelch7@hotmail.com>
    Subject: VOMs again. . .
    >I sure would be nice to have a > handy VOM that gets some low R values. > Any suggestions? > PaulW Paul=2C When this subject came up a couple of months ago=2C I had recommended the Etek digital VOM=2C model #10709=2C sold at Walmart. It has a good fee l in your hands=2C and several extra functions (built-in flashlight=2C temp prob e=2C etc.) that make it a GREAT model for the money. I had one I used in doing the electrics for my house I was building. Som eone ruined it by spilling coffee in it. I did like it=2C so I made it a point of going back to Walmart and getting another one! For $21 you simply can't go wrong! Mike Welch


    Message 12


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    Time: 09:23:12 AM PST US
    From: Marvin Haught <handainc@madisoncounty.net>
    Subject: Re: VOMs again. . .
    The WalMart stores in our area no longer sell that model - what they've got in stock is just junk. Since my wasn't working, I took it back to get it replaced, and they no longer stock it. I'm trying to find another one now since I've got all the leads and everything. M. Haught On 1/25/2011 10:57 AM, Mike Welch wrote: > >I sure would be nice to have a > > handy VOM that gets some low R values. > > Any suggestions? > > PaulW > > Paul, > > When this subject came up a couple of months ago, I had recommended > the Etek digital VOM, model #10709, sold at Walmart. It has a good > feel in > your hands, and several extra functions (built-in flashlight, temp > probe, etc.) > that make it a GREAT model for the money. > > I had one I used in doing the electrics for my house I was > building. Someone > ruined it by spilling coffee in it. I did like it, so I made it a > point of going > back to Walmart and getting another one! > > For $21 you simply can't go wrong! > > Mike Welch > * > > > *


    Message 13


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    Time: 09:43:04 AM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: Comm Antenna & SWR Reading
    To accurately measure VHF frequencies the meter has to have fast acting diodes. Usually meters designed for HF (under 30 mHz) are not fast enough gating to accurately read swr for higher frequencies. To be sure take your meter to someone who has a bird or similar meter and see if the calibration is close. A technician at a local phone company or amateur who works on repeaters may be a good place to start. Noel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of paul wilson Sent: January 24, 2011 3:25 PM Subject: RE: AeroElectric-List: Comm Antenna & SWR Reading I am not Bob , but I use a forward/reflected SWR meter. Its a low cost unit that did not have serious badmouthing from the Ham guys. MFJ-862 SWR/Wattmeter. It has a 30 and 300w max range setting PaulW ======== At 08:14 AM 1/24/2011, Noel Loveys wrote: <noelloveys@yahoo.ca> > >Bob what did you use to measure the forward and reverse power? A bird or >just a regular SWR meter? > >Noel


    Message 14


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    Time: 09:58:21 AM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: cable ties
    Although I have seen those tools I have never seen one used in aviation... Too bad... they work. Noel From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Janet Amtmann Sent: January 24, 2011 5:20 PM Subject: AeroElectric-List: cable ties To those of you having trouble with cable tie injuries, try a relatively inexpensive ($31) tensioning tool from Waytek. It has a cutter that cuts so close to the tie head that you can't feel the edges. Try tool #412, and use Thomas & Betts "Ty-Rap" brand ties. Never had a problem with injuries with this combination. The jewelers' diags that Bob mentioned work also on a lower budget. Do not archive J=FCrgen Amtmann


    Message 15


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    Time: 10:02:16 AM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: Comm Antenna & SWR Reading: Additional Info
    Another problem with making the feed line much too long is what to do with the access. If you coil it up you have just made another electrical tuning circuit. This can be really bad with unshielded zip wire like used in some stereo systems. Noel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Dj Merrill Sent: January 24, 2011 5:39 PM Subject: Re: AeroElectric-List: Comm Antenna & SWR Reading: Additional Info On 01/24/2011 03:24 PM, Bob Falstad wrote: > Is there a rule of thumb in how long to make antenna feed lines for optimum performance? Typically the longer the cable run, the higher the loss induced by the cable, so I strive to make the cable runs as short as practical while still leaving adequate length for maintenance, moving things, etc. An extra foot or two won't make much difference, but I wouldn't leave an extra ten feet, for example. > > When re-running the tests, would it make any difference to use a more powerful transmitter than my little hand-held? Or should I stick with what I used originally to eliminate one more variable that might affect the follow-on data? I typically test with a 5 watt handheld. I can see no reason to throw more power at it. However, it might be worth trying the test with a different handheld to remove the radio itself as a potential source of the problem. -Dj -- Dj Merrill - N1JOV Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/ Please use Netiquette Guidelines http://tools.ietf.org/html/rfc1855 Kindly TRIM your email replies and post AFTER the relevant text


