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BruceP

Well Known Member
Hi all,
I'm looking to purchase the RG-58 cable for doing my antennas (looked at RG-400 but too expensive). When I go to the websites (Mouser, Digikey, etc.) there are 30-50 choices of cable to buy. I don't understand the differences and would appreciate some tips on the EXACT part numbers to order and best places to buy. Also, in my reading it has been suggested that RG-223 would be preferred for high power items such as transponders. Thoughts (and part numbers) on that would be appreciated as well. Thanks in advance for the help.
 
why?

Please do yourself a BIG favor: Bite the bullet, spend a little more for something that isn't considered garbage by today's standards. RG-58 is major "El Cheapo" stuff, dude. Sorry, but if you put $10K into your panel, what's a few dollars more for some top-of-the-line coax? Make the investment. You'll thank yourself later.
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I don't mean to be argumentative, just curious why folks think it's necessary to go big bucks on the coax if using radios that work fine with RG-58?
My 1947 Cessna 140 radios worked fine with RG-58 and my RV avionics installation manuals didn't preclude using it, so after looking at prices, I went to Fry's and picked up a large roll of RG-58 for pretty cheap and with the appropriate (inexpensive) crimp terminals and tools, it has worked just fine in my RV with SL-30 and GTX-327 transponder. And the harness I was required to buy with the avionics to maintain the warranty also came with RG-58 installed for the pigtails at the back of the radio trays that connect to the coax I installed in the RV.

Downside I see is that I'll have to replace installed coax with RG-400 if I ever upgrade the radios to something that requires it (I think the 430/530 series or similar maybe?). That would be a little bit of a pain, but really not that difficult with my installation.

I'll admit I went cheap in this area during the build, but did it knowing that if I was unhappy with the performance, I could upgrade the coax relatively easily. With almost 170 hours on the RV so far, I haven't found it necessary yet.
 
OneCharlieKilo said:
I don't mean to be argumentative, just curious why folks think it's necessary to go big bucks on the coax if using radios that work fine with RG-58?
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Just wondering, how much vinyl (PVC) jacketed wire did you use in your airplane besides the RG-58?

--Paul
 
Just wondering, how much vinyl (PVC) jacketed wire did you use in your airplane besides the RG-58?
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None. Why, is there concern that RG-58 presents a significant insulation fire hazard? Most of the arguments I've heard on coax debates are along the lines of performance concerns which is a different issue than the wire insulation question you raise, which I consider a safety concern not a performance question. Obviously I wouldn't expect my coax cable to get as hot as a current carrying wire in the electrical system or to be at risk of shorting to ground and causing an RG-58 insulation fire.

But back to my original question, is there a performance penalty folks think is being paid for using RG-58 vs RG-400?

And to Bruce's orginal question, I'd use whatever version they have in bulk at local Fry's Electronics, Radio Shack, Home Depot, etc. It works for many radios and transponders, and no I don't consider it a hazard comparable to using non-Tefzel wire in your electrical system.
 
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Sky Geek sells RG58 and RG400.

RG58 is $0.42 per foot

Mil Spec RG400 is $1.89 per foot.

Bearing in mind the small amount of cable that is required, the overall cost saving is a pitance compared to the total cost of the airplane.

I suppose some people build on the NASA principle that the lowest quote wins the contract.

Sorry not this builder. I will use the best parts for the job, even if it means spending extra. Of course I will shop around for the best deal.
 
Holy smoking wire.

OneCharlieKilo said:
None. Why, is there concern that RG-58 presents a significant insulation fire hazard? Most of the arguments I've heard on coax debates are along the lines of performance concerns which is a different issue than the wire insulation question you raise, which I consider a safety concern not a performance question. Obviously I wouldn't expect my coax cable to get as hot as a current carrying wire in the electrical system or to be at risk of shorting to ground and causing an RG-58 insulation fire.
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I accidentally shorted my ELT RG-58 antenna wire to the battery while doing some maintenance in the tail of my RV-8. The entire length of vinyl insulation burned in less than three seconds and emitted noxious smoke so thick that I couldn't even see what was burning. If this had happened while flying I would have had to jettison the canopy to survive.
I don't know how burning RG-400 compares, but it couldn't be worse.
 
I suppose some people build on the NASA principle that the lowest quote wins the contract.

Sorry not this builder. I will use the best parts for the job, even if it means spending extra. Of course I will shop around for the best deal.
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That's the great thing about experimentals - you get to consider the pros and cons and make your own decision, hopefully without taking the time to insult those who choose a different, cheaper, safe alternative. Sure, I understand RG-400 is new and improved over RG-58, but not in real world performance as far as I can tell. If others have information on actual performance differences between the two, I'd be interested in seeing that data posted.

I'm happy with the performance I've got with my radio and transponder and I expect Bruce will be too. What he really asked was for source recommendations, not unsubstatiated opinions and implications that planes with RG-58 are unsafe to fly (they're not - there are a lot of them out there).

It's quite a stretch to imply that my, or Bruce's, decision to use RG-58 somehow makes our planes unsafe.....we're not talking about Tefzel vs PVC insulation wiring, or hardware store bolts vs AN bolts, etc. We're talking about coax cable and antenna performance.

