[amsat-bb] Re: Frustration

Bruce Robertson ve9qrp at gmail.com
Sun Nov 29 16:29:27 PST 2009

On Sun, Nov 29, 2009 at 8:02 PM, Michael Tondee <mat_62 at netcommander.com> wrote:
> I've been trying to get my receive setup going the last few days but I'm
> having horrible results. I have my 11 element 70cm "cheap yagi" back up
> on the mast and my homebrew SaebrTrack and OR-360  AZ/EL TV rotator
> system interfaced to SatPC32.
>  I have an ARR preamp mounted at the mast fed with a seperate 12VDC
> feed and about a 40 foot run of  JEFA  brand LMR 400. Once I get into
> the shack there is a bit of patchwork to the cables. I'm using a Yaesu
> VX3 to receive and due to the SMA connector on the HT and not wanting to
> strain it I have a 4 foot adapter cable  of  LMR 100 that goes from an
> SMA to a SO-239. I then have to use a short length of coax with a PL-259
> to N male to mate up with a N barrel connector connected to my LMR 400
> coming from outside. Now obviously, I know this isn't optimum and eats
> up valuable RF and I intend to change it ASAP  but I'm hearing
> absolutely nothing on AO-51 passes. Not even the hint of signals.
> I'm thinking with that preamp in the line I should at lest hear
> something discernible besides noise regardless of the patchwork of
> cables. Am I off base in thinking this? I did catch just a bit of
> discernible signal off  SO-50 last night but it was almost overhead.
>  I'm not a beginner at this but I'm frustrated. Perhaps I'm putting too
> much faith in the preamp to push the signals through my hodgepodge of
> adapters and cables? Any thoughts are appreciated.
> 73,
> Michael, W4HIJ

Michael --

I think something is quite amiss here, perhaps a connector is bad or a
bad joint in one of the cables. I bet a couple of hours with a
volt-ohmmeter will find the guilty party. Alternatively, you could be
in a bad noise situation.

By way of comparison, because of my digital project right now I have a
very minimal station, with a 70cm vertical antenna soldered directly
onto a N-connector. About 10' of LMR400 goes to the preamp, which then
has another 100' of cable to my FT-817. AO-51 is not great copy, but I
know it is there. Similarly, all the usual cubesats in CW mode, and
SEEDS (CO-66) with its fine FM signal of cheering Japanese

(Actually, this got me thinking that SEEDS would make a pretty good
way of evaluating two side-by-side receiving systems. Pass the
resulting wav files through a SSTV decoder, and the one with the
better picture wins!)

You might consider making a very simple vertical antenna, attaching it
to one end of the preamp with a very small patch cord between it and
the radio, and using that as a kind of baseline.

73, Bruce

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