    Message 16


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    Time: 10:50:53 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Comm Antenna & SWR Reading -- Too High?
    At 10:07 AM 1/25/2011, you wrote: ><nuckolls.bob@aeroelectric.com> > >At 06:18 AM 1/25/2011, you wrote: >><Tom@CostanzaAndAssociates.com> >> >>Bob, >> >>In a previous life, I was a seat-of-the-pants, self-taught >>technician. I was told that the length of the coax didn't affect >>the SWR. But intuition, and more importantly, your test clearly >>shows that it does. >> Extrapolating from this, it seems it would be possible to reduce >> the SWR to near zero by varying the length of the coax. Permit me a further expansion on this idea. See: http://www.antennex.com/preview/New/quarter.htm Here we are tutored on a a really cool feature of high SWR in a transmission line. The article talks about two cases were two low SWR systems, like a 100 ohm antenna and a 50 ohm coax would like to be joined. It is the nature of a 1/4 wavelength of transmission line to do a 'mirror image' of not-perfect SWR terminations at each end. In the case cited, putting a piece of 75 ohm transmission line in series with a 100 ohm load 'mirrors' that 100 ohms into a 50 ohm value at the other end. Viola! Hooking your 50 ohm coax to a 100 ohm load would give you 2:1 SWR. Putting a short section of hi SWR coax in the gap gives you a nice place to tie 50 ohm coax and have a good match to 100 ohms at the other end. This condition optimizes at one and one frequency only. SWR in the matching stub is never 1:1 and SWR on the feed-point end is 50 ohms resistive only at one frequency. This is a small insight into what appears to be experimental success in "lowering the SWR by fiddling with feed line lengths." In fact, adjusting the feed line length only alters the combination of R+X for the combined feed line and antenna such that the transmitter works a bit better (stronger radiated signal). In no way does it go to "lowering SWR" . . . in fact, just as SWR in the 1/4-wave matching section is never 1:1, diddling with feed line length depends on SWR within the feed line being anything BUT 1:1. If it WERE 1:1, length would have no difference. Something other than 1:1 allows you to slide out along the line to find to optimize the combination of R+X for your particular situation. Bob . . .


    Message 17


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    Time: 11:10:21 AM PST US
    Subject: vor antenna
    From: "dlicheri" <triangulumx@googlemail.com>
    chaps and fellow aviators, good day. just joined and here is a brief intro. name is dino, I am uk based and fly my bird (jabiru sk 2200A 2 seat) out of a farm strip in essex. fly as much as weather permits. pilot since 1999 ... here is my question. I recently aquired a Narco NAV 11 in perfect working condition (just had it tested). i have checked out vor antenna prices and they are extorsionate. i was wondering if it is possible to DIY a vor ariel and if there are any web based resources/plan for making one. much appreciated and many thanx Read this topic online here: http://forums.matronics.com/viewtopic.php?p=328454#328454


    Message 18


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    Time: 11:14:28 AM PST US
    From: paul wilson <pwmac@sisna.com>
    Subject: VOMs again. . .
    Mike what was it R scale? Max value? PW ======= At 08:57 AM 1/25/2011, Mike Welch wrote: > >I sure would be nice to have a > > handy VOM that gets some low R values. > > Any suggestions? > > PaulW > >Paul, > > When this subject came up a couple of months ago, I had recommended >the Etek digital VOM, model #10709, sold at Walmart. It has a good feel in >your hands, and several extra functions (built-in flashlight, temp >probe, etc.) >that make it a GREAT model for the money. > > I had one I used in doing the electrics for my house I was > building. Someone >ruined it by spilling coffee in it. I did like it, so I made it a >point of going >back to Walmart and getting another one! > > For $21 you simply can't go wrong! > >Mike Welch >


    Message 19


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    Time: 11:16:43 AM PST US
    From: "Stein Bruch" <stein@steinair.com>
    Subject: cable ties
    The reason we don=92t use them extensively in aviation is they are sometimes really difficult to actually use in the places/locations you=92d want to use them (up under panels, etc..). The =93automatic tools=94 frankly can be clunky to use in confined areas. We own several, but usually choose to use a little $8 flush cutter / diagonal flush cutter (the more expensive ones are slightly higher in quality). Much easier, faster, cheaper=85and much smaller. My vote is for the flush cutters=85and I feel your pain! Lots of scratched hands/arms over the years of doing this! Cheers, Stein From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Noel Loveys Sent: Tuesday, January 25, 2011 11:55 AM Subject: RE: AeroElectric-List: cable ties Although I have seen those tools I have never seen one used in aviation... Too bad... they work. Noel From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Janet Amtmann Sent: January 24, 2011 5:20 PM Subject: AeroElectric-List: cable ties To those of you having trouble with cable tie injuries, try a relatively inexpensive ($31) tensioning tool from Waytek. It has a cutter that cuts so close to the tie head that you can't feel the edges. Try tool #412, and use Thomas & Betts "Ty-Rap" brand ties. Never had a problem with injuries with this combination. The jewelers' diags that Bob mentioned work also on a lower budget. Do not archive J=FCrgen Amtmann http://www.matronics.com/Navigator?AeroElectric-List http://forums.matronics.com http://www.matronics.com/contribution


