Picked up an S38B to relive my childhood and it seems to work on AM
about as well as my only other receiver, TS430.

I am going to make it my AM station receiver if and when I can get the
BFO to work. I still need the Kenwood to know where the Ranger is at.

I tried moving the E wire around as suggested in the manual but it did
not help. No heterodyne at all.

Anyone with any experience with this?

JACK K9ACT

--
PHOTO OF THE WEEK: http://schmidling.com/pow.htm
Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver http://schmidling.com

Jack,
Try the S 38 website. He has lots of info.
http://www.the-s38-guy.com/ 73 KF6KXG Mike

On Dec 31, 5:48 pm, Jack Schmidling wrote:
Picked up an S38B to relive my childhood and it seems to work on AM
about as well as my only other receiver, TS430.

I am going to make it my AM station receiver if and when I can get the
BFO to work. I still need the Kenwood to know where the Ranger is at.

I tried moving the E wire around as suggested in the manual but it did
not help. No heterodyne at all.

Anyone with any experience with this?

JACK K9ACT

--
PHOTO OF THE WEEK:http://schmidling.com/pow.htm
Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silverhttp://schmidling.com

"Jack Schmidling" wrote in message
...
Picked up an S38B to relive my childhood and it seems to work on AM about
as well as my only other receiver, TS430.

I am going to make it my AM station receiver if and when I can get the BFO
to work. I still need the Kenwood to know where the Ranger is at.

I tried moving the E wire around as suggested in the manual but it did not
help. No heterodyne at all.

Anyone with any experience with this?

JACK K9ACT


Brian Ripley, K8BR of Ogden, Utah has a great site devoted to the care and
restoration of the Hallicrafters S-38 series.
http://www.the-s38-guy.com/

Your BFO question
http://www.the-s38-guy.com/Page_63.html

Back cover S38 series reproductions are available from
Bob's Antique Radio & Electronics - LaGrange Park, IL
http://www.radioantiques.com/mall.html

tchrme wrote:
Jack,
Try the S 38 website. He has lots of info.
http://www.the-s38-guy.com/ 73 KF6KXG Mike

I found that site about 5 mins after posting the question. The first
time I went there I got side tracked in a bra site... like size 38 b?

It was very strange.. S38 guy but whenever I clicked on the link to s38b
I got this stupid bra site.

Anyway, I tried his fix and it worked like a charm, only too well. I
now have a BFO but the sig strength suffers dramatically even in the am
mode.

Wish I understood what was going on. Before I "fixed" it, the sigs got
louder when I switched to CW.

JACK K9ACT


--
PHOTO OF THE WEEK: http://schmidling.com/pow.htm
Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver http://schmidling.com

Jack Schmidling wrote:

Picked up an S38B to relive my childhood and it seems to work on AM
about as well as my only other receiver, TS430.

I am going to make it my AM station receiver if and when I can get the
BFO to work.

Just for fun, try a kludge BFO. Place an AM broadcast band radio (non-digital)
as physically close to the S38 as you can get it. Tune the broadcast band radio
until you hear a beat with the AM or CW signal you are listening to on the S38.
The oscillator in the AM radio should leak into the S38 to cause the beat.
Course it depends on somewhat poor shielding on both receivers to work. I
sometimes used this method as a kid to listen to SSB and CW on those old SW
receivers that didn't have a BFO. Those were the days...

Jack Schmidling ) writes:
tchrme wrote:
Jack,
Try the S 38 website. He has lots of info.
http://www.the-s38-guy.com/ 73 KF6KXG Mike

I found that site about 5 mins after posting the question. The first
time I went there I got side tracked in a bra site... like size 38 b?

It was very strange.. S38 guy but whenever I clicked on the link to s38b
I got this stupid bra site.

Anyway, I tried his fix and it worked like a charm, only too well. I
now have a BFO but the sig strength suffers dramatically even in the am
mode.

Wish I understood what was going on. Before I "fixed" it, the sigs got
louder when I switched to CW.

