http://home.comcast.net/~chnord/S38S.jpgHere is the latest project. Sort of a “Silk purse from a pigs ear” project
Took a standard Hallicrafters S-38 5 tube series filament cheapo rcvr chassis I had and souped it up to a 160, 80 and 40 only rcvr.
Did the following:
Changed power supply from AC/DC, added transformer and changed tubes to all 6 volt (was 3-12 volt, a 35 v rectifier and 50L6
Wired filaments in parallel
Added real BFO using 6C5. S-38 uses real kluge feedback setup on IF
Added IF Gain control
Added S meter, made up scale for meter
Switchable AVC
Tone control cap
Changed out osc and ant tuning caps to two 0-50PF Added appropriate capacitors in parallel with the alignment
Installed in new cabinet with National dial. Calibrated dial on Photoshop
Removed part of band A (BC) ant coil to get it to resonate at 160
Added Ant trim
Added regulator tube to control voltage to osc, if and BFO stages
Added fuse
Speaker connection external to radio
Added accessory octal socket on rear
Tried various IF filters but could not get them to work appropriately. So selectivity is not the best, but it is not bad either. I think I may try and get some better IF transformers (these are really AM radio types) from a communications grade rcvr and see how they work. Or maybe add an IF stage
Side by side comparison to the HQ-140X shows about the same sensitivity on these band but the selectivity is not as good. All in all not a bad little rcvr
Thanks to those who added suggestions and to Ed for the filters. I tried em but could not get them to work correctly. The selectivity improved but the audio sounded awful.
73- Now maybe the 813 rig will get started