I checked the schematic notes and the inverted pyramid symbol is the chassis
ground. The other symbol is the cabinet ground. Apparently the chassis is
isolated from the cabinet except for a single 0.25 mfd capacitor which
connects the two.

DaveW


"coffelt2" wrote in message
...
First, I don't have an answer, but am preparing to recap an even older
S-38 myself. I think I remember
from many, many years ago, that some of those "hot chassis" rigs had two
ground systems, that were actually connected together at some point.
Something about "ground loops" and hum
reduction. In the schematic you linked here, there are two different
ground symbols. Could one be the actual chassis connection, and the other
sort of a slightly "lifted" or signal/RF ground? Just guessing, hope
someone knows the real answer!

Old Chief Lynn, W7LTQ


"DaveW" wrote in message
...
I've begun the restoration of an S-38B. Just started to replace the
filters an I already have a question. The old multi-section cap ground
is connected to pin 2 of the 35Z5 rather than directly to the chassis
ground as shown in the schematic he
http://i1206.photobucket.com/albums/...gFilterCap.png
Pin2 is connected to the chassis ground through the filament string,
which has a 125 ohm resistance when cold. Is this a problem or were all
S38's wired in this manner?

The filter cap appears to be original but you can't always be certain.
It's clear other repairs have been made during its lifetime.

If anyone can recall recapping an S-38 I'd be interested in your
observation regarding the filter cap ground wire location.

Thanks,

DaveW

Yikes! That's why you could get quite a jolt just from the cabinet, and it
wasn't too cool
to use the S-38 right next to a grounded piece of gear. I think I remember
something in
QST "Hints and Kinks" about putting a light bulb (small wattage) between the
S-38's cabinet
and an adjacent, grounded piece of gear. If the lamp illuminated, reverse
the S-38's AC
wall plug.

Old Chief Lynn, W7LTQ


"DaveW" wrote in message
...
I checked the schematic notes and the inverted pyramid symbol is the
chassis ground. The other symbol is the cabinet ground. Apparently the
chassis is isolated from the cabinet except for a single 0.25 mfd capacitor
which connects the two.

DaveW


"coffelt2" wrote in message
...
First, I don't have an answer, but am preparing to recap an even older
S-38 myself. I think I remember
from many, many years ago, that some of those "hot chassis" rigs had two
ground systems, that were actually connected together at some point.
Something about "ground loops" and hum
reduction. In the schematic you linked here, there are two different
ground symbols. Could one be the actual chassis connection, and the other
sort of a slightly "lifted" or signal/RF ground? Just guessing, hope
someone knows the real answer!

Old Chief Lynn, W7LTQ


"DaveW" wrote in message
...
I've begun the restoration of an S-38B. Just started to replace the
filters an I already have a question. The old multi-section cap ground
is connected to pin 2 of the 35Z5 rather than directly to the chassis
ground as shown in the schematic he
http://i1206.photobucket.com/albums/...gFilterCap.png
Pin2 is connected to the chassis ground through the filament string,
which has a 125 ohm resistance when cold. Is this a problem or were all
S38's wired in this manner?

The filter cap appears to be original but you can't always be certain.
It's clear other repairs have been made during its lifetime.

If anyone can recall recapping an S-38 I'd be interested in your
observation regarding the filter cap ground wire location.

Thanks,

DaveW

coffelt2 wrote:
Yikes! That's why you could get quite a jolt just from the cabinet, and it
wasn't too cool
to use the S-38 right next to a grounded piece of gear. I think I remember
something in
QST "Hints and Kinks" about putting a light bulb (small wattage) between the
S-38's cabinet
and an adjacent, grounded piece of gear. If the lamp illuminated, reverse
the S-38's AC
wall plug.

Back in my mispent youth, I took an S-38B which I had been given, and stuffed
a small 120v output AC transformer in it to use as an isolation transformer.

