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Cheap Antenna rotators for LEO sats



At Dayton, someone was selling dozens of "returned" TV rotators for $15,
then $10, then $5 each.  To use these for simple automatic tracking of the
LEO birds, I wrote a two-bit interface to the parallel port for APRStk
that not only gives full rotator control for any 24v AC rotator, but also
automatic radio QSY and Doppler tracking for the Kenwood APRS radios:  

      http://web.infoave.net/~n4wyk/satcheaprotor.htm 

With this arrangement, you won't miss a thing from any of the 10 or so
birds that you can hear/work more than 50 times a day with the Kenwood FM
rigs. It's low class, and not suitable for precision AO-40 S band
pointing, but it should be within about 10 degrees which is good enough
for most LEO's and a modest small beam... Here's all it takes:

1) Any old 386 or better PC (running DOS)                      $ 10
2) Any ole' $64 Radio Shack TV rotator                         $ 64
3) The $20 rotator controller kit (see web page below)         $ 20
4) APRStk (Tracks, tunes radio, decodes packets and plots them)
5) Either the Kenwood D700 or TH-D7 w built in 12/9600 TNC     $390

This set up left sitting in a corner will tune the radio to all satellites
in view and you wont miss a thing... 

a) Listen to all voice QSO's                  (UO14, AO27, ISS)
b) Capture PCSAT TELEMETRY, STATUS, USER logs (UO22, KO23,25,TI31)
c) Capture APRS positions, STATUS and Messages (SO35,OO38,UO22,ISS)
d) Listen to data and inverted CW telemetry    (UO11, LO19)

It does not try to capture the megabytes from the PACSATs, just their
telemetry, status, and user logs.   But if you have another WINDOWS PC
running WISP in receive-only, then you will also capture a lot of the data
and files on the PACSATS...

One advantage of the old DOS PC is as a lightening fuse... 
And the TV rotators are a dime a dozen...

There is no reason why this $20 interface wont work with any other
software if the authors will just raise BIT0 to go left and BIT1 to go
right.. on the LPT1 port.  But someone said this is not easy to do in
Winders... ergo the old DOS machine...

de WB4APR@amsat.org, Bob




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