On Aug 5, 7:31 pm, "Walter Maxwell" wrote:
Do really believe that there was a transmitter in the 1920's that could deliver
500 kw?. The first station that could come up with that amount of power was in
the 1930's,W8XO, the experimental station of Powell Crosley, that became WLW
again when the experimental period was over. Are you aware of the technical
difficulties that obtained in just getting that monster to work? General
Electric and Westinghouse supplied most of the parts, the rest by RCA, and RCA
was the company that strived and strived before it was workable at that power
level. I once worked for Harold Vance, the RCA engineer in charge of the
project. Certainly this didn't happen in the 1920's, and not in Schenectady.
Somebody's been
feeding you horse hockey.

Walt, W2DU

On the other hand, there were spark transmitters well before that in a
similar power class. As I understand it, the powers actually achieved
as output were often either not well known or were kept quiet for
various reasons, but they were clearly in excess of 100kW. Apparently
the Oct. 1920 issue of "General Electric Review has an article by
Alexanderson about a 200kW alternator-driven transmitter. I
understand that there were also some high-powered (Poulsen) arc
transmitters (quite distinct from the shock-excitation of spark). I
found one reference to a Poulsen arc transmitter that ran at 3.6 MW
input power which was "still active in the early 1920s..." It ran on
~50kHz. Pretty much all this early stuff was below 100kHz, which of
course yields very reliable propagation if you put enough power into
it.

Our plant used to be less than a wavelength from a 1MW transmitting
system, and I was always somewhat surprised that we weren't bothered
more by them, as we made sensitive spectral analyzers that covered the
frequency range on which they transmitted. We moved, and now we're a
couple wavelengths away. We're more bothered by the 5kW AM broadcast
station a few miles away, though that's easily filtered/shielded.

Cheers,
Tom

"K7ITM" wrote in message
...
On Aug 5, 7:31 pm, "Walter Maxwell" wrote:
Do really believe that there was a transmitter in the 1920's that could
deliver
500 kw?. The first station that could come up with that amount of power
was in
the 1930's,W8XO, the experimental station of Powell Crosley, that became
WLW
again when the experimental period was over. Are you aware of the
technical
difficulties that obtained in just getting that monster to work? General
Electric and Westinghouse supplied most of the parts, the rest by RCA,
and RCA
was the company that strived and strived before it was workable at that
power
level. I once worked for Harold Vance, the RCA engineer in charge of the
project. Certainly this didn't happen in the 1920's, and not in
Schenectady.
Somebody's been
feeding you horse hockey.

Walt, W2DU

On the other hand, there were spark transmitters well before that in a
similar power class. As I understand it, the powers actually achieved
as output were often either not well known or were kept quiet for
various reasons, but they were clearly in excess of 100kW. Apparently
the Oct. 1920 issue of "General Electric Review has an article by
Alexanderson about a 200kW alternator-driven transmitter. I
understand that there were also some high-powered (Poulsen) arc
transmitters (quite distinct from the shock-excitation of spark). I
found one reference to a Poulsen arc transmitter that ran at 3.6 MW
input power which was "still active in the early 1920s..." It ran on
~50kHz. Pretty much all this early stuff was below 100kHz, which of
course yields very reliable propagation if you put enough power into
it.

But WLW ran 500KW of 100% AM modulation. I understand just the modulation
transformer was the size of a room in order to handle the 250 KW of audio. I
believe it was on 700 KHz. See the link I gave above.

Tam/WB2TT

Our plant used to be less than a wavelength from a 1MW transmitting
system, and I was always somewhat surprised that we weren't bothered
more by them, as we made sensitive spectral analyzers that covered the
frequency range on which they transmitted. We moved, and now we're a
couple wavelengths away. We're more bothered by the 5kW AM broadcast
station a few miles away, though that's easily filtered/shielded.

Cheers,
Tom

On Aug 6, 8:21 am, "Tam" wrote:
"K7ITM" wrote in message

...

On Aug 5, 7:31 pm, "Walter Maxwell" wrote:
Do really believe that there was a transmitter in the 1920's that could
deliver
500 kw?. The first station that could come up with that amount of power
was in
the 1930's,W8XO, the experimental station of Powell Crosley, that became
WLW
again when the experimental period was over. Are you aware of the
technical
difficulties that obtained in just getting that monster to work? General
Electric and Westinghouse supplied most of the parts, the rest by RCA,
and RCA
was the company that strived and strived before it was workable at that
power
level. I once worked for Harold Vance, the RCA engineer in charge of the
project. Certainly this didn't happen in the 1920's, and not in
Schenectady.
Somebody's been
feeding you horse hockey.

