Hello everybody,
I am writing about the attempt to transform my TR503 into TR502 to use it with the SA 7L13. I started by replacing the 55 MHz crystal with a 52.5 MHz one (thanks James) and after some testing I added a 180 ohm resistor in series with R412 on the "Iosc" circuit to bring the oscillator to 2095 MHz (thanks to Miguel and Ed). Then I re-calibrated the four-cavity filter to 2200 MHz. Now it works quite well up to a BW Resolution of 300 Hz (on Max span the amplitude variation is in the 2 dB), but when switching the resolution at 30 Hz the output signal from the TR503 drops by - 30 dBm and it is not possible to bring it back to normal level by acting on the "Tracking Adjust" of the TR503.
At the moment I don't know what to do, could it be the four cavity BPF that is not calibrated precisely?
Thanks for your help.
--Cheers
Attilio
Attilio