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Old August 2nd 03, 05:26 PM
Frederick Bray
 
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Default Hallicrafters SX-42 Alignment

I am having some problems aligning my SX-42. I replaced all the paper
caps and a number the aged resistors that are usually found to be way
out of spec.

I find that I am having problems obtaining proper dial calibration. I
can generally set the high end of the band using the trimmer cap. But
after I set the low end by adjusting the coil, the high end is off
again. Repeated efforts don't significantly narrow the gap.

On the highest band, the problem is most pronounced. The 60 MHz low
point was dead on to start with. However the high end is 1 to 2 MHz off
and there is not enough adjustment in the trimmer cap to fix this.

I wonder whether anyone else has had this type of problem and found a
solution? I am considering doing some further re-capping, but it is my
understanding that generally this is not necessary.

The one other factor, which I have yet to fully explore, is the B+.
Apparently, at one point the power transformer was replaced and the B+
is about 30 volts higher than spec. I am going to try putting a
dropping resistor in to bring it down to the 250 volts indicated in the
manual and attempt one more alignment, starting with the IF's. I wonder
whether anyone has encountered this and whether this 10+% voltage
overage is a problem to worry about?

Many thanks in advance.