[Hallicrafters] SX-28 snipped wire puzzle

[rrkrr]

There were some minor factory modifications to the SX-28 IF circuits 
during the years of production.  There was an article or two in Electric 
Radio about this in recent years.  I believe one of the changes involved 
modifications to the Lamb noise limiter circuit, and there was more.  I 
believe there was a change in tube type for one of the circuits. I'll 
have to look up the article in order to remember.

Bob K4ERR

Julian Bunn wrote:
> Hi Rob,
>
> This is an SX-28. I need to double-check, but I haven't seen this
> difference on the various schematics I have (including for the SX-28a).
>
> Gary Brown has suggested it might be an accidental snip, during mods
> or re-capping. I'm 100% sure I didn't snip it, so maybe when the PO
> altered the circuit for the ANL it was done.
>
> The crystal filter was working before I started on the set. I don't see
> from the circuit why this snip would affect the crystal filter 
> especially?
>
> Julian
>
>
>
> Rob Copeland wrote:
>> Hi Julian,
>>
>> Is this a sx-28 or a sx-28a? If it is a sx-28 then they might of 
>> upgraded
>> the circuitry to sx-28a specs. I would compare schematics of an 
>> sx-28a to
>> your sx-28 to see if this is true. Otherwise, this would be a mod 
>> that is
>> not part of either spec. If this is the case you can google for 
>> sx-28/sx-28a
>> mods and see if this is mentioned somewhere on the internet. If it 
>> was me I
>> would just rebuild it to sx28a specs this is what I have done with 
>> mine and
>> it is rather easy to do as the differences are subtle. Thinking about 
>> this
>> now makes wonder if the snipping was a mistake, because the 2nd IF 
>> can is
>> part of the Crystal Filter. If the Crystal Filter is not working this 
>> may be
>> why.
>>
>> Good Luck!
>>
>> Rob
>>
>>
>>
>> -----Original Message-----
>> From: hallicrafters-bounces at mailman.qth.net
>> [mailto:hallicrafters-bounces at mailman.qth.net]On Behalf Of Julian Bunn
>> Sent: Thursday, February 08, 2007 11:11 PM
>> To: hallicrafters at mailman.qth.net
>> Subject: [Hallicrafters] SX-28 snipped wire puzzle
>>
>>
>> In the process of re-capping my SX-28, I noticed that the wire between
>> the tap on the secondary of the
>> 2nd IF transformer, T2, and C33/R19 has been snipped.
>>
>> Can anyone offer a suggestion why this might have been done, and/or any
>> reason why I shouldn't
>> reconnect it?
>>
>> Thanks!
>> Julian
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>