[Hallicrafters] SX-28 switch nut and IF alignment

[Don Ehrlich]

> 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?

If you got your if alignment that close without a sweep generator then you
are doing better than I have.  In my opinion a sweep gen is mandatory for
aligning those SX28 if's but if anyone out there knows how to do it without
one I sure would like to know the secret.

> 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.
>

I found that the IF must be aligned at the xtal frequency.  You did the
right thing.  Wish someone had told me that before I wasted all that time
trying it at 455 !

Don K7FJ