why not 4cx-250 for audio tube amp?
kt Chan
What is wrong?
Any home builder out there?
Regards
K.T.Chan
from Hong Kong
Fré Jorritsma
CHOKY
www.soundpractices.com for some info about back