One for Brian???

I was wondering back when men were men and Libby Purves worked on the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?

--
Chris

Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?

There are big semiconductor devices capable.

However old transmitters are expensive to convert to new devices. I
seem to remember that the Radio 4 transmitter on 198kHz is still a
valve and that they only have one more spare.

--
Chris Green
·

On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?

solid state up to a kilowatt or so. then add more modules. I don't think
valves used anywhere any more. Maybe up at magnetron frequencies

--
"In our post-modern world, climate science is not powerful because it is
true: it is true because it is powerful."

Lucas Bergkamp

On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?

can't beat an 807

On 26/01/2021 10:55, Jimmy Stewart ... wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing
the
necessary output power? Or are valves still used?

can't beat an 807
or a 6js6c or two or 6146

On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the other
side of the mic, radio transmitters used valves.

And many still do...

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?

Transmitters are just big RF amplifiers.

So while many of the really big amps are still valve or cavity resonator
based designs, there are solid state amps as well.

Much depends on just how much power you need. You can do a few 100's of
watts and into the early kW easily enough in a single solid state amp
module, and can do or more than that by combining the RF output of
multiple amps.

I worked on a 20kW HF amp (for a radar application) where the
fundamental unit of amplification was (IIRC) a 400W MOSFET amp. Those
were combined 4 to module to get a bit over a kW out, then those
combined 4 at a time in a bigger rack mounting unit to get a few kW.
Then finally there were 4 racks combined up to get the required 20kW.

Some pictures of the amp he

https://marconiradarhistory.pbworks....20and%20 JORN




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Jimmy Stewart ... wrote:
On 26/01/2021 10:55, Jimmy Stewart ... wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of
producing the
necessary output power? Or are valves still used?

can't beat an 807
or a 6js6c or two or 6146

There are still some good-sized vacuum tubes kicking about.

https://www.nutsvolts.com/magazine/a...e-21st-century

"The filament of this tube alone requires 23V at 500A €” thats almost
12 kW, or enough to power an average house."

Even their filament power is bigger than all of your
rigs put together.

And lots of copper pipe with cooling water running in it.

Paul

On Tue, 26 Jan 2021 10:56:29 +0000, Jimmy Stewart ... wrote:

On 26/01/2021 10:55, Jimmy Stewart ... wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing
the necessary output power? Or are valves still used?

can't beat an 807
or a 6js6c or two or 6146

QY3-125 or CV2130

In article ,
Chris Green wrote:
I
seem to remember that the Radio 4 transmitter on 198kHz is still a
valve and that they only have one more spare.

it was a long long time ago that was mentioned. But it's till going 24/7.

--
*Do infants enjoy infancy as much as adults enjoy adultery? *

Dave Plowman London SW
To e-mail, change noise into sound.

On 26/01/2021 11:51, Paul wrote:
Jimmy Stewart ... wrote:
On 26/01/2021 10:55, Jimmy Stewart ... wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on
the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of
producing the
necessary output power? Or are valves still used?

can't beat an 807
or a 6js6c or two or 6146

There are still some good-sized vacuum tubes kicking about.

https://www.nutsvolts.com/magazine/a...e-21st-century


Â*Â*Â* "The filament of this tube alone requires 23V at 500A €” thats almost
Â*Â*Â*Â* 12 kW, or enough to power an average house."

Even their filament power is bigger than all of your
rigs put together.

And lots of copper pipe with cooling water running in it.

One of the valve based bits of kit I worked on would stick 10kW of HF
out the main feeder, and 16kW of heat out of the top vent (force fed by
blowers under a raised floor)[1]. That was a two valve stage design.
There was a solid state pre-amp, then a valve based penultimate stage to
lift to about 400W, and then a main valve to go to 10kW


[1] Don't know if the energy drawn by the blowers was included in the
vent total - I expect probably not.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 26/01/2021 09:52, Chris Green wrote:
Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?

There are big semiconductor devices capable.

However old transmitters are expensive to convert to new devices. I
seem to remember that the Radio 4 transmitter on 198kHz is still a
valve and that they only have one more spare.

