Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

I'm considering building the am/cw transmitter in the 1966 handbook
(probably in others, too). It runs a single 6146 in the final.

I am curious if anyone has ever built that rig. If I build it, it will
probably be with an outboard power supply, and a single switch for input /
tank band switching.

Also curious: Anyone ever homebrewed a DX-60?

Jeff
W8KZW

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

Jeffrey Bauman wrote:
I'm considering building the am/cw transmitter in the 1966 handbook
(probably in others, too). It runs a single 6146 in the final.

I am curious if anyone has ever built that rig. If I build it, it will
probably be with an outboard power supply, and a single switch for input /
tank band switching.

Also curious: Anyone ever homebrewed a DX-60?

Jeff
W8KZW


I built a similar rig, but it was weakly based on that design.
Mine had a 6GK6 oscillator and a 6146 final. It was built inside
a chassis with the tubes mounted on a subchassis inside. The tubes
were "sideways" and holes were drilled in the chassis-cabinet for
ventilation.

I am assuming the same transmitter was described in the 1967 HB (which
was the first HB I ever bought). You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone. Low cost SSB xcvrs wiped out AM by the mid 1970's.

I was thinking of building a simple rig again but with a 1625 in the final.
I have about a dozen of these bottles in the junk box along with half as many
6AG7's. The crystals will be the scarce items these days (well expensive
anyway).

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

On Sun, 22 Jan 2006 15:17:47 -0500, wa2mze(spamless) wrote:

You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone.

OH, Really!?? Snert! - Sporf! - Snurt! TNX for the laugh!

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
Pueblo, Colorado | @ | Jonesy | OS/2 __
38.24N 104.55W | config.com | DM78rf | SK

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

"Dale Parfitt" wrote in message
news:bxSAf.3549$Ez3.3368@trnddc03...

I am assuming the same transmitter was described in the 1967 HB (which
was the first HB I ever bought). You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone. Low cost SSB xcvrs wiped out AM by the mid 1970's.

Are you serious? The only phone I listen to are the A.M. gang- wonderful
rigs from the past on 3885, 7290 etc. There's someone on all day long- and
unlike the SSB gang, these guys know theory and are active builders/
restorers- perhaps the best that amateur radio has to offer today.

Dale W4OP
I have to wait a bit later in the evening (season/band changes) and they can
be heard in Chicago area ... there is also the 160 meter gang .. and that
truly is like listening to late night AM broadcast.

w9gb

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone.

OH, Really!?? Snert! - Sporf! - Snurt! TNX for the laugh!

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
Pueblo, Colorado | @ | Jonesy | OS/2 __
38.24N 104.55W | config.com | DM78rf | SK

Yepper ....just like the fellow on 2 meters said .......nobody uses CW
anymore .....its DOA . I just like to put up my feet, lean back, and open
an Iron City Beer and enjoy the quality of those AM signals ... and this
from a 99.99% CWist. My buddy built on of those rigs in 66 and it worked
fine with his Mor-Gain antenna ...even with the hardware cloth safety mesh
covering the chassis. Lots 'o fun.

God Bless and 73 all ..... KI3R Tom in Belle Vernon PA

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

wa2mze(spamless) wrote:




You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone. Low cost SSB xcvrs wiped out AM by the mid 1970's.

Uh-oh.

-Bill

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

wa2mze(spamless) wrote:

Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You need to get out more. AM is alive and well on both 160 and 75
meters every day, and on ten meters when it's open.

Bill, W6WRT

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

Jeffrey Bauman wrote:
I'm considering building the am/cw transmitter in the 1966 handbook
(probably in others, too). It runs a single 6146 in the final.

I am curious if anyone has ever built that rig. If I build it, it will
probably be with an outboard power supply, and a single switch for input /
tank band switching.

Not that exact rig, but I've built similar 6146 transmitters. One
gotcha with the oscillator-final setup is that you may not end up with
enough drive on 21 and 28 MHz, if those bands matter to you. The Eico
720 improves on this by using a buffer/multiplier.

