---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 02/24/17: 18 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:52 AM - Revmaster with EFIS (William) 2. 06:10 AM - Re: Coaxial Cable (Charlie England) 3. 07:01 AM - Re: Coaxial Cable (Alec Myers) 4. 07:09 AM - Re: Revmaster with EFIS (user9253) 5. 08:02 AM - Re: Coaxial Cable (Charlie England) 6. 08:04 AM - Re: Coaxial Cable (Robert McCallum) 7. 08:30 AM - Re: Coaxial Cable (Alec Myers) 8. 09:36 AM - Re: Reedswitch (Airdog77) 9. 09:46 AM - Re: Coaxial Cable (Charlie England) 10. 09:52 AM - Re: Re: Reedswitch (Charlie England) 11. 10:12 AM - Re: Re: Reedswitch (Robert McCallum) 12. 10:33 AM - Re: Reedswitch (user9253) 13. 10:43 AM - Re: Reedswitch (Airdog77) 14. 10:44 AM - Re: Coaxial Cable (Kelly McMullen) 15. 10:45 AM - Re: Coaxial Cable (Kelly McMullen) 16. 11:46 AM - Contactors (Wladimir Kummer) 17. 01:26 PM - Re: Contactors (Stephen Richards) 18. 01:26 PM - Re: Contactors (Charlie England) ________________________________ Message 1 _____________________________________ Time: 03:52:31 AM PST US From: William Subject: AeroElectric-List: Revmaster with EFIS I am working on my electrical bus diagram. Is it better to have both PM Alternators connected at the same time or switch between them? I have not been able to find much on this. Ive included my rough draft version. Thanks Bill Thatcher CX-5 ________________________________ Message 2 _____________________________________ Time: 06:10:04 AM PST US From: Charlie England Subject: Re: AeroElectric-List: Coaxial Cable Here are links to cable specs for RG58a/u (stranded; note that RG58 can be had with solid center conductor, so beware when ordering), and RG400. I picked this site/brand to get both sets of specs in the same format. http://www.awcwire.com/part.aspx?partname=m17/28-rg58 http://www.awcwire.com/part.aspx?partname=m17/128-rg400 Relevant data: 400's center conductor is 0.0384" vs 58's 0.0355" dielectric (center insulation) is the same dia, but 400 has marginally better properties; relevant only at the extreme high end of design use: capacitance of 400 is 29.4pF/ft, vs 58's 30.8pF/ft test freq of 400 is 12.4 GHz, vs 58's 1 GHz (but we use the cable at a max of ~1 GHz) 400's loss at 1 GHz is 14.7 dB/100ft; 58's is 22.6 dB/100ft (unfortunately, I had to pull this spec from other sources; it doesn't show up in the linked pages) Doing the math, for a 10 foot run (more than enough to mount the antenna on the belly of most planes), 400's loss would be 1.47dB vs 58's 2.26dB. For those that don't know, dB's are a logarithmic measurement. 0.79dB of difference is so small that it could get lost in the noise of connector quality, installation technique, phase of the moon... At comm & nav frequencies (~100 MHz; 1/10 thefrequency), the spread would be even smaller. Biggest difference is the outer jacket material; 400 is rated to 200 C, while 58 is PVC rated to 85 C. Unless you're bonding it to your cylinder head, that shouldn't be a big factor. Yes, 400 is 'better'. But is 58 good enough? There are planes flying with 58 that is still good after 40 years..... Charlie On Thu, Feb 23, 2017 at 10:52 PM, Art Zemon wrote: > Folks, > > I have been following this thread because I, too, am trying to decide > which coax to buy for my plane. I'm a computer engineer; I shied away from > EE in college and especially antenna design because... well... I heard that > antenna designers were a special kind of crazy.. :-) > > Seriously, though, if I understand correctly, in the context of an > installation in a homebuilt airplane, the biggest difference between RG58 > and RG400 seems to be that the RG400 is less loss-y. Yes? In other words, > if an antenna puts a weak signal in one end of the coax, the signal that > reaches the radio receiver will be stronger if the coax is RG400 than if it > is RG58. > > I'm looking at 10 feet of coax from the GPS and comm antennas to the > receivers, including service loops. I am looking at 20 feet for the VOR/GS > antenna. The transponder antenna will be less than 10 feet. > > At those distances, does RG400 vs RG58 matter? How do I evaluate it? > > And then there is the LMR-195 that Bob just showed us. How does that fit > in? > > Thanks, > -- Art Z. > > -- > https://CheerfulCurmudgeon.com/ > > *"If I am not for myself, who is for me? And if I am only for myself, what > am I? And if not now, when?" Hillel* > ________________________________ Message 3 _____________________________________ Time: 07:01:34 AM PST US Subject: Re: AeroElectric-List: Coaxial Cable From: Alec Myers I've been following this discussion. Isn't it better to move away from PVC jacketed cables, for fire safety reasons? Who uses PVC wire vs 22759-16 ETFE insulated stuff? On 24Feb2017, at 9:06 AM, Charlie England wrote: Here are links to cable specs for RG58a/u (stranded; note that RG58 can be had with solid center conductor, so beware when ordering), and RG400. I picked this site/brand to get both sets of specs in the same format. http://www.awcwire.com/part.aspx?partname=m17/28-rg58 http://www.awcwire.com/part.aspx?partname=m17/128-rg400 Relevant data: 400's center conductor is 0.0384" vs 58's 0.0355" dielectric (center insulation) is the same dia, but 400 has marginally better properties; relevant only at the extreme high end of design use: capacitance of 400 is 29.4pF/ft, vs 58's 30.8pF/ft test freq of 400 is 12.4 GHz, vs 58's 1 GHz (but we use the cable at a max of ~1 GHz) 400's loss at 1 GHz is 14.7 dB/100ft; 58's is 22.6 dB/100ft (unfortunately, I had to pull this spec from other sources; it doesn't show up in the linked pages) Doing the math, for a 10 foot run (more than enough to mount the antenna on the belly of most planes), 400's loss would be 1.47dB vs 58's 2.26dB. For those that don't know, dB's are a logarithmic measurement. 