The only one spare is ********. When the spare is placed into use, the
one removed goes back to the manufacturer to be rebuilt.

On 26/01/2021 18:33, Tim Streater wrote:
On 26 Jan 2021 at 14:55:31 GMT, John Rumm
wrote:

On 26/01/2021 11:51, Paul wrote:
Jimmy Stewart ... wrote:
On 26/01/2021 10:55, Jimmy Stewart ... wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on
the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of
producing the
necessary output power? Or are valves still used?

can't beat an 807
or a 6js6c or two or 6146

There are still some good-sized vacuum tubes kicking about.

https://www.nutsvolts.com/magazine/a...e-21st-century


Â*Â*Â* "The filament of this tube alone requires 23V at 500A €” thats almost
Â*Â*Â*Â* 12 kW, or enough to power an average house."

Even their filament power is bigger than all of your
rigs put together.

And lots of copper pipe with cooling water running in it.

One of the valve based bits of kit I worked on would stick 10kW of HF
out the main feeder, and 16kW of heat out of the top vent (force fed by
blowers under a raised floor)[1]. That was a two valve stage design.
There was a solid state pre-amp, then a valve based penultimate stage to
lift to about 400W, and then a main valve to go to 10kW


[1] Don't know if the energy drawn by the blowers was included in the
vent total - I expect probably not.

Try these klystrons:

https://www6.slac.stanford.edu/virtu...ystron-gallery

rated at 75MW.

Puts those tiny 1MW radio and TV transmitters in their place! :-)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

jon Wrote in message:
On Tue, 26 Jan 2021 10:56:29 +0000, Jimmy Stewart ... wrote:

On 26/01/2021 10:55, Jimmy Stewart ... wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing
the necessary output power? Or are valves still used?

can't beat an 807
or a 6js6c or two or 6146

QY3-125 or CV2130


You can't beat a DS19/87B radio valve!

73s G3ZVT.
--

%Profound_observation%


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

In article , John
Rumm scribeth thus
On 26/01/2021 18:33, Tim Streater wrote:
On 26 Jan 2021 at 14:55:31 GMT, John Rumm
wrote:

On 26/01/2021 11:51, Paul wrote:
Jimmy Stewart ... wrote:
On 26/01/2021 10:55, Jimmy Stewart ... wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on
the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of
producing the
necessary output power? Or are valves still used?

can't beat an 807
or a 6js6c or two or 6146

There are still some good-sized vacuum tubes kicking about.

https://www.nutsvolts.com/magazine/a...-for-the-21st-
century


Â*Â*Â* "The filament of this tube alone requires 23V at 500A €” thats almost
Â*Â*Â*Â* 12 kW, or enough to power an average house."

Even their filament power is bigger than all of your
rigs put together.

And lots of copper pipe with cooling water running in it.

One of the valve based bits of kit I worked on would stick 10kW of HF
out the main feeder, and 16kW of heat out of the top vent (force fed by
blowers under a raised floor)[1]. That was a two valve stage design.
There was a solid state pre-amp, then a valve based penultimate stage to
lift to about 400W, and then a main valve to go to 10kW


[1] Don't know if the energy drawn by the blowers was included in the
vent total - I expect probably not.

Try these klystrons:

https://www6.slac.stanford.edu/virtu...ystron-gallery

rated at 75MW.

Puts those tiny 1MW radio and TV transmitters in their place! :-)



Well Klystrons are now no longer in use with the passing of analogue TV
back in 2012.

In modern UHF TV transmitters they are using a such as travelling wave
tubes solid state doesn't quite rule the roost!...

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article , mm0fmf
scribeth thus
On 26/01/2021 09:52, Chris Green wrote:
Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?

There are big semiconductor devices capable.

However old transmitters are expensive to convert to new devices. I
seem to remember that the Radio 4 transmitter on 198kHz is still a
valve and that they only have one more spare.

The only one spare is ********. When the spare is placed into use, the
one removed goes back to the manufacturer to be rebuilt.

