[Hallicrafters] SX-42 Alignment saga

[Rich Soennichsen]

Rodger,

On 2/19/07, Rodger <WQ9E at dtnspeed.net> wrote:
> Hi Rich,
>
> Do you have the IF aligned on the crystal peak frequency?  It is probably
> not exactly on 455 khz and you will need to determine the crystal peak and
> then realign the IF transformers for this frequency.  After this you will
> probably be able to get it to operate properly on all of the xtal filter
> settings.

Would this mean setting it to use the crystal filter and then
re-peaking the IF sections?

>
> For the RF alignment, you will definitely find the mixer adjustments will
> pull the oscillator frequency on the higher bands.  I would do a rough
> alignment using your signal generator and then use a noise source to provide
> a broad signal for the final peaking of the mixer adjustments.  A nearby
> light dimmer, portable kitchen mixer, or the noisy appliance of your choice
> should work just fine.  If you have one of the modern little digital
> shortwave radios with multiple memories, you can use this to make the
> oscillator tracking alignment much easier.  On the SX-62 the oscillator will
> be offset by the ~455 khz. IF frequency on the 4 lower ranges and by the
> 10.7 mhz. IF frequency on the 2 upper ranges.  So for example, on band 1 if
> you tune the SX-42 to 600 khz. you should hear the oscillator at 1055 khz.
> and at a receiver frequency of 1600 khz. you should hear the oscillator at
> 2055 khz.  This is assuming your xtal filter and IF is exactly 455 khz., if
> it is 457 khz. then you would listen at 1057 and 2057 khz. For me this
> process is much faster than moving the generator back and forth while
> setting the oscillator tracking.  You will need to check the manual (since I
> don't have mine handy) to see if the oscillator tracks below the receiver
> frequency on some bands.  I am sure that on bands 1-3 it tracks above the
> received frequency and if like many hallicrafters it will have low side
> tracking on band 4.  I believe that bands 5 and 6 will use high side
> tracking (received frequency +10.7 mHz.) but you should check this in the
> manual.  These higher bands are where the little Japanese "DC to daylight"
> receivers really become handy as alignment aids.

You are beyond my understanding here!  I will have to come back to
this when I start the RF alignment.

>
> I cannot remember if you have replaced caps in the receiver but many of the
> RF section bypass capacitors are accessible through the removable side panel
> over the adjustments for bands 5 and 6.  You will need a good set of needle
> nose pliers, plenty of light, and a long tipped soldering iron but it can be
> done since I have done so on my SX-42,62 and 62A.

I have replaced all the paper caps with orange drops but not the
rectangular ones with the colored dots (MICA?).

>
> Persevere, you are making good progress!

Thanks.
Rich
W7SOE