Reply
 
Thread Tools Display Modes
  #1   Report Post  
Posted to rec.audio.tubes
diecasthoop diecasthoop is offline
external usenet poster
 
Posts: 12
Default What is a 4X250F?

I have a few of these I got in a box of tubes. What are they used for?
They are strange looking guys. Any of Yall need any?

  #2   Report Post  
Posted to rec.audio.tubes
John Byrns John Byrns is offline
external usenet poster
 
Posts: 1,441
Default What is a 4X250F?

In article .com,
diecasthoop wrote:

I have a few of these I got in a box of tubes. What are they used for?
They are strange looking guys. Any of Yall need any?


One use of these tubes was in the cutting amplifiers used to cut the old
vinyl records, where a pair could provide 500 Watts or so of drive to
the cutter head. If you have 4 of them they could be used to build a
nice high power stereo amplifier.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
  #3   Report Post  
Posted to rec.audio.tubes
John Byrns John Byrns is offline
external usenet poster
 
Posts: 1,441
Default What is a 4X250F?

In article .com,
Bret Ludwig wrote:

On Jul 31, 4:28 pm, John Byrns wrote:
In article .com,

diecasthoop wrote:
I have a few of these I got in a box of tubes. What are they used for?
They are strange looking guys. Any of Yall need any?


One use of these tubes was in the cutting amplifiers used to cut the old
vinyl records, where a pair could provide 500 Watts or so of drive to
the cutter head. If you have 4 of them they could be used to build a
nice high power stereo amplifier.


If one were wanting to use such a type in audio one would use the
4CS250, a conduction cooled variant, and heat sink it to a VERY large
aluminum plate via a beryllium oxide link.


On the contrary, the Fairchild stereo cutting system used 4 of the
forced air cooled version of this tube in the stereo power amplifier
that drove the cutting head.

In other words, only a ****head would persist very far with building
an audio amp around them. It would be like putting a Jaguar six
cylinder engine in an airplane.


How so, are you calling Fairchild a "****head"? You were just praising
Fairchild in a parallel thread.

On second thought you may be partially correct, now that I think about
it, it was probably the 4CX150 that fairchild used, I will have to look
it up.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
  #4   Report Post  
Posted to rec.audio.tubes
diecasthoop diecasthoop is offline
external usenet poster
 
Posts: 12
Default What is a 4X250F?

OK, in the trash they go. Wife is bitching all the time about junk
gathering dust I will never use.

  #5   Report Post  
Posted to rec.audio.tubes
Chris Hornbeck Chris Hornbeck is offline
external usenet poster
 
Posts: 1,744
Default What is a 4X250F?

On Tue, 31 Jul 2007 12:54:52 -0700, diecasthoop
wrote:

I have a few of these I got in a box of tubes. What are they used for?
They are strange looking guys. Any of Yall need any?


This family was very common for VHF transmitter finals
in point-to-point service when I was in the Army. Track24
era, anyone? PCM was just coming into use; digital audio
was considered so secure that it didn't need to be
manipulated at all; raw transmissions were considered
secure.

And even in that era, only a captured American receiver
could have made any sense of even frequency-division-multiplexed
telephone signals.

You're making me feel old. OTOH, what doesn't?

Some VHF ham guy will likely want your box of tubes. Put
'em in a visible spot, and expect your reward in Heaven.

All good fortune,

Chris Hornbeck
"I would much rather be able to say it sounds like such and such, but
when it's not obvious distortion and/or noise, when the specs are really
good for those factors and IM and slew rate and a host of other stuff I
probably can't bring to consciousness right now, yet one preamp lets me
hear as if the source is alive and right there, and the next one makes
me feel as if I'm listening to the equivalent of a very detailed
cardboard Elvis, I don't know what words to offer that might help. But
hell, I'm willing to try. Everything we might like to know isn't known
yet, and through history people have come up with ways to measure stuff
that previously went unmeasured." - Hank Alrich 07 May 2005


  #6   Report Post  
Posted to rec.audio.tubes
John Byrns John Byrns is offline
external usenet poster
 
Posts: 1,441
Default What is a 4X250F?

In article ,
Chris Hornbeck wrote:

On Tue, 31 Jul 2007 12:54:52 -0700, diecasthoop
wrote:

I have a few of these I got in a box of tubes. What are they used for?
They are strange looking guys. Any of Yall need any?


