Hallicrafters S-20R - mods from previous owner

[C.Copperpot]

I bought this radio a couple years ago from an audio shop near
hollywood. It looks like it may have been used as a movie prop at one
time.
The original FC speaker was replaced by a PM type. There was a
unsecured choke rattling around in the case. I decided to replace the
choke with a 1.4k 10W resistor (original FC was 1400 ohms DC res.). I
replaced all of the wax and electrolytic caps, bad resistors. I never
powered it up previous to component replacements

There is a hum you can hear with the volume all the way down and stays
the same when it's turned up. I tried increasing the electolytic value
to about 100 mfd (the one after where the FC would have been) and that
helps a little. Should I just get a new choke (the old one was beat to
sh*t and only reads less than 100 ohms DC) and ditch the resistor?

This radio has a couple of these weird coils hooked up on the
transformer where the AC lines go in. Definitely added later. They
look like miniature woven indian baskets. Any idea what they are and
what they were trying to do? Should I take them off?

[Foxs Mercantile]

Post by C.Copperpot
The original FC speaker was replaced by a PM type. There was a
unsecured choke rattling around in the case. I decided to replace the
choke with a 1.4k 10W resistor (original FC was 1400 ohms DC res.). I
replaced all of the wax and electrolytic caps, bad resistors. I never
powered it up previous to component replacements

The original FC inductance was probably inthe neighborhood of 10-20
Henries.

Post by C.Copperpot
This radio has a couple of these weird coils hooked up on the
transformer where the AC lines go in. Definitely added later. They
look like miniature woven indian baskets. Any idea what they are and
what they were trying to do? Should I take them off?

An attempt at AC line filtering for RF.

[Hank]

Post by C.Copperpot
I bought this radio a couple years ago from an audio shop near
hollywood. It looks like it may have been used as a movie prop at one
time.
The original FC speaker was replaced by a PM type. There was a
unsecured choke rattling around in the case. I decided to replace the
choke with a 1.4k 10W resistor (original FC was 1400 ohms DC res.). I
replaced all of the wax and electrolytic caps, bad resistors. I never
powered it up previous to component replacements
There is a hum you can hear with the volume all the way down and stays
the same when it's turned up. I tried increasing the electolytic value
to about 100 mfd (the one after where the FC would have been) and that
helps a little. Should I just get a new choke (the old one was beat to
sh*t and only reads less than 100 ohms DC) and ditch the resistor?
This radio has a couple of these weird coils hooked up on the
transformer where the AC lines go in. Definitely added later. They
look like miniature woven indian baskets. Any idea what they are and
what they were trying to do? Should I take them off?

Your best bet would be to go over it and restore it back to original.
There's some good information on
http://bama.edebris.com/manuals/hallicra/s20r/

This set is a "typical Hallicrafters," superb design, but built quite
cheaply. It's also the precursor to the S-40 postwar set. As I recall,
it did better than the S-40 overall, particularly inasmuch as it uses a
6K8 instead of a 6SA7. Still gets rather deaf at higher frequencies.

On the power supply, I'd get a Hammond choke, maybe 10 henries for 100
ma., and use that in place of the speaker field. The 30 mike filter
caps are already overkill; don't go higher. Adjust the voltage on the
RF/IF screens to original. As I recall, it is 100-120 volts. Use
resistance following the second filter cap to adjust. This supply is
critical for hum control; the plates are not.

Check the values of all the resistors. Originals were 20%, and if you
are beyond that, replace. Consider replacing all the wax paper
capacitors. One critical cap is the coupling cap between the 6SQ7 plate
and 6F6 grid. If that is leaky (and/or the 6F6 grid leak has gone
high), you'll get a lot of DC in the 6F6 circuit.

On hum in general: If it is B+, it is 120 CPS. If it is 60 cycle, it's
something leaking into the audio circuits.

Hank

[Frank]

Check for heater to cathode leakage on the detector/1st audio (6SQ7?) and
the audio output tube. (6F6?)

[C.Copperpot]

Still working on it. So far I've found a couple resistors that had
been replaced with the wrong value. There was also a cap missing
(C22). I'm thinking that the wiring for C28, C29 electorlytics have
been swapped (not reversed polarity). Ill' trace the wires some more
tomorrow.
When I replaced all of the wax and electrolytic caps, I ASSumed they
were right. I'm not used to working on radios that have been tinkered
with.

[o***@tubes.com]

On Tue, 17 Oct 2017 17:06:19 -0700, C.Copperpot

Post by C.Copperpot
Still working on it. So far I've found a couple resistors that had
been replaced with the wrong value. There was also a cap missing
(C22). I'm thinking that the wiring for C28, C29 electorlytics have
been swapped (not reversed polarity). Ill' trace the wires some more
tomorrow.
When I replaced all of the wax and electrolytic caps, I ASSumed they
were right. I'm not used to working on radios that have been tinkered
with.

That was likely a kit. so the builder may have screwed up something. I
saw your followup post that said you found the wires reversed on the
filter caps. So, the kit builder probably screwed it up. Also with the
missing cap.

