[Hallicrafters] Re: S-40B alignment questions

[Bruce Wilson]

This is a follow-up on an alignment job (my first) of an S-40B receiver.

It went pretty well. I didn't have a very good RF generator, so I had to use 
my digital SW radio to peak the oscillator frequency, then use my RF 
generator to peak the voltage on the speaker.

I got bands 1-3 aligned very nicely. For some bands there is no dial 
misreading at all, but it does get worse the higher frequency I tune. In 
Band 3 (5.5 - 15 MHz) I can get 15 and 8 lined up perfectly, but 10 if about 
.15 off. I can live with that.

The problem is Band 4, which I can't get even close to what it should be. 
When I try to tune 30 MHz I can't get the oscillator up that high, no matter 
the settings of the variable capacitor and coil slug labeled A and S8, 
respectively. I could get 18 MHz to tune, but when I did the 30 MHz tuning 
got even worse. It's almost as though a mica capacitor has gone bad or 
something.

Any ideas? I haven't found on the web a description of this sort of problem. 
I have not tested the mica caps (difficult removal, can't test in place).

Bruce Wilson
http://science.uvsc.edu/wilson
----- Original Message ----- 
From: "Mark Shaum" <k9tr at dtnspeed.net>
To: "Bruce Wilson" <b.e.wilson at usa.net>
Cc: <hallicrafters at mailman.qth.net>
Sent: Tuesday, August 02, 2005 4:47 PM
Subject: [Hallicrafters] Re: S-40B alignment questions


> Bruce,
>
> My S-40B has the alignment hole cover but it is attached with removable
> rivet-appearing pins in the corners.  It was easy to remove the pins and
> replace them along with the warning cover when the alignment was
> completed as they are press-fitting.
>
> And yes, dial calibration will suffer a bit, especially on the higher
> frequency bands, if alignment is done "out of cabinet".  There won't be
> a huge difference but those alignment holes are there for a reason!
>
> Hint, in case your label is not removable: Have a large, flat cookie
> sheet available when doing alignment.  Sit the receiver on the cookie
> sheet to check calibration.  Re-adjust as necessary.  The result should
> be pretty close to what you will have when inserting the chassis into
> its official cabinet.
>
> The wax in the coils is removable.  A directable hot air stream (small
> heat gun and tip) and paper towels to absorb melting wax should work.  A
> soldering iron tip held near but not touching will also melt the wax,
> but your hands had better be steadier than mine.  It likely will not be
> necessary to remove all the wax before the inner slug becomes movable.
>
> The rubber band fragment is inserted between the core and coil to keep
> the slug from slipping in the coil.  The wax is generally just extra
> insurance if both are applied to the same coil.
>
> 73! - Mark K9TR
>
> ----- Original Message ----- 
> From: "Bruce Wilson" <b.e.wilson at usa.net>
>>
>> 1. My radio (from eBay) still has the paper warning covering the
> alignment
>> access holes on the bottom of the enclosure. Not wanting to disturb
> it, I
>> aligned the RF stages with the chassis out the box. Will that disturb
> my
>> alignment very much? Is it better to retain the warning in place to
> maintain
>> pristinity, or pull it off and align it properly?
>>
>>
>
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