This family was very common for VHF transmitter finals
in point-to-point service when I was in the Army. Track24
era, anyone? PCM was just coming into use; digital audio
was considered so secure that it didn't need to be
manipulated at all; raw transmissions were considered
secure.


When was that, I didn't know that there was ever a time that raw PCM was
considered secure?

And even in that era, only a captured American receiver
could have made any sense of even frequency-division-multiplexed
telephone signals.


I would think it would be child's play to make sense of FDM telephone
signals, why would a captured American receiver be needed?


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
  #7   Report Post  
Posted to rec.audio.tubes
Chris Hornbeck Chris Hornbeck is offline
external usenet poster
 
Posts: 1,744
Default What is a 4X250F?

On Wed, 01 Aug 2007 03:51:18 GMT, John Byrns
wrote:


PCM was just coming into use; digital audio
was considered so secure that it didn't need to be
manipulated at all; raw transmissions were considered
secure.


When was that, I didn't know that there was ever a time that raw PCM was
considered secure?


1970. It was a simpler, but no less mean, time. Sadly.

I would think it would be child's play to make sense of FDM telephone
signals, why would a captured American receiver be needed?


1970. We were fighting starving peasants, which helped.

Thanks, as always,

Chris Hornbeck
"I would much rather be able to say it sounds like such and such, but
when it's not obvious distortion and/or noise, when the specs are really
good for those factors and IM and slew rate and a host of other stuff I
probably can't bring to consciousness right now, yet one preamp lets me
hear as if the source is alive and right there, and the next one makes
me feel as if I'm listening to the equivalent of a very detailed
cardboard Elvis, I don't know what words to offer that might help. But
hell, I'm willing to try. Everything we might like to know isn't known
yet, and through history people have come up with ways to measure stuff
that previously went unmeasured." - Hank Alrich 07 May 2005
  #8   Report Post  
Posted to rec.audio.tubes
Skipp Skipp is offline
external usenet poster
 
Posts: 1
Default What is a 4X250F?

There are many different versions of the 4x250 family. You will find
similar tubes as the 4cx250 and 4x150/4cx150 (little brother) around.

The 4x means glass body sealed tetrode with 250 watts plate diss when
you properly cool it with an adequate size blower.

A ceramic type body seal "upgrade" makes the current tube a 4CX250.

The various trailing letters often indicate the tube version, heater
voltage and socket type.

So your tube is a 26.5 volt (ac or dc) Beam Power tube. The higher
heater voltage means your tube were not as popular in the consumer
market or with amateurs so they are often found much cheaper on the
surplus market. You can also see they have special socket and
chimney requirements and often operate around +2,000 volts for typical
operation. And once again forced air is required. The tubes are not
extra linear in AB2 grounded grid operation so you must consider how
to properly use/operate them.

Since they are industry work-horse power tubes you can/will find them
rf amplifiers, plasma cutter/generator circuits and similar circuits.
They have been used in some audio amplifier circuits but the higher
anode potentials and operational requirements make the more than unwieldy
to use in most audio locations.

There is a Yahoo group related to rfamplifiers, which is free to
join. Please drop in if you're interested in these sort of amplifier
topics (not limited to rf).

http://groups.yahoo.com/group/rfamplifiers/

Great tubes for an amplifier project... don't throw them away.

cheers,
skipp




: diecasthoop wrote:
: I have a few of these I got in a box of tubes. What are they used for?
: They are strange looking guys. Any of Yall need any?

  #9   Report Post  
Posted to rec.audio.tubes
John Byrns John Byrns is offline
external usenet poster
 
Posts: 1,441
Default What is a 4X250F?

In article ,
Chris Hornbeck wrote:

On Wed, 01 Aug 2007 03:51:18 GMT, John Byrns
wrote:


PCM was just coming into use; digital audio
was considered so secure that it didn't need to be
manipulated at all; raw transmissions were considered
secure.


When was that, I didn't know that there was ever a time that raw PCM was
considered secure?


