[Hallicrafters] SX-100 MK2 Alignment

[David C. Hallam]

Jim,

Yes, I used a modulated signal 400 Hz 30%

No, I did not replace the capacitors on the bandwidth selection switch.  
I replaced about 10 of the easiest to get to capacitors under the 
chassis.  Out of the 10 only 1 tested bad after I removed them.  I was 
fairly certain it would be bad because a burned resistor was associated 
with it.

I thought I would try to align the receiver to see what happened before 
I got carried away and started tearing the front panel apart to get to 
the ones buried under it.

David
KW4DH

On 6/14/2013 7:23 PM, Jim Liles wrote:
> Hi David:
> Did you use a modulated signal?
>
> Did you replace the capacitors on the bandwidth selection switch and 
> if so did you use film caps.  If you used ceramic caps, replace them 
> with film before you do any further alignment.
>
> Kindest regards Jim K9AXN
>
>
>
>
> -----Original Message----- From: David C. Hallam
> Sent: Friday, June 14, 2013 3:37 PM
> To: hallicrafters at mailman.qth.net ; Roger Shultz
> Subject: [Hallicrafters] SX-100 MK2 Alignment
>
> I have a question about step 5-3-2, alignment of the 1600 KHz oscillator
> and 1650 KHz IF.  I think I have carefully followed the procedure in the
> manual, but can not seem to get the IF peak centered in the pass band.
> I have peaked and repeaked T1 and T2 as well readjusting the 1600 KHz
> oscillator.  My adjustment was to turn the slug into the coil until the
> crystal stopped oscillating, then back the slug out until it output
> peaked.  When I reached the peak, I kept turning it out until the output
> voltage as measured by a VTVM on the detector voltage dropped to 1/2 of
> the peak voltage.  After than I peaked top and bottom of T! & T2.
>
> The pass band center is about 1/3-2/3.  Have I done things correctly and
> how important is pass band centering?
>
> David
> KW4DH
>

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