If that was mine, I'd probably put a choke where the speaker field was.

Hank said its similar to the S-40. I have a S-40A. I found that at an
antique store with no power cord, so the seller took a low bid from me,
cuz he said he cant test it if he cant plug it in. But I have too many
projects going on to start on that one right now....

We never did hear or find out what those coils are on the power cord.
That has me puzzled....

[Peter Wieck]

Post by o***@tubes.com
That was likely a kit.

I do not believe that Hallicrafters ever made kits. If you have information to the contrary, please let us know.

Now, given that S20R is a 1939-series radio, it is more than likely that it has been repaired/altered/muddled over the last 78+ years. Further to this, many SW radios were, apparently, emasculated during the war so as to prevent German and Italian-born residents from listening. That could also be in play.

Keep in mind that SW listening was immensely popular during the war and into the cold war, and as civilian production stopped more-or-less in late 1941/early 1942, this radio would be even more treasured. Point being that anything is possible to explain its present condition.

Peter Wieck
Melrose Park, PA

[Frank]

Post by Peter Wieck
I do not believe that Hallicrafters ever made kits. If you have
information to the contrary, please let us know.

I don't think Hallicrafters marketed kit radios, although I have a dim,
probably false, recollection that they sold a kit version of their 3 tube
sky buddy in the early 60s. I'm probably thinking of the Heathkit regen,
which looked similar.

Hallicrafters did sell some test equipment kits such as a VTVM and a
signal generator. They're uncommon. I've never seen one in person, only
pictures in the Dachis book and in a couple of ebay auctions.

Post by Peter Wieck
Now, given that S20R is a 1939-series radio, it is more than likely that
it has been repaired/altered/muddled over the last 78+ years.

Likely ham repairs. There's a few explanations for why radio amateurs
are called hams. I'm going with "Ham handed".

[C.Copperpot]

Post by o***@tubes.com
On Tue, 17 Oct 2017 17:06:19 -0700, C.Copperpot

Post by C.Copperpot
Still working on it. So far I've found a couple resistors that had
been replaced with the wrong value. There was also a cap missing
(C22). I'm thinking that the wiring for C28, C29 electorlytics have
been swapped (not reversed polarity). Ill' trace the wires some more
tomorrow.
When I replaced all of the wax and electrolytic caps, I ASSumed they
were right. I'm not used to working on radios that have been tinkered
with.

That was likely a kit. so the builder may have screwed up something. I
saw your followup post that said you found the wires reversed on the
filter caps. So, the kit builder probably screwed it up. Also with the
missing cap.
If that was mine, I'd probably put a choke where the speaker field was.
Hank said its similar to the S-40. I have a S-40A. I found that at an
antique store with no power cord, so the seller took a low bid from me,
cuz he said he cant test it if he cant plug it in. But I have too many
projects going on to start on that one right now....
We never did hear or find out what those coils are on the power cord.
That has me puzzled....

The electrolytics had been replaced probably in the 60's and swapped
one of the wires to the wrong place. The FC speaker had been replaced
with a PM type and they wired a big choke in there. Unfortunatly they
didn't bolt it down and it bashed all over the place during shipping.
I spent hours re-bending the tuning capacitor fins so they wouldn't
short out (bent by that choke). They're really close together on this
model. These radios were usually owned by people who had knowlege of
electronics, so finding weird mods, etc in them is probably normal. I
forgot to mention that those coils attached on the transformer at the
line-in have tuneable slugs. Maybe they were trying to filter out the
buzz that was caused by mis-wiring the cap. I just left them in there
- they don't seem to be hurting anything.

[Foxs Mercantile]

Post by o***@tubes.com
That was likely a kit.

Hallicrafters did NOT sell kit versions of their
production radios.

The S-20R was in production from 1939-1945.
That makes it between 72-78 years old.

Back in the '50s and '60s you just about couldn't
give them away. (Pre-boat anchor collection era.)

Many of them were given to Novice class amateurs.
Others were snapped up at swap meets for $5-10.

Almost all of them have had many different owners
over the years with their own ideas of "I can fix
this."

Some of them were properly repaired/restored, but
a good number of them were butchered because they
were "cheap throw away" radios.

[C.Copperpot]

Post by Foxs Mercantile

Post by o***@tubes.com
That was likely a kit.

Hallicrafters did NOT sell kit versions of their
production radios.
The S-20R was in production from 1939-1945.
That makes it between 72-78 years old.
Back in the '50s and '60s you just about couldn't
give them away. (Pre-boat anchor collection era.)
Many of them were given to Novice class amateurs.
Others were snapped up at swap meets for $5-10.
Almost all of them have had many different owners
over the years with their own ideas of "I can fix
this."
Some of them were properly repaired/restored, but
a good number of them were butchered because they
were "cheap throw away" radios.

