[amsat-bb] TS2000 Birdie Follow-Up

John Papay john at papays.com
Wed Nov 30 11:12:38 PST 2011

KC9DOA mentions that he still had the birdie
problem with a downconverter and that is understandable.
The TS2000 radiates the birdie and if your downconverter
is not shielded or the UHF antenna is too close to the
radio, you might still pick it up.  Simple experimentation
will find the right combination to virtually eliminate the
birdie.  So try a UHF handi or mobile unit and see if it
hears the birdie on 436.798.  Then move things around to
see if you can minimize the effect.  I've been able to do
that in the sat truck and don't have the problem at the base
station.  Try a dummy load on the UHF antenna jack on the
TS2000 as well.  Use quality coax with good shielding.

Drew posted a link to High Sierra Microwave for a UHF down-
converter that is up-to-date in design and performance, all
at a reasonable price.  The specs call for a 5v supply but
Bill N6GHZ advised that the converter will operate fine up
to 16vdc input.  No special supply required.  He also mentioned
that the converter will perform well from 432 to 438 MHz.  So this
is one possible source of a current production downconverter
manufactured by someone who knows satellites.  The output IF is
lower but the TS2000 receiver is continuous so there should be
no problem.  Instead of a 407MHz offset, use 425MHz and the receiver
shifts down to 10MHz for a 435MHz input:

doppler.sqf entry:

I've not seen a whole lot mentioned about the Funcube performance
when connected to a big antenna in a crowded RF environment.  I've
had mine on the KLM's and the performance is poor because of
overload.  Cavity filters work wonders but not everyone has them.
High Sierra also makes front end filters and filter/LNA combinations
for the Funcube as well as other products which make the Funcube more
versatile.  It's worth checking out the webpage to see what is

John K8YSE  

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