0.79dB of difference is so small that it could get lost in the noise of connector quality, installation technique, phase of the moon... At comm & nav frequencies (~100 MHz; 1/10 thefrequency), the spread would be even smaller. Biggest difference is the outer jacket material; 400 is rated to 200 C, while 58 is PVC rated to 85 C. Unless you're bonding it to your cylinder head, that shouldn't be a big factor. Yes, 400 is 'better'. But is 58 good enough? There are planes flying with 58 that is still good after 40 years..... Charlie On Thu, Feb 23, 2017 at 10:52 PM, Art Zemon wrote: Folks, I have been following this thread because I, too, am trying to decide which coax to buy for my plane. I'm a computer engineer; I shied away from EE in college and especially antenna design because... well... I heard that antenna designers were a special kind of crazy.. :-) Seriously, though, if I understand correctly, in the context of an installation in a homebuilt airplane, the biggest difference between RG58 and RG400 seems to be that the RG400 is less loss-y. Yes? In other words, if an antenna puts a weak signal in one end of the coax, the signal that reaches the radio receiver will be stronger if the coax is RG400 than if it is RG58. I'm looking at 10 feet of coax from the GPS and comm antennas to the receivers, including service loops. I am looking at 20 feet for the VOR/GS antenna. The transponder antenna will be less than 10 feet. At those distances, does RG400 vs RG58 matter? How do I evaluate it? And then there is the LMR-195 that Bob just showed us. How does that fit in? Thanks, -- Art Z. -- https://CheerfulCurmudgeon.com/ "If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel ________________________________ Message 4 _____________________________________ Time: 07:09:05 AM PST US Subject: AeroElectric-List: Re: Revmaster with EFIS From: "user9253" Alternators with field coils can fight each other if the regulator voltage set points are near each other. I do not know about permanent magnet dynamos. But regardless, I would leave the switch controls as they are. Leave it up to the pilot to turn on one at a time or both at once. Trying to design it so that only one dynamo will supply power at a time will result in a single failure point. The indicator lights are not necessary or even desired. The pilot will soon become accustomed to one being on and ignore the lights. The EFIS should warn of low voltage. A PDF schematic would be much easier to read then a blurry JPG. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=466572#466572 ________________________________ Message 5 _____________________________________ Time: 08:02:42 AM PST US Subject: Re: AeroElectric-List: Coaxial Cable From: Charlie England http://www.wikiwand.com/en/ETFE "Combustion of ETFE occurs in the same way as a number of otherfluoropolymers , in terms of releasing hydrofluoric acid (HF). HF is extremely corrosive and toxic, and so appropriate caution must be exercised." You decide. On 2/24/2017 8:59 AM, Alec Myers wrote: > > I've been following this discussion. Isn't it better to move away from PVC jacketed cables, for fire safety reasons? Who uses PVC wire vs 22759-16 ETFE insulated stuff? > > > On 24Feb2017, at 9:06 AM, Charlie England wrote: > > Here are links to cable specs for RG58a/u (stranded; note that RG58 can be had with solid center conductor, so beware when ordering), and RG400. I picked this site/brand to get both sets of specs in the same format. > http://www.awcwire.com/part.aspx?partname=m17/28-rg58 > > http://www.awcwire.com/part.aspx?partname=m17/128-rg400 > > Relevant data: > 400's center conductor is 0.0384" vs 58's 0.0355" > > dielectric (center insulation) is the same dia, but 400 has marginally better properties; relevant only at the extreme high end of design use: capacitance of 400 is 29.4pF/ft, vs 58's 30.8pF/ft > > test freq of 400 is 12.4 GHz, vs 58's 1 GHz (but we use the cable at a max of ~1 GHz) > > 400's loss at 1 GHz is 14.7 dB/100ft; 58's is 22.6 dB/100ft (unfortunately, I had to pull this spec from other sources; it doesn't show up in the linked pages) > > Doing the math, for a 10 foot run (more than enough to mount the antenna on the belly of most planes), 400's loss would be 1.47dB vs 58's 2.26dB. For those that don't know, dB's are a logarithmic measurement. 0.79dB of difference is so small that it could get lost in the noise of connector quality, installation technique, phase of the moon... > > At comm & nav frequencies (~100 MHz; 1/10 thefrequency), the spread would be even smaller. > > Biggest difference is the outer jacket material; 400 is rated to 200 C, while 58 is PVC rated to 85 C. Unless you're bonding it to your cylinder head, that shouldn't be a big factor. > > Yes, 400 is 'better'. But is 58 good enough? There are planes flying with 58 that is still good after 40 years..... > > Charlie > > On Thu, Feb 23, 2017 at 10:52 PM, Art Zemon wrote: > Folks, > > I have been following this thread because I, too, am trying to decide which coax to buy for my plane. I'm a computer engineer; I shied away from EE in college and especially antenna design because... well... I heard that antenna designers were a special kind of crazy.. :-) > > Seriously, though, if I understand correctly, in the context of an installation in a homebuilt airplane, the biggest difference between RG58 and RG400 seems to be that the RG400 is less loss-y. Yes? In other words, if an antenna puts a weak signal in one end of the coax, the signal that reaches the radio receiver will be stronger if the coax is RG400 than if it is RG58. > > I'm looking at 10 feet of coax from the GPS and comm antennas to the receivers, including service loops. I am looking at 20 feet for the VOR/GS antenna. The transponder antenna will be less than 10 feet. > > At those distances, does RG400 vs RG58 matter? How do I evaluate it? > > And then there is the LMR-195 that Bob just showed us. How does that fit in? > > Thanks, > -- Art Z. > ________________________________ Message 6 _____________________________________ Time: 08:04:54 AM PST US From: Robert McCallum Subject: Re: AeroElectric-List: Coaxial Cable Charlie; I've followed your many posts and generally "good opinions" on many subjects over a lengthy period of time and respect those opinions and advice, but in this case I'm curious. Did you wire your bird with automotive PVC wire because it was "good enough" or did you use Tefzel insulated wire because that's what is recognized as "correct" current practice? Did you use "hardware store" hardware because it's probably "good enough" or did you use correct "AN hardware"? Did you use proper "braided hoses" (Aeroquip style) or did you use "good enough" rubber hoses? I'm a bit mystified why you seem to be advocating "good enough" RG-58 when "better" (by how much may be debatable) RG-400 is readily available for a small overall increase in $$$$. Wouldn't it seem that doing "the best we know how" be the most prudent "best" approach?? There is no labour difference, the fittings are essentially the same, the only actual "difference" might be a hundred dollars or so which in the overall scheme of things is peanuts for the average finished project? There's also "pride of workmanship" and the self satisfaction of doing it right as opposed to "good enough". Just my alternate view two cents worth. Respectfully Bob McC > ---------- Original Message ---------- > From: Charlie England > Date: February 24, 2017 at 9:06 AM > > Here are links to cable specs for RG58a/u (stranded; note that RG58 can be > had with solid center conductor, so beware when ordering), and RG400. I picked > this site/brand to get both sets of specs in the same format. > http://www.awcwire.com/part.aspx?partname=m17/28-rg58 > > http://www.awcwire.com/part.aspx?partname=m17/128-rg400 > > Relevant data: > 400's center conductor is 0.0384" vs 58's 0.0355" > > dielectric (center insulation) is the same dia, but 400 has marginally > better properties; relevant only at the extreme high end of design use: > capacitance of 400 is 29.4pF/ft, vs 58's 30.8pF/ft > > test freq of 400 is 12.4 GHz, vs 58's 1 GHz (but we use the cable at a max > of ~1 GHz) > > 400's loss at 1 GHz is 14.7 dB/100ft; 58's is 22.6 dB/100ft > (unfortunately, I had to pull this spec from other sources; it doesn't show up > in the linked pages) > > Doing the math, for a 10 foot run (more than enough to mount the antenna > on the belly of most planes), 400's loss would be 1.47dB vs 58's 2.26dB. For > those that don't know, dB's are a logarithmic measurement. 0.79dB of > difference is so small that it could get lost in the noise of connector > quality, installation technique, phase of the moon... > > At comm & nav frequencies (~100 MHz; 1/10 thefrequency), the spread would > be even smaller. > > Biggest difference is the outer jacket material; 400 is rated to 200 C, > while 58 is PVC rated to 85 C. Unless you're bonding it to your cylinder head, > that shouldn't be a big factor. > > Yes, 400 is 'better'. But is 58 good enough? There are planes flying with > 58 that is still good after 40 years..... > > Charlie > > On Thu, Feb 23, 2017 at 10:52 PM, Art Zemon < art@zemon.name > > wrote: > > > > Folks, > > > > I have been following this thread because I, too, am trying to > > decide which coax to buy for my plane. I'm a computer engineer; I shied away > > from EE in college and especially antenna design because... well... I heard > > that antenna designers were a special kind of crazy.. :-) > > > > Seriously, though, if I understand correctly, in the context of an > > installation in a homebuilt airplane, the biggest difference between RG58 > > and RG400 seems to be that the RG400 is less loss-y. Yes? In other words, if > > an antenna puts a weak signal in one end of the coax, the signal that > > reaches the radio receiver will be stronger if the coax is RG400 than if it > > is RG58. > > > > I'm looking at 10 feet of coax from the GPS and comm antennas to the > > receivers, including service loops. I am looking at 20 feet for the VOR/GS > > antenna. The transponder antenna will be less than 10 feet. > > > > At those distances, does RG400 vs RG58 matter? How do I evaluate it? > > > > And then there is the LMR-195 that Bob just showed us. How does that > > fit in? > > > > Thanks, > > -- Art Z. > > > > -- > > https://CheerfulCurmudgeon.com/ > > > > "If I am not for myself, who is for me? And if I am only for myself, > > what am I? And if not now, when?" Hillel > > > > > > ________________________________ Message 7 _____________________________________ Time: 08:30:27 AM PST US Subject: Re: AeroElectric-List: Coaxial Cable From: Alec Myers The noxious gases released are only one consideration - some others might be ease of initial flammability, tendency to spread fire along the cable, melting point, and probably some others I haven't thought of. I don't know how FEP-insulated RG-400 stacks up but I believe PVC is pretty bad in these respects. Noting that your coax doesn't carry any current, and a short circuit because the insulation has melted isn't a further ignition risk, I'm genuinely surprised that RG58 is still on the table. On 24Feb2017, at 9:59 AM, Alec Myers wrote: I've been following this discussion. Isn't it better to move away from PVC jacketed cables, for fire safety reasons? Who uses PVC wire vs 22759-16 ETFE insulated stuff? On 24Feb2017, at 9:06 AM, Charlie England wrote: Here are links to cable specs for RG58a/u (stranded; note that RG58 can be had with solid center conductor, so beware when ordering), and RG400. I picked this site/brand to get both sets of specs in the same format. http://www.awcwire.com/part.aspx?partname=m17/28-rg58 http://www.awcwire.com/part.aspx?partname=m17/128-rg400 Relevant data: 400's center conductor is 0.0384" vs 58's 0.0355" dielectric (center insulation) is the same dia, but 400 has marginally better properties; relevant only at the extreme high end of design use: capacitance of 400 is 29.4pF/ft, vs 58's 30.8pF/ft test freq of 400 is 12.4 GHz, vs 58's 1 GHz (but we use the cable at a max of ~1 GHz) 400's loss at 1 GHz is 14.7 dB/100ft; 58's is 22.6 dB/100ft (unfortunately, I had to pull this spec from other sources; it doesn't show up in the linked pages) Doing the math, for a 10 foot run (more than enough to mount the antenna on the belly of most planes), 400's loss would be 1.47dB vs 58's 2.26dB. For those that don't know, dB's are a logarithmic measurement. 