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: AO-27,436795,145850,FM,FM,NOR,425000,0
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 available.
73, John K8YSE