[amsat-bb] TS2000 ~436.798 MHz Birdie Solution

John Papay john at papays.com
Wed Nov 30 07:49:39 PST 2011

As many of you know, my satellite radio is a TS2000X.
If you have visited my satellite webpage, you have seen
many recordings of AO-27 and SO50 from AOS to LOS.  Most
of these recordings were made when I was not sitting in
front of the radio.

At first I used a uhf mobile to hear AO-27 and SO-50.  The
problem was that those radios were not computer controlled
so you had to tune for the doppler.  That worked fine when
I was in the shack, but it didn't work when I was away.  The
obvious solution was another radio that didn't have the birdie
problem, or a simple UHF to 10M downconverter which wouldn't
have the birdie problem.  Back in the day, UHF and VHF down-
converters were very popular because we didn't have a lot of
DC to Light radios out there.  Now these converters are sitting
in junk boxes and are long forgotten by their owners.

One of the more popular manufacturers of these inexpensive
downconverters was Hamtronics.  They made all kinds of stuff
for repeaters etc.  At first their products were not that great,
but they evolved into some better designs including their
UHF to 10m downconverters.  Unfortunately most downconverter
manufacturers stopped making them when the devices they were using
became obsolete and unavailable.  The use of current production
devices required a redesign of their PC boards and since the demand
was no longer there, these products were abandoned.

I was fortunate to find a Hamtronics converter on a qrz.com posting
from several years back.  It never sold back then and the owner still
had it.  I purchased it and ran some tests on it against the receiver
in the TS2000.  It turned out that the downconverter had a slightly
better sensitivity than the TS2000!

The big concern when using a converter or preamp is the fear of
transmitting into it and smoking the front end.  But the TS2000
has an auxiliary antenna jack which is receive only and perfect for
a downconverter output on HF.  As Drew mentioned, SatPC32 can
compensate for a downconverter and tune the TS2000 for doppler
in the 10m band.  This allowed me to track AO-27 AO-51 and SO-50
unattended and make all those recordings without any human

A coaxial transfer relay was inserted into the uhf antenna line so
that when the converter was in use, the UHF antenna was switched
to the downconverter input (which outputs to the aux antenna jack
on the TS2000) and the UHF antenna jack on the TS2000 is switched
to a dummy load.  So if you transmit on UHF, power goes into the
dummy load and all equipment is safe.  When I want to transmit on
UHF (VO-52 and AO-7 mode B), the coax relay switches the UHF antenna
back to the UHF antenna port on the TS2000.  The downconverter is out
of the antenna circuit at this point.  I did not use the downconverter
when operating on FO-29 so the aux antenna jack had to be switched to
normal in the tS2000, menu #18 (FO-29 is a linear bird that outputs on
UHF, currently not working).

Every owner of a TS2000 that operates satellites needs a UHF to 10M
downconverter.  Hamtronics is making a VHF to 10M downconverter now.
If everyone emailed them to encourage them to make a UHF model, they
might just do it.  The only other solution is to make one yourself,
or find a used downconverter or transverter that is gathering dust on
someone's shelf.  I now have an IC910H and am doing comparisons against
the TS2000.  My first impression it that I prefer the TS2000 but that
might be because I'm so familiar with it.  I use another TS2000 in the
mobile sat truck but don't have a downconverter for it.  I simply use
a uhf mobile for receive on AO-27 and SO-50 since I'm in front of the
radio and don't run it unattended.  I have a coax switch to switch
the UHF antenna from the TS2000 to the UHF mobile.

Now that AO-51 is silent, all of the FM operation is on SO-50 and AO-27.
If you have a TS2000, you'll want to investigate the use of a downconverter.

John K8YSE

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