I like the Eico 720 design, but a weakness is lack of VR regulation
leading to chirp (especially if you multiply up.)

The handbook transmitter doesn't include a clamping tube, so if for
some reason you have no or insufficient drive you can find your final
tube dissipating too much power and melting down. But, elsewhere in
that handbook you will find several examples of clampers.

Bandswitching and plate choke resonances are easier to deal with if you
limit yourself to 2 bands or so (say 80 and 40 or 40 and 20).

Every handbook from the late 40's up through the early 70's has a CW
transmitter rig of similar spirit, earlier ones using a 1625 or 807 or
something similar.

Tim.

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

On Sun, 22 Jan 2006 15:17:47 -0500, "wa2mze(spamless)"
wrote:


You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone.

Thats interesting, I wonder what mode I was using on 2m last Sunday
morning?.
It was an AM qso over a distance of about 90 miles, received an R5-S3
and gave an R5-S2. Both of us were running about 2.5w
--

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

I'm considering building the am/cw transmitter in the 1966 handbook
(probably in others, too). It runs a single 6146 ....
I built a similar rig, but it was weakly based on that design.
Mine had a 6GK6 oscillator and a 6146 final....

I was thinking of building a simple rig again but with a 1625 in the final.
I have about a dozen of these bottles in the junk box ....

When I find the right round tuit I want to use TEN 1625's with their
filaments series'd across the 120 VAC line in a simple CW rig. Can't
find it right now, but somewhere around here I have an article from
an old radio magazine describing just such a transmitter.

IIRC, the capacitance from ten tubes limited it to the lower HF band(s),
but it still seems like an easy way to get 750 watts!
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

On Sun, 22 Jan 2006 03:44:05 GMT, "Jeffrey Bauman"
wrote:

I'm considering building the am/cw transmitter in the 1966 handbook
(probably in others, too). It runs a single 6146 in the final.

I am curious if anyone has ever built that rig. If I build it, it will
probably be with an outboard power supply, and a single switch for input /
tank band switching.

Also curious: Anyone ever homebrewed a DX-60?

Jeff
W8KZW

I have the "Inexpensive 75-Watt Transmitter" from the 1964 Handbook.
It's a 12BY7 oscillator driving a 1625. I bought it on eBay a couple
of years ago, and it looks just like the one in the Handbook, with the
vertically mounted meter, coil shields and exact layout. For some
reason, it got painted black somewhere along the way.

I tried it out a few months ago, and should have reformed the caps.
Kerpow!!! So, I've got some work to do on it.
Ted KX4OM

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

I built one around '62-'63 from the Handbook. It was ONLY a 6146 amp. I
duplicated the osc/driver of the Eico 720 to drive it. I think the amp had
a "gimmic* neutralizing cap. I'll probably find it in my mom's house when I
have to sell it.
73, Steve, K,9.D;C'I



"Jeffrey Bauman" wrote in message
link.net...
I'm considering building the am/cw transmitter in the 1966 handbook
(probably in others, too). It runs a single 6146 in the final.

I am curious if anyone has ever built that rig. If I build it, it will
probably be with an outboard power supply, and a single switch for input /
tank band switching.

Also curious: Anyone ever homebrewed a DX-60?

Jeff
W8KZW

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

Forgot. 3885 is an AM freq and I think 7295, but not sure. You'll also
hear some on 160.
73, K9DCI


"Mike W" wrote in message
...
On Sun, 22 Jan 2006 15:17:47 -0500, "wa2mze(spamless)"
wrote:


You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone.

Thats interesting, I wonder what mode I was using on 2m last Sunday
morning?.
It was an AM qso over a distance of about 90 miles, received an R5-S3
and gave an R5-S2. Both of us were running about 2.5w
--

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

"wa2mze(spamless)" wrote in message
...
Jeffrey Bauman wrote:
I'm considering building the am/cw transmitter in the 1966 handbook
(probably in others, too). It runs a single 6146 in the final.