1970. It was a simpler, but no less mean, time. Sadly.


It may have been a simpler time, but I can assure you from personal
experience that "raw PCM" was not considered secure in 1970. That is
not to say that there may not have been some people using "raw PCM" when
it should have been encrypted.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
  #10   Report Post  
Posted to rec.audio.tubes
Arny Krueger Arny Krueger is offline
external usenet poster
 
Posts: 17,262
Default What is a 4X250F?

"John Byrns" wrote in message

In article ,
Chris Hornbeck wrote:

On Wed, 01 Aug 2007 03:51:18 GMT, John Byrns
wrote:


PCM was just coming into use; digital audio
was considered so secure that it didn't need to be
manipulated at all; raw transmissions were considered
secure.

When was that, I didn't know that there was ever a time
that raw PCM was considered secure?


1970. It was a simpler, but no less mean, time. Sadly.


It may have been a simpler time, but I can assure you
from personal experience that "raw PCM" was not
considered secure in 1970. That is not to say that there
may not have been some people using "raw PCM" when it
should have been encrypted.


In the late 1960s I served at a Hawk site south of Miami that used a digital
RF link to receive and share real time command and control information. My
recollection is that the link was enciphered. The enciphering box had the
only DIP TTL chips in the whole battery - the rest was tubes and discrete
semiconductors.




  #11   Report Post  
Posted to rec.audio.tubes
Chris Hornbeck Chris Hornbeck is offline
external usenet poster
 
Posts: 1,744
Default What is a 4X250F?

On Wed, 01 Aug 2007 18:57:46 GMT, John Byrns
wrote:

It may have been a simpler time, but I can assure you from personal
experience that "raw PCM" was not considered secure in 1970. That is
not to say that there may not have been some people using "raw PCM" when
it should have been encrypted.


Maybe so, but you'll have to take it up with the US Army.
Wasn't my call.

Thanks, as always,

Chris Hornbeck
"I would much rather be able to say it sounds like such and such, but
when it's not obvious distortion and/or noise, when the specs are really
good for those factors and IM and slew rate and a host of other stuff I
probably can't bring to consciousness right now, yet one preamp lets me
hear as if the source is alive and right there, and the next one makes
me feel as if I'm listening to the equivalent of a very detailed
cardboard Elvis, I don't know what words to offer that might help. But
hell, I'm willing to try. Everything we might like to know isn't known
yet, and through history people have come up with ways to measure stuff
that previously went unmeasured." - Hank Alrich 07 May 2005
  #12   Report Post  
Posted to rec.audio.tubes
Bob Weiss Bob Weiss is offline
external usenet poster
 
Posts: 5
Default What is a 4X250F?

Bret Ludwig wrote:


The 4X250 is a 4CX250 derivative. It probably has a glass underseal
instead of the ceramic of the 4CX. I'm guessing C is for ceramic since
transmitting types of this family that do not have the C usually have
a glass section through which the bright filament-operating at
domestic lightbulb color temperature more or less-is visible.


Neither the 4X150 or the 4CX250 types used a bright tungsten filament.
Both use indirectly heated cathodes, operating at modest temperatures.

Bob Weiss N2IXK
  #13   Report Post  
Posted to rec.audio.tubes
Skipp says hello[_2_] Skipp says hello[_2_] is offline
external usenet poster
 
Posts: 1
Default What is a 4X250F?

: Bret Ludwig wrote:
: Great tubes for an amplifier project... don't throw them away.
: An RF amplifier in a repeater or radio room rack, sure.

It's not a big deal to build a desktop 4cx250 amplifier. Many have been
made and even some commercial units. But the 4cx tube family is not the
most practical consumer audio tube.

: The ARRL handbooks still show tube linears so people are still
: building them to some extent.

They can be a great dollar per watt value and fun to build if like any
electronics project... you're willing to do the work.

: The needed blower is a Dayton centrifugal one but some people use
: converted vacuum cleaner motors.

Keyword is blower... a fan just doesn't move enough air with the right
amount of pressure to cool the tube(s). Doesn't have to be a Dayton brand
blower. I don't know if a vacuum cleaner blower would be practical to
adapt and you'd always want to check it for enough air.

: If you like to listen to the stereo with the vacuum running then....

Anyone with experience knows you can find low noise blowers and learn
how they are mounted to minimize heat. Don't be silly now... a casual
stereo music listener is probably not going to use these type of tubes.

