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Man that's a pretty cool background - all my stuff works too otherwise why have it . I hooked up the b&k 415 for fun tonight and aligned the if pass band with the avc disconnected, it looks much better now. Also aligned the detector s curve, it looks good too. I notice that the maximum avc voltage does not correspond with the maximum audio strength, I think the if oscillator frequency didn't perfectly match 10.7 MHz, but the market is in the centre as it should be, so I tweaked the oscillator a bit so peak audio corresponds with peak avc voltage,
The radio is more sensitive now but still some distortion, sounds like IM distortion possibly with power supply ripple. This radio has such small speaker there could be a fair bit of ripple on the power supply before it's audible as hum - Will check that next.
I think at this point I need to do some reading about fm receivers and how to align them, my theory is a little too weak for my comfort level.
As for relatives and friends appreciating this stuff, a friend of mine asked me why I wouldn't just buy a $20 radio instead of investing the effort... I said because that would be boring. Also, one other point - you only live once, and international travel is surprisingly easy these days... Go for it what's to lose?
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