I am curious if anyone has ever built that rig. If I build it, it will
probably be with an outboard power supply, and a single switch for input
/
tank band switching.

Also curious: Anyone ever homebrewed a DX-60?

Jeff
W8KZW


I built a similar rig, but it was weakly based on that design.
Mine had a 6GK6 oscillator and a 6146 final. It was built inside
a chassis with the tubes mounted on a subchassis inside. The tubes
were "sideways" and holes were drilled in the chassis-cabinet for
ventilation.

I am assuming the same transmitter was described in the 1967 HB (which
was the first HB I ever bought). You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone. Low cost SSB xcvrs wiped out AM by the mid 1970's.

I was thinking of building a simple rig again but with a 1625 in the
final.
I have about a dozen of these bottles in the junk box along with half as
many
6AG7's. The crystals will be the scarce items these days (well expensive
anyway).


Just curious why you think the AM modulator will be "useless today" ?????
I'll have to tell those AMers running DX-?? equipment to stop talking into
the mic, right?

Dan/W4NTI

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

I was thinking of building a simple rig again but with a 1625 in the
final.
I have about a dozen of these bottles in the junk box ....

When I find the right round tuit I want to use TEN 1625's with their
filaments series'd across the 120 VAC line in a simple CW rig. Can't
find it right now, but somewhere around here I have an article from
an old radio magazine describing just such a transmitter.

IIRC, the capacitance from ten tubes limited it to the lower HF band(s),
but it still seems like an easy way to get 750 watts!
--
--Myron A. Calhoun.

Hey, Man, I don't know about TEN 1625's, but I did try five 1625's (in
parallel, of course) and could work up to 40 CW....... (as an American in
France, F7CT). Almost 1000VDC on the plates, and they did get pretty rosy
on a long "dah". 1625's could be drawn by the basket full from the MARS
storeroom at Toul Rosieres Air Base, France. 1962......1963?
Old Chief Lynn...... W7LTQ

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

garigue wrote:
You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone.

OH, Really!?? Snert! - Sporf! - Snurt! TNX for the laugh!

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
Pueblo, Colorado | @ | Jonesy | OS/2 __
38.24N 104.55W | config.com | DM78rf | SK


Yepper ....just like the fellow on 2 meters said .......nobody uses CW
anymore .....its DOA . I just like to put up my feet, lean back, and open
an Iron City Beer and enjoy the quality of those AM signals ... and this
from a 99.99% CWist. My buddy built on of those rigs in 66 and it worked
fine with his Mor-Gain antenna ...even with the hardware cloth safety mesh
covering the chassis. Lots 'o fun.

God Bless and 73 all ..... KI3R Tom in Belle Vernon PA


Well I havn't heard any AM on the HF bands in a long time, but I stand
corrected that some people still use it. Granted it's in the minority
and on "calling frequencies". I don't think those screen grid modulators
found in novice rigs were of much use though. They didn't have
much punch and poor audio. If you are going to go AM, a real plate
modulator is the only way to go. (I shudder to think what a plate
modulation transformer would cost these days....)

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

Mike W wrote:
On Sun, 22 Jan 2006 15:17:47 -0500, "wa2mze(spamless)"
wrote:



You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone.


Thats interesting, I wonder what mode I was using on 2m last Sunday
morning?.
It was an AM qso over a distance of about 90 miles, received an R5-S3
and gave an R5-S2. Both of us were running about 2.5w
--


I remember having a Gonset 2m communicator I as a novice.
Is there any am left on 2m? Can those new multi mode rigs
even transmit on am?

I never said AM doesn't have it's place. It's gone as a DX mode,
but on a quiet band is great for rag chewing.

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

Lynn Coffelt wrote:
I was thinking of building a simple rig again but with a 1625 in the

final.

