Also. on 2M o/p the level is around 20dB higher than all the other bands, does this indicate fault in filter, for these tests not going through RF switch.
The pulsed spurious at 42.6 (71 * (6 / 10)) does not seem like is should be there. I have never noticed it. Is it there on the output from your ADF4351, or only after the LO filter?
Stupid question - please confirm that you have put the LO filter between the ADF4351 and the F-M board? Sorry to ask the obvious, but I have seen this error!
Where are you measuring the power difference for 146 MHz? At the output of the F-M board or before the F-M board?
Thanks for coming back quickly. The filter does go after the LO and before modulator board. I am now going to bypass filter and check o/p of LO.
The power difference is similar after the RF switch and the o/p of the modulator. The RF switch appears to be OK. All other functions on TX work fine, frequency selection etc. So I assume there are no errors on the LSB/MSB bus.
It looks like duff filter board, 71MHz o/p has now died, 2m and 1.3GHz o/ps reasonably OK, lower o/p on 437MHz. Bypassing the filter showed no o/p at 42.6MHz!
So will order new PCB and set of parts from Digikey. That was my first go at SMD and not pretty so maybe s/c somewhere. RF switch was quite neat attempt.
Looking on spectrum analyser everything looks OK, FM board functioning correctly, tried Mpeg, H264, Low and High SRs and ticked low SR box when relevant. Camera and test card as well. mmmmm?
My afternoon spent building my second filter board (having expired the previous) and all ready to test - nowt coming out.
Back up the chain disconnecting stuff and nothing emerging from either DDS sockets.
Ugly mode works well though, so I'll use that and the pi-cam for demo purposes Monday night at my annual club construction contest.
Ordered parts from digikey Sunday, they arrived today. Good service.
Yes, Digikey are very good, most probably get mine by Saturday or even Friday.
I assume on your DDS board the Lock LED is not illuminating on TX, or if it is then the o/p stage has failed.
That was an expensive exercise.
I've had a close look at my original board, seems OK but in extracting the dead switch I've lost tracks 1&2, DC power. Easy enough to run a couple of wires.....