The decision to use RG-58 does not mean I built my plane with a "lowest bidder" mentality or cut corners on safety; I assure you that neither is true.
I chose to put any "gold plating" money towards safety items like engine, prop, fuel systems, etc rather than performance of installed coax that I can change out if desired to RG-400 or otherwise should it prove necessary. As it turns out for my VFR mission and pretty basic avionics, RG-58 works great in my RV. And RG-58 worked great for the 5 years I owned my Cessna 140, and decades before that according to the logbooks.

Ron - thanks for adding your experience. If any of my cabling ran near my battery, I'd probably change that out or move the battery.
 
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islandmonkey said:
I suppose some people build on the NASA principle that the lowest quote wins the contract.
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If you were a US taxpayer, you'd probably realize that the government doesn't actually work this way...(as a taxpayer, I sometimes wish it did....):D;)

Seriously, there are hundreds of thousands of certified airplanes flying around with RG-58 (or earlier) coax for antenna wires, and they aen't falling out of the sky and burning up every day. I wouldn't be so hard on someone who decides to go with an industry standard that is known to work.

Sure, improvements come along, and it is nice to use them when you can, but just because a person doesn't buy the absolute latest stuff is no reason for ridicule.

My opinion, of course - have used RG-58 for decades - will go with 400 on the new airplane because the avionics spec says to...

Paul
 
ronschreck said:
I accidentally shorted my ELT RG-58 antenna wire to the battery while doing some maintenance in the tail of my RV-8. The entire length of vinyl insulation burned in less than three seconds and emitted noxious smoke so thick that I couldn't even see what was burning. If this had happened while flying I would have had to jettison the canopy to survive.
I don't know how burning RG-400 compares, but it couldn't be worse.
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Now I know where your callsign (Smokey) comes from. :D
 
I bought mine from Aircraft Spruce - offers 2 RG-58s

BruceP said:
Hi all,
I'm looking to purchase the RG-58 cable for doing my antennas (looked at RG-400 but too expensive). When I go to the websites (Mouser, Digikey, etc.) there are 30-50 choices of cable to buy. I don't understand the differences and would appreciate some tips on the EXACT part numbers to order and best places to buy. Also, in my reading it has been suggested that RG-223 would be preferred for high power items such as transponders. Thoughts (and part numbers) on that would be appreciated as well. Thanks in advance for the help.
Click to expand...

When I was installing my new SL-30 a few weeks ago I needed a short coax cable from the special splitter (which Aircraft Spruce does not carry but can get it for you in a week or so but Garmin AT says is required to preserve the glide slope signal if you plan to use a single NAV antenna to drive the SL-30 as well as another NAV radio - Terra in my case) to the second NAV radio (input to the existing divider in my case). Aircraft spruce offers 2 types of RG-58 and RG-400. I was under a tremendous schedule crunch but not a severe money crunch so I bought all three and a full set of the compatible connectors (I already had the high quality ratcheting coax crimper from the original build). I installed one of the RG-58s, and as it does for all of my other coax in the airplane, it is working fine. In your case where you are under a money crunch I would go to a reputable aircraft supply company and buy the cheapest RG-58 and use it with confidence.

Bob Axsom
 
All of the...

Garage Guy said:
Just wondering, how much vinyl (PVC) jacketed wire did you use in your airplane besides the RG-58?

--Paul
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...strobe wiring provided by Whelen - running higher voltages and curreents than your antenna co-ax...
 
RG-58C/U (stranded center conductor) is what you are looking for.
Check Amazon. Buy a cable assembly and cut off what you don't need.
Maybe Radio Shack, but the tradeoff will be price vs. shipping.
 
az_gila said:
...strobe wiring provided by Whelen -
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Yes. That really does bother me. It's "certified", too.

In our plane, there's also the handheld GPS connections (GPS antenna, XM antenna, data/power cable); the modular telephone cable to the ELT (actually its antenna cable is RG-58 too... will be replaced with RG-400 when we upgrade to 406MHz); and of course various temporary panel connections (headsets, Ipod, cell phone etc.).

But besides the temperature considerations, PVC jacketed wire is not as abrasion resistant as tefzel; it doesn't pull through conduit nearly as well; it snags on dikes when snipping cable ties... Overall, a pain to deal with, even if you're never soldering it.

--Paul
 
RG-58 vs RG-400, etc

All,
Sorry to ignite a big debate but appreciate all points of view and appreciate the advice so far. I had done some of my own research, particularly 2 articles. The first was Jim Weir's in Kitplanes from February 2007 (http://www.kitplanes.com/issues/pdfs/0207-6566.pdf) in which he did a comparison of coax cables after reading Marc Cooks article in the November 2006 issue (http://www.kitplanes.com/issues/pdfs/1106-5456.pdf). This is also where I got the idea for using RG-223 for the transponder. Anyway, this was the foundation of my original question and thought you all might like to read them.
 
fl-mike said:
Buy a cable assembly and cut off what you don't need.
Maybe Radio Shack, but the tradeoff will be price vs. shipping.
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Most store-bought RG-58 assemblies nowadays are nothing but made-in-China rubbish. The "shield" is a layer of aluminum foil wrapped around the center conductor, and a sparse tiny number of frail copper strands loosely wound around the the foil. You'll have a heck of a time making a good ground connection using a standard BNC connector on this garbage coax.

The good mil-spec RG-400 coax has much lower dB loss per foot than even the best Belden RG-58 coax. That alone is worth the extra expense to me. Might make the difference in several miles of extra range for your comm/vor/ils.
 
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