I have about a dozen of these bottles in the junk box ....

When I find the right round tuit I want to use TEN 1625's with their
filaments series'd across the 120 VAC line in a simple CW rig. Can't
find it right now, but somewhere around here I have an article from
an old radio magazine describing just such a transmitter.

IIRC, the capacitance from ten tubes limited it to the lower HF band(s),
but it still seems like an easy way to get 750 watts!
--
--Myron A. Calhoun.


Hey, Man, I don't know about TEN 1625's, but I did try five 1625's (in
parallel, of course) and could work up to 40 CW....... (as an American in
France, F7CT). Almost 1000VDC on the plates, and they did get pretty rosy
on a long "dah". 1625's could be drawn by the basket full from the MARS
storeroom at Toul Rosieres Air Base, France. 1962......1963?
Old Chief Lynn...... W7LTQ


Let's see... the output C of an 807 (1625 is the same) is 7pf, the input C
is 12pf. With 10 tubes thats 70pf output and 120pf input. Won't work
at all on 10m, and iffy on 20. Would be fine on 80 and 40.

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

Dan/W4NTI wrote:
"wa2mze(spamless)" wrote in message
...

Jeffrey Bauman wrote:

I'm considering building the am/cw transmitter in the 1966 handbook
(probably in others, too). It runs a single 6146 in the final.

I am curious if anyone has ever built that rig. If I build it, it will
probably be with an outboard power supply, and a single switch for input
/
tank band switching.

Also curious: Anyone ever homebrewed a DX-60?

Jeff
W8KZW



I built a similar rig, but it was weakly based on that design.
Mine had a 6GK6 oscillator and a 6146 final. It was built inside
a chassis with the tubes mounted on a subchassis inside. The tubes
were "sideways" and holes were drilled in the chassis-cabinet for
ventilation.

I am assuming the same transmitter was described in the 1967 HB (which
was the first HB I ever bought). You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone. Low cost SSB xcvrs wiped out AM by the mid 1970's.

I was thinking of building a simple rig again but with a 1625 in the
final.
I have about a dozen of these bottles in the junk box along with half as
many
6AG7's. The crystals will be the scarce items these days (well expensive
anyway).



Just curious why you think the AM modulator will be "useless today" ?????
I'll have to tell those AMers running DX-?? equipment to stop talking into
the mic, right?

Dan/W4NTI


I stand corrected that some people are still rag chewing on AM.
I never did like the screen modulator's though. No punch.

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

Well I havn't heard any AM on the HF bands in a long time, but I stand
corrected that some people still use it. Granted it's in the minority
and on "calling frequencies". I don't think those screen grid modulators
found in novice rigs were of much use though. They didn't have
much punch and poor audio. If you are going to go AM, a real plate
modulator is the only way to go. (I shudder to think what a plate
modulation transformer would cost these days....)

Have to agree there Ken as I have had a few screen jobs in the "good old
days". They weren't good for too much only to get on phone for a youngster
who didn't have the bucks for a SSB or plate modulated rig. My old Globe
Chief had the screen modulator but did not perform well at all .

God Bless ....Tom KI3R Belle Vernon PA

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

You will probably be best off winding your own. My advice is this:
find the core size required to handle an amount of power at 60HZ equal
to the audio power needed, find an old power transformer of that core
size, and unwind it. Count the turns on the 117VAC winding to get turns
per volt, and figure the wire size from the DC input to the modulator
for the primary windings, and from the DC input to the PA(for each
side), and turns from the turns per volt for power. Do not push wire
size the the limit(small) becuase the windings also must handle the
peak currents produced by the audio power, which are higher than the DC
average.

This transformer will have more than enough iron in the core to handle
the AC power, as audio is at a higher frequency and the inductive
reactance higher. DC in the secondary will lower the inductance, but
you should still have enough. If you were trying to handle deep bass
frequencies(not needed nor wanted in a "communications" app as they eat
percentage of modulation), you would use a still larger core, figuring
audio power PLUS the power represented by a 60HZ AC current whose RMS
value is equal to the current drawn by the PA. This "overkill"
transformer would give less distortion on deep bass.

