The Souper 38

[Carl WA1KPD]

http://home.comcast.net/~chnord/S38S.jpg


Here 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

[AF9J]

Something little that has some spunk to it - coool!

73,
Ellen - AF9J

[xe1yzy]

Carl...

Little Frankstein looks nice! good job!

[Ed-VA3ES]

  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.

Probably a group delay problem.  I belive the input and output Z of those filters is approx. 1500 ohms?  Z matching is important to eliminate egregious group delay, which manifests itself as severe ripple or even  large frequency slope  in the passband. As well there is loss, which must be accounted for.

[Todd, KA1KAQ]

Nice, Carl. The S-38 Slayer!   

[WBear2GCR]

Tsk, tsk...

Heresy I say!

A Nat'nul dial on a Halli?

 

             _-_-bear

[WB2RJR]

Carl,

A great project. My complements. I have an RCA 5 Tube All American I got for $5 in Kansas that was working. It's no vintage prize. I'm pulling it apart to make an 80 meter receiver, like you, I have to add to it, BFO, Q multiplier etc. etc, and maybe converters for the higher bands.

To take a cheap BCB rig to SW, is an interesting task. At least you have the IF transformers etc. which are hard to come by these days.

Yours looks great. Where can I get a good dial. Looks to me like I may have to make it. My BCB rig is a knob on the capacitor, not quite the tuning rate we want on 80 meters.

Thanks for posting......you've got me inspired again.

Marty WB2RJR

[Carl WA1KPD]

Marty,
Send me the scale and I will make the dial for ya

[Vortex Joe - N3IBX]

Carl - It's a work of art! Who woulda thunk there was a S38 unduh de hood?

I particularly like the Large National dial, National diascale, and the guessmeter! Verykewl indeed.

Best Regards,
                  Joe N3IBX

PS: Who says you can't polish a turd?

[Jeff W9GY]

Carl, Happy to see you are a Shep fan!  I've downloaded all his MP-3 stuff available on the Internet and play them on my Ipod while heading off to dreamland.... BTW "The Bear Missed The Train" Hi!