[amsat-bb] S Band Activity 08/2009

[John Papay]

Many of you have no idea what goes on when AO51 is in
the S band downlink mode.  Until this past week, I was
in the dark as well.  Who operates S band and what is it
like compared to the more popular V/U mode?  What kind
of equipment does it take to get on S band.  If you don't
have S Band equipment, should you invest in some?  Are
you going to work anybody new or perhaps a new grid?
After a week of making q's and listening to 29 passes of
S band, there is some data and observations to share.

A lot of people are using the K5GNA setup.  My setup was
quite different.  The antenna used was a Hyperlink
Technologies (now L-Com in Florida) 18dbi Wifi Panel
Antenna.  It is well made and comes with stainless mounting
hardware including a 2-1/2" U-bolt that will fit most any
mast.  It's about 2" thick and 14"x9" rectangular.  Price
is $50, not bad for a well made weatherproof outdoor antenna.
The Down East Microwave preamp kit and outdoor housing for it
is about $85.  The outdoor box is as expensive as the preamp
kit itself.  It was mounted on the antenna with a 7' 9913
pigtail.  The 45' of coax into the shack is 3/8" Andrew
Heliax.  In the shack is a Drake 2880 down converter with
a new crystal from G0MRF to get the output on 145 MHz.  Both
the preamp and the downconverter are powered through the coax
so you need two power inserters. I used a second radio for
the IF so that there was no chance of transmitting into
the downconverter. Doppler is about =/- 55 KHz from horizon
to horizon.  You can see what it looks like on the tower
on my qrz.com page.  Click the image to enlarge.

At first I was disappointed because I am used to hearing
435.300 down to the horizon in most directions.  It didn't
happen with S-band.  But after listening to other stations,
it was apparent that my setup was hearing better than most.
There has been discussion about the slow roll of AO51 and
that is certainly apparent, however, I could not hear much
below 6 degrees, ever.  Maybe a bigger antenna would help
out, but those that were active didn't seem to have any
better receive capabilities so it makes you wonder.

Now for the activity data.  Below is each pass that I
operated or listened to and the stations I worked (with
an asterisk) or ones that I just heard (no asterisk).

8/16/2009 2245Z (first S-Band mode pass)
KC9ELU* KJ4MC KD8CAO*

8/17/2009 0036Z
KC9ELU* N6PAA W7LRD

8/17/2009 1053Z
KC9ELU*

8/17/2009 1234Z
VE2DWE* KC9ELU* KD8CAO* KB2M* W8KHP N5ZNL*

8/17/2009 2359Z
W8KHP* N5ZNL* VE2DWE* W7JPI* K5WH* W7LRD* K9QHO*

8/18/2009 1151Z
WB8OTH* W7JPI* N5ZNL* W8KHP*

8/18/2009 1331Z
K9QHO* W7JPI*

8/18/2009 2128Z
WB8OTH* KC9ELU* W8KHP

8/18/2009 2305Z
W7JPI* KC9ELU N0JY* W8KHP* N5ZNL K9QHO KD6IRE? XE2BHL

8/19/2009 1116Z
KC9ELU

8/19/2009 1252Z
WB8OTH* XE2BHL* KC9ELU*

8/19/2009 2230Z
W8KHP* VE2DWE*

8/20/2009 0006Z
N5ZNL/P* N5UXT* N0JY* VE2DWE* W8KHP* WB8OTH W7LRD*

8/20/2009 1213Z
KC9ELU* KB2M* W8KHP* N5UXT* N5ZNL

8/20/2009 1353Z
AI7W* W7JPI* KC9ELU WB6QVU?

8/20/2009 2153Z
NO STATIONS HEARD

8/20/2009 2326Z
W7JPI W8KHP K9QHO W7LRD WHISTLER

8/21/2009 0111Z
2 DEGREE PASS, NOTHING HEARD

8/21/2009 1145Z
N5ZNL* KB2M*

8/21/2009 1314Z
KC9ELU* N5UXT* W7JPI*

8/21/2009 2246Z
KG4ZLB* WB8OTH* N0JY* W8KHP* AK5V*

8/22/2009 0029Z
AK5V* KB2M N0JY* W7LRD*

8/22/2009 1053Z
KC9ELU* KB2M*

8/22/2009 1234Z
KC9ELU* W7JPI* K8KHP*

8/22/2009 2207Z
KC9ELU*

8/22/2009 2347Z
WA5KBH* WD9EWK* N5ZNL* XE2BHL* KC9ELU*

8/23/2009 1156Z
W2NBJ* KC9ELU* WA4SCA*

8/23/2009 1332Z
KC9ELU* W7JPI* N5UXT* XE2BHL

8/23/2009 2127Z
KC9ELU* N1RCN*

Mike, KC9ELU was on vacation this past week and was the
most active station on S-Band. It was interesting to
compare our reception and have airtime to discuss it.

The only new guys I'm aware of were myself and N1RCN who
got things working on the very last S-Band pass.  Drew,
where were you?

Some have been asking for more S Band, but if you take a look
at the activity, it pales in comparison to what we have in
the V/U mode.  The last AO51 V/U pass tonight (8/25/2009
0007Z max elevation 17 degrees to the west for me) had at
least 23 stations on it.  More were trying.  It's a Monday
night!  I never heard more than 8 stations on any S-Band pass,
and there were plenty with just one, two or three.

If you have AO40 equipment laying around, you might be a
good candidate for S band.  But unless you are prepared
for a very high dollar investment/qso, you probably won't
be buying S-Band equipment to work the few stations that
get on that mode.  If you want to do L/S, there will most
likely be even less activity since making noise on 1.2GHz
is even more expensive.  (When L/S comes on, I'll have
another report.)  My antenna system could be improved but
there's not much point in spending more effort and putting
more windload on the az/el rotor to hear down to the horizon.

We need to balance the interests of everyone and that is
understood.  We need some V/S or L/S from time to time. I'm
not sure, however, that an entire week should be devoted to
it considering the usage.  Maybe a few days at a time would
make more sense.  You work on your equipment and get ready
for the three day period.  If your setup doesn't work, you
figure out why and get on the next time.  Shorter sessions
would focus the activity rather than spread it out over a
week's time.

We should do things that will interest new people in working
satellites.  V/U is the entry level for newcomers and we
should make that available as much as possible.  There are
other FM birds, but nothing compares to what AO-51 does to
attract new hams to satellite technology.  It's signal level,
available time/pass and morning/evening pass schedule over
the US are ideal.

There is a lot of debate over what we should be doing for the
future.  But it is as important to debate how we should use
the resources we have available to us right now.  My hope is
that this post will inspire some constructive comments and
discussion on this subject.

John K8YSE