    Message 20


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    Time: 11:18:08 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: VOMs again. . .
    At 11:07 AM 1/25/2011, you wrote: > >Sure Lots of message for good meters. And the HF $4 unit is great >for checking voltages and continuity. >What about a low cost meter that can be used for low resistance >measurements? No need to go down to less than ~2 ohms. But a 20k >lower scale dosen't do much for my needs and I have to drag out my >ancient VTVM to see the resistance. I sure would be nice to have a >handy VOM that gets some low R values. >Any suggestions? Only my brother-in-law would get such a deal as I have for you. See: http://tinyurl.com/4l3tuj6 A few years back we were wrestling with some switch and relay issues on fielded airplanes that required accurate measurements below 1 ohm. As you've noted, most multimeters don't have the resolution to tell you much about low resistances. Further, the resistance of the test leads become a significant portion of the total resistance being measured. I crafted a series of devices cited in the article above. This paper was published to the HBC field service community. Setting up the adapter to generate a 0.1 amp constant current means that resistance across the 4-wire test connections has a voltage drop of of 100 mV/ohm. So a reading of 1 volt indicates a resistance value of 10 ohms. LM317 needs to have about 2 volts of head-room so the 3 cell instrument should not be depended on for measurements above 20 ohms. The 4-cell instrument can go up to 35 ohms. Depending on resolution of your VOM, you can accurately resolve very small resistance values. For example, the HF $4 VOM on the 200 mV scale displays 199.9 millivolts. The instrument display offers you 1 milliom resolution at 2.0 ohms full scale. Many small, low cost VOMs don't have 3/4" spaced banana jacks. You can buy banana plugs that mount on screws with a spacing of your choice Emacs! http://tinyurl.com/4d465gx Alternatively, you can build the larger adapter that stands alone and connects to your multimeter of choice with appropriate wiring. >Like to measure sensors on my truck that are supposed to be 3 ohm. >and the truck is 1000 miles from the VTVM because I only carry the >cheepy VOM and leave the VTVM home. - Sigh. >PaulW Build one of these critters up. You'll be glad you did. I made up several and gave them to guys in the shops. Bob . . .


    Message 21


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    Time: 11:25:40 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: cable ties
    At 12:54 PM 1/25/2011, you wrote: >Although I have seen those tools I have never seen one used in >aviation... Too bad... they work. Our guys on the line and in experimental flight used them all the time. They were too bulky for my very compact 'engineers toolbox' so I never owned one . . . the flush-cutter had to suffice. But it wasn't uncommon for one of the techs to hand me his tool if he observed my 'neanderthal' techniques. At least I wasn't chewing them off with my teeth! Bob . . .


    Message 22


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    Time: 11:42:25 AM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: "Emacs!" in Response
    Having read this thread from the beginning again I would do a continuity test for ground from the ground plane back to the grounded case of the radio. While you are at it do a continuity test for the centre conductor of the RG400. I've seen similar readings caused by a crack in the centre conductor of coax. As for the ground plane assuming your ground bond is good to your aluminium and the centre conductor is intact you may want to try bonding the aluminium to the aircraft ground system with a separate wire. I've seen instances where that had to be done on fibreglass boats. Noel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of bakerocb@cox.net Sent: January 25, 2011 9:14 AM Subject: AeroElectric-List: "Emacs!" in Response 1/25/2011 Hello Bob Falstad, You wrote (see copied below): "However, your response had three"Emacs!" in it that appear to refer to graphics that I can't view." I have the same problem with Bob Nuckolls' postings, but here is a solution for me: a) Go to the Matronics forum web site. http://forums.matronics.com/ b) Click on the aeroelectric list. http://forums.matronics.com/viewforum.php?f=3 c) Click on the original subject of the email(s) in question. (Comm Antenna & SWR Reading -- Too High?) http://forums.matronics.com/viewtopic.php?t=78934 d) Scroll down to the posted email in question and you should be able to see any attached graphics or photos. Please let me / us know how this works for you. 'OC' Baker Says: "The best investment we can make is the time and effort to gather and understand knowledge." PS to all: Bob, Bob, Who has got the Bob? Or which Bob? It is pretty important to me (and I am sure many others) to know which Bob author that they are reading or which Bob is being addressed. Would all posters please identify in each case by last name which Bob they are addressing and which Bob is writing by last name in each instance? Many thanks. ===================================================================== Time: 10:38:42 AM PST US From: Bob Falstad <bobair@me.com> Subject: AeroElectric-List: Re: "Emacs!" in Response: Was Comm Antenna & SWR Reading Bob, Many thanks for your quick and detailed response. However, your response had three "Emacs!" in it that appear to refer to graphics that I can't view. I searched the AeroElectric lists archives and the most detailed message re "Emacs!" was yours dated July 31, 2009. I couldn't find any other relevant messages on how to view your graphics/photos. I'm using a Macbook with OS 10.4.6 (Snow Leopard) that also has a full install of Windows XP in it. I opened your reply in three different browsers -- Safari, Firefox and Internet Explorer 8 but no joy. Any thoughts on how I can retrieve/view your "Emacs!" graphical inserts? Best regards, Bob Falstad