0.79dB of difference is so small that it could get lost in the noise of connector quality, installation technique, phase of the moon... At comm & nav frequencies (~100 MHz; 1/10 thefrequency), the spread would be even smaller. Biggest difference is the outer jacket material; 400 is rated to 200 C, while 58 is PVC rated to 85 C. Unless you're bonding it to your cylinder head, that shouldn't be a big factor. Yes, 400 is 'better'. But is 58 good enough? There are planes flying with 58 that is still good after 40 years..... Charlie On Thu, Feb 23, 2017 at 10:52 PM, Art Zemon wrote: Folks, I have been following this thread because I, too, am trying to decide which coax to buy for my plane. I'm a computer engineer; I shied away from EE in college and especially antenna design because... well... I heard that antenna designers were a special kind of crazy.. :-) Seriously, though, if I understand correctly, in the context of an installation in a homebuilt airplane, the biggest difference between RG58 and RG400 seems to be that the RG400 is less loss-y. Yes? In other words, if an antenna puts a weak signal in one end of the coax, the signal that reaches the radio receiver will be stronger if the coax is RG400 than if it is RG58. I'm looking at 10 feet of coax from the GPS and comm antennas to the receivers, including service loops. I am looking at 20 feet for the VOR/GS antenna. The transponder antenna will be less than 10 feet. At those distances, does RG400 vs RG58 matter? How do I evaluate it? And then there is the LMR-195 that Bob just showed us. How does that fit in? Thanks, -- Art Z. -- https://CheerfulCurmudgeon.com/ "If I am not for myself, who is for me? And if I am only for myself, what am I? And if not now, when?" Hillel ________________________________ Message 8 _____________________________________ Time: 09:36:08 AM PST US Subject: AeroElectric-List: Re: Reedswitch From: "Airdog77" Bob, et al, I'm a little confused on the implementation of a reed switch in a scenario as you have shown in the diagram on page 3 of your document: "Failure Warning w/ On Annunciation". I guess I don't understand why when using an LED to annunciate that is sourced with the SAME power as to the load being monitored. Why not just tie into the relay (say out of the FastOn connector) with a separate wire with a 470 ohm resistor to the LED, then to ground. IF using the SAME power as the end component being monitored (here, pitot heat), isn't an added wire as I described above really the end result that the reed switch provides when it's activated/closed? I could understand using the reed switch in a manner as a "poor man's relay" if the power source for the LED was completely separate from power source of the monitored load (again, here a pitot tube). But in using the same power as the pitot heat, in this case, it seems like a bit of added complexity for no real gain? I hope my question makes sense. Not trying to be snarky, just trying to learn so I can implement the simplest, cleanest system possible ... and I have this exact issue for driving a few annunciator LEDs. Thanks! Wade -------- Airdog Wade Parton Building Long-EZ 916WP www.longezpush.com Read this topic online here: http://forums.matronics.com/viewtopic.php?p=466587#466587 ________________________________ Message 9 _____________________________________ Time: 09:46:49 AM PST US From: Charlie England Subject: Re: AeroElectric-List: Coaxial Cable I used tefzel wire for almost everything, because the cost difference really was negligible to get the tougher insulation, and I knew that I'd have big bundles carrying (in some cases) significant current and some really tight routing. Fire hazard wasn't a consideration; either product will produce toxic fumes. Around the engine, long term heat resistance *would* be a factor for me. Yes, I use a/n hardware. Yes, I use a/n style (but not actual certified) hoses for oil lines. But for my water cooled engine's coolant lines, I'm using reinforced silicone fluid lines. Some have used a/n hoses & fittings for these lines, but they weigh a *lot* more and there's no evidence that they actually improve safety over quality silicone hoses *in that application*. (This ignores, of course, the massive difference in cost.) A/n hoses are 'better' than aluminum tubing, which is 'better' than tygon, yet early RV-x's are still flying with tygon brake lines, and the new kits still ship with aluminum brake lines. Either are 'good enough', though the aluminum is safer if the operator (the guy standing on the brakes constantly) isn't. A lot of guys building RV-x's are replacing the $40 brass/nylon fuel selector (included in the price of the kit) with a $400+ Andair fuel selector. No doubt, the Andair is 'better'; it's got to be, for 10X the money, right? But is it, after factoring in weight, altered fittings needed, altered line routing, and expense? Thousands of RV's flying the brass valve prove that it's 'good enough', even if it isn't 'aircraft quality'. (Of course, the Andair isn't *certified* a/c quality either, but that doesn't deter devotees.) Four part Urethane paint is 'better' than acrylic enamel (at ~10 times the cost). It's also quite capable of killing you, if sprayed without perfectly functioning protective gear. Yet lots of planes are still flying with decent looking enamel, 40 years later. Honestly, if I were buying 10' of coax, I'd probably (well, I might) go ahead & order the 400; it's certainly prettier. But I've got a box of 58 on hand, and I'm pre-wiring for