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Permalink Reply by Greg Browning on December 20, 2010 at 7:04pm

I bought my antenna from a local shop and the owner said he would crimp the ends when I determined the legnth.. When it came time to do that he charged me 8 bucks per end just to give it a squeeze with his crimpers! Should have just bought my own...Greg

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Permalink Reply by Dave Gardea on December 20, 2010 at 7:53pm

Pat, I bought a set of the BNC crimpers at http://www.bandc.biz/bnccoaxconnectorcrimptool.aspx for $40. I was able to make all my own coax connections with these and they worked great //Dave

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Permalink Reply by Michael Herder on December 20, 2010 at 8:26pm

You can get the jaw inserts for b and c connections, and just get different inserts for the insulated and unisulated crimps you'll have to make.  Get a coax stripper remember that you only get one shot with the little pin end that comes with the femail end, they don't sell those separatedly.  Ask me how I know.

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Permalink Reply by Bill Carter on December 20, 2010 at 9:07pm

Pat, Believe it or not they do make BNC connections that screw on and work very well. I used to use them in another business and got them at Radio Shack some years, I am sure that someone still makes them. Or if you have a friend who works for the local cable TV installers you might be able to borrow a set or just get your cables ready and stop by to see if they will crimp them for you. Finally, if you're ever near the Zenith factory give me a call, Bill, 573-721-4400, I will be happy to loan you mine. Don't spend $120 for a one time use.

Bill Carter

American Light Sport Aircrafters

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Permalink Reply by Jim Belcher on December 21, 2010 at 10:10am

I wonder a bit at the quality of the electrical connection of the "screw-on" type coaxial fittings. I believe they were really intended for receive-only applications, and not necessarily for some of the transmit applications found in aircraft. The transponder, for example, is outputting anywhere from a 100 watt to 250 watt pulse in a light aircraft.

 

A high resistance joint there can lead to an impedance mismatch, and power being reflected back into the transmitter, causing damage. It's not a risk I would take, although I have used these connectors in receive-only applications.

 

I build all my cables, since most of the commercial cables were intended for receive-only applications.It is desirable that the cables be of the exact length (plus a small service loop), since the longer the cable is, the most signal loss occurs. There is also the extra cable length to hide somewhere, plus a minor amount of additional weight. Unless you pay someone to make a custom cable, the only way to solve this is to build your own.

 

Early in construction, I bought a hydraulic wire crimping tool (Central Hydraulics Model 66150) from Harbor Freight for something like $70. It has a variety of dies, ranging from #12, to #00. I used it to crimp my battery cables, and also the coaxial connectors (I used BNC-58s from All Electronics, (www.allelectronics.com)). Mouser and Digi-Key are also good sources for coaxial connectors and cable.

 

I am aware that the tools one gets from Harbor Freight often have limited life spans. However, no more connectors than one has to crimp in a Zenith Aircraft, I would be surprised if the crimping tool did not survive the experience. So far, it has for me.

 

That's my 25 cents worth, reminding everyone as always that 25 cents won't buy what it once would.

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Permalink Reply by Bill Carter on December 21, 2010 at 11:31am

Jim,

It sounds like the voice of experience so I will have to defer to you. However, I have successfully used these screw on connections for both applications successfully.

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Permalink Reply by Jim Belcher on December 21, 2010 at 2:30pm

Bill, I wouldn't challenge or question your success in this area. My concerns would be 1) how repeatable it may be with this type connector, and 2) if the connection will hold up over time. I see it as something that may work,  and may also cease to work without much warning. What can happen if it doesn't work, or quits working, is just too high a price for me to take the chance.

 

However, one of the nice things about home builts is that one can weigh the alternatives, and make the best personal choice. There are almost certainly some areas in my plane where more knowledgeable people in that area might not make the same choice as I did.

 

This means my radios may work fine, but the wings may fall off. :-)

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Permalink Reply by Bill Carter on December 21, 2010 at 7:20pm

Jim,

I sincerely hope that does not happen.

Having deferred to your expertise in this area I would agree that the screw on type would not be the best choice for this. Just because it happened to work for me previously doesn't make it the best way or even an acceptable way of doing it.

After all, another nice thing about home builts is the community of people that we have to draw knowledge from in areas such as this. I hope that I never reach the point that I feel like I know it all.

Thanks for your correction and best of luck with those wings staying on in flight.

Bill

 

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Permalink Reply by Jonathan Porter on December 22, 2010 at 12:42pm

For the record, we tried the screw on type from Radio Shack (because somebody brought those out instead of the crimped type) - and they were a disaster.... received fine, but we had to hold the connection down by hand to transmit if out of the circuit... that is my 25cents worth, which wont even pay for a one minute phone call to the USA from here!

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Permalink Reply by Jim Belcher on December 23, 2010 at 1:51pm

Jonathan, that's the kind of thing I'm afraid of - poor reliability. It sounds like the coax did not make really good contact with the body of the connector, giving an impedance mismatch.

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