[Hallicrafters] Questions on S-38A Restoration

[Michael Melland]

About two years ago I picked up a pretty nice (but dead) 
Hallicrafters S-38A at a hamfest.  Sunday I finally had an 
opportunity to work on it ( yeah... I know I'm slow ) and 
got it running very well.  It's amazing how sensitive this 
little rig is, and how good it still sounds... but band 
two seems a bit low on sensitivity and I wanted to check 
the calibration on all the bands to see if I could tweak 
them a bit closer (they aren't too bad as they are).

This S-38A is in pretty nice shape.  I replaced the multi 
section electrolytic as well as all the paper tubular 
caps.  I can still detect a low level of hum which may 
mean I have a bad mica cap somewhere or it's picking up 
hum from the isolation transformer someone added to the 
chassis years ago (nicely I add).  The speaker had also 
been replaced and almost touches the transformer from 
above.

I have two questions for the sages on the list.

The manual calls for fabrication of a dummy antenna (RMA 
antenna) that you run a sig generator through to perform 
the alignment and sensitivity adjustments.  What purpose 
is this RMA dummy antenna ?  I have a HP8640B... why can't 
I simply feed low level RF into the antenna connection on 
the S-38 to tweak things up ?

I also found the schematic and parts list to indicate only 
a 4 section electrolytic capacitor ( 40/30/30/20) which I 
replaced.  However, I also located a 150V 30 MFD "dry" 
Electrolytic under the chassis not indicated on the 
schematic or in the parts list.  If I remember right it 
was to the bottom and right of the multisection filter cap 
along the rear of the chassis and I think connected to 
either the the audio amp or 12SQ7.  It was under the leads 
and wires of other components... like it was present when 
built.  But then why not on the schematic or parts list ? 
 Anyone else have this ?

Regards,

Mike 

--
Michael Melland, W9WIS
Winneconne, WI USA