ELT, comm, nav, glideslope, xponder, GPS,spare GPS, both wingtips, etc with what I have on hand. Whatever I don't use can be easily removed to save weight. I wouldn't have done the same thing with 400, at up to $4/ft. You're right; a hundred dollars over the total cost of a project is 'peanuts'. You could say the same thing about a $.50 ATC fuse vs a $20 aircraft quality circuit breaker. Now multiply that (and the weight difference) times 30. Which is 'better'? Now extrapolate that over the dozens (hundreds?) of other decisions throughout the airframe. Everybody should make their own decisions based on valid data and their comfort levels, but they shouldn't make them based on paranoia or worse, bad data. The 58 is certainly good enough, and it *is* aircraft quality cable. If you want 'better', there's certainly nothing wrong with that. Charlie On Fri, Feb 24, 2017 at 10:02 AM, Robert McCallum < robert.mccallum2@sympatico.ca> wrote: > Charlie; > > I've followed your many posts and generally "good opinions" on many > subjects over a lengthy period of time and respect those opinions and > advice, but in this case I'm curious. > > Did you wire your bird with automotive PVC wire because it was "good > enough" or did you use Tefzel insulated wire because that's what is > recognized as "correct" current practice? Did you use "hardware store" > hardware because it's probably "good enough" or did you use correct "AN > hardware"? Did you use proper "braided hoses" (Aeroquip style) or did you > use "good enough" rubber hoses? > > I'm a bit mystified why you seem to be advocating "good enough" RG-58 when > "better" (by how much may be debatable) RG-400 is readily available for a > small overall increase in $$$$. Wouldn't it seem that doing "the best we > know how" be the most prudent "best" approach?? There is no labour > difference, the fittings are essentially the same, the only actual > "difference" might be a hundred dollars or so which in the overall scheme > of things is peanuts for the average finished project? There's also "pride > of workmanship" and the self satisfaction of doing it right as opposed to > "good enough". Just my alternate view two cents worth. > > Respectfully > > Bob McC > > > ---------- Original Message ---------- > From: Charlie England > Date: February 24, 2017 at 9:06 AM > > Here are links to cable specs for RG58a/u (stranded; note that RG58 can be > had with solid center conductor, so beware when ordering), and RG400. I > picked this site/brand to get both sets of specs in the same format. > http://www.awcwire.com/part.aspx?partname=m17/28-rg58 > > http://www.awcwire.com/part.aspx?partname=m17/128-rg400 > > Relevant data: > 400's center conductor is 0.0384" vs 58's 0.0355" > > dielectric (center insulation) is the same dia, but 400 has marginally > better properties; relevant only at the extreme high end of design use: > capacitance of 400 is 29.4pF/ft, vs 58's 30.8pF/ft > > test freq of 400 is 12.4 GHz, vs 58's 1 GHz (but we use the cable at a max > of ~1 GHz) > > 400's loss at 1 GHz is 14.7 dB/100ft; 58's is 22.6 dB/100ft > (unfortunately, I had to pull this spec from other sources; it doesn't show > up in the linked pages) > > Doing the math, for a 10 foot run (more than enough to mount the antenna > on the belly of most planes), 400's loss would be 1.47dB vs 58's 2.26dB. > For those that don't know, dB's are a logarithmic measurement. 0.79dB of > difference is so small that it could get lost in the noise of connector > quality, installation technique, phase of the moon... > > At comm & nav frequencies (~100 MHz; 1/10 thefrequency), the spread would > be even smaller. > > Biggest difference is the outer jacket material; 400 is rated to 200 C, > while 58 is PVC rated to 85 C. Unless you're bonding it to your cylinder > head, that shouldn't be a big factor. > > Yes, 400 is 'better'. But is 58 good enough? There are planes flying with > 58 that is still good after 40 years..... > > Charlie > > On Thu, Feb 23, 2017 at 10:52 PM, Art Zemon < art@zemon.name> wrote: > > Folks, > > I have been following this thread because I, too, am trying to decide > which coax to buy for my plane. I'm a computer engineer; I shied away from > EE in college and especially antenna design because... well... I heard that > antenna designers were a special kind of crazy.. :-) > > Seriously, though, if I understand correctly, in the context of an > installation in a homebuilt airplane, the biggest difference between RG58 > and RG400 seems to be that the RG400 is less loss-y. Yes? In other words, > if an antenna puts a weak signal in one end of the coax, the signal that > reaches the radio receiver will be stronger if the coax is RG400 than if it > is RG58. > > I'm looking at 10 feet of coax from the GPS and comm antennas to the > receivers, including service loops. I am looking at 20 feet for the VOR/GS > antenna. The transponder antenna will be less than 10 feet. > > At those distances, does RG400 vs RG58 matter? How do I evaluate it? > > And then there is the LMR-195 that Bob just showed us. How does that fit > in? > > Thanks, > -- Art Z. > > -- > https://CheerfulCurmudgeon.com/ > > *"If I am not for myself, who is for me? And if I am only for myself, what > am I? And if not now, when?" Hillel* > > ________________________________ Message 10 ____________________________________ Time: 09:52:08 AM PST US From: Charlie England Subject: Re: AeroElectric-List: Re: Reedswitch On Fri, Feb 24, 2017 at 11:32 AM, Airdog77 wrote: > > Bob, et al, > > I'm a little confused on the implementation of a reed switch in a scenario > as you have shown in the diagram on page 3 of your document: "Failure > Warning w/ On Annunciation". > > I guess I don't understand why when using an LED to annunciate that is > sourced with the SAME power as to the load being monitored. Why not just > tie into the relay (say out of the FastOn connector) with a separate wire > with a 470 ohm resistor to the LED, then to