On Thu, 13 Nov 2003 17:33:19 -0800, Roy Lewallen
wrote:

As I recall, Armstrong invented and patented the FM radio before WWII.
If I'm correct, his patent should show a schematic of the circuit he
used. It's probably still available from the patent office.

Roy Lewallen, W7EL

Roy-

Armstrong's classic paper "A Method of Reducing Disturbances in Radio
Signaling by a System of Frequency Modulation" was published in 1936
in the November Proc. IRE. (The paper was presented in a demonstration
at the Nov 1935 IRE New York meeting.)

His field work started 1934, at 44 MHz, with a 2KW 44 MHz transmitter
on the Empire State Building shortly thereafter (the article is a bit
vague on the timing of this part of his operation). (Also, the
frequency was changed to 41 MHz at some point during the trials.)

Armstrong also notes the problem with receiver RF amplifiers at this
frequency and thanks RCA for its provision of experimental VHF
receiving tubes.

His detector circuit looks like a conventional discriminator to me;
two detectors each coupled to a tuned circuit with the outputs summed.
One detector gives + and the other a - output. One tuned circuit
resonates on the high side of the IF passband the the other on the low
side. Each detector fed by an independent buffer amplifier. The
receiver was a double conversion, with the first IF at 6 MHz and the
second IF (and detection) at 400 KHz and a passband of 150 KHz.


Jack K8ZOA

Now waitaminnit! We have TWO Bill Turners in this mess. Do we have to play
To Tell The Truth?

"Bill Turner" wrote in message
...
On Fri, 14 Nov 2003 02:41:36 GMT, Robert Casey
wrote:

Today hams have a
small 10 meter sub-band for FM somewhere around 29MHz.

__________________________________________________ _______

That's for WIDE band FM. Narrow band FM is permitted anywhere phone is
allowed, although rarely used.

--
Bill, W6WRT

Now waitaminnit! We have TWO Bill Turners in this mess. Do we have to play
To Tell The Truth?

"Bill Turner" wrote in message
...
On Fri, 14 Nov 2003 02:41:36 GMT, Robert Casey
wrote:

Today hams have a
small 10 meter sub-band for FM somewhere around 29MHz.

__________________________________________________ _______

That's for WIDE band FM. Narrow band FM is permitted anywhere phone is
allowed, although rarely used.

--
Bill, W6WRT

The other one is WA0ABI, I believe.

"Bill Turner" wrote in message
...
On Fri, 14 Nov 2003 16:19:33 -0700, "Steven Dinius"
wrote:

Now waitaminnit! We have TWO Bill Turners in this mess. Do we have to
play
To Tell The Truth?

__________________________________________________ _______

Mom would never lie to me... would she?

--
Bill, W6WRT

The other one is WA0ABI, I believe.

"Bill Turner" wrote in message
...
On Fri, 14 Nov 2003 16:19:33 -0700, "Steven Dinius"
wrote:

Now waitaminnit! We have TWO Bill Turners in this mess. Do we have to
play
To Tell The Truth?

__________________________________________________ _______

Mom would never lie to me... would she?

--
Bill, W6WRT

Yep, he's W6 William R Turner. Congrats on snagging your vanity call.

"Steven Dinius" wrote in message
...
The other one is WA0ABI, I believe.

"Bill Turner" wrote in message
...
On Fri, 14 Nov 2003 16:19:33 -0700, "Steven Dinius"
wrote:

Now waitaminnit! We have TWO Bill Turners in this mess. Do we have to
play
To Tell The Truth?

__________________________________________________ _______

Mom would never lie to me... would she?

--
Bill, W6WRT

Yep, he's W6 William R Turner. Congrats on snagging your vanity call.

"Steven Dinius" wrote in message
...
The other one is WA0ABI, I believe.

"Bill Turner" wrote in message
...
On Fri, 14 Nov 2003 16:19:33 -0700, "Steven Dinius"
wrote:

Now waitaminnit! We have TWO Bill Turners in this mess. Do we have to
play
To Tell The Truth?

__________________________________________________ _______

Mom would never lie to me... would she?

--
Bill, W6WRT

"David Forsyth" wrote in message
...
Would it be possible, though not necessarily practical, to make a reciever
for the modern FM broadcast band, using only pre-WWII tube technology? I
know they had FM on a lower frequency band at that time. What sorts of
tubes could one use from the 1930's to make a reciever that could tune in
the modern FM band? I'm sure I wont actually attempt such a thing,
especially any time soon, but just wondered how difficult it might be.
Are
there any schematics or construction articles from the late 30's about
making FM radios that might be adapted over to the new FM band?

just curious,

Dave

"David Forsyth" wrote in message
...
Would it be possible, though not necessarily practical, to make a reciever
for the modern FM broadcast band, using only pre-WWII tube technology? I
know they had FM on a lower frequency band at that time. What sorts of
tubes could one use from the 1930's to make a reciever that could tune in
the modern FM band? I'm sure I wont actually attempt such a thing,
especially any time soon, but just wondered how difficult it might be.
Are
there any schematics or construction articles from the late 30's about
making FM radios that might be adapted over to the new FM band?

just curious,

Dave

"David Forsyth" wrote in message
...
Would it be possible, though not necessarily practical, to make a reciever
for the modern FM broadcast band, using only pre-WWII tube technology? I
know they had FM on a lower frequency band at that time. What sorts of
tubes could one use from the 1930's to make a reciever that could tune in
the modern FM band? I'm sure I wont actually attempt such a thing,
especially any time soon, but just wondered how difficult it might be.
Are
there any schematics or construction articles from the late 30's about
making FM radios that might be adapted over to the new FM band?

just curious,

Dave



The RCA 10T tombstone used the new metal tubes, and had an
UltraShortwave band that reached to over 60 mc. Unfortunately,
most of the RCAs had serious problems with the LO dropping off
at about 50 mc orso, very few of the radios ever seemed to actually
tune that high! I think I've seen one example that worked across the
full tuning range without twiddling the circuitry to make it work.
Bu, in 1936, probably no one even noticed, or cared.

Pete