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RE: AO-51 V/S tonight



Hi Ed:

Thanks for the reply !  I made 4 QSO's this morning using the home station
on AO-51 while in V/S mode. Really nice signal too, but lots of illegal
activity south of the border causing much QRM. My first thought about my
portable situation is that the receive characteristics at 123 MHz are not
optimal with this HT. Well, I have a DEMI downconverter that converts to 144
MHz, so I'm going to try that next. Your other point that a 5 turn helix may
be too directional I have also thought about. Rather than waiving
frantically in the dark trying to get a decent signal long enough to grab
the mike on the other radio, and then hope you can get back to the receive
rig and deal with pointing and Doppler long enough to get a complete report
(!), I thought about a simpler, less directional antenna - perhaps a patch.

Anyway, I'll keep plugging away ... it's certainly a challenge ! BTW, if you
are rigged for 160M, I need KL7 for my last one for 160M WAS.

73, Jamie
WB4YDL


Jamie,

First off, I have yet to try hearing AO-51 on mode-S, so I have no
first-hand knowledge of reception characteristics.  

A few questions to ask yourself:
1)  You state that you "opened up" the TH-77A.  I assume you mean to
receive frequencies not standard to the radio.  Have you determined how
good it recieves at 123-MHz?  If not retuning was done it might be quite
poor.

2)  How did you connect the s-band convertor to the helix:  directly or
thru coax?  These converters are not real low noise, so its very important
to connect them directly without using coax.  At 2.4-Ghz even a foot or two
of RG-8 will increase the noise figure significantly. 

3)  The 5-turn helix has quite bit of directivity (gain = 10-dB, about the
same as an 8-element yagi).  You need to point it.  Don't expect to point
it straight up for the whole pass.  I'm just wondering from your mentioning
mobile operation.

4)  Recheck all your connections, dc-voltages, IF cables.  If it has not
been used for some time one of these may the culprit.  Do you have a
2.4-GHz signal source?  Does it produce as loud a signal as when you used
it for AO-40?  Inspect the helix carefully for bad solder joints or
corrosion.

5) Keep trying :-)

73's,
Ed - KL7UW  <new call>
===================================
BP40iq,  Nikiski, AK      http://www.qsl.net/al7eb
Amsat #3212
Modes: V - U - L - S
===================================
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