ground. > > IF using the SAME power as the end component being monitored (here, pitot > heat), isn't an added wire as I described above really the end result that > the reed switch provides when it's activated/closed? > > I could understand using the reed switch in a manner as a "poor man's > relay" if the power source for the LED was completely separate from power > source of the monitored load (again, here a pitot tube). But in using the > same power as the pitot heat, in this case, it seems like a bit of added > complexity for no real gain? > > I hope my question makes sense. Not trying to be snarky, just trying to > learn so I can implement the simplest, cleanest system possible ... and I > have this exact issue for driving a few annunciator LEDs. > > Thanks! > Wade > > -------- > Airdog > Wade Parton > Building Long-EZ 916WP > www.longezpush.com > > If the LED is wired directly to the power wire, and the wire breaks anywhere after your attach point for the LED, the LED is still lit but you have no pitot heat and no awareness. If the pitot heater itself fails, your LED is still lit, but you have no pitot heat & no awareness. Using the coil & reed switch senses *current flow* through the heating element. If the circuit opens for any reason, the LED goes out, telling you you have no pitot heat. ________________________________ Message 11 ____________________________________ Time: 10:12:58 AM PST US From: Robert McCallum Subject: Re: AeroElectric-List: Re: Reedswitch Wade; The LED connected to the load as you describe only confirms that voltage is available at the load, not that the load is actually working. The read switch scenario confirms that current is being drawn by the load and therefore the pitot heater is actually heating and is not burned out. Bob McC > > ---------- Original Message ---------- > From: Airdog77 > Date: February 24, 2017 at 12:32 PM > > > > Bob, et al, > > I'm a little confused on the implementation of a reed switch in a scenario > as you have shown in the diagram on page 3 of your document: "Failure Warning > w/ On Annunciation". > > I guess I don't understand why when using an LED to annunciate that is > sourced with the SAME power as to the load being monitored. Why not just tie > into the relay (say out of the FastOn connector) with a separate wire with a > 470 ohm resistor to the LED, then to ground. > > IF using the SAME power as the end component being monitored (here, pitot > heat), isn't an added wire as I described above really the end result that the > reed switch provides when it's activated/closed? > > I could understand using the reed switch in a manner as a "poor man's > relay" if the power source for the LED was completely separate from power > source of the monitored load (again, here a pitot tube). But in using the same > power as the pitot heat, in this case, it seems like a bit of added complexity > for no real gain? > > I hope my question makes sense. Not trying to be snarky, just trying to > learn so I can implement the simplest, cleanest system possible ... and I have > this exact issue for driving a few annunciator LEDs. > > Thanks! > Wade > > -------- > Airdog > Wade Parton > Building Long-EZ 916WP > www.longezpush.com > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=466587#466587 > > > > > > > > > > ________________________________ Message 12 ____________________________________ Time: 10:33:54 AM PST US Subject: AeroElectric-List: Re: Reedswitch From: "user9253" Double pole reed switches (Form C) are available with normally closed contacts. The circuit could be wired so that a red LED illuminates only when the pitot heating element burns open. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=466591#466591 ________________________________ Message 13 ____________________________________ Time: 10:43:43 AM PST US Subject: AeroElectric-List: Re: Reedswitch From: "Airdog77" Ahh, ok! I was looking at it more from the binary on/off of the pitot tube. But now I see the reed switch allows for a more qualitative monitoring of the pitot heat element's health in case it goes inop, wiring issue, etc. Thanks all. Love this forum! Cheers, Wade -------- Airdog Wade Parton Building Long-EZ 916WP www.longezpush.com Read this topic online here: http://forums.matronics.com/viewtopic.php?p=466592#466592 ________________________________ Message 14 ____________________________________ Time: 10:44:16 AM PST US Subject: Re: AeroElectric-List: Coaxial Cable From: Kelly McMullen If one uses the available information, RG-58 is and has been more than adequate for VHF applications for the past 50 years or so. In fact, much of that installed in aircraft 50 years ago is still doing a fine job. The only application that gets a noticeable benefit from the expensive RG-400 is those devices operating in the Gigahertz frequency spectrum such as GPS and transponders and DME. Most Mode C transponders and DME will in fact operate satisfactorily, passing all required performance checks with RG-58 coax if the coax length isn't excessive. The only case I can think of where RG-58 has needed to be removed and replaced with RG-400 is for certified WAAS GPS installations, where Garmin specifically upgraded their requirement due to their design needing a certain insertion loss for the proper performance. They could have used a different design that would have eliminated the need for coax entirely. (see the Dynon 2020 GPS as an example that meets ADS-B performance without coax). Unlike the type certified advanced technology half million dollar production wonders, most amateur built aircraft are necessarily on a tight budget, and not spending $200-300 on unnecessary coax makes a difference. Using RG-400 for VHF com and nav antennas is huge overkill. Using RG-58 for those applications is not wrong, and makes the servicing in Timbuktu and 50 miles from Nowheresville substantially simpler. AFAIK Radio Shack and Fry's still don't stock RG-400 connectors. In