I have the 6 tube version which has a second 12SQ7 for BFO. The 12SQ7 plate connection isn't per schematic, and I'm wondering if this was a factory change.<P>As found, the plate had a 15K ohm resistor (drifted to 23K) instead of a 470, and the .01 MFD to ground from this resistor wasn't present. Instead it was connected to a Micamold cap and back into a real mica cap to the grid for this same tube. The 15K resistor is wired CW/AM switch per schematic. <P>The Micamold is a 6-dotter, >black-gray-traces of red on the brown background>, bottom row >black-gray-red>. I'm taking this to mean .008 mfd at 0 volts? I don't see a cap of this value in the parts list (from BAMA website). <P>Any idea why this may have been set up this way? There were some obvious sloppy repairs to this set, but this socket didn't look kludged.<P>Brad in Columbus, OH<BR><P>------------------<BR>

The circuit you describe doesn't make much sense. The Micamold you describe may be a resistor. They made resistors which looked like caps, but skinnier. Check with an ohmmeter. I would put the circuit back to the original There is nothing tricky about it. It's a standard oscillator; no reason to change it. Note that the BFO signal is coupled into the diodes of the 12SQ7 detector through a pair of insulated wires twisted together to make a very small capacitor ("gimmick"). Be sure that hasn't been removed or tampered with.<P>------------------<BR>

Sounds like someone tried to do the 'stability mod' on your set. Many hams tried to do this 'modification' which was to replace the gimmick cap with a fixed value stable cap. It was a way to try and hot rod the S-38 for SSB reception. Since the radio was never intended for SSB operation (the BFO is for CW), this 'modification' should be reversed anyway.<P>------------------<BR>

All the S-38's that I have played around with seemed to do reasonably well on SSB, but they suffer from oscillator instability, both the local oscillator and the beat frequency oscillator. Also line voltage changes from an appliance like a refrigerator coming on sent you scrambling for the bandspread dial constantly.<P>They were an economical way for a person to get started in short wave listening or ham radio. So don't expect them to perform like some of the other Hallicrafter sets that cost vastly greater amounts of money at the time they were made.<P>A side note: Hallicrafters was so "tuned in" to helping the starting ham in those days that they even built a CW transceiver along the lines of the S-38. I don't recall its nomenclature at the moment, but it had a crystal controlled oscillator for a transmitter and ran about 15 watts or so. All in the same cabinet. Not too many were made and if one is found today, it is worth quite a bit.<BR>Curt<P>------------------<BR>Curt, N7AH

<P>Curt - <P>Your memory is excellent - it was the SR-75. Receive section was that of an S-38B; the transmitter was a 10-watt crystal controlled CW unit. <P>Here's a picture: <A HREF="http://www.rigpix.com/hallicrafter/sr75.htm" TARGET=_blank>http://www.rigpix.com/hallicrafter/sr75.htm</A> <P>I've seen a couple on ebay, but you're right, they seem to be pretty rare.<P>Kevin<P>------------------<BR>

Yep, that's it Kevin. Probably one of the "unknowns" in collecting old Halliscratchers.<BR>Curt<P>------------------<BR>Curt, N7AH

They also did one using the S-53 cabinet.<P>------------------<BR>

I think it was only in the S-53 cabinet if I remember correctly. The two cabinets were very similiar, as I recall.<BR>Curt<P>------------------<BR>Curt, N7AH

<P>As Curt says, it just shared the S-53 cabinet - it was the HT-18 transmitter (not a transceiver).<P>Kevin<BR><P>------------------<BR>