Circuit diagram of AM Modulator based on triode valve/tube

[Robert Wilson]

Hello,
I would like to find a circuit diagram of an AM Modulator scheme based
on a Triode Thermionic valve/tube. I have a SPICE package that has a
Triode valve as a component. The package i'm using is
Simetrix, from Cadence.

Can anyone help please?

Regards,

Robert.

 

[Frank Raffaeli]

Hello,
I would like to find a circuit diagram of an AM Modulator scheme based
on a Triode Thermionic valve/tube. I have a SPICE package that has a
Triode valve as a component. The package i'm using is
Simetrix, from Cadence.

Can anyone help please?

Regards,

Robert.

Why use a tube? What are your specifications?

Frank

 

[Robert Wilson]

Hello,
Thanks for the reply. I am actually doing a piece of work for my
University course investigating the key advantages and disadvantaged of
high and low level modulation of AM transmitters. I was hoping someone
had something I could use.

Regards,

Robert.

 

[[email protected]]

Hello,
I would like to find a circuit diagram of an AM Modulator scheme based
on a Triode Thermionic valve/tube. I have a SPICE package that has a
Triode valve as a component. The package i'm using is
Simetrix, from Cadence.

Lots of stuff on here. Took me 30 seconds using Google.

http://www.vias.org/basicradio/

Look under "Transmission Of Signals".

Where you will find some modulator circuits using triodes

Plate (anode) modulation:-

http://www.vias.org/basicradio/basic_radio_17_04.html

Grid modulation:-

http://www.vias.org/basicradio/basic_radio_17_05.html

a Class C amplifier with plate modulation from a Class B modulator:-

http://www.vias.org/basicradio/basic_radio_29_02.html

 

[Ancient_Hacker]

Hello,
I would like to find a circuit diagram of an AM Modulator scheme based
on a Triode Thermionic valve/tube. I have a SPICE package that has a
Triode valve as a component. The package i'm using is
Simetrix, from Cadence.

Can anyone help please?

Regards,

Robert.

Go to a library and find an ARRL Handbook from the years 1935 to 1970.
Those have several chapters on AM modulation, with theory and actual
working transmitters and modulators.

The "Theory" in these books is not quite up to EE textbook standards,
but good enough for most purposes.

BTW did you know it's possible to make a very good AM transmitter by
taking an old tube AA5 radio, swapping the audio output and converter
tubes, and moving 4 wires? Cool^3 IMHO.

Now that you know it can be done, doing so is left as an exercise for
the reader

 

[Frank Raffaeli]

Hello,
Thanks for the reply. I am actually doing a piece of work for my
University course investigating the key advantages and disadvantaged of
high and low level modulation of AM transmitters. I was hoping someone
had something I could use.

Regards,

Robert.

Thanks for the clarification. Here are some interesting papers on
broadcast modulation:
http://sujan.hallikainen.org/BroadcastHistory/index.php/Historic Papers

Frank

 

[Tam/WB2TT]

Thanks for the clarification. Here are some interesting papers on
broadcast modulation:
http://sujan.hallikainen.org/BroadcastHistory/index.php/Historic Papers

Frank

Take a look at the Harris digital AM transmitters. It will blow your mind
away.

Tam

 

[Michael A. Terrell]

Take a look at the Harris digital AM transmitters. It will blow your mind
away.

Which generation? The first units had TO-3 final transistors, and a
CPU board to monitor the transmitter. There were more computer problems
than failed RF trays, so later version left it out. Then, the RF output
went to plastic packages. They are interesting transmitters but are
more expensive to repair, at times. WQBQ has one of the first built,
and the engineering room had a large pile of unrepairable RF trays, and
other modules the last time I was there. Some failures cause the PC
boards to overheat and burn large holes.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Tam/WB2TT]

Which generation? The first units had TO-3 final transistors, and a
CPU board to monitor the transmitter. There were more computer problems
than failed RF trays, so later version left it out. Then, the RF output
went to plastic packages. They are interesting transmitters but are
more expensive to repair, at times. WQBQ has one of the first built,
and the engineering room had a large pile of unrepairable RF trays, and
other modules the last time I was there. Some failures cause the PC
boards to overheat and burn large holes.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

I got my info from a local broadcast engineer who had done some work at WLW.
I think his link lead me to a DX60. I had not heard of problems, and it is
still an awesome way to do it. Anybody learning about AM modulation should
at least be aware of it.

Tam

 

[[email protected]]

Which generation? The first units had TO-3 final transistors, and a
CPU board to monitor the transmitter. There were more computer problems
than failed RF trays, so later version left it out. Then, the RF output
went to plastic packages. They are interesting transmitters but are
more expensive to repair, at times. WQBQ has one of the first built,
and the engineering room had a large pile of unrepairable RF trays, and
other modules the last time I was there. Some failures cause the PC
boards to overheat and burn large holes.

How do they stand up to lightning?

 

[Michael A. Terrell]

How do they stand up to lightning?

Not as well as the older tube transmitters. The old 5 KW Gates tube
transmitter might trip the plate relay at WLBE in the Leesburg/Eustis
area, but it could be remotely reset by the engineer over his cell
phone.

I have heard that the later Harris are better at handling lightning
strikes, but I haven't seen one in operation. I have pretty much quit
doing broadcast engineering consulting, due to health problems which is
OK, because the stations have pretty well replaced the older equipment
that their young engineers didn't understand.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

I got my info from a local broadcast engineer who had done some work at WLW.
I think his link lead me to a DX60. I had not heard of problems, and it is
still an awesome way to do it. Anybody learning about AM modulation should
at least be aware of it.

Have you ever seen the experimental 500 KW transmitter WLW used in
the '40s? Now, THAT is a real transmitter!

http://hawkins.pair.com/wlw.shtml


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida