[Hallicrafters] SX-28 switch nut and IF alignment

[John Monaco]

Hello, I would like to replace the stripped knurled nuts that hold the
standby and bass switches to the front panel of my SX-28 (and a couple
other radios). I see that Mouser Electronics has them listed in their
catalog, but I don't know that the thread size should be. They list one as
15/32-32 and some that are metric. Is 15/32-32 the correct size? All
switches of this type used on many radios all seem to have the same
threading. Also, I think this was discussed here previously, but what is
the best way to screw these on and off without damage?

Also, I have a question about IF alignment. I have re-aligned the RF and
IF secions according to the original manual. However this method is very
difficult and hard to get right. I have it close, but not perfect. The
medium xtal setting seems broader than the broad xtal setting. Would it be
better to obtain a RF sweep generator so that the response of the IF
section can be viewed as its adjusted? Also, I assume it should be aligned
at the crystals actual frequency, not 455kHz. My crystal is 450.7kHz. Is
this a correct assumption? I found this frequency by connecting the
crystal in series with an RF generator and oscilloscope, noting the
frequency that passed the maximum signal. I could not get the crystal
filter working when the set was aligned at 455kHz.


Thanks