And companies around who will sell you a new one but as longwave seems
to be dying i can see the time 198 Khz will disappear like RTE 252 kHz
in Ireland may do it gets reprieved due to Irish here wanting to hear
what's going on back home!...
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article , Chris Holmes
scribeth thus

One for Brian???

I was wondering back when men were men and Libby Purves worked on the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?


For VHF transistors exist around the 1500 watts mark made be Freescale
but they are put into modules the modules are connected together to make
higher outputs!..


Like this one

https://www.eddystone-broadcast.com/10kw/
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article , tony sayer
scribeth thus
In article , John
Rumm scribeth thus
On 26/01/2021 18:33, Tim Streater wrote:
On 26 Jan 2021 at 14:55:31 GMT, John Rumm
wrote:

On 26/01/2021 11:51, Paul wrote:
Jimmy Stewart ... wrote:
On 26/01/2021 10:55, Jimmy Stewart ... wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on
the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of
producing the
necessary output power? Or are valves still used?

can't beat an 807
or a 6js6c or two or 6146

There are still some good-sized vacuum tubes kicking about.

https://www.nutsvolts.com/magazine/a...-for-the-21st-
century


Â*Â*Â* "The filament of this tube alone requires 23V at 500A €” thats
almost
Â*Â*Â*Â* 12 kW, or enough to power an average house."

Even their filament power is bigger than all of your
rigs put together.

And lots of copper pipe with cooling water running in it.

One of the valve based bits of kit I worked on would stick 10kW of HF
out the main feeder, and 16kW of heat out of the top vent (force fed by
blowers under a raised floor)[1]. That was a two valve stage design.
There was a solid state pre-amp, then a valve based penultimate stage to
lift to about 400W, and then a main valve to go to 10kW


[1] Don't know if the energy drawn by the blowers was included in the
vent total - I expect probably not.

Try these klystrons:

https://www6.slac.stanford.edu/virtu...ystron-gallery

rated at 75MW.

Puts those tiny 1MW radio and TV transmitters in their place! :-)



Well Klystrons are now no longer in use with the passing of analogue TV
back in 2012.

In modern UHF TV transmitters they are using a such as travelling wave
tubes solid state doesn't quite rule the roost!...

Correction!! IOT's Inductive Output Tubes !!!
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article , Chris Green
scribeth thus
Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?

There are big semiconductor devices capable.

However old transmitters are expensive to convert to new devices. I
seem to remember that the Radio 4 transmitter on 198kHz is still a
valve and that they only have one more spare.

There aren't conversions as such, usually the old Valve transmitter is
scrapped and a new solid state one goes in its place..

Broadcast transmitters have a very long life the Droitwich long wave one
will be kept going until its switched off a decision that the BBC will
make..

Nothing to do with the valves plenty of re-builders in Russia and
China!..

And new ones are around still..

https://www.nautel.com/products/am-t...ers/nx-series/


https://thomsonbroadcast.tv/product/...nsmitter-s7hp-
neo/
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

Really big powers of several kilowatts tend to use Valves still, You can get
surprisingly high powers from mosfets but they are still more fragile than
the old bottles from the abuse point of view. High powers using
semiconductors seems to mean devices parrarelled up and I just wonder what
happens to the others if one dies in such a stack?
Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Chris Holmes" wrote in message
...

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing the
necessary output power? Or are valves still used?

--
Chris

Yes but he presumably meant dab and FM, presumably the latter as the
modulation type on digital is more complex and a lot more powerful due to
the duty cycle.
After all you are just sending a movable blank carrier on fm, more or less.
I think they probably my use travelling wave tubes at uhf though not sure
about the dab as that is band 3.
With regard to Long wave, there are whole transmitters around I think that
could be used at those low frequencies, but its true, the more specialist
the valve, the less likely it is to be available against when everyone was
using them. I'd imagine the low end of Medium wave type transmitters use
similar devices but the current Long wave transmitter is much higher power
than most of the medium wave outlets.


Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Chris Green" wrote in message
...
Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing
the
necessary output power? Or are valves still used?

There are big semiconductor devices capable.

However old transmitters are expensive to convert to new devices. I
seem to remember that the Radio 4 transmitter on 198kHz is still a
valve and that they only have one more spare.

