[amsat-bb] Station advice: coax

[Mark D. Johns]

With that kind of coax run, you'll definitely want the lowest loss feedline
you can afford, and you'll probably want the pre-amps sooner than later. If
hard line is out of the picture, LMR 600 is a good alternative. Several
outlets will sell custom lengths with connectors attached. You can get by
with LMR 400 or Belden 9913 on the 2 meter side, but loss at 435 MHz will
be greater. I would avoid the diplexer like the plague.

As GEO mentioned, you really only need the flexy stuff at the point where
things are rotating. I run LMR 600 to the pre-amp, just below the rotor,
and ultra-flex from the pre-amp to the antenna. A good, moderate-cost
alternative for pre-amps are the "Mini" pre-amps from SHF Elektronik in
Germany http://www.shf-elektronik.de/en/
--
Mark D. Johns
KØJM / MØGZO / ex-9H3DJ / ex-KØMDJ
Brooklyn Park, MN USA   EN35hd
-----------------------------------------------
"Heaven goes by favor; if it went by merit,
   you would stay out and your dog would go in."
    ---Mark Twain


On Sat, Nov 17, 2018 at 1:12 PM GEO Badger via AMSAT-BB <amsat-bb at amsat.org>
wrote:

> Keith,
> You want the lowest loss coax you can afford for your run. ½" hard line
> would be a good choice, though not inexpensive and neither are the
> connectors. Plus it is rather rigid and can be difficult to handle.
> Terminate it at the rotator and use a flexible jumper from there to the
> antennas.
> To use a diplexer you'll need one at both ends, assuming 2 antennas.
> Recall that a diplexer will have insertion loss of >3 dB. And that I don't
> believe they will pass DC. Though I haven't ever checked that. ---
>  Ciao baby, catch you on the flip side.
>  GEO
>
>  http://www.w3ab.org
>
> Time flies like an arrow, fruit flies like a banana.
>
>       From: "Keith E. Brandt, WD9GET" <wd9get at amsat.org>
>  To: amsat-bb at amsat.org
>  Sent: Saturday, November 17, 2018 10:11 AM
>  Subject: [amsat-bb] Station advice: coax
>
> There's been a lot of good station advice on the reflector recently that
> I've really appreciated. I'm slowly but surely building up my sat ground
> station. I've got my Yaesu G5400B connected and running and I've got an
> antenna plan. The next issue is running coax.
>
> What's the recommendation on coax runs? It looks like I'll have between
> 75 and 100 ft from the shack to the mount. I can envision running a
> separate line for 2m and 440, but is it also effective to use a diplexer
> at the antenna? Does that limit my ability to later add a mast-mounted
> preamp with power-over-coax? (I'll probably add preamp(s) at a later date)
>
> Is the ultraflex coax really necessary for hooking up around the
> rotator? I'm sure it's better, but is it really worth the extra cost? I
> certainly don't want to pay the high price for ultraflex for the full
> run, especially if I'm using two lines.
>
> Thoughts appreciated.
>
> 73,
> Keith
> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Keith E. Brandt, MD, MPH
> /wd9get at amsat.org/
>
> /Christianity and science are opposed… but only in the same sense as my
> thumb
> and forefinger are opposed- and between them I can grasp everything.
> /—Sir William Bragg (Nobel Prize for Physics- 1915)
>
> *This message transmitted with 100% recycled electrons
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
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