[amsat-bb] AO-40 receive freqs

[Art Goldman <aegoldm@xxxxxxxxxxxx>]

I'm  kinda in the bag this morning because I stayed up to
try my new AIDC-3733 converter on the late AO-40 pass last
night (East Coast USA).

Unfortunately, I didn't hear anything, so in pondering the
myriad of variables, I thought I would poll the collected
knowledge here on the BB and try to nail down some of them.

So first, for an unmodified 3733, where should I look for
the receive signal (let's ignore doppler for the moment).
I've seen both 123 and 125 Mhz mentioned as the downconvert
from 2401 Mhz. Which is right? What would be my base receive
freq for the beacon before applying doppler correction?

Now doppler. Winorbit showed something like -25Khz. It
sounds right to me but thought I would ask anyway.

Finally, a couple of lessons learned (by me). RTFM! I was
powering the converter from my FT-847 which puts 12V on the
antenna port when you set the proper menu configuration for
VHF Ant, AND you turn on the RF Amp from the front panel. So
that's the first lesson learned -- thanks Bernie K3BAZ. The
second lesson was that the 3733 has a 12V regulator, so
sending 12V to it isn't going to cut it. If only I hadn't
misplaced the info sheet... Time to make a bias tee.

FYI for all those who ordered DEM converters -- ours came
yesterday, so they are shipping now. I'll try mine in the
next couple of days. I think they will work on the 12V from
the 847 because they use a 9V regulator. I have two
Philips-Tech SPG-36 parabolic grid antennas. I replaced the
feed assembly on one of them with the 3733. Took some
digital pictures which I'll put up on my web site tonight.
Very neat installation. So, with both antennas mounted on
either side of the rotator, I should be able to do a pretty
good comparison of the two units. Stay tuned.

By the way, Sam at Philips-Tech (
http://www.philips-tech.com/main.asp?page=page6.asp ) tells
me the focal length of the SPG-36 is 15 inches. (He also
mentioned that they have plenty of stock now.)

In any case, any other pointers you all can provide WRT
working AO-40 would be greatly appreciated.

Tnx and 73,
Art N3OY


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