Re: [amsat-bb] New to satellites, with coax question

[Bruce Nolte N3LSY <n3lsy@xxxxxxx>]

>Hi everyone,
> I'm new to the satellite game but it's something I've always wanted to 
>try. I'm on a tight budget but I've finally decided to give some of the 
>LEO FM birds a try anyway.
>I have some 9913 cable here and I'm thinking I might want to hook it up 
>to a homebrew 70cm beam on a rotator. I want to use a short length of 
>something more flexible to feed the antenna like maybe RG8-U to avoid 
>the twisting of the rotator maybe breaking the center conductor of the 
>9913. What's the best way to make the connection between the short 
>length of RG8-U and the 9913?  An actual splice or some type of 
>connectors? I don't want something lossy there that will defeat the 
>purpose of using the 9913. Also, my radio has an N connector on the 70cm 
>antenna jack. An N to SO-239 adapter there would be a no no as well 
>wouldn't it because of signal loss in the adapter, right? I'm trying to 
>get as much signal to my receiver as I can without a preamp which I 
>don't have funds for.
>Tnx and 73,
>Michael, W4HIJ
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>  
>
How far do you have to go with the cable? If your rotor setup is only a 
25 or 30 foot run from the shack, then the type of cable is less 
important. As Gary said, keep the number of connections low, and avoid 
the use of adapters if at all possible.  Particularly at UHF, using 9913 
or LMR400 is a good idea, but you have to be careful to make sure you 
waterproof your exterior connections. I have had pretty good luck with a 
3 step process: Pack Coax Seal around the connectors themselves, then 
wrap the whole connection with self-vulcanizing rubber tape, such as 
Bishop Tape. Bishop Tape makes a good watertight seal, but it tends to 
deteriorate when exposed to sunlight, so I overwrap the Bishop Tape with 
a good grade of Electrical Tape such as 3M Temflex 33. A final touch is 
to secure the free end of the electrical tape with a small sun-resistant 
tywrap. I had antennas up for 7 years using this process, and it worked 
well.  The Bishop Tape does a pretty good job, and I have seen CATV 
installers use it in protected below ground, but damp junction boxes 
without any supplemental seals, and I might try  using just the Bishop 
Tape and the overwrap with electrical tape on some accessible connectors 
when I reassemble the antenna system. If they hold up, well, I will do 
the same with my HF and VHF/UHF antennas that will go on my tower when 
it goes back up.
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