: you still need a 10-20K:4/8/16 output transformer that is rated for
: 4 kV working on the primary for, oh, 300 watts.

The transformer is not going to be some off the shelf item you can find
without doing a lot of homework... but they are around and can be spec'd
for a project. Regardless it would be large in size and quite costly.
Surplus audio transformers of the 4x/4cx tube family parameters are not
easily found anymore.

: This is the reason why power tubes bigger than 811s or 211s find
: little commercial audio application. Sure you can build a delightful
: amp around a pair of 4-400s or 5-125s or any of ten other cool looking
: Eimac or WE/Machlett types...but the transformer is infeasible. Varian
: EIMAC absolutely hated audio for whatever reason and refused to
: consider making the low mu triodes audio people wanted.

One person from early tube amplifier history once told me the tube
selection process for amplifiers his company produced were based on
size and anode voltage first. They did not want to deal with 2kv
plate potentials in a consumer device.

Consumer Audio was not the market Eimac was selling to... Most people
often listen to less than 10 watts of real audio better than probably
80% of the time.

: Al Bereskin built a twin 4-1000A power amp which is described in the
: Journal of the IRE somewhere. The opt is a monster-but it's a voice
: band only affair at that.

And a bit of work to make a voice band only unit. If he built the
amplifier in an AB1 layout he would have had to worry about parasitic
oscillations and design the audio amplifier not to be an oscillator. Not
an easy task for the amateur or first time builder(s).

: A considerable body of knowledge exists on
: the building of LF wideband magnetics in the 1-10 kW range, because
: they were used in submarine and surface ship sonar applications. Much
: of it, fifty years on even, is classified today but a good search of
: library resources will reveal a few unclassified publications that are
: quite explicit. Generally transformers in these voltage classes are
: oil filled.

A modern day toroid transformer would work just fine with many less
demons. But you end up with an amplifier that costs 30dB more than you
had hoped.

cheers,
s.
  #14   Report Post  
Posted to rec.audio.tubes
RapidRonnie RapidRonnie is offline
external usenet poster
 
Posts: 159
Default What is a 4X250F?


: The needed blower is a Dayton centrifugal one but some people use
: converted vacuum cleaner motors.

Keyword is blower... a fan just doesn't move enough air with the right
amount of pressure to cool the tube(s). Doesn't have to be a Dayton brand
blower. I don't know if a vacuum cleaner blower would be practical to
adapt and you'd always want to check it for enough air.


Most of them were Daytons. Not all. Royal the vacuum company supplied
a few. AiResearch which became Garrett did a few too.


: If you like to listen to the stereo with the vacuum running then....

Anyone with experience knows you can find low noise blowers and learn
how they are mounted to minimize heat. Don't be silly now... a casual
stereo music listener is probably not going to use these type of tubes.

: you still need a 10-20K:4/8/16 output transformer that is rated for
: 4 kV working on the primary for, oh, 300 watts.

The transformer is not going to be some off the shelf item you can find
without doing a lot of homework... but they are around and can be spec'd
for a project. Regardless it would be large in size and quite costly.
Surplus audio transformers of the 4x/4cx tube family parameters are not
easily found anymore.


They were never ever surplus. None had low impedance voice coil
windings AFAIK.


: This is the reason why power tubes bigger than 811s or 211s find
: little commercial audio application. Sure you can build a delightful
: amp around a pair of 4-400s or 5-125s or any of ten other cool looking
: Eimac or WE/Machlett types...but the transformer is infeasible. Varian
: EIMAC absolutely hated audio for whatever reason and refused to
: consider making the low mu triodes audio people wanted.

One person from early tube amplifier history once told me the tube
selection process for amplifiers his company produced were based on
size and anode voltage first. They did not want to deal with 2kv
plate potentials in a consumer device.

Consumer Audio was not the market Eimac was selling to... Most people
often listen to less than 10 watts of real audio better than probably
80% of the time.


Many people contacted Eimac about getting a purpose built audio
triode over the years. Including myself. They avoided that like the
plague. The bottom line was if there wasn't a government tit somewhere
they were not interested. The 3-500Z they made for years strictly for
hams but the rest of their tubes had government customers. They even
made a special small signal diode that went into HP VTVM probes.

Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT +1. The time now is 05:23 PM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"