I also added a little bit of 1960's technology to it, I put two silicon diodes
in as a noise limiter.

In a fit of cleaning out, having long since gotten digital showrtwave radios,
in the 1980's I gave the radio away.

Geoff.
--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(

On Sun, 11 Mar 2012, Geoffrey S. Mendelson wrote:

coffelt2 wrote:
Yikes! That's why you could get quite a jolt just from the cabinet, and it
wasn't too cool
to use the S-38 right next to a grounded piece of gear. I think I remember
something in
QST "Hints and Kinks" about putting a light bulb (small wattage) between the
S-38's cabinet
and an adjacent, grounded piece of gear. If the lamp illuminated, reverse
the S-38's AC
wall plug.

Back in my mispent youth, I took an S-38B which I had been given, and stuffed
a small 120v output AC transformer in it to use as an isolation transformer.

I also added a little bit of 1960's technology to it, I put two silicon diodes
in as a noise limiter.

In a fit of cleaning out, having long since gotten digital showrtwave radios,
in the 1980's I gave the radio away.

There was a story in "73" in the mid-sixties about someone trading in his
S38 for a better receiver (and obviously cash needed too). So the story
is basically about all the modifications he had to undo to put it back to
"normal". And right when he's at the store, he realizes he's forgotten
one mod, so he takes that out in the parking lot, I seem to recall having
to do some makeshift arrangement to cover the extra hole from that mod.

The isolation transformer wouldn't improve the receiver's ability to
receive one bit, but it sure made it a lot safer to use.

Michael

Just last week, I came across one for sale near Pittsburgh.
The owner bought it for $3.00 and was trying to sell it for $100.00

Before I approached him, I informed him about the floating ground issue and how the radio was dangerous and how it needed a transformer to make it more safe - due to the fact that it was designed for use with 120 VDC current not AC...

I could have bought it for $25.00 - but was unwilling to drive 120 miles to go pick it up.
When I stopped by a couple of days later - he had already sold it.

The radio is of little value - since it only did CW AM and has no SSB....
Just looking on Flea Bay tells me that they had issues with the cardboard on the rear of the radio - lot's of reproductions.

It would be ok if all you wanted it for was to listen to local traffic on the 11 meters - since it is mostly AM anyways!

"Channel Jumper" wrote in message
...
Just last week, I came across one for sale near Pittsburgh.
The owner bought it for $3.00 and was trying to sell it for $100.00

Before I approached him, I informed him about the floating ground issue
and how the radio was dangerous and how it needed a transformer to make
it more safe - due to the fact that it was designed for use with 120 VDC
current not AC...

I could have bought it for $25.00 - but was unwilling to drive 120 miles
to go pick it up.
When I stopped by a couple of days later - he had already sold it.

The radio is of little value - since it only did CW AM and has no
SSB....
Just looking on Flea Bay tells me that they had issues with the
cardboard on the rear of the radio - lot's of reproductions.

It would be ok if all you wanted it for was to listen to local traffic
on the 11 meters - since it is mostly AM anyways!

Channel Jumper

.......and thus fully qualifies as a genuine BOATANCHOR!

Old Chief Lynn, W7LTQ (Let's hear it for the old S-38 !!!!!!!!!!!!!!)

With all this discussion on the S 38 series, I wonder if everyone
knows about the S 38 website? http://www.the-s38-guy.com/ He has
some great information and hints. 73 Mike KF6KXG

Channel Jumper wrote:

The radio is of little value - since it only did CW AM and has no
SSB....
Just looking on Flea Bay tells me that they had issues with the
cardboard on the rear of the radio - lot's of reproductions.

Sure it will do SSB! The BFO isn't adjustable, but the IF is wide as a
barn, wide enough that you can just set it on CW and then tune back and
forth until you get clear audio. Mind you it's unusable in a pileup...
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Mon, 12 Mar 2012, Scott Dorsey wrote:

Channel Jumper wrote:

The radio is of little value - since it only did CW AM and has no
SSB....
Just looking on Flea Bay tells me that they had issues with the
cardboard on the rear of the radio - lot's of reproductions.