For a ham or any other communications application, frequencies below
300 HZ or so are far less important than they are to a broadcaster, but
be SURE not to allow frequencies to pass the modulator's driver that
the output transformer is not efficient at, or heavy currents will be
drawn and efficiency will suffer badly. If you design a modulation
transformer only to handle a narrowband voice range, the modulator
input transformer should also reject any frequencies lower than the
output transformer can handle, or these frequencies can be filtered out
elsewhere.

Otherwise, just speaking too close to the mike(which produces a deep
bass response) will heat up your modulator.




garigue wrote:
Well I havn't heard any AM on the HF bands in a long time, but I stand
corrected that some people still use it. Granted it's in the minority
and on "calling frequencies". I don't think those screen grid modulators
found in novice rigs were of much use though. They didn't have
much punch and poor audio. If you are going to go AM, a real plate
modulator is the only way to go. (I shudder to think what a plate
modulation transformer would cost these days....)

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

"Ken Scharf" wrote in message
...
garigue wrote:
You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone.

OH, Really!?? Snert! - Sporf! - Snurt! TNX for the laugh!

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
Pueblo, Colorado | @ | Jonesy | OS/2 __
38.24N 104.55W | config.com | DM78rf | SK


Yepper ....just like the fellow on 2 meters said .......nobody uses CW
anymore .....its DOA . I just like to put up my feet, lean back, and
open
an Iron City Beer and enjoy the quality of those AM signals ... and this
from a 99.99% CWist. My buddy built on of those rigs in 66 and it worked
fine with his Mor-Gain antenna ...even with the hardware cloth safety
mesh
covering the chassis. Lots 'o fun.

God Bless and 73 all ..... KI3R Tom in Belle Vernon PA


Well I havn't heard any AM on the HF bands in a long time, but I stand
corrected that some people still use it. Granted it's in the minority
and on "calling frequencies". I don't think those screen grid modulators
found in novice rigs were of much use though. They didn't have
much punch and poor audio. If you are going to go AM, a real plate
modulator is the only way to go. (I shudder to think what a plate
modulation transformer would cost these days....)

Ken,

You admit you have NO knowledge of present day ham usage of AM. And
apparently NO knowledge of old timey AM use. Properly designed, built and
used low level modulation works and sounds good.

I get glowing reports with my DX-60B, slightly modified to improve the bass
response. And a Bullet Astatic Mic.

And with the new rice boxes, if you adjust it right, you can get excellent
audio out of them.

With the FCC reduction of power for AM full carrier, plate modulated
(375watts) the big monsters are going the way of the Dinosaur.

Dan/W4NTI

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

Dan/W4NTI wrote:
"Ken Scharf" wrote in message
...

garigue wrote:

You might as well leave out the
AM modulator since it will be useless today. Back in '66-'67 there
were still some people on AM (mostly on 80 and 10 meters), but today
it's completly gone.

OH, Really!?? Snert! - Sporf! - Snurt! TNX for the laugh!

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
Pueblo, Colorado | @ | Jonesy | OS/2 __
38.24N 104.55W | config.com | DM78rf | SK


Yepper ....just like the fellow on 2 meters said .......nobody uses CW
anymore .....its DOA . I just like to put up my feet, lean back, and
open
an Iron City Beer and enjoy the quality of those AM signals ... and this
from a 99.99% CWist. My buddy built on of those rigs in 66 and it worked
fine with his Mor-Gain antenna ...even with the hardware cloth safety
mesh
covering the chassis. Lots 'o fun.

