Quote:
Originally Posted by miniman82
Have fun with the alignment! I've read in a supplement that IF alignment should not be attempted as a fix, only as a last resort if all other fixes fail. Guess that shows to go ya how much the techs liked doing alignments, huh?
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Less than 1/8 turn of one of the cores in that dual-core coil can throw it out of spec (45% +10/-5% lower marker, 55% +10/-5% on the upper, IIRC). I can see that if you had no idea of how a double-tuned circuit should behave, you could be in trouble.
This reminds me of a job I had one summer at a UHF tuner manufacturer doing final alignment. Those who had experience (mostly women who had no electronics knowledge, but lots of experience aligning tuners) could do it about three times as fast as I could at first - because they knew what to expect for that design and could quickly see which way to go from an initial out-of-tune state. That was much worse than doing an IF alignment, since it involved getting stages to track across the whole band - and the tuner had peculiarities where it would develop a suckout at certain channels that could be reduced by very slight compromise of the over-all tuning. So, my first output tended to be very good on the good channels, but to fail inspection at the bad frequencies.