--
Chris Green
·

Assuming they still exist and are interested.
Have you ever looked at the cost of refurbished ordinary ham radio
transmitting valves capable of half a kilowatt?

Not that I have, but I hear that new ones are often crap since the Chinese
never really test them and the assemblies can be poor quality in plating
and construction, but there aware still some big triodes around ex Russian
military that can be pressed into use and the only issue is supplying the
heater current of several amps.

Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"mm0fmf" wrote in message
...
On 26/01/2021 09:52, Chris Green wrote:
Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing
the
necessary output power? Or are valves still used?

There are big semiconductor devices capable.

However old transmitters are expensive to convert to new devices. I
seem to remember that the Radio 4 transmitter on 198kHz is still a
valve and that they only have one more spare.

The only one spare is ********. When the spare is placed into use, the one
removed goes back to the manufacturer to be rebuilt.

The signal on 252 is compromised by another station these days, sadly.
That transmitter was as I'm sure folk know a semi legal commercial outlet
trying to gain access to the uk market but eventually closed and the
transmitter taken over by RTE.
Its nowhere near as strong as radio 4, I guess in the age of the internet
it will eventually close, but the fact is that internet is not a radio
station, its reliant on the good will of those who own it to keep it running
in all weathers and natural disasters and wars, which of course I feel is pi
in the sky, since communication channels are the main target in any war.

Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"tony sayer" wrote in message
...
In article , mm0fmf
scribeth thus
On 26/01/2021 09:52, Chris Green wrote:
Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing
the
necessary output power? Or are valves still used?

There are big semiconductor devices capable.

However old transmitters are expensive to convert to new devices. I
seem to remember that the Radio 4 transmitter on 198kHz is still a
valve and that they only have one more spare.

The only one spare is ********. When the spare is placed into use, the
one removed goes back to the manufacturer to be rebuilt.

And companies around who will sell you a new one but as longwave seems
to be dying i can see the time 198 Khz will disappear like RTE 252 kHz
in Ireland may do it gets reprieved due to Irish here wanting to hear
what's going on back home!...
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

On 27/01/2021 10:10, Brian Gaff (Sofa) wrote:
Really big powers of several kilowatts tend to use Valves still, You can get
surprisingly high powers from mosfets but they are still more fragile than
the old bottles from the abuse point of view. High powers using
semiconductors seems to mean devices parrarelled up and I just wonder what
happens to the others if one dies in such a stack?

They tend to have redundancy built in, and many seem to use hot
swappable modules and PSUs these days, so you can replace failed ones
while still continuing to operate.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 26/01/2021 10:13, The Natural Philosopher wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of
producing the
necessary output power? Or are valves still used?

solid state up to a kilowatt or so. then add more modules. I don't
think valves used anywhere any more. Maybe up at magnetron frequencies

Many of the UHF DTT sites are using IoT 'valve' based transmitters, they
were installed about about 10 years at DSO

https://en.wikipedia.org/wiki/Inductive_output_tube

On Wed, 27 Jan 2021 10:16:22 -0000, "Brian Gaff \(Sofa\)"
wrote:

Yes but he presumably meant dab and FM, presumably the latter as the
modulation type on digital is more complex and a lot more powerful due to
the duty cycle.
After all you are just sending a movable blank carrier on fm, more or less.
I think they probably my use travelling wave tubes at uhf though not sure
about the dab as that is band 3.
With regard to Long wave, there are whole transmitters around I think that
could be used at those low frequencies, but its true, the more specialist
the valve, the less likely it is to be available against when everyone was
using them. I'd imagine the low end of Medium wave type transmitters use
similar devices but the current Long wave transmitter is much higher power
than most of the medium wave outlets.

Is the valve used specific to the frequency transmitted or could we
buy valves from long-wave transmitters that are closing down?

Brian Gaff (Sofa) wrote

Really big powers of several kilowatts tend to use Valves still, You can
get surprisingly high powers from mosfets but they are still more fragile
than the old bottles from the abuse point of view. High powers using
semiconductors seems to mean devices parrarelled up and I just wonder what
happens to the others if one dies in such a stack?