    Message 23


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    Time: 11:42:25 AM PST US
    From: Mike Welch <mdnanwelch7@hotmail.com>
    Subject: VOMs again. . .
    Hi Paul=2C 20M=2C 2M=2C 200K=2C 20K=2C 2K & 200. Marvin was right about them not be ing at Walmart=2C it appears. I did a Walmart online search=2C and they didn't come up. I checked on eBay. There are two different sellers. One guy wants $40 + s h. The other guy wants $32 total. Walmart sold them at $20-$21=2C but they we re quite a deal at that=2C IMO. Here's the cheaper guy's auction=3B http://cgi.ebay.com/ebaymotors/E-Tek-10709-Professional-Digital-Multimeter- _W0QQcmdZViewItemQQhashZitem41563d5b42QQitemZ280619735874QQptZMotorsQ5fCarQ 5fTruckQ5fPartsQ5fAccessories > Date: Tue=2C 25 Jan 2011 11:08:51 -0800 > To: aeroelectric-list@matronics.com > From: pwmac@sisna.com > Subject: RE: AeroElectric-List: VOMs again. . . > > > Mike what was it R scale? Max value? > PW


    Message 24


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    Time: 11:42:25 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Comm Antenna & SWR Reading
    At 12:38 PM 1/25/2011, you wrote: > >To accurately measure VHF frequencies the meter has to have fast acting >diodes. Usually meters designed for HF (under 30 mHz) are not fast enough >gating to accurately read swr for higher frequencies. To be sure take your >meter to someone who has a bird or similar meter and see if the calibration >is close. > >A technician at a local phone company or amateur who works on repeaters may >be a good place to start. Certainly the characteristics of detector diodes become more critical as the frequency goes up. Criticality is also increased as the magnitude of exciting signal goes down. We touched on this when questioning whether or not the .5 watt excitation was going to yield good measurements on a 5 watt full scale instrument. The rule of thumb for even the Bird instruments is to select a signal source and element that produces forward readings in the upper half of scale travel (greater than 2W on a 5W element). All of the DIY antenna analyzer projects routinely call out specialty detector diodes line the 1N5711 (point contact Schottky). It's equally critical to build the bridge from the right kind of resistors and very tight geometry. There's a lot of reference data out there for folks interested in DIY antenna measurements. Bob . . .


    Message 25


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    Time: 11:46:13 AM PST US
    From: Dan Morrow <danfm01@butter.toast.net>
    Subject: Re: "Emacs!" in Response
    On 01/25/2011 07:11 AM, John Morgensen wrote: > <john@morgensen.com> > > No problem here. I get the individual emails. Is the problem only on > the digest? > Enclosures are not posted to the digest lists. Here is an excerpt from the Matronics FAQ at www.matronics.com/ftp/Archives/RV-List.FAQ.html **Limited posting of enclosures such as pictures, documents, and spreadsheets is supported on the Lists. There are a number of restrictions, and these are detailed below. Please abide by the rules put forth regarding the content of enclosures. These are some of the features and limits of enclosures on the Matronics lists: 1) Enclosures will only be posted to the Real Time version of the Lists. 2) Enclosures will NOT be included in the Daily Digest version of the Lists. ** The full FAQ file is too big to quote here.


    Message 26


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    Time: 11:54:15 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: vor antenna
    At 02:07 PM 1/25/2011, you wrote: ><triangulumx@googlemail.com> > >chaps and fellow aviators, > >good day. just joined and here is a brief intro. name is dino, I am >uk based and fly my bird (jabiru sk 2200A 2 seat) out of a farm >strip in essex. fly as much as weather permits. pilot since 1999 ... > >here is my question. > >I recently aquired a Narco NAV 11 in perfect working condition (just >had it tested). i have checked out vor antenna prices and they are >extorsionate. i was wondering if it is possible to DIY a vor ariel >and if there are any web based resources/plan for making one. Sure. Make your own 'cat whiskers' from suitable steel rod. CB antennas can be salvaged for their corrosion resistant parts. Fabricate a BALUN as described http://www.aeroelectric.com/articles/BALUN/Balun_Fabrication.html Make an insulating configured to fit to your airplane . . . usually the top cap of a vertical fin. Fabricate fittings (silver soldered to your 26" 'whiskers') to mount the antenna elements to your fin cap with about 45 degree sweep-back. Emacs! Attach BALUN to interior ends and route coax to your VOR receiver. The anti-rotation scheme shown above is perhaps not sufficiently robust. I think I'd silver solder the whiskers into a 5/16 or 3/8" threaded stud. Bob . . .


    Message 27


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    Time: 11:56:37 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: "Emacs!" in Response
    >As for the ground plane assuming your ground bond is good to your aluminium >and the centre conductor is intact you may want to try bonding the aluminium >to the aircraft ground system with a separate wire. Wires use to connect RF ground systems to any other ground system are never useful for controlling antenna system performance. Bob . . .


    Message 28


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    Time: 11:58:25 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Comm Antenna & SWR Reading
    Oops! Re-posted with the proper subject line to keep it attached to the proper thread. >As for the ground plane assuming your ground bond is good to your aluminium >and the centre conductor is intact you may want to try bonding the aluminium >to the aircraft ground system with a separate wire. Wires use to connect RF ground systems to any other ground system are never useful for controlling antenna system performance. Bob . . .