This one had a couple of extra holes drilled in the front. Probably
for a toggle switch and a jewell light. It had a 4 ft lead with a male
phono jack lead wired under the chassis (I took that out). Someone
also added a tuning eye to it in the upper left corner.That works
pretty good, but they ran the wires for it through a tiny hole in the
chassis. I drilled that out and added a rubber grommet.

[Foxs Mercantile]

Post by C.Copperpot
This one had a couple of extra holes drilled in the front.
Probably for a toggle switch and a jewel light.

This is what I refer to as Joe "Claw Hammer" Ham getting his
monkey little fingers into the radio to fuck it up.

Post by C.Copperpot
It had a 4 ft lead with a male phono jack lead wired under
the chassis (I took that out).

Either one of two reasons for that. Either a phono input, or
an output to a panadaptor or a "Q-5er" additional IF stage.

Post by C.Copperpot
Someone also added a tuning eye to it in the upper left
corner.That works pretty good, but they ran the wires for it
through a tiny hole in the chassis. I drilled that out and
added a rubber grommet.

That was a popular "add on" for low end radios.

This is what it's supposed to look like:
<Loading Image...>

[C.Copperpot]

Post by Foxs Mercantile

Post by C.Copperpot
This one had a couple of extra holes drilled in the front.
Probably for a toggle switch and a jewel light.

This is what I refer to as Joe "Claw Hammer" Ham getting his
monkey little fingers into the radio to fuck it up.

Post by C.Copperpot
It had a 4 ft lead with a male phono jack lead wired under
the chassis (I took that out).

Either one of two reasons for that. Either a phono input, or
an output to a panadaptor or a "Q-5er" additional IF stage.

Post by C.Copperpot
Someone also added a tuning eye to it in the upper left
corner.That works pretty good, but they ran the wires for it
through a tiny hole in the chassis. I drilled that out and
added a rubber grommet.

That was a popular "add on" for low end radios.
<http://w2dtc.com/w2dtc-s-20r-receiver/2004-0707-s-20r-001.jpg>

And here's what mine looks like https://imgur.com/a/UwRsE
I really believe it may have been used as a movie prop because the way
it was painted was to puposely look old/military. I bought from an
audio shop in Hollywoodm CA. The only thing I did to the front was I
wrote the knob functions with perm. marker and filled a couple holes
with plastic plugs.

[Foxs Mercantile]

And here's what mine looks likehttps://imgur.com/a/UwRsE

Those holes in the upper right hand corner.
These switches were a "Big item" in surplus sales.
Almost in the same category of "Buy something and
we'll throw in a hand full of these."
<Loading Image...>

I really believe it may have been used as a movie prop because the way
it was painted was to puposely look old/military. I bought from an
audio shop in Hollywoodm CA. The only thing I did to the front was I
wrote the knob functions with perm. marker and filled a couple holes
with plastic plugs.

And at least it's being brought back from the dead.

[C.Copperpot]

Post by Foxs Mercantile

And here's what mine looks likehttps://imgur.com/a/UwRsE

Those holes in the upper right hand corner.
These switches were a "Big item" in surplus sales.
Almost in the same category of "Buy something and
we'll throw in a hand full of these."
<https://thumbs.worthpoint.com/zoom/images1/1/1211/12/vintage-wwii-aircraft-instrument_1_bbb288b89edaf1adf4dd5a19ccdf320f.jpg>

Ah - that's probably what was there

Post by Foxs Mercantile

I really believe it may have been used as a movie prop because the way
it was painted was to puposely look old/military. I bought from an
audio shop in Hollywoodm CA. The only thing I did to the front was I
wrote the knob functions with perm. marker and filled a couple holes
with plastic plugs.

And at least it's being brought back from the dead.

I was going to re-paint but it's so buggly (butt ugly), I decided to
keep it that way for fun. There was so much hacking under the chassis
that I really didn't spend alot of time trying to make it look real
nice (it's real hard to polish a turd).

[o***@tubes.com]

On Mon, 11 Dec 2017 10:38:47 -0800, C.Copperpot

Post by C.Copperpot

Post by Foxs Mercantile

Post by o***@tubes.com
That was likely a kit.

Hallicrafters did NOT sell kit versions of their
production radios.
The S-20R was in production from 1939-1945.
That makes it between 72-78 years old.
Back in the '50s and '60s you just about couldn't
give them away. (Pre-boat anchor collection era.)
Many of them were given to Novice class amateurs.
Others were snapped up at swap meets for $5-10.
Almost all of them have had many different owners
over the years with their own ideas of "I can fix
this."
Some of them were properly repaired/restored, but
a good number of them were butchered because they
were "cheap throw away" radios.

This one had a couple of extra holes drilled in the front. Probably
for a toggle switch and a jewell light. It had a 4 ft lead with a male
phono jack lead wired under the chassis (I took that out). Someone
also added a tuning eye to it in the upper left corner.That works
pretty good, but they ran the wires for it through a tiny hole in the
chassis. I drilled that out and added a rubber grommet.

I would have added the grommet too. I enver liked the idea of wires
going thru a bare hole in metal.