You just get a drop in the transmitted power.

"Chris Holmes" wrote in message
...

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of producing
the
necessary output power? Or are valves still used?

--
Chris

On Thu, 28 Jan 2021 04:53:21 +1100, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH the trolling senile pest's latest troll**** unread

--
about senile Rot Speed:
"This is like having a conversation with someone with brain damage."
MID:

In article , Brian Gaff (Sofa)
scribeth thus
The signal on 252 is compromised by another station these days, sadly.
That transmitter was as I'm sure folk know a semi legal commercial outlet
trying to gain access to the uk market but eventually closed and the
transmitter taken over by RTE.
Its nowhere near as strong as radio 4, I guess in the age of the internet
it will eventually close, but the fact is that internet is not a radio
station, its reliant on the good will of those who own it to keep it running
in all weathers and natural disasters and wars, which of course I feel is pi
in the sky, since communication channels are the main target in any war.

Brian


This does seem the way of it they have reduced the TX power in order to
save some money. I think the equipment is OK and whilst the broadcaster
is wanting to move listeners to other mediums theres a diehard Irish
population especially in the North West of England oddly enough who can
still receive it on an ordinary transistor, possible valve! wireless and
they can get it in their cars.

It is receivable down here in mid Anglia and its nice to have a brief
listen from time to time to the land of my descent!, an all 'n all...

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article , Brian Gaff (Sofa)
scribeth thus
Yes but he presumably meant dab and FM, presumably the latter as the
modulation type on digital is more complex and a lot more powerful due to
the duty cycle.
After all you are just sending a movable blank carrier on fm, more or less.
I think they probably my use travelling wave tubes at uhf though not sure
about the dab as that is band 3.
With regard to Long wave, there are whole transmitters around I think that
could be used at those low frequencies, but its true, the more specialist
the valve, the less likely it is to be available against when everyone was
using them. I'd imagine the low end of Medium wave type transmitters use
similar devices but the current Long wave transmitter is much higher power
than most of the medium wave outlets.


Brian


We look after a small DAB system that comprises of a modulator thats
running a bit of free open source software on a small NUC machine. That
drives a small universal software programmable driver unit. The output
of that goes to a linear Class A power amp of a 100 watts capacity
thence to a sharp passband filter and then to the aerials.

All there is to that bigger systems will have a somewhat more elaborate
mod and driver and a larger amp system by makers such as Rodent and
Black in Germany!


https://www.rohde-schwarz.com/uk/pro...d-media/radio-
transmitter/pg_overview_64079.html

or..

https://tinyurl.com/y4cexbtu
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article , Brian Gaff (Sofa)
scribeth thus
Assuming they still exist and are interested.
Have you ever looked at the cost of refurbished ordinary ham radio
transmitting valves capable of half a kilowatt?

Not that I have, but I hear that new ones are often crap since the Chinese
never really test them and the assemblies can be poor quality in plating
and construction, but there aware still some big triodes around ex Russian
military that can be pressed into use and the only issue is supplying the
heater current of several amps.

Brian


Dunno about vales for Ham use but the prices they charge for much bigger
valves will have a shade more care lavished n them!..

Here you go, for a look at the place that uses them excellent PDF called
Droitwich calling here worth a look!...


http://tx.mb21.co.uk/gallery/gallery...54&pageid=2072
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article , Mark Carver
scribeth thus
On 26/01/2021 10:13, The Natural Philosopher wrote:
On 26/01/2021 09:24, Chris Holmes wrote:

One for Brian???

I was wondering back when men were men and Libby Purves worked on the
other
side of the mic, radio transmitters used valves.

Are there now solid state devices (big MOSFETs??) capable of
producing the
necessary output power? Or are valves still used?

solid state up to a kilowatt or so. then add more modules. I don't
think valves used anywhere any more. Maybe up at magnetron frequencies

Many of the UHF DTT sites are using IoT 'valve' based transmitters, they
were installed about about 10 years at DSO

https://en.wikipedia.org/wiki/Inductive_output_tube


Indeed they did bit they seem to be out of fashion these days, the LDMOS
rules!...

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.