---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 03/29/12: 16 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:53 AM - Re SWR Meter? (paul wilson) 2. 07:10 AM - Re: Re SWR Meter? (Harley) 3. 08:18 AM - Re: Re SWR Meter? (Robert L. Nuckolls, III) 4. 08:18 AM - Re: Re SWR Meter? (Robert L. Nuckolls, III) 5. 08:48 AM - Re: Should I Buy an SWR Meter? (Robert L. Nuckolls, III) 6. 09:09 AM - Re: Re SWR Meter? (paul wilson) 7. 09:13 AM - Re: Re: HID lighting observations (Robert L. Nuckolls, III) 8. 10:13 AM - Re: Re SWR Meter? (Miskelly, Francis G) 9. 11:31 AM - Re: Re SWR Meter? (Robert L. Nuckolls, III) 10. 11:57 AM - Re: Re: Wingtip VOR antenna . . . a clearer picture (Mark Harris) 11. 01:13 PM - Re: Re: Wingtip VOR antenna . . . a clearer picture (Robert L. Nuckolls, III) 12. 01:41 PM - Re: Re SWR Meter? (Miskelly, Francis G) 13. 03:32 PM - Uneven dipole elements (Dave Saylor) 14. 07:48 PM - Re: Uneven dipole elements (Robert L. Nuckolls, III) 15. 09:34 PM - Re: Re: HID lighting observations (Thomas Johnson) 16. 10:41 PM - Re: Uneven dipole elements (Dave Saylor) ________________________________ Message 1 _____________________________________ Time: 06:53:06 AM PST US From: paul wilson Subject: AeroElectric-List: Re SWR Meter? Some input I use my meter to check from time to time to verify all is well. This link has info on the meters http://www.eham.net/reviews/products/40?ehamsid=a9efc7e8e58a376ce24c0118effd4579 The one I use is an MFJ-862 It has 2 needles for Forward and Reflected and will read watts for both. This is a low price unit, definately not a high, but had OK reviews. I have no idea if one can still buy it? PaulW ________________________________ Message 2 _____________________________________ Time: 07:10:13 AM PST US From: Harley Subject: Re: AeroElectric-List: Re SWR Meter? Paul... Yep, still available...(a little more than you probably paid for it): www.mfjenterprises.com/Product.php?productid=MFJ-862 Harley > I use my meter to check from time to time to verify all is well. > This link has info on the meters > http://www.eham.net/reviews/products/40?ehamsid=a9efc7e8e58a376ce24c0118effd4579 > > > The one I use is an MFJ-862 It has 2 needles for Forward and > Reflected and will read watts for both. This is a low price > unit, definately not a high, but had OK reviews. I have no idea > if one can still buy it? > PaulW ________________________________ Message 3 _____________________________________ Time: 08:18:04 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re SWR Meter? OOPS! Stubbed my toe on that one. The price I latched onto was for the DC power supply, the instrument itself sells for about $70. ----------------------------------------------------- At 08:07 AM 3/29/2012, you wrote: Some input I use my meter to check from time to time to verify all is well. This link has info on the meters http://www.eham.net/reviews/products/40?ehamsid=a9efc7e8e58a376ce24c0118effd4579 The one I use is an MFJ-862 It has 2 needles for Forward and Reflected and will read watts for both. This is a low price unit, definately not a high, but had OK reviews. I have no idea if one can still buy it? PaulW I found one offered here: http://tinyurl.com/6m8zrru Given it's rather complex set of features (rear panel calibration pots) and low price ($16) I'm wondering if they don't have an inventory that they'd REALLY like to get rid of. MFJ is usually pretty good stuff and this item does claim to cover VHF but I'm not convinced that this is a good buy. I'm tempted to order one at this price just to take it apart for a looksee . . . If you'd like to compare your personal item with a set of BIRD measurements, I'd be pleased to do the work. I'll pay return postage. Bob . . . ________________________________ Message 4 _____________________________________ Time: 08:18:04 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re SWR Meter? At 08:07 AM 3/29/2012, you wrote: >Some input > >I use my meter to check from time to time to verify all is well. >This link has info on the meters >http://www.eham.net/reviews/products/40?ehamsid=a9efc7e8e58a376ce24c0118effd4579 > > >The one I use is an MFJ-862 It has 2 needles for Forward and >Reflected and will read watts for both. This is a low price unit, >definately not a high, but had OK reviews. I have no idea if one can >still buy it? >PaulW I found one offered here: http://tinyurl.com/6m8zrru Given it's rather complex set of features (rear panel calibration pots) and low price ($16) I'm wondering if they don't have an inventory that they'd REALLY like to get rid of. MFJ is usually pretty good stuff and this item does claim to cover VHF but I'm not convinced that this is a good buy. I'm tempted to order one at this price just to take it apart for a looksee . . . If you'd like to compare your