[amsat-bb] Re: FD Postmortem: was "a cheap LEO tracker for single op"

i8cvs domenico.i8cvs at tin.it
Wed Jun 26 14:29:32 PDT 2013

Hi Bill, W1PA

You are tuning the uplink 432.125 MHz (LSB) and 145.975 MHz (USB)
for down link but so you are at the very edge of the transponder passband.

I suggest to tune the uplink in the middle of the passband at 432.150 MHz
(LSB) and while transmitting a CW string of dots tune very slowly the
downlink in the middle of the passband around 145.950 MHz (USB) moving
the RX tuning knob a little bit up and down on frequency until you hear
your CW coming back.

The rest of your station seems to be all OK.

Have fun.

73" de

i8CVS Domenico

----- Original Message -----
From: "Bill (W1PA)" <w1pa at hotmail.com>
To: <amsat-bb at amsat.org>
Sent: Wednesday, June 26, 2013 8:35 PM
Subject: [amsat-bb] FD Postmortem: was "a cheap LEO tracker for single op"

A quick follow-up and some questions.

I made it to the FD site about 11pm local.
Schedule had two passes of SO-50 (1am and 3am) and two
passes of AO-7 (at 4am and 6am local).

Let's focus on AO-7. I had my FT-847, two 10 ft lengths of coax,
and the trusty Arrow dual-band.
I had my Ubuntu netbook with gpredict and a printed frequency list.
I ran AO-40 full manual back in the day (no computer
assist or Doppler) --I can do this, right?:

AO-7 (B) 432.125-175  up, 145.975-925 down.

Load 432.125 on the main VFO, and 145.975 (USB) on the secondary. Set Sat
mode, (tracking REVERSE)
Hear the bird great --   can’t find my downlink. Nada.  Voice or CW.
Confirmed 432 TX and power out with a meter --  ran up to 30 watts in. Moved
the sub-tune up and down on the RX side for Doppler (at least 15khz each
side).  Coax was connected correctly.

Nothing on the next pass either....  excellent hearing, can’t find myself.
Bird is directly overhead. Epic fail.

So what did I do wrong?  Did I have a de-sense issue because of the crossed
yagi?  Enough power? What sideband should the uplink have been (LSB,
correct)? Even if it was wrong, I should have heard CW, right?

Bill  W1PA

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