17-01-2025, 07:27 PM
Note the sound IF can be almost peaked (it's wider band than AM Radio, so 20 kHz wide), but the video wants more than 3 MHz (vestigial sideband), so I think the IFT must be slightly staggered, rather than peaked which is too narrow. Easy with a noise source and spectrum analyser, or tracking gen and spectrum analyser. It was historically done with a wobbulator. The scope X sweep frequency modulated the IF generator and diode detector fed the Y axis. I had a Meguro or some such Japanese one for AM/FM radio for a while with built in swept IF generators and marker oscillators to mark centre and band edges.
No doubt you can magic the DDS Sig gen you have and a scope (or PC scope via sound card) to do the same thing.
Alternately for the video (audio is straight forward), you roughly put all the video IFTs in alignment and then fine tune using the test card gratings. Back in the day I only had the test card to align the IFs.a
No doubt you can magic the DDS Sig gen you have and a scope (or PC scope via sound card) to do the same thing.
Alternately for the video (audio is straight forward), you roughly put all the video IFTs in alignment and then fine tune using the test card gratings. Back in the day I only had the test card to align the IFs.a
