[amsat-bb] Re: SO-50 under-utilized over North America

John Mock KD6PAG kd6pag at amsat.org
Wed Nov 8 19:39:49 PST 2006

> SO-50 is one of the sats that I am going to try out because all I have
> is an FM handie-talkie.  I've built an (admittedly heavy!) antenna
> which is a 6 element 70cm beam and a 4 element 2m beam joined
> together, but I'm not sure if it will have enough gain for SO-50, my
> H/T will only do about 4W max, and if possible I'd like to run it at
> 0.5 or 1.5W to extend the battery life.

Good.  That should give you gain comparable to an Arrow, that is, about
10dBi at 70cm and 6dBi at 2m.  Be careful how you feed it; as you will
probably need a diplexer if you not using different radios for transmit
and receive.

> I noticed your signature line "Satellite QRPer" so I thought you might
> know if I ought to be able to transmit only 1/2W and have a reliable
> QSO.

In the absence of QRM, 1.5W should be enough to work both coasts with 
your antenna and you will probably do fine with 1/2W.  I doubt if you'll 
need 4W.  I rarely run more than 1W myself (and generally only when i'm
roving and want to make sure i don't miss anyone).

>> transcontinental passes on SO-50

> What does that mean?  I'm looking at a pass for example which is at
> 00:20 tonight EST, which goes South to North just west of Florida
> right overhead Ottawa.  Is that what you meant by a transcontinental
> pass?

I don't think that pass covers the West Coast, but the next one does:

Thu 09Nov06  07:16:45 07:23:00 07:29:20  00:12:36  256 322  30  21.4  Ottawa
Thu 09Nov06  07:10:15 07:16:00 07:21:40  00:11:25  166 109  52  14.6  SFBay
  SO-50       07:16:45  07:21:40  4.9 min overlap (Thu 02:16 EST/23:10 PST)

Transcontinental are passes on which both the East Coast and West Coast
can be heard.  On the West Coast, that's an azimuth between about 20 and
160 degrees; on the East Coast, between 200 and 340 degrees.  (Over the
middle of the US, these would then be overhead passes.)  You can also
ascertain this information graphically if your satellite prediction 
program offers a map as well as numeric displays.  (The one that i use
only does this in real-time, and not for predictions.)

> Anyway I've got the radio all programmed up and ready to go.  The next
> reasonable pass that I will be able to try is the one on Saturday
> morning at 8:20am EST.  It comes to me from the West and so it should
> be very busy by the time it gets to me... anyway I'll have a go!

I looked at that pass and it doesn't quite reach the West Coast, as i have
it as being only 7 degrees in Denver, Colorado,

Sat 11Nov06  13:24:09 13:30:56 13:37:55  00:13:46  323 230 147  86.6* Ottawa
Sat 11Nov06  13:22:56 13:27:33 13:32:19  00:09:24  348  32  76   7.1  Denver
  SO-50       13:24:09  13:32:19  8.2 min overlap (Sat 08:24 EST/06:22 MST)

and a bit early at that. So there won't be many people on out west.  But
if you are able to work that pass, come back in about an hour and a half,
as then you should be able to work California if at least part of your
western horizon is clear (and there's anyone on to listen -- i'll try for
that pass):

Sat 11Nov06  15:05:42 15:10:59 15:16:20  00:10:38  303 252 201  11.2  Ottawa
Sat 11Nov06  15:01:49 15:07:02 15:12:19  00:10:30  348  39  90  10.1  SFBay
  SO-50       15:05:42  15:12:19  6.6 min overlap (Sat 10:05 EST/07:01 PST)

I'll try to be on Thursday morning, albeit that's a more difficult pass and
you will need a good western horizon:

Thu 09Nov06  15:47:37 15:52:27 15:57:25  00:09:47  299 254 207   8.8  Ottawa
Thu 09Nov06  15:43:17 15:48:50 15:54:23  00:11:06  346  41  95  12.0  SFBay
  SO-50       15:47:37  15:54:23  6.8 min overlap (Thu 10:47 EST/07:43 PST)

Starting on Monday, AO-51 should be back in mode J-FM, and being in a sun-
sychronous orbit, its approximate times don't change more than a couple of
hours from day to day.  SO-50's schedule drifts alot, and during the first
half of November, it's going to be on mostly in the middle of the night.

You can get a graphical display of their schedules for your location by
going to:

Don't forget to specify your local time zone.  73's and good luck!

			      -- KD6PAG

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