    Message 29


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    Time: 12:27:09 PM PST US
    From: Harley <harley@AgelessWings.com>
    Subject: Re: cable ties
    That's the biggest reason I liked that little T&B unit (WT1-TB) I directed you to in an earlier message today...it is small, fits in the palm of your hand and can be used anyplace that you can get your closed hand and point your finger at. It worked great in all the tight places in the systems I designed at Pennwalt. And it cuts the tie off flush with the buckle. Harley ----------------------------------------------------------------- > III" <nuckolls.bob@aeroelectric.com> > > At 12:54 PM 1/25/2011, you wrote: >> Although I have seen those tools I have never seen one used in >> aviation... Too bad... they work. > > Our guys on the line and in experimental flight used > them all the time. They were too bulky for my very compact > 'engineers toolbox' so I never owned one . . . the > flush-cutter had to suffice. But it wasn't uncommon > for one of the techs to hand me his tool if he observed > my 'neanderthal' techniques. At least I wasn't chewing them > off with my teeth! > > > Bob . . . >


    Message 30


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    Time: 12:42:11 PM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: cable ties
    I don't like seeing... make that feeling the tie wraps but on occasion I do use them... whenever I do I use the small side cuts but I always make one or two passes over the cut end with a piece of reasonably fine grit sandpaper. So far I have yet to cut myself on a tie wrap that I have personally installed. Speaking of which I now have to do the wiring on my 912 installation. After that controls... Gee its cold outside. Supposed to go up to the green side of 0C Thursday. Noel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: January 25, 2011 2:52 PM Subject: RE: AeroElectric-List: cable ties <nuckolls.bob@aeroelectric.com> At 12:54 PM 1/25/2011, you wrote: >Although I have seen those tools I have never seen one used in >aviation... Too bad... they work. Our guys on the line and in experimental flight used them all the time. They were too bulky for my very compact 'engineers toolbox' so I never owned one . . . the flush-cutter had to suffice. But it wasn't uncommon for one of the techs to hand me his tool if he observed my 'neanderthal' techniques. At least I wasn't chewing them off with my teeth! Bob . . .


    Message 31


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    Time: 12:44:29 PM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: Comm Antenna & SWR Reading
    Thanks for filling in the gaps Bob. What I was getting at was trying to remove any errors that may have been caused by the meters. Noel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: January 25, 2011 3:09 PM Subject: RE: AeroElectric-List: Comm Antenna & SWR Reading <nuckolls.bob@aeroelectric.com> At 12:38 PM 1/25/2011, you wrote: <noelloveys@yahoo.ca> > >To accurately measure VHF frequencies the meter has to have fast acting >diodes. Usually meters designed for HF (under 30 mHz) are not fast enough >gating to accurately read swr for higher frequencies. To be sure take your >meter to someone who has a bird or similar meter and see if the calibration >is close. > >A technician at a local phone company or amateur who works on repeaters may >be a good place to start. Certainly the characteristics of detector diodes become more critical as the frequency goes up. Criticality is also increased as the magnitude of exciting signal goes down. We touched on this when questioning whether or not the .5 watt excitation was going to yield good measurements on a 5 watt full scale instrument. The rule of thumb for even the Bird instruments is to select a signal source and element that produces forward readings in the upper half of scale travel (greater than 2W on a 5W element). All of the DIY antenna analyzer projects routinely call out specialty detector diodes line the 1N5711 (point contact Schottky). It's equally critical to build the bridge from the right kind of resistors and very tight geometry. There's a lot of reference data out there for folks interested in DIY antenna measurements. Bob . . .


    Message 32


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    Time: 12:48:50 PM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: "Emacs!" in Response
    The bond I was referring to would be to the same system. Doing that could nullify the effects of a bad connection to the braid at the antenna end. Noel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: January 25, 2011 3:23 PM Subject: RE: AeroElectric-List: "Emacs!" in Response <nuckolls.bob@aeroelectric.com> >As for the ground plane assuming your ground bond is good to your aluminium >and the centre conductor is intact you may want to try bonding the aluminium >to the aircraft ground system with a separate wire. Wires use to connect RF ground systems to any other ground system are never useful for controlling antenna system performance. Bob . . .


    Message 33


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    Time: 12:58:15 PM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: vor antenna
    I was once asked if it made any difference to the VOR whether the cats whiskers were sloping forward or rearward. What's your take? Mine was simply to follow the directions.. but in homebuilt planes you may have to write your own directions. Noel From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: January 25, 2011 3:20 PM Subject: Re: AeroElectric-List: vor antenna At 02:07 PM 1/25/2011, you wrote: <triangulumx@googlemail.com> chaps and fellow aviators, good day. just joined and here is a brief intro. name is dino, I am uk based and fly my bird (jabiru sk 2200A 2 seat) out of a farm strip in essex. fly as much as weather permits. pilot since 1999 ... here is my question. I recently aquired a Narco NAV 11 in perfect working condition (just had it tested). i have checked out vor antenna prices and they are extorsionate. i was wondering if it is possible to DIY a vor ariel and if there are any web based resources/plan for making one. Sure. Make your own 'cat whiskers' from suitable steel rod. CB antennas can be salvaged for their corrosion resistant parts. Fabricate a BALUN as described http://www.aeroelectric.com/articles/BALUN/Balun_Fabrication.html Make an insulating configured to fit to your airplane . . . usually the top cap of a vertical fin. Fabricate fittings (silver soldered to your 26" 'whiskers') to mount the antenna elements to your fin cap with about 45 degree sweep-back. Emacs! Attach BALUN to interior ends and route coax to your VOR receiver. The anti-rotation scheme shown above is perhaps not sufficiently robust. I think I'd silver solder the whiskers into a 5/16 or 3/8" threaded stud. Bob . . .