personal item with a set of BIRD measurements, I'd be pleased to do the work. I'll pay return postage. Bob . . . ________________________________ Message 5 _____________________________________ Time: 08:48:05 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Should I Buy an SWR Meter? At 10:52 PM 3/28/2012, you wrote: Bob, I=92m building an RV7A and I=92m into electronics. Should I buy an SWR meter? I know it can help me optimize the antenna systems for my com transmitters and I enjoy geeking-out on things like this. Just how MUCH do you enjoy it? I have two shops and a large inventory of tools and materials . . . MOST of which has not been touched in months to perhaps decades. NEED? Obviously small. Potential for addressing a design goal? Obviously great . . . but every project usually requires some purchases . . . of materials and the occasional tool. Any borrow/buy advice offered by any of us will be polluted with personal perceptions of need/usefulness. I'd suggest that it comes down to expendable cash. Suppose you DID run off and spend $100 on a nice VHF SWR instrument. Suppose further that 10 years from now you find that you've used the device perhaps a few times at the outset but not once in the last 8 years? How would you judge your return on investment then? Can an SWR meter help w/ the setup of VOR receivers as well. Can it help me w/ the installation of the Bob Archer antenna for VOR? (I thought that SWR was used primarily for measurements w/ transmitters). It is true that ALL such instruments need to excite the antenna or feed line at the frequency of interest. But that excitation can come from a variety of sources depending on the sensitivity of the instrument. SWR meters like the Red Dot device we've discussed recently need a watt or so. Antenna analyzers like the MJF-259 (and close cousins) have internal signal generators to supply the necessary excitation. In the case of your VOR antenna, I'd suggest using a hand held and some device like the Red Dot SWR meter. You can tune for optimum performance at the lowest COMM frequency which is at the upper end of the VOR band. This would be great verification of gross performance and more than adequate for VOR reception. Is there a =93Big Dummies Guide to Antenna Theory=94 book available? I=92d like to squelch some of my ignorance in this area. Hmmmm . . . the short answer is YES. But the constellation of antenna styles and design goals is . . . shall we say . . . HUGE? I have antenna books on the shelves wherein 98% of the pages offered nothing useful to my professional activities . . . but the 2% of useful stuff was very helpful. I'm reluctant to suggest specific titles. Do some 'net searches on VHF antennas and SWR. Look over the construction articles, techniques for adjusting, etc. You will probably learn more that is useful to your aviation interests by playing with antennas in the shop that are also destined to go on your airplane. Remember this picture? I don't even recall what we were discussing on the List but I did this little 1/4-Comm antenna setup on a sheet of copper clad right here in the shop. But I'm confident that we learned or demonstrated something interesting or useful. Emacs! Then there is the constellation of grey-matter here on the list that is accessible to you. I've been gathering the stuff together to do a back-yard-antenna-range evaluation of performance for BALUN versus NOBALUN. During this exercise I'll explore the notion that a Pawsy stub does behave like transmission line with some small dielectric effects for velocity factor and should be mechanically shortened to center it up at the frequency of interest. I'll document that experiment and post it to AeroElectric.com (so many questions, so little time=85) You got that right. Education is expensive. It goes far beyond the cost of tuition, tools and materials. The big expense is $time$. Hence the notion that participation in activities like the AeroElectric-List can and should offer significant reduction in the expenditure of $time$. This applies to both academic science and practical arts of our shared interests. Buy an SWR meter? You bet! But with the caveats I've cited above tucked into your hip pocket. Bob . . . ________________________________ Message 6 _____________________________________ Time: 09:09:52 AM PST US From: paul wilson Subject: Re: AeroElectric-List: Re SWR Meter? MFJ-862 Reviews http://www.eham.net/reviews/detail/4367 Cannot remember what I paid back when. Withouit a long search looks like $65-70 is the going price I bought it to cover my mobiles 144/220/440 MGHz and of course that includes the aviation band. Ok for the 5 watt as well as my 50 watt units. PaulW ========= At 08:12 AM 3/29/2012, you wrote: >At 08:07 AM 3/29/2012, you wrote: >>Some input >> >>I use my meter