God Bless and 73 all ..... KI3R Tom in Belle Vernon PA



Well I havn't heard any AM on the HF bands in a long time, but I stand
corrected that some people still use it. Granted it's in the minority
and on "calling frequencies". I don't think those screen grid modulators
found in novice rigs were of much use though. They didn't have
much punch and poor audio. If you are going to go AM, a real plate
modulator is the only way to go. (I shudder to think what a plate
modulation transformer would cost these days....)


Ken,

You admit you have NO knowledge of present day ham usage of AM. And
apparently NO knowledge of old timey AM use. Properly designed, built and
used low level modulation works and sounds good.

I get glowing reports with my DX-60B, slightly modified to improve the bass
response. And a Bullet Astatic Mic.

And with the new rice boxes, if you adjust it right, you can get excellent
audio out of them.

With the FCC reduction of power for AM full carrier, plate modulated
(375watts) the big monsters are going the way of the Dinosaur.

Dan/W4NTI



Well I have to agree with the other poster who also owned a novice rig
with a grid modulator and nobody could hear him. I had the same
experience. The DX-60B may have had a well designed modulator and you
have it adjusted just right. (also you are not trying to over drive
the final). A plate modulator for a low power rig would make sense
if you really want to operate AM and put out a good signal.
I remember in some old ARRL handbooks there were some mobile am rigs
that used a filament transformer as a modulation transformer with a
pair of DS501 transistors (from old car radios) in the modulator.

Anyone built the 6146 cw/am transmitter in the 1966 Handbook?
 

WSQT wrote:

You will probably be best off winding your own. My advice is this:
find the core size required to handle an amount of power at 60HZ equal
to the audio power needed, find an old power transformer of that core
size, and unwind it. Count the turns on the 117VAC winding to get turns
per volt, and figure the wire size from the DC input to the modulator
for the primary windings, and from the DC input to the PA(for each
side), and turns from the turns per volt for power. Do not push wire
size the the limit(small) becuase the windings also must handle the
peak currents produced by the audio power, which are higher than the DC
average.

This transformer will have more than enough iron in the core to handle
the AC power, as audio is at a higher frequency and the inductive
reactance higher. DC in the secondary will lower the inductance, but
you should still have enough. If you were trying to handle deep bass
frequencies(not needed nor wanted in a "communications" app as they eat
percentage of modulation), you would use a still larger core, figuring
audio power PLUS the power represented by a 60HZ AC current whose RMS
value is equal to the current drawn by the PA. This "overkill"
transformer would give less distortion on deep bass.

For a ham or any other communications application, frequencies below
300 HZ or so are far less important than they are to a broadcaster, but
be SURE not to allow frequencies to pass the modulator's driver that
the output transformer is not efficient at, or heavy currents will be
drawn and efficiency will suffer badly. If you design a modulation
transformer only to handle a narrowband voice range, the modulator
input transformer should also reject any frequencies lower than the
output transformer can handle, or these frequencies can be filtered out
elsewhere.

Otherwise, just speaking too close to the mike(which produces a deep
bass response) will heat up your modulator.


A hint on rewinding transformers. When you disassemble a power transformer
you will note that the laminations alternate (IE: open end of even numbered "E"s
point left, odd numbered ones right). If you took apart a filter choke you
would find that ALL the laminations were oriented the same way. For an
audio transformer, arrange the laminations in groups, and alternate the
groups. Divide the total laminations into 3-10 groups.

Why? In the case of the choke, which must carry DC, we don't want the magnetic
flux to saturate or the inductance will start to drop at some current.
Having all the laminations go in one way leaves a nice air gap in the core
which prevents core saturation. In the case of a power transformer which
carries only AC we want the magnetic flux to be tight to keep efficiency up.
For an audio transformer which must carry some dc (tube plate current),
and ac (audio), a mix of these works out best. Note that in the case of
a push pull primary (modulation or output transformer) the balanced dc
current cancels out and we don't get much saturation of the core. A single
ended output transformer WILL have this problem, as will the secondary
winding of the modulation transformer.

A swinging filter choke should have some core saturation, probably it uses
two or three groups of laminations.