    Message 34


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    Time: 01:05:29 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Comm Antenna & SWR Reading
    As for the ground plane assuming your ground bond is good to your aluminium and the centre conductor is intact you may want to try bonding the aluminium to the aircraft ground system with a separate wire. Wires use to connect RF ground systems to any other ground system are never useful for controlling antenna system performance. ------------ The bond I was referring to would be to the same system. Doing that could nullify the effects of a bad connection to the braid at the antenna end. You lost me. This is a composite aircraft with an aluminum sheet on the inside surface for a ground plane and approx 7/16" worth of composite structure between the ground plane and the base of the antenna. I presume there's a centrally located clearance hole in the composite material for the coax connector. He described 4 threaded fasteners holding this 'sandwich' together. To be sure, a low resistance (micro-ohms), high integrity (gas tight) connections between the base and the ground plane are called for. Having "soft" material in the makeup of this sandwich is counter productive to achieving that goal. Hence the suggestion for metallic spacers through the structure to take the mate-up tension loads in the screws and provide low-inductance jumpers (4 in parallel) between the antenna base and the ground plane. "Ground system" is generally interpreted to mean the DC power ground. On this aircraft, it may well be a firewall single point ground with lots of wires returning to it. In this instance, no potential benefits to be gained by adding conductors between power ground and anything associated with this antenna installation. Bob . . .


    Message 35


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    Time: 01:12:13 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: vor antenna
    At 03:52 PM 1/25/2011, you wrote: >I was once asked if it made any difference to the VOR whether the >cats whiskers were sloping forward or rearward. What's your >take? Mine was simply to follow the directions.. but in homebuilt >planes you may have to write your own directions. > >Noel Good question. I've seen them both ways. Putting any kind of rake angle on them will have effects on radiation pattern, feed point impedance and aerodynamics. I suppose somebody had a reason for selecting one over the other but I doubt that it had to do with optimization in more than one of the three areas of investigation. From the performance perspective, it's almost sure to make no perceivable difference. Sometimes things are done just because that's the way we've been doing it for a long time . . . and nobody remembers why. Most folks would probably think they look sexier with a rearward rake . . . and indeed, that may have been the reason. Bob . . .


    Message 36


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    Time: 01:42:35 PM PST US
    Subject: Re: cable ties
    From: Robert Borger <rlborger@mac.com>
    Gents, My 2... Personally, I like Cobra Cable Ties ( http://cobracabletie.com/ ). They are low profile and the trimmed end is protected when trimmed properly. Ya, they cost a bit more than the cheepo stuff, but I think they are worth it. Bob Borger Europa Kit #A221 N914XL, XS Tri-Gear, Intercooled 914, Airmaster C/S Prop On Jan 25, 2011, at 14:38, Noel Loveys wrote: > > I don't like seeing... make that feeling the tie wraps but on occasion I do > use them... whenever I do I use the small side cuts but I always make one > or two passes over the cut end with a piece of reasonably fine grit > sandpaper. So far I have yet to cut myself on a tie wrap that I have > personally installed. > > Speaking of which I now have to do the wiring on my 912 installation. After > that controls... Gee its cold outside. Supposed to go up to the green side > of 0C Thursday. > > Noel


    Message 37


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    Time: 01:50:00 PM PST US
    Subject: Re: vor antenna
    From: Jared Yates <email@jaredyates.com>
    On an airplane with conventional landing gear, you might want to consider walkaround safety in your forward/aft decision. I had a friend with an old Piper and he just about poked his eye out one time on a set that was bent forward. On Tue, Jan 25, 2011 at 3:07 PM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > nuckolls.bob@aeroelectric.com> > > At 03:52 PM 1/25/2011, you wrote: > >> I was once asked if it made any difference to the VOR whether the cats >> whiskers were sloping forward or rearward. What's your take? Mine was >> simply to follow the directions.. but in homebuilt planes you may have to >> write your own directions. >> >> Noel >> > > Good question. I've seen them both ways. Putting any > kind of rake angle on them will have effects on radiation > pattern, feed point impedance and aerodynamics. I suppose > somebody had a reason for selecting one over the other > but I doubt that it had to do with optimization in more > than one of the three areas of investigation. From the > performance perspective, it's almost sure to make no > perceivable difference. > > Sometimes things are done just because that's the way > we've been doing it for a long time . . . and nobody > remembers why. Most folks would probably think they look > sexier with a rearward rake . . . and indeed, that may > have been the reason. > > > Bob . . . > >