Walt, W2DU

On the other hand, there were spark transmitters well before that in a
similar power class. As I understand it, the powers actually achieved
as output were often either not well known or were kept quiet for
various reasons, but they were clearly in excess of 100kW. Apparently
the Oct. 1920 issue of "General Electric Review has an article by
Alexanderson about a 200kW alternator-driven transmitter. I
understand that there were also some high-powered (Poulsen) arc
transmitters (quite distinct from the shock-excitation of spark). I
found one reference to a Poulsen arc transmitter that ran at 3.6 MW
input power which was "still active in the early 1920s..." It ran on
~50kHz. Pretty much all this early stuff was below 100kHz, which of
course yields very reliable propagation if you put enough power into
it.

But WLW ran 500KW of 100% AM modulation. I understand just the modulation
transformer was the size of a room in order to handle the 250 KW of audio. I
believe it was on 700 KHz. See the link I gave above.

Well, admittedly I was taking it a bit out of context, but my posting
was a response to Walter's "Do really believe that there was a
transmitter in the 1920's that could deliver
500 kw?" And the answer is, yes, I do. Maybe not valve-based, but
more than one transmitter, and capable of modulation as well:
apparently Poulsen arc transmitters were FSK, since they couldn't be
keyed on and off. And apparently the alternator based transmitters
could be keyed at up to 100wpm. I'm pretty impressed with what the
radio engineers of that era were able to achieve.

Cheers,
Tom

K7ITM wrote:
.. See the link I gave above.

Well, admittedly I was taking it a bit out of context, but my posting
was a response to Walter's "Do really believe that there was a
transmitter in the 1920's that could deliver
500 kw?"

I think the operative word here is "deliver", by which I would mean
"radiated into the far field". Dissipating half a megawatt in the
system is impressive, but not necessarily as a transmitter.


And the answer is, yes, I do. Maybe not valve-based, but
more than one transmitter, and capable of modulation as well:
apparently Poulsen arc transmitters were FSK, since they couldn't be
keyed on and off.

One scheme was to change the resonant frequency of the antenna (via taps
on a coil), which was the frequency determining part of the system, the
arc providing a negative resistance characteristic for making an oscillator.

And apparently the alternator based transmitters
could be keyed at up to 100wpm. I'm pretty impressed with what the
radio engineers of that era were able to achieve.

It IS very impressive, but whether they could *radiate* half a megawatt
is sort of a good question.

Consider for comparison the ELF transmitters in Michigan..several
Megawatts to radiate less than 10 Watts

Or Project Sanguine, which was soemthing like 800 MW to radiate a few watts.


I know of several Tesla coils that have average power inputs in the
hundreds of kW range, but they don't radiate a whole lot, even with 20+
meter sparks as an antenna.



Cheers,
Tom

Tam wrote:

But WLW ran 500KW of 100% AM modulation. I understand just the
modulation transformer was the size of a room in order to handle the 250
KW of audio. I believe it was on 700 KHz. See the link I gave above.

The modulation transformer at VOA's Bethany relay station (located quite
near WLW's Mason, Ohio transmitter site) took up much of a very large
room. If you stood in that room, you could hear the transmitted audio
from the laminations. The sound was so loud that it was necessary to
shout to be heard over it.

Dave K8MN

Wow. We can learn something new every day. Joe Rice (W4RHZ) was one of my
idols when I had my first licenses during 1959-61. He was a key member of
NKARC (Northern Kentucky ARC). Google says his "Early Cincinnati Radio" was
privately published, so I am unlikely to run across a copy. (Ebay and
half.com, etc, have no hits for it.)

Bill
W2WO (Was K4DFO in those days)

Bill Ogden wrote:
Wow. We can learn something new every day. Joe Rice (W4RHZ) was one of my
idols when I had my first licenses during 1959-61. He was a key member of
NKARC (Northern Kentucky ARC). Google says his "Early Cincinnati Radio" was
privately published, so I am unlikely to run across a copy. (Ebay and
half.com, etc, have no hits for it.)

Bill
W2WO (Was K4DFO in those days)

Bill,

Yep, Joe was a Norwood boy who became a Northern Kentucky transplant.
I was WB4KTR when I moved from Miami to Fort Thomas in 1968. I didn't
meet Joe until coming back from the Air Force in 1972. He was my first
160m contact, good for about ten miles. :-)

I found the Early Cincinnati Radio at a used book store in downtown
Cincy in '73 or so. I have two other books by Joe which he inscribed to
me. One is called "Cincinnati's Powel Crosley". The other is entitled
"Early Norwood Radio"

Joe was a bit eccentric but he certainly knew his stuff about broadcast
radio. He was engineer at many of those Cincinnati area stations and
worked, at one time or another, for many of the electronic/radio
manufacturers in the area as well.

I, too, was an NKARC member until I moved across the river in 1977.

73,

Dave K8MN