JACK K9ACT

Unless I'm confusing it with a different version that did have a real
BFO (which does't seem the case given your comments), the "BFO" on
that radio is actually the IF amplifier going into oscillation. The
wire you mention is positive feedback, so the stage will oscillate
and thus beat with the incoming signal.

It's a cheap way of getting a beat signal, since it doesn't require
a separate tube. On the other hand, it doesn't give you much control.

The stage is being used like a regenerative receiver, ie positive
feedback. A real regen detector has something to control the
level of feedback. So it goes from merely being an amplifier to
where there is regeneration (the same stage amplifies the signal,
and the feedback means it amplifies it again and again), so the
gain goes up, and selectivity should also improve. But, when
the stage kicks into oscillation, that isn't necessarily the best
place for amplification (I've heard conflicting views about this,
and some have said it's merely that one isn't controlling the stage
properly and good gain and selectivity can be had while the stage
is oscillating).

What it sounds like is you had the feedback wire set so the stage
did have some positive feedback, but not enough for the stage
to go into oscillation, so you noticed the increased gain.

I don't know if there is a control to adjust the regeneration, but
if there is, that might help. Turning it down from where it oscillates
would simply give you gain and better selectivity.

When using the IF stage as the beat oscillator, you really don't get
much control since the same stage is doing two different things. On
the other hand, at the time of the receiver's design, a BFO was really
mostly so you'd hear some tone when tuning a CW station, and it was
sufficient. It was only as SSB became more popular that such schemes
might not provide enough of a beat signal for proper demodulation.

Michael VE2BVW

"Michael Black" wrote in message
...
....
when
the stage kicks into oscillation, that isn't necessarily the best
place for amplification (I've heard conflicting views about this,
and some have said it's merely that one isn't controlling the stage
properly and good gain and selectivity can be had while the stage
is oscillating).

The general fact is that a stage has maximum useable amplification and
selectivity just *before* the point of oscillation

AaronJ wrote:

Just for fun, try a kludge BFO. Place an AM broadcast band radio (non-digital)
as physically close to the S38 as you can get it. Tune the broadcast band radio
until you hear a beat with the AM or CW signal you are listening to on the S38.

Actually, I already did that but it's a pretty academic exercise.

After all is said, seems like there should be some way to control the
feedback to both provide a beat and optimize the gain/selectivity.

I have no interest in CW or sideband with this radio but I do need some
way to set my ranger on the station I am listening to.

Any thoughts on an outboard tweak?

js

--
PHOTO OF THE WEEK: http://schmidling.com/pow.htm
Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver http://schmidling.com

Jack Schmidling ) writes:
AaronJ wrote:

Just for fun, try a kludge BFO. Place an AM broadcast band radio (non-digital)
as physically close to the S38 as you can get it. Tune the broadcast band radio
until you hear a beat with the AM or CW signal you are listening to on the S38.

Actually, I already did that but it's a pretty academic exercise.

After all is said, seems like there should be some way to control the
feedback to both provide a beat and optimize the gain/selectivity.

There's no control for it? That seems odd.

The trick is to make the cathode resistor variable, and use that to
control the level of regeneration.

I have no interest in CW or sideband with this radio but I do need some
way to set my ranger on the station I am listening to.

Any thoughts on an outboard tweak?

js

Don't put it on transmit, but key the oscillator? Old rigs often
were set up that way, so you'd have a weak signal from the transmitter
to set the receiver to.

Or, they'd have some spotting function specifically for it.

Michael VE2BVW

The simplest way I can think of is to go over to the shelf of test equipment
and grab the old Heath signal generator and attach a foot long wire close to
the S-38. Then tune the generator to 455 kc (whoops, that is kHz). You
will have a nice beat note.

Like the others have said, convert the if stage into an oscillator - then
reduce the feedback to get it to stop oscillating. That will then be sort
of a Q multiplier while in the feedback but not enough to oscillate stage.
You would need a control to put in and out of oscillation. A pot, a
variable capacitor or a switch.

Or, just a hum a few bars into the Ranger mike and tune for best audio.

73, Colin