20-08-2014, 08:22 PM
Thanks Lawrence, I did some more playing around this afternoon using a sig gen and scope, etc. Things are looking much better now. I can get it to tune across the MW band and the Q seems to work as well. I turned out that the variable resistors on the pcb needed tweaking - one to match the FET's characteristics for the Q multiplier, and the other to set the low end of the frequency range where it would still tune.
I didn't appreciate how sensitive the tuning is (even though the text warns that it is the case). I was moving the coarse tuning pot much too quickly to catch the tuning point. I'll need to make a decal for the front panel and calibrate the tuning control at least so I'll roughly know where to go to tune a given frequency. As expected the Q multiplier has an impact on the final audio tone.
I'm pleased with progress so will continue 'tweaking' until I'm happy with the results when using the main sets that I use regularly. I picked up a UK sports station earlier on - never did that before!
Cheers, John
I didn't appreciate how sensitive the tuning is (even though the text warns that it is the case). I was moving the coarse tuning pot much too quickly to catch the tuning point. I'll need to make a decal for the front panel and calibrate the tuning control at least so I'll roughly know where to go to tune a given frequency. As expected the Q multiplier has an impact on the final audio tone.
I'm pleased with progress so will continue 'tweaking' until I'm happy with the results when using the main sets that I use regularly. I picked up a UK sports station earlier on - never did that before!
Cheers, John
Time flies like an arrow, fruitflies like a banana!