Sure it will do SSB! The BFO isn't adjustable, but the IF is wide as a
barn, wide enough that you can just set it on CW and then tune back and
forth until you get clear audio. Mind you it's unusable in a pileup...

Which was often the case for a lot of receivers. They had BFOs but
weren't so great when SSB came along, or required you to turn back the RF
gain a lot (so the BFO was strong compared to the incoming signal), which
made it relatively insensitive.

They weren't good receivers, but neither were a lot of low end ones back
then. But we bought them because we couldn't afford something better.

It wasn't a good choice, but a lot of people did start by shortwave
listening, so they got a general coverage receiver. A ham band only
receiver tended to be more expensive. So they had to live with a receiver
that wasn't particularly great for the ham bands, until they could
scrounge something better.

When I got my Hallicracter's S-120A in the summer of 1971, it was the
cheapest I could get, and almost more than I could afford, using up all
the birthday money saved in my relatively new bank account. It was junk,
not just cheap like the S38, but solid state and thus made worse because
the thing overloaded badly. But at the time, getting a ham license seemed
some years in the future, since at the time you had to be 15 or older to
get a license in Canada. So I bought that receiver, and never got much
out of it. At least it wsa a time when there were lots of SW broadcast
sttions, and I could thrill to WWV on six frequencies. And yes, it did
"well" on CB, because there were local signals, and when the band opened
up, it was wall to wall heterodynes.

It didn't do SSB, until I put a potentiometer between the antenna and the
antenna terminals and reduced signals so the BFO was strong enough,
leaving very few signals that were strong enough. But it wsa a period
when there were some AM stations, I thought at the time they were younger
and doing AM as "something new" but maybe not, maybe they just never
switched to SSB. So I could listen to them every night on 80m and it was
sort of what ham radio must have sounded like in earlier decades.

And then five months later, I read in the paper that the law was changing,
so you didn't need to be fifteen to get a ham license in Canada.

I couldn't use that receiver for CW, not enough selectivity, so I was
reduced to a record to learn the code. And then I was lucky, someone at
the ham club when I finally found it lent me an SP-600 (I had it for about
a decade), so I actually had a decent receiver. (It didn't do anything
differently than the S-120A when it came to SSB either, except it was a
much better receiver, much more sensitive and of course more selective, so
when I turned down the RF gain to use the BFO properly, there were still
plenty of SSB signals to receive.

Michael VE2BVW

"Scott Dorsey" wrote in message
...
Channel Jumper wrote:

The radio is of little value - since it only did CW AM and has no
SSB....
Just looking on Flea Bay tells me that they had issues with the
cardboard on the rear of the radio - lot's of reproductions.

Sure it will do SSB! The BFO isn't adjustable, but the IF is wide as a
barn, wide enough that you can just set it on CW and then tune back and
forth until you get clear audio. Mind you it's unusable in a pileup...
--scott

Bought my FIRST S-38 from the base exchange at Amarillo AFB, Tx, in
1951.
It was small enough to fit under my bunk, behind my lined up (and shined)
shoes. I was
already a ham, but Uncle Sam had better things for me to do!
Don't remember when I parted with that little Honey, but the following
year, 1952,
in the barracks in Germany, I built Heathkit's AR-1 (or was it AR-2?). A
crowd gathered
when I first plugged it in. A little curl of smoke from a resistor had them
all laughing, but
then loud music erupted, and there were cheers!
Now, a couple of years later, I found a maybe 6 of 10, 6 tube S-38. I
haven't got
my new cardboard back or bottom yet, but knobs are perfect. Some Gentleman
in the
Midwest is selling capacitor (condensers, really) kits, which I have. (for
three years)
Rome was not built in a day.

Old Chief Lynn, W7LTQ