Yes the vision and audio IF's were generally split after the tuner stage, with the vision IF having traps to remove the sound carrier and the sound being taken from one of the traps. That is what I will be trying soon.
If you look at most domestic receivers many will only have one stage of gain at IF using double tuned circuits as you are doing. As the IF frequencies go higher then yes the more gain seems to be required.
When I had 2 x EF81's in there I had something 60 dB plus gain and yes if not careful I could get the stage to oscilate, then I actually got around to connecting the top of the board to the bottom of the board to make a better ground plane and it cured it, but it also showed how much noise was being generated by the switch mode power supply I am using as a temp. No wonder the HF bands have become unusable.
The detector is a CV4007 which is just a smaller version of the EB91.
Time to play again.
Adrian
If you look at most domestic receivers many will only have one stage of gain at IF using double tuned circuits as you are doing. As the IF frequencies go higher then yes the more gain seems to be required.
When I had 2 x EF81's in there I had something 60 dB plus gain and yes if not careful I could get the stage to oscilate, then I actually got around to connecting the top of the board to the bottom of the board to make a better ground plane and it cured it, but it also showed how much noise was being generated by the switch mode power supply I am using as a temp. No wonder the HF bands have become unusable.
The detector is a CV4007 which is just a smaller version of the EB91.
Time to play again.
Adrian
Learning as I go!
Youtube EF91 Valve
Youtube EF91 Valve
