08-01-2025, 10:38 PM
You need a Pi5.
I don't think the Pi4 can do 405. Though I did get my Pi4 to NTSC and PAL composite. However use a separate SD card as it's a pain to change modes.
Is it the rotary tuner with "biscuits"? Even in 1971 I had to take those partially apart and clean. Some you can clean the chassis spring contacts by removing two sets of biscuits at a a spacing. Cleaning the spuds of the biscuits is easier. For some weird reason I still have a few in a box of random coils. Maybe Band III as few turns and brass cores.
You'd get some noise just from IF working. Others may do it differently but I'd start with a DMM or scope on a detector diode and work stage by stage back to tuner with the IF freq from a signal gen coupled with capacitor and 100 K ohm in series to avoid much detuning.
If you get stuck I'll dig out my R&TVS. I have all (inc most multiple early versions, some have different models not in main set) up to 1975-1976. I didn't see the point in getting later ones.
I expect the video IF is 34.65 MHz and sound IF: 38.15 MHz, so even my 1944 generator would manage. You don't need any modulation if DC coupled to detector diodes with DMM. Otherwise the normal audio carrier for radio will for for video or audio and then a Scope is nice.
Just when I stopped restoring or repairing anything or building, I got a Rigol spectrum analyser / generator because my old HP141T analyser had died.
I don't think the Pi4 can do 405. Though I did get my Pi4 to NTSC and PAL composite. However use a separate SD card as it's a pain to change modes.
Is it the rotary tuner with "biscuits"? Even in 1971 I had to take those partially apart and clean. Some you can clean the chassis spring contacts by removing two sets of biscuits at a a spacing. Cleaning the spuds of the biscuits is easier. For some weird reason I still have a few in a box of random coils. Maybe Band III as few turns and brass cores.
You'd get some noise just from IF working. Others may do it differently but I'd start with a DMM or scope on a detector diode and work stage by stage back to tuner with the IF freq from a signal gen coupled with capacitor and 100 K ohm in series to avoid much detuning.
If you get stuck I'll dig out my R&TVS. I have all (inc most multiple early versions, some have different models not in main set) up to 1975-1976. I didn't see the point in getting later ones.
I expect the video IF is 34.65 MHz and sound IF: 38.15 MHz, so even my 1944 generator would manage. You don't need any modulation if DC coupled to detector diodes with DMM. Otherwise the normal audio carrier for radio will for for video or audio and then a Scope is nice.
Just when I stopped restoring or repairing anything or building, I got a Rigol spectrum analyser / generator because my old HP141T analyser had died.
