[Hallicrafters] SX-28 Vintage question additional information

[David Box]

I forgot to add in the question below that the set in question does not 
have the socket for external mute on the back panel.  This is the socket 
that on all others I have seen is above the phono input jack and looks 
like a 60 cycle power plug.  I have seen no documentation where this 
socket is not pictured, looked at the "SX-28 old" manual and it shows 
the socket so guess I am looking for the "SX-28 really old".

Tnx  Dave K5MWR



This past weekend a friend and I started getting an SX-28 he had 
acquired working.  The unit was basically DOA when we started but after 
some of the basics of cleaning and cycling contacts we got it to at 
least receive local AM.  Major problem was the coupling in the 
bandswitch shaft was loose and as a result the oscillator was not active 
as the switches on that section were slightly out of phase.

My main question has to do with when this set was built as it is 
completely different in the area of the rf and oscillator stages.  The 
mechanical construction is different and the types of components are 
completely different in the transformers.  This set has some large 
rectangular transformers with rough looking slugs internal to the 
transformers instead of the round, piston adjust transformers in the 
other two units I have and what are shown in all the manuals I have.  
Getting access to the parts in this area is about 10 times harder than 
on the higher SN units I have.

One other clue is that the topside cover for the rf oscillator section 
is a solid piece held on by 4 clamps that pop over the top.

SN for this unit is 11895 which means it is probably an early production 
unit.  Can anyone tell me where to look for the documentation that 
represents this unit.

Also need to know where are best places to look for replacements for the 
electrolytics in the power supply as these are going to require replacing.

Thanks for information

Dave K5MWR