[amsat-bb] Re: WD9EWK's first time on AO-51 V/S tonight

Patrick STODDARD (WD9EWK/VA7EWK) amsat-bb@wd9ewk.net
Sat Sep 2 08:58:40 PDT 2006

Good morning, Andre!

> Reading your story I set out this morning in my backyard trying to make
> a mode V/S QSO on AO-51 using my portable setup. I already tried
> receiving AO-51 mode S some time ago and that went very well but never
> tried uplinking.
> The first pass this morning at 0805 UTC was not very good as the
> trajectory of the satellite was blocked several times by houses of
> neighbors and trees. I managed to copy myself once though.
> The second pass, 0945 UTC, was much better. I didn't hear many stations
> but managed my first V/S QSO with ON5SA :)

Congratulations!  The uplink part for V/S is easy, as it is the same thing as
V/U except there is no PL currently required.  I had no worries I could do
that, but needed to get the downlink and all those issues sorted out when I
tried it for the first time.

> I used a K5GNA downconverter with a homebrew hybrid quad antenna
> connected to a Icom IC-R20 all-mode receiver. The hybrid quad antenna
> with the downconverter were mounted on a tripod.
> Uplink was a FT817ND (5W) using VOX with a headset with mic. Uplink
> antenna was an hand-held Arrow.

I could use my FT-817ND in the same role, but I decided to stick with
HTs as my TX and RX radios since I had already used them for more
satellite work than the 817.

> I think that it's better to mount the Arrow on the tripod and hold the
> K5GNA in my hand as it is much easier changing polarisation that way.
> Something for next time ;)

Or if the downconverter and its antenna were mounted on the Arrow, so it
is a V/S antenna and then maybe the tripod.  I saw pictures of someone
who put an S-band downconverter on their Arrow antenna, and that would
have been very helpful.  Could I stand outside and hold the V/S Arrow for
an entire pass while transmitting and keeping up with the receive Doppler?
Not sure, but something to think about.

> Also, my backyard is not ideal for mode V/S experiments as much of the
> lower elevation sky is blocked by plants/trees or buildings.

My home QTH has mountains about 2-3 miles (3-5km) to the south and
southwest.  Not very good for those directions, even for V/U.  Outside my
office near downtown Phoenix and at a park near my house, I can do
better and work lower passes without many problems.  My backyard is
also not a great place for satellite experiments; the front yard is a little
better except those mountains are still there.

I have other 2.4 GHz antennas, including some for WiFi stuff, that I might
try.  I've probably run out of time for much S-band experimentation for this
week, but now that I've made some QSOs I will try for more the next time
V/S returns to the AO-51 schedule.  Or try to improve my L-band setup
so I can make some L/S and L/U QSOs from a portable/temporary setup.



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