[amsat-bb] Re: Questions on practical aspects of coax and preamps.
Gordon JC Pearce MM3YEQ
gordonjcp at gjcp.net
Sat Oct 25 06:43:30 PDT 2008
Curt Nixon wrote:
> 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.
I built a simple "Arrow-style" antenna using the WA5VJB Cheap Yagi
designs. One on 2m, one for 70cm, at right angles to each other, with
an HB9ABX-design diplexer for the two. I use this handheld with my
Kenwood TH-F7E HT and get into AO-51, SO-50 and AO-27 without any real
difficult. Total time for construction about an hour ;-)
If you've got an antenna analyser or even just a good SWR meter, it will
help a lot with getting the 2m part right. I didn't bother tuning the
diplexer much for 70cm because the MFJ-259 antenna analyser I was using
didn't cover UHF - so I just woke up a 70cm repeater on the other side
of town and tuned until I could hear it best.
I find it hard to get into AO-51 when it's busy and people are hammering
it with huge stacked arrays of antennas. When it's in QRP mode I get in
no bother at all, with good reports from all over Europe. Not bad for
an aerial build out of a bit of scrap wood, some brazing rods and a few
feet of hydraulic pipe ;-)
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