[amsat-bb] Questions on practical aspects of coax and preamps.
cptcurt at flash.net
Sat Oct 25 06:00:30 PDT 2008
Good Morning All:
So, after this last week of ISS fun, I have the bug to upgrade into some
simple satellite work. I will be confined to simple FM untill I can
upgrade to all-mode rigs. My question is on coax and preamps.
I will use a pair of vertically polarized yagis to begin with. One for
144MHz and one on 70cm. I have some LMR 400 I got for the ISS project
on 144 but it is so stiff, I didn't use it.
1. If you use LMR 400, do you add flexible sections at the antenna end
and in the shack, using LMR400UF?
Or, should I just use all UF and forget the additional connections? The
cost of the additional connectors (N) both in loss and $$ is probably
advantage $ for UF. Not sure about the loss potential for adding two
sets of interface connections.
2. With a 5-7 element yagi on 144, is it really necessary to use low
loss coax as a opposed to 8x or 8x mini.
Runs here are 35' if munted at 12' and 60' if mounted to roof tower at
3. On 70cm, I plan to add a mast preamp, but will use the yagi
"barefoot" to begin with. With a preamp at the antenna, is low loss
coax still required or can the cost increment be put to better use in
the preamp to begin with? The preamp of course also gives a convenient
place for a connector interface from stiff to flexible if desired.
Anyway...I appreciate input from those that have been there and done that.
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