    Message 38


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    Time: 02:50:40 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: VOMs again. . .
    At 11:07 AM 1/25/2011, you wrote: > >Sure Lots of message for good meters. And the HF $4 unit is great >for checking voltages and continuity. >What about a low cost meter that can be used for low resistance >measurements? No need to go down to less than ~2 ohms. But a 20k >lower scale dosen't do much for my needs and I have to drag out my >ancient VTVM to see the resistance. I sure would be nice to have a >handy VOM that gets some low R values. >Any suggestions? Only my brother-in-law would get such a deal as I have for you. See: http://tinyurl.com/4l3tuj6 A few years back we were wrestling with some switch and relay issues on fielded airplanes that required accurate measurements below 1 ohm. As you've noted, most multimeters don't have the resolution to tell you much about low resistances. Further, the resistance of the test leads become a significant portion of the total resistance being measured. I crafted a series of devices cited in the article above. This paper was published to the HBC field service community. Setting up the adapter to generate a 0.1 amp constant current means that resistance across the 4-wire test connections has a voltage drop of of 100 mV/ohm. So a reading of 1 volt indicates a resistance value of 10 ohms. LM317 needs to have about 2 volts of head-room so the 3 cell instrument should not be depended on for measurements above 20 ohms. The 4-cell instrument can go up to 35 ohms. Depending on resolution of your VOM, you can accurately resolve very small resistance values. For example, the HF $4 VOM on the 200 mV scale displays 199.9 millivolts. The instrument display offers you 1 milliom resolution at 2.0 ohms full scale. Many small, low cost VOMs don't have 3/4" spaced banana jacks. You can buy banana plugs that mount on screws with a spacing of your choice Emacs! http://tinyurl.com/4d465gx Alternatively, you can build the larger adapter that stands alone and connects to your multimeter of choice with appropriate wiring. >Like to measure sensors on my truck that are supposed to be 3 ohm. >and the truck is 1000 miles from the VTVM because I only carry the >cheepy VOM and leave the VTVM home. - Sigh. >PaulW Build one of these critters up. You'll be glad you did. I made up several and gave them to guys in the shops. Bob . . .


    Message 39


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    Time: 03:17:33 PM PST US
    From: paul wilson <pwmac@sisna.com>
    Subject: Re: VOMs again. . .
    Bob, I remember this article well, which is why I asked if something is out there to buy. I seriously doubt a succesful build of your device considering my abilities. Maybe you would consider a new product to sell us or even a kit? Thanks, PaulW ======== At 10:14 AM 1/25/2011, you wrote: >At 11:07 AM 1/25/2011, you wrote: >> >>Sure Lots of message for good meters. And the HF $4 unit is great >>for checking voltages and continuity. >>What about a low cost meter that can be used for low resistance >>measurements? No need to go down to less than ~2 ohms. But a 20k >>lower scale dosen't do much for my needs and I have to drag out my >>ancient VTVM to see the resistance. I sure would be nice to have a >>handy VOM that gets some low R values. >>Any suggestions? > > Only my brother-in-law would get such a deal as I > have for you. See: > >http://tinyurl.com/4l3tuj6 > > A few years back we were wrestling with some switch > and relay issues on fielded airplanes that required > accurate measurements below 1 ohm. As you've noted, > most multimeters don't have the resolution to tell > you much about low resistances. Further, the resistance > of the test leads become a significant portion of > the total resistance being measured. > > I crafted a series of devices cited in the article > above. This paper was published to the HBC field > service community. > > Setting up the adapter to generate a 0.1 amp > constant current means that resistance across > the 4-wire test connections has a voltage drop of > of 100 mV/ohm. So a reading of 1 volt indicates > a resistance value of 10 ohms. LM317 needs to > have about 2 volts of head-room so the 3 cell > instrument should not be depended on for > measurements above 20 ohms. The 4-cell > instrument can go up to 35 ohms. Depending > on resolution of your VOM, you can accurately > resolve very small resistance values. For > example, the HF $4 VOM on the 200 mV scale > displays 199.9 millivolts. The instrument > display offers you 1 milliom resolution at > 2.0 ohms full scale. > > Many small, low cost VOMs don't have 3/4" > spaced banana jacks. You can buy banana > plugs that mount on screws with a spacing > of your choice > >Emacs! > > >http://tinyurl.com/4d465gx > > Alternatively, you can build the larger > adapter that stands alone and connects > to your multimeter of choice with appropriate > wiring. > > >>Like to measure sensors on my truck that are supposed to be 3 ohm. >>and the truck is 1000 miles from the VTVM because I only carry the >>cheepy VOM and leave the VTVM home. - Sigh. >>PaulW > > Build one of these critters up. You'll > be glad you did. I made up several and > gave them to guys in the shops. > > > Bob . . .