fact, for under $15 one could carry a spare 10 or 20 ft RG-58 cable with BNC connectors installed. JMHO. Kelly A&P/IA EAA Tech Counselor On 2/24/2017 12:01 AM, Bernie Willis wrote: > Ive got to submit my two cents worth on the conversation about coax. > As an A&P IA what I hate the most is having to do something over > because I did it wrong. Typically coax is under the floor boards or > above the head liner. Most times it goes places where its hard to get > at and left there. The extra money for the best is soon forgotten but > the frustration for replacement just goes on and on. > > The radio shop in our area, which is very busy, urges RG400. The > installation money is all the same to me. > > Bernie >> On Feb 23, 2017, at 9:36 PM, don van santen > > wrote: >> >> After Bob posted the info on the LMR-195 I looked for additional >> information. One thing that seems a little strange is that it is solid >> core. It is also said to be flexible. It was my understanding that >> solid core cable is less flexible than multi strand cable. Any one >> know the minimum bend radius for LMR-195? >> Don. >> >> On Feb 23, 2017 21:14, "Art Zemon" > > wrote: >> >> Folks, >> >> I have been following this thread because I, too, am trying to >> decide which coax to buy for my plane. I'm a computer engineer; I >> shied away from EE in college and especially antenna design >> because... well... I heard that antenna designers were a special >> kind of crazy.. :-) >> >> Seriously, though, if I understand correctly, in the context of an >> installation in a homebuilt airplane, the biggest difference >> between RG58 and RG400 seems to be that the RG400 is less loss-y. >> Yes? In other words, if an antenna puts a weak signal in one end >> of the coax, the signal that reaches the radio receiver will be >> stronger if the coax is RG400 than if it is RG58. >> >> I'm looking at 10 feet of coax from the GPS and comm antennas to >> the receivers, including service loops. I am looking at 20 feet >> for the VOR/GS antenna. The transponder antenna will be less than >> 10 feet. >> >> At those distances, does RG400 vs RG58 matter? How do I evaluate it? >> >> And then there is the LMR-195 that Bob just showed us. How does >> that fit in? >> >> Thanks, >> -- Art Z. >> >> -- >> https://CheerfulCurmudgeon.com/ >> >> /"If I am not for myself, who is for me? And if I am only for >> myself, what am I? And if not now, when?" Hillel/ >> > ________________________________ Message 15 ____________________________________ Time: 10:45:52 AM PST US Subject: Re: AeroElectric-List: Coaxial Cable From: Kelly McMullen I'm with Charlie. There are huge differences with the other examples you cite, such as hardware store fasteners vs AN hardware. The difference in performance and safety between RG58 and RG400 is minuscule for a very real price difference. RG58 has been the accepted aircraft coax for at least 50 yrs. AFAIK RG400 didn't become recommended until after the turn of the century. Mainly over performance with WAAS GPS, not safety, not anything else that matters for other avionics. I'll not argue Tefzel vs automotive wire. There is a huge durability difference there, as well as insulation thickness difference. OTOH I have inspected many aircraft with RG58 installed 50-60 yrs ago and it is still performing fine. Unlike the general wiring that was used back then. On 2/24/2017 9:02 AM, Robert McCallum wrote: > Charlie; > > I've followed your many posts and generally "good opinions" on many > subjects over a lengthy period of time and respect those opinions and > advice, but in this case I'm curious. > > Did you wire your bird with automotive PVC wire because it was "good > enough" or did you use Tefzel insulated wire because that's what is > recognized as "correct" current practice? Did you use "hardware store" > hardware because it's probably "good enough" or did you use correct "AN > hardware"? Did you use proper "braided hoses" (Aeroquip style) or did > you use "good enough" rubber hoses? > > I'm a bit mystified why you seem to be advocating "good enough" RG-58 > when "better" (by how much may be debatable) RG-400 is readily available > for a small overall increase in $$$$. Wouldn't it seem that doing "the > best we know how" be the most prudent "best" approach?? There is no > labour difference, the fittings are essentially the same, the only > actual "difference" might be a hundred dollars or so which in the > overall scheme of things is peanuts for the average finished project? > There's also "pride of workmanship" and the self satisfaction of doing > it right as opposed to "good enough". Just my alternate view two cents > worth. > > Respectfully > > Bob McC > > >> ---------- Original Message ---------- >> From: Charlie England >> Date: February 24, 2017 at 9:06 AM >> >> Here are links to cable specs for RG58a/u (stranded; note that RG58 >> can be had with solid center conductor, so beware when ordering), and >> RG400. I picked this site/brand to get both sets of specs in the same >> format. >> http://www.awcwire.com/part.aspx?partname=m17/28-rg58 >> >> http://www.awcwire.com/part.aspx?partname=m17/128-rg400 >> >> Relevant data: >> 400's center conductor is 0.0384" vs 58's 0.0355" >> >> dielectric (center insulation) is the same dia, but 400 has marginally >> better properties; relevant only at the extreme high end of design >> use: capacitance of 400 is 29.4pF/ft, vs 58's 30.8pF/ft >> >> test freq of 400 is 12.4 GHz, vs 58's 1 GHz (but we use the cable at a >> max of ~1 GHz) >> >> 400's loss at 1 GHz is 14.7 dB/100ft; 58's is 22.6 dB/100ft >> (unfortunately, I had to pull this spec from other sources; it doesn't >> show up in the linked pages) >> >> Doing the math, for a 10 foot run (more than enough to mount the >> antenna on the belly of most planes), 400's loss would be 1.47dB vs >> 58's 2.26dB. For those that don't know, dB's are a logarithmic >> measurement. 