Hallicrafters S38E

I picked up a nice little Hallicrafters S38E over the week end. This is one of those "it lights up but it hums" radios... I always ask what was it humming? ( I usually get a go to you know where look) :)

Here it is out of the chassis, mostly dusty.

There are 5 miniature tubes in this receiver. The dial string is in excellent condition so it will stay put.

 A look under the hood. A few black beauties to replace not too hard to get to either.

Interesting mod done this this receiver. I am guessing the 25 MF section went bad so they cut the blue wire and added it externally.  Probably would have been safer to use tape or heat shrink tubing on it rather that just let it float around bare.... The orange cap was substituted for one of the black capacitors.

All the caps are now replaced with the proper caps and heat shrink tubing applied where needed. Total time one and a half hours.

If you can not receive CW on your S38E, here is the fix. The grey pointer is on what is called a "gimmick". This one is formed when the brown heavy wire is twisted with one and a half turns of wire one end is on the IF CAN and the other is on the IF tube pin one. The brown wire snakes through the IF CAN and into a metal tie down. Remove the tie down, unsolder the short wire connecting these points and add one long enough to make 1 and a half turns around it. Keep the brown "BFO" wire in the IF CAN area and make it come as close as possible to the IF tube socket.

When you need just a couple PF of capacitance twist two wires together, for every inch or so you get a couple PF of capacitance.

This is what the brown wire "BFO" should look like on this end.

Between the next IF CAN and tube socket you will see a green wire. This one is long enough to unsolder and wrap around the heavy brown wire. Look back at the under chassis picture above  and you will see that it was wrapped onto and back under the brown wire. No good, it needs to go one and a half times around your "BFO" wire ......would this be a FAUX  BFO??    :) Sorry.....

A.M. Passive Antenna Loop

Here is an antenna for the A.M. band I built out of a recycled cardboard tube, some wire and an air variable capacitor. The loop is 16 3/8 tall with 24 turns of 20 gauge wire about an 1 in wide. So if my math is right I have about 103 feet of wire.

Not a real work of art, but it does work fine. I sprayed it with clear lacquer to keep the wire in place on the cardboard tube. I used tape to hold the wire in position (close wound) while I sprayed it. One note here the lacquer I used melted the tape in some places so I hit in between, let it dry then took off the tape to finish it. The hot-glue gun was used to fasten it to the wooden plaque.

A short demo of the loop in action. I found a very hard to hear signal down in the noise and tuned up the loop to hear it (them). There were actually two stations that came in. I'll have to listen to them to see where they are broadcasting from. Anyhow I am pleased with the result.

Twinplex Regenerative Receiver part 5 done deal

The Twinplex Regenerative Receiver has taught me a lot. It is amazing to think about all the experimentation that went on years ago to get to where we are today in radio.

I wound a coil for the upper part of the AM band. 87 or so turns to start, then removing 3 at a time until I hit where I wanted. I ended up with 76 to 16 (tickler) and may still take a few off the tickler coil to find the effect there. It is kind of narrow banded I think 920 to 1380.

  A side view Of the Twinplex with the AM (lower end) coil.

Front view of the Twinplex with the knob indicator and control plates I made for it. My wife says I should find copper screws or rivets to match.

A special thanks to my mentor on this project.

Twinplex on AM

A short video of the Twinplex working on the AM band. Listening to Baseball will be a hoot on this radio...

I found a 100 MMF capacitor in one of my coil forms. I wonder what this coil was used for in the past.

Twinplex Regenerative Receiver part 4

I ran a test with the receiver with a 9 to 3 coil and picked up this beacon station WLO. I wanted to make sure everything worked before mounting the front panel for the final time. I also picked up several religious broadcasts so I figure it must have been up in the 8500 over 40 meters anyhow.

I also built a 40 meter coil 9 to 2 turns. I listened to several QSOs and what sounded like PSK so I am happy with that coil.

 I mounted the knobs, and bolted everything down good. I still had a couple of hours to kill so I decided to try to build an AM coil. I found an AM loop stick that came in one of my son's old electronics kits. After mounting it inside one of my coil forms, I added 2 loops for a tickler coil. Worked first try! I found stations from 620 up to 770 so far. but it works surprisingly well.

The AM loop stick is laying on its side in the coil form. I do not know if that causes a problem or not. I'll try centering it to see later.

Belton Hamfest

Went down to Belton for the hamfest last weekend and had a blast. Scored some real deals on parts I was looking for, and some I wasn't. If you get a chance go down to Belton or any ham swap-meet. It is is good time plus you can get parts for a LOT less than online sellers.

I meet James KC5LDO for an eyeball QSO and a tour of his shack, while my wife and his chatted for a while. ( I think this was the highlight of the trip for my wife, she gets dragged along and usually has to fend for herself.)

I had a chance to look over some of the great projects he had built. I got a first hand demonstration on how his Regenerative Receiver works. That is one hot little receiver. With only a short antenna, it pulled in many stations. Home brewing at its finest! We talked radios, antennas, and all the things you expect radio nuts to discuss. I showed James what I had so far with my own Regenerative Receiver and of course he spotted right off a problem I had been working on for the last few days.

Well it wasn't long before I had to get back on the road ( had to work that night).  James loaded me up with a sack full of parts, (thanks again James) we all said our goodbys and hit the road...

Oh yea there was this UFO thing we saw on the way back :)

You just never know what you might see on the road...

Twinplex Regenerative Receiver Part 3

Got a little more done today. The chassis paint came out great, so we have this process down. A deep Emerald green.

Installed the Hardware for the backside of the receiver. Broke down and bought a box of screws and nuts plus washers. A lot cheaper in the long run. Here is a picture of the backside with the parts installed.

On to the underside of the chassis. The filament transformer and audio transformer are installed. I also put in a few caps and resistors.

Back to the top side of the chassis now. I mounted the Band-set and Band-spread capacitors. Using the big knobs made putting plastic spacers underneath a must, but they are secure. Added the binding posts for the B+  voltage.

More to come....