to check from time to time to verify all is well. >>This link has info on the meters >>http://www.eham.net/reviews/products/40?ehamsid=a9efc7e8e58a376ce24c0118effd4579 >> >> >>The one I use is an MFJ-862 It has 2 needles for Forward and >>Reflected and will read watts for both. This is a low price unit, >>definately not a high, but had OK reviews. I have no idea if one >>can still buy it? >>PaulW > > I found one offered here: > >http://tinyurl.com/6m8zrru > > Given it's rather complex set of features > (rear panel calibration pots) and low > price ($16) I'm wondering if they don't > have an inventory that they'd REALLY like > to get rid of. > > MFJ is usually pretty good stuff and this > item does claim to cover VHF but I'm not > convinced that this is a good buy. I'm > tempted to order one at this price just to > take it apart for a looksee . . . > > If you'd like to compare your personal item > with a set of BIRD measurements, I'd be pleased > to do the work. I'll pay return postage. > > Bob . . . > > >http://www.matronics.com/Navigator?AeroElectric-List >http://www.matronics.com/contribution > ________________________________ Message 7 _____________________________________ Time: 09:13:21 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: re: HID lighting observations >When I upgraded from halogen to HID lights >several years ago I had a problem with this. My >own design PIC based wig-wag controller no longer worked at all. Did the PIC wander off into the weeds and lock up? > I found that the HID lights had a huge inrush > current each time they switched on. I tried a > few fixes and got the best results by running > the HID power and ground wires together through > a 1/2 dia X 1 long ferrite core. Using two in series worked even better. Ferrites are sometimes useful for repetitive events like noise but less useful for transient events like inrush currents. I'll try to get some transient/running captures on the two HID units I have here. I could probably get some data on the ones in the car too if I can find my current probes for the 'scope. I'm still un-packing move boxes. > >The first time I tested the ferrites I used a >split half type because it is easier to pop on >and off in different locations. While I was >watching the scope I noticed a new, fairly loud >clicking sound coming from the HID controller >area. It turned out to be the split ferrite >half's snapping together each time power came >on. That is some serious energy transfer! I'm reminded of some strange noises I used to hear periodically up in the ceiling structure of a new building put up by my employer. Out in the shops I used to hear a noise that seemed to come from the conduits. I later came to understand that this was the convulsive thrashing of the ac wiring that went out to large motors at the back of the building. Every time a big motor started up, induced repulsion of the adjacent wires in the conduit made noises. Good data Tom. Bob . . . ________________________________ Message 8 _____________________________________ Time: 10:13:04 AM PST US From: "Miskelly, Francis G" Subject: RE: AeroElectric-List: Re SWR Meter? Does the MFG-862 cover the aviation band (108-116 MHz) - Frank ________________________________________ From: owner-aeroelectric-list-server@matronics.com [owner-aeroelectric-list-server@matronics.com] on behalf of paul wilson [pwmac@sisna.com] Sent: 29 March 2012 17:05 Subject: Re: AeroElectric-List: Re SWR Meter? MFJ-862 Reviews http://www.eham.net/reviews/detail/4367 Cannot remember what I paid back when. Withouit a long search looks like $65-70 is the going price I bought it to cover my mobiles 144/220/440 MGHz and of course that includes the aviation band. Ok for the 5 watt as well as my 50 watt units. PaulW ========= At 08:12 AM 3/29/2012, you wrote: At 08:07 AM 3/29/2012, you wrote: Some input I use my meter to check from time to time to verify all is well. This link has info on the meters http://www.eham.net/reviews/products/40?ehamsid=a9efc7e8e58a376ce24c0118effd4579 The one I use is an MFJ-862 It has 2 needles for Forward and Reflected and will read watts for both. This is a low price unit, definately not a high, but had OK reviews. I have no idea if one can still buy it? PaulW I found one offered here: http://tinyurl.com/6m8zrru Given it's rather complex set of features (rear panel calibration pots) and low price ($16) I'm wondering if they don't have an inventory that they'd REALLY like to get rid of. MFJ is usually pretty good stuff and this item does claim to cover VHF but I'm not convinced that this is a good buy. I'm tempted to order one at this price just to take it apart for a looksee . . . If you'd like to compare your personal item with a set of BIRD measurements, I'd be pleased to do the work. I'll pay return postage. Bob . . . AeroElectric-List Email Forum - http://www.matronics.com/Navigator?AeroElectric-List - MATRONICS WEB FORUMS - http://forums.matronics.com - List Contribution Web Site - -Matt Dralle, List Admin. http://www.matronics.com/contribution ________________________________ Message 9 _____________________________________ Time: 11:31:19 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Re SWR Meter? At 12:10 PM 3/29/2012, you wrote: > > > >Does the MFG-862 cover the aviation band (108-116 MHz) > - Frank Probably not guaranteed to published specifications but still useful. There was some discussion a few weeks back about suitability of the LO Band (3-30 Mhz) devices being used at VHF. Typically devices like this: Emacs! These do perform as advertised in the 3-30 Mhz range but tend to run off into the weeds at 4x the top design frequency. On the other hand, the MFJ862 used at 108-135 (full range aviation) is still at 75% of lower end of 144 ham band. Maybe not quite as accurate with respect to absolute readings but still a good indicator of performance and useful for finding frequency of lowest SWR. For about the same $ you can pick up one of these http://tinyurl.com/6pjbckd which is designed for our particular frequencies of interest. On the other hand, there are some DIY options too. Take a look at this article: http://tinyurl.com/7dmupav This DIY project is tailored to the 2.5 GHz range for WiFi work but the same technique can be easily adapted to lower frequencies. Here's another one. http://tinyurl.com/83e5u2q All it takes is $time$ and patience . . . but it can be fun . . . Bob . . . ________________________________ Message 10 ____________________________________ Time: 11:57:53 AM PST US Subject: Re: AeroElectric-List: Re: Wingtip VOR antenna . . . a clearer picture From: Mark Harris Bob Ok now I have a problem ,at the weekend I made the VOR antenna to the dimensions previously discussed/aero electrics book I believe,these are very different to the ones shown on the previous link ,which should I use? Thanks Mark Rent our beautiful 3 bedroom luxury villa in Orlando, Florida. View our virtual tour but book direct with us. See the link below:- http://www.florida1strentals.com/property.php?id=21 Contact Emma and Mark Harris 01582 529820 harrisfloridavilla@hotmail.com On 28 Mar 2012, at 21:47, "Robert L. Nuckolls, III" wrote: > > Thanks to List member van Saten, we've got some > better details for a DIY wingtip VOR antenna. See: > > http://tinyurl.com/6v5gvhx > > It seems that the sketch I was working from years ago > was either not up to date or in error. > > The insulator turns out to be either glass or cloth > filled phenolic, 0.062 inches thick. The measured > value of an off-the-shelf gamma-match capacitor is > 34 pf @ 1 KHz. > > I think the data above will get the builder closer to > a workable example of this particular antenna. > > Thanks Don! Your antenna will be back in the mail today. > > > Bob . . . > > > > > ________________________________ Message 11 ____________________________________ Time: 01:13:58 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Wingtip VOR antenna . . . a clearer picture At 01:56 PM 3/29/2012, you wrote: > >Bob > >Ok now I have a problem ,at the weekend I made the VOR antenna to >the dimensions previously discussed/aero electrics book I >believe,these are very different to the ones shown on the previous >link ,which should I use? The dimensions I published originally were parroted from an article in an Van's Air Force publication . . . probably 10-12 years ago. It was not until I put my hands on a 'real' antenna (thanks to Don S) did I have an opportunity to check/update the VAF drawings. Are you flying or close to flying the earlier 'version'? It would be interesting to do a seat-of-the-pants observation on differences in performance. You could build up a 'new' antenna but keep it in reserve until you've flown the 'old' one. I'm thinking that it would be difficult to tell much difference from the pilot's seat but you might perhaps dispel that notion for me. The question that started this thread involved procurement of 1/32" Bakelite . . . while in fact, 1/16" Phenolic is the 'real' material. It was something of a windfall that other discrepancies were discovered. Sorry 'bout that. Bob . . . ________________________________ Message 12 ____________________________________ Time: 01:41:13 PM PST US From: "Miskelly, Francis G" Subject: RE: AeroElectric-List: Re SWR Meter? Many thanks Bob. That's extremely helpful. You're a true gentleman! - Frank ________________________________________ From: owner-aeroelectric-list-server@matronics.com [owner-aeroelectric-list -server@matronics.com] on behalf of Robert L. Nuckolls, III [nuckolls.bob@a eroelectric.com] Sent: 29 March 2012 19:29 Subject: RE: AeroElectric-List: Re SWR Meter? At 12:10 PM 3/29/2012, you wrote: imperial.ac.uk> Does the MFG-862 cover the aviation band (108-116 MHz) - Frank Probably not guaranteed to published specifications but still useful. There was some discussion a few weeks back about suitability of the LO Band (3-30 Mhz) devices being used at VHF. Typically devices like this: [Emacs!] These do perform as advertised in the 3-30 Mhz range but tend to run off into the weeds at 4x the top design frequency. On the other hand, the MFJ862 used at 108-135 (full range aviation) is still at 75% of lower end of 144 ham band. Maybe not quite as accurate with respect to absolute readings but still a good indicator of performance and useful for finding frequency of lowest SWR. For about the same $ you can pick up one of these http://tinyurl.com/6pjbckd which is designed for our particular frequencies of interest. On the other hand, there are some DIY options too. Take a look at this article: http://tinyurl.com/7dmupav This DIY project is tailored to the 2.5 GHz range for WiFi work but the same technique can be easily adapted to lower frequencies. Here's another one. http://tinyurl.com/83e5u2q All it takes is $time$ and patience . . . but it can be fun . . . Bob . . . ________________________________ Message 13 ____________________________________ Time: 03:32:22 PM PST US From: Dave Saylor Subject: AeroElectric-List: Uneven dipole elements Bob, We managed to chop about 3 inches off the end of a dipole comm antenna. Would that have any appreciable effect on performance? --Dave Saylor ________________________________ Message 14 ____________________________________ Time: 07:48:01 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Uneven dipole elements At 05:30 PM 3/29/2012, you wrote: > > >Bob, > >We managed to chop about 3 inches off the end of a dipole comm >antenna. Would that have any appreciable effect on performance? Sure, but if I were to give you a 'number' . . . it wouldn't have much practical meaning. Is this an internal antenna? Can't you splice it back on? Bob . . . ________________________________ Message 15 ____________________________________ Time: 09:34:23 PM PST US From: "Thomas Johnson" Subject: AeroElectric-List: Re: re: HID lighting observations > Did the PIC wander off into the weeds and lock up? Usually it would make one and a half wig-wags and then lock up, requiring a power cycle to recover. At that time I was not utilizing the PIC Brown-out Reset (BOR) feature. I=99ll bet that would have given me a clean reset. Once I knocked the inrush spike down a little I never saw the problem again. I had never needed to fix an inrush issue before and I assumed that a quick internet search would yield a handful of simple solutions. What I found is that high inrush current is a growing problem for modern electronics, and if it=99s not dealt with in the original design it can be real hard to fix later. The neatest solution I read about (but never got around to trying) is to ramp up voltage to the HID controller slowly. I was already using a P-FET to switch power on/off so it didn=99t sound too difficult to do that. Tom Johnson ________________________________ Message 16 ____________________________________ Time: 10:41:19 PM PST US From: Dave Saylor Subject: Re: AeroElectric-List: Uneven dipole elements >>Can't you splice it back on?<< Short answer--no. We had to lop the tip off a vertical stab to make room for more rudder horn on a Lancair ES. I didn't stop to think about an internal antenna. I shoulda. On further inspection, the antenna seems to have three elements. Two run up each side of the Vstab trailing edge, aft of the stern post. They're embedded in the fiberglass and are nearly equal in length. The element that was cut off is 8" forward of the Vstab trailing edge. I can't tell exactly how the three segments are connected. The aft-most two elements are visible through the fiberglass when the rudder is removed. I can see a lot of the cut element using a boroscope inside the Vstab. Would I hurt the radio to try transmitting and receiving? If this isn't easy to fix, we have the option of installing a belly-mounted replacement antenna using a spray-on ground plane. --Dave Saylor On Thu, Mar 29, 2012 at 7:45 PM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > nuckolls.bob@aeroelectric.com**> > > > At 05:30 PM 3/29/2012, you wrote: > >> dave.saylor.aircrafters@**gmail.com > >> >> Bob, >> >> We managed to chop about 3 inches off the end of a dipole comm >> antenna. Would that have any appreciable effect on performance? >> > > Sure, but if I were to give you a 'number' . . . it wouldn't > have much practical meaning. Is this an internal antenna? > Can't you splice it back on? > > > Bob . . . > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.