0.79dB of difference is so small that it could get lost >> in the noise of connector quality, installation technique, phase of >> the moon... >> >> At comm & nav frequencies (~100 MHz; 1/10 thefrequency), the spread >> would be even smaller. >> >> Biggest difference is the outer jacket material; 400 is rated to 200 >> C, while 58 is PVC rated to 85 C. Unless you're bonding it to your >> cylinder head, that shouldn't be a big factor. >> >> Yes, 400 is 'better'. But is 58 good enough? There are planes flying >> with 58 that is still good after 40 years..... >> >> Charlie >> >> On Thu, Feb 23, 2017 at 10:52 PM, Art Zemon < art@zemon.name >> > wrote: >> >> Folks, >> >> I have been following this thread because I, too, am trying to >> decide which coax to buy for my plane. I'm a computer engineer; I >> shied away from EE in college and especially antenna design >> because... well... I heard that antenna designers were a special >> kind of crazy.. :-) >> >> Seriously, though, if I understand correctly, in the context of an >> installation in a homebuilt airplane, the biggest difference >> between RG58 and RG400 seems to be that the RG400 is less loss-y. >> Yes? In other words, if an antenna puts a weak signal in one end >> of the coax, the signal that reaches the radio receiver will be >> stronger if the coax is RG400 than if it is RG58. >> >> I'm looking at 10 feet of coax from the GPS and comm antennas to >> the receivers, including service loops. I am looking at 20 feet >> for the VOR/GS antenna. The transponder antenna will be less than >> 10 feet. >> >> At those distances, does RG400 vs RG58 matter? How do I evaluate it? >> >> And then there is the LMR-195 that Bob just showed us. How does >> that fit in? >> >> Thanks, >> -- Art Z. >> >> -- >> https://CheerfulCurmudgeon.com/ >> >> /"If I am not for myself, who is for me? And if I am only for >> myself, what am I? And if not now, when?" Hillel/ >> >> > > ________________________________ Message 16 ____________________________________ Time: 11:46:10 AM PST US From: Wladimir Kummer Subject: AeroElectric-List: Contactors Could one use a starter contactor as a battery contactor? I understand they are subjected to different duties but also understand the on/off action is when they are most abused. Would I be wasting too much power just by keeping the contactor on (power to the coils)? Wlad ________________________________ Message 17 ____________________________________ Time: 01:26:56 PM PST US From: Stephen Richards Subject: RE: AeroElectric-List: Contactors SSB0aGluayB5b3Ugd2lsbCBmaW5kIHRoYXQgdGhlIGNvaWxzIGFyZSBub3QgY29udGludW91c2x5 IHJhdGVkIGFuZCB3aWxsIGJ1cm4gb3V0IGFsc28gYSBiYXR0ZXJ5ICBjb250YWN0b3IgY29pbCBp cyBub3JtYWxseSBjb25uZWN0ZWQgaW50ZXJuYWxseSB0byArIHNvIC0gc2lkZSBpcyBjb25uZWN0 ZWQgdG8gZ3JvdW5kIHZpYSBtYXN0ZXIgc3dpdGNoLiBBIHN0YXJ0ZXIgc29sZW5vaWQgIGNvaWwg LSBpcyBjb25uZWN0ZWQgaW50ZXJuYWxseSB0byBncm91bmQgaW4gbW9zdCBjYXNlcw0KQ2xpdmUg DQoNCi0tLS0tT3JpZ2luYWwgTWVzc2FnZS0tLS0tDQpGcm9tOiAiV2xhZGltaXIgS3VtbWVyIiA8 d2xhZGltaXJrdW1tZXJAZ21haWwuY29tPg0KU2VudDog4oCOMjQv4oCOMDIv4oCOMjAxNyAxOTo1 Mg0KVG86ICJhZXJvZWxlY3RyaWMtbGlzdEBtYXRyb25pY3MuY29tIiA8YWVyb2VsZWN0cmljLWxp c3RAbWF0cm9uaWNzLmNvbT4NClN1YmplY3Q6IEFlcm9FbGVjdHJpYy1MaXN0OiBDb250YWN0b3Jz DQoNCi0tPiBBZXJvRWxlY3RyaWMtTGlzdCBtZXNzYWdlIHBvc3RlZCBieTogV2xhZGltaXIgS3Vt bWVyIDx3bGFkaW1pcmt1bW1lckBnbWFpbC5jb20+DQoNCkNvdWxkIG9uZSB1c2UgYSBzdGFydGVy IGNvbnRhY3RvciBhcyBhIGJhdHRlcnkgY29udGFjdG9yPyBJIHVuZGVyc3RhbmQgdGhleSBhcmUg c3ViamVjdGVkIHRvIGRpZmZlcmVudCBkdXRpZXMgYnV0IGFsc28gdW5kZXJzdGFuZCB0aGUgb24v b2ZmIGFjdGlvbiBpcyB3aGVuIHRoZXkgYXJlIG1vc3QgYWJ1c2VkLiBXb3VsZCBJIGJlIHdhc3Rp bmcgdG9vIG11Y2ggcG93ZXIganVzdCBieSBrZWVwaW5nIHRoZSBjb250YWN0b3Igb24gKHBvd2Vy IHRvIHRoZSBjb2lscyk/DQoNCldsYWQNCl8tPT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09DQpfLT0gICAgICAgICAgLSBUaGUgQWVyb0Vs ZWN0cmljLUxpc3QgRW1haWwgRm9ydW0gLQ0KXy09IFVzZSB0aGUgTWF0cm9uaWNzIExpc3QgRmVh dHVyZXMgTmF2aWdhdG9yIHRvIGJyb3dzZQ0KXy09IHRoZSBtYW55IExpc3QgdXRpbGl0aWVzIHN1 Y2ggYXMgTGlzdCBVbi9TdWJzY3JpcHRpb24sDQpfLT0gQXJjaGl2ZSBTZWFyY2ggJiBEb3dubG9h ZCwgNy1EYXkgQnJvd3NlLCBDaGF0LCBGQVEsDQpfLT0gUGhvdG9zaGFyZSwgYW5kIG11Y2ggbXVj aCBtb3JlOg0KXy09DQpfLT0gICAtLT4gaHR0cDovL3d3dy5tYXRyb25pY3MuY29tL05hdmlnYXRv cj9BZXJvRWxlY3RyaWMtTGlzdA0KXy09DQpfLT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PQ0KXy09ICAgICAgICAgICAgICAgLSBNQVRS T05JQ1MgV0VCIEZPUlVNUyAtDQpfLT0gU2FtZSBncmVhdCBjb250ZW50IGFsc28gYXZhaWxhYmxl IHZpYSB0aGUgV2ViIEZvcnVtcyENCl8tPQ0KXy09ICAgLS0+IGh0dHA6Ly9mb3J1bXMubWF0cm9u aWNzLmNvbQ0KXy09DQpfLT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PQ0KXy09ICAgICAgICAgICAgICAtIE5FVyBNQVRST05JQ1MgTElT VCBXSUtJIC0NCl8tPSBBZGQgc29tZSBpbmZvIHRvIHRoZSBNYXRyb25pY3MgRW1haWwgTGlzdCBX aWtpIQ0KXy09ICAgLS0+IGh0dHA6Ly93aWtpLm1hdHJvbmljcy5jb20NCl8tPT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09DQpfLT0gICAg ICAgICAgICAgLSBMaXN0IENvbnRyaWJ1dGlvbiBXZWIgU2l0ZSAtDQpfLT0gIFRoYW5rIHlvdSBm b3IgeW91ciBnZW5lcm91cyBzdXBwb3J0IQ0KXy09ICAgICAgICAgICAgICAgICAgICAgICAgICAg ICAgLU1hdHQgRHJhbGxlLCBMaXN0IEFkbWluLg0KXy09ICAgLS0+IGh0dHA6Ly93d3cubWF0cm9u aWNzLmNvbS9jb250cmlidXRpb24NCl8tPT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09DQoNCg0KDQo ________________________________ Message 18 ____________________________________ Time: 01:26:56 PM PST US From: Charlie England Subject: Re: AeroElectric-List: Contactors On Fri, Feb 24, 2017 at 12:54 PM, Wladimir Kummer wrote: > wladimirkummer@gmail.com> > > Could one use a starter contactor as a battery contactor? I understand > they are subjected to different duties but also understand the on/off > action is when they are most abused. Would I be wasting too much power just > by keeping the contactor on (power to the coils)? > > Wlad > > I think most starter contactors are rated 'intermittent duty'. assuming that's correct, you'd risk not just wasting current, but overheating the coil in the contactor. ------------------------------------------------------------------------------------- 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.