    Message 40


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    Time: 05:22:47 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Low resistance measurement adapter.
    At 05:37 PM 1/25/2011, you wrote: >Bob, I remember this article well, which is why I asked if something >is out there to buy. I seriously doubt a succesful build of your >device considering my abilities. Nobody in your local acquaintance that could help you? >Maybe you would consider a new product to sell us or even a kit? Hmmm . . . possibly a product. "Kits" tend to be more expensive to gin-up and sell than completed products. I think something like this would sell for $35 to $40. It would be interesting to know if other folks on the List have an interest in having this class of measurement capability. Maybe I could do a one-of-a-kind. It would take about 30 minutes to built one. Bob . . .


    Message 41


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    Time: 05:39:44 PM PST US
    Subject: Re: Low resistance measurement adapter.
    From: Robert Borger <rlborger@mac.com>
    Bob, I'd be interested. Bob Borger 3705 Lynchburg Dr. Corinth, TX 76208 Home: 940-497-2123 Cel: 817-992-1117 On Jan 25, 2011, at 18:18, Robert L. Nuckolls, III wrote: > > At 05:37 PM 1/25/2011, you wrote: >> Bob, I remember this article well, which is why I asked if something is out there to buy. I seriously doubt a succesful build of your device considering my abilities. > > Nobody in your local acquaintance that could > help you? > >> Maybe you would consider a new product to sell us or even a kit? > > Hmmm . . . possibly a product. "Kits" tend to be more expensive > to gin-up and sell than completed products. I think something > like this would sell for $35 to $40. It would be interesting > to know if other folks on the List have an interest in having this > class of measurement capability. > > Maybe I could do a one-of-a-kind. It would take about > 30 minutes to built one. > > > Bob . . .


    Message 42


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    Time: 07:55:49 PM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: Comm Antenna & SWR Reading
    Bob: I think we are talking about slightly different things here. I suspect there is no direct connection between the braid of the coax (ground) and the ground plane. Most of these antennas are designed to be mounted on aluminium skins. I am thinking that the ground plane is totally afloat and not connected in any way to the braid. Of course this is easy to check by simply ringing between the ground plane and the exterior of the BNC. Noel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: January 25, 2011 4:31 PM Subject: RE: AeroElectric-List: Comm Antenna & SWR Reading <nuckolls.bob@aeroelectric.com> As for the ground plane assuming your ground bond is good to your aluminium and the centre conductor is intact you may want to try bonding the aluminium to the aircraft ground system with a separate wire. Wires use to connect RF ground systems to any other ground system are never useful for controlling antenna system performance. ------------ The bond I was referring to would be to the same system. Doing that could nullify the effects of a bad connection to the braid at the antenna end. You lost me. This is a composite aircraft with an aluminum sheet on the inside surface for a ground plane and approx 7/16" worth of composite structure between the ground plane and the base of the antenna. I presume there's a centrally located clearance hole in the composite material for the coax connector. He described 4 threaded fasteners holding this 'sandwich' together. To be sure, a low resistance (micro-ohms), high integrity (gas tight) connections between the base and the ground plane are called for. Having "soft" material in the makeup of this sandwich is counter productive to achieving that goal. Hence the suggestion for metallic spacers through the structure to take the mate-up tension loads in the screws and provide low-inductance jumpers (4 in parallel) between the antenna base and the ground plane. "Ground system" is generally interpreted to mean the DC power ground. On this aircraft, it may well be a firewall single point ground with lots of wires returning to it. In this instance, no potential benefits to be gained by adding conductors between power ground and anything associated with this antenna installation. Bob . . .


    Message 43


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    Time: 08:14:38 PM PST US
    From: "Noel Loveys" <noelloveys@yahoo.ca>
    Subject: vor antenna
    Several early Pipers and Cessnas had the VOR antennas pointed forward. That is the way the Maintenance Manual required they be installed. I suppose to legally turn them around would require an STC. Noel From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Jared Yates Sent: January 25, 2011 6:16 PM Subject: Re: AeroElectric-List: vor antenna On an airplane with conventional landing gear, you might want to consider walkaround safety in your forward/aft decision. I had a friend with an old Piper and he just about poked his eye out one time on a set that was bent forward. On Tue, Jan 25, 2011 at 3:07 PM, Robert L. Nuckolls, III <nuckolls.bob@aeroelectric.com> wrote: <nuckolls.bob@aeroelectric.com> At 03:52 PM 1/25/2011, you wrote: I was once asked if it made any difference to the VOR whether the cats whiskers were sloping forward or rearward. What's your take? Mine was simply to follow the directions.. but in homebuilt planes you may have to write your own directions. Noel Good question. I've seen them both ways. Putting any kind of rake angle on them will have effects on radiation pattern, feed point impedance and aerodynamics. I suppose somebody had a reason for selecting one over the other but I doubt that it had to do with optimization in more than one of the three areas of investigation. From the performance perspective, it's almost sure to make no perceivable difference. Sometimes things are done just because that's the way we've been doing it for a long time . . . and nobody remembers why. Most folks would probably think they look sexier with a rearward rake . . . and indeed, that may have been the reason. Bob . . . , www.matronics.com/Navigator?AeroElectric-List" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List ronics.com/" target="_blank">http://forums.matronics.com Matt Dralle, List Admin. ====




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