The Kenwood TS-2000 has a strong birdie (false signal) at 436.800MHz. This is the 28th harmonic of X400, the 15.6 MHz TCXO.
The 436.8 MHz TS-2000 birdie interferes with the first third of AO-27 and SO-50 passes, as the 436.795 MHz downlink of these satellites is well within the ± 7.5 kHz bandwidth of the TS-2000 FM receiver. The maximum 436 MHz Doppler shift for these LEO satellites is about ± 9 kHz. Thus near AOS of a given pass, AO-27 or SO-50 apparent center frequency is as high as 436.804 MHz. It’s not until the satellite is reaching maximum elevation that the Doppler shift makes the apparent center frequency low enough (say 463.796 MHz) so that Narrow FM (bandwidth ± 3.75 kHz) and tuning away from the birdie can help greatly.
Aside from hacking the circuitry around X400, the easy fix is simple to use a 436 → 29 MHz downconvertor that completely eliminates the birdie concern.
Kenwood TS-2000 internal TNC UNDOCUMENTED COMMANDS:
PASSALL ON SOFTDCD ON
The effectiveness of
SOFTDCD doesn’t match a “real” external TNC–the TNC still relies on the hardware squelch.
This means that the internal TNC may miss packets from mobile/portable devices with fluttering signals common to VHF/UHF.
fix no TX with internal TNC
try “S-meter Squelch (menu #19A)” to enable you to transmit when the received signal is strong and transmits constantly (such as packet satellites like GO-32).
This is ONLY effective when the station you desire to communicate with can receive while transmitting. You must manually turn up the squelch for an instant, then turn it back down so that the TS-2000 can receive the other station after the TS-2000 sends its data.
The Kenwood TS-2000 with internal TNC is capable of ARISS packet operations. The performance of the internal TNC can be a little frustrating on receive.
TRACE feature of the TS-2000 is ONLY useful in conjunction with computer tuning, since it does not account for Doppler shift magnitude increasing relative to frequency.
That is, 1:1 frequency tuning of TRACE is OK for quick adjustments in a satellite linear transponder passband, but computer frequency tracking is necessary to account for Doppler shift during the satellite pass.
For example, a -1.0 kHz Doppler shift on 146 MHz will be about -2.99 kHz on 436 MHz, and so on.