12-14-2014, 09:38 PM
Well,
The single thing I couldn't quite finish so far is the alignment. Namely the IF of the 1st IF stage.
The sch is here:
http://www.nostalgiaair.org/PagesByModel...001472.pdf
I first tried the regular approach.
I found AK559 radio alignment procedure (the closest to AK808, as the 808 does not have a procedure written for it - I guess AK relied on people knowing it, on the alt. forum there was something written to that effect by AK specialists: not every AK radio has a procedure written specifically for it).
Some of it is self-evident, like IF alignment, set the generator to 472.5kHz and go.
Well, all the trimmers aligned well except the A8 (the load of the 1st IF). It first did not peak, then when I was able to peak it, it would oscillate, motorboat, howl......depending on the strength (it could not handle the small signal). It took un-peaking it for the signal to come through well. In fact radio works well this way, lots of SW, good BC.
Then I re-read the instruction - they use a balancing circuit, an RC of 0.06uF and 40kOhm in series to shunt the winding while aligning the opposite one.
Well, I had the parts, made the circuit, tried it.
No measurable difference.
they even predicted some oscillations while aligning, though with the 2nd IF stage, recommending two circuits in parallel. I did not have any problems with that one.
At any rate, with this dial a super accuracy is not needed much and it seems to be pretty close to what it should be.
BTW I probably should not touch the trimmers - they all were at peak positions...except that one I mentioned.
The single thing I couldn't quite finish so far is the alignment. Namely the IF of the 1st IF stage.
The sch is here:
http://www.nostalgiaair.org/PagesByModel...001472.pdf
I first tried the regular approach.
I found AK559 radio alignment procedure (the closest to AK808, as the 808 does not have a procedure written for it - I guess AK relied on people knowing it, on the alt. forum there was something written to that effect by AK specialists: not every AK radio has a procedure written specifically for it).
Some of it is self-evident, like IF alignment, set the generator to 472.5kHz and go.
Well, all the trimmers aligned well except the A8 (the load of the 1st IF). It first did not peak, then when I was able to peak it, it would oscillate, motorboat, howl......depending on the strength (it could not handle the small signal). It took un-peaking it for the signal to come through well. In fact radio works well this way, lots of SW, good BC.
Then I re-read the instruction - they use a balancing circuit, an RC of 0.06uF and 40kOhm in series to shunt the winding while aligning the opposite one.
Well, I had the parts, made the circuit, tried it.
No measurable difference.
they even predicted some oscillations while aligning, though with the 2nd IF stage, recommending two circuits in parallel. I did not have any problems with that one.
At any rate, with this dial a super accuracy is not needed much and it seems to be pretty close to what it should be.
BTW I probably should not touch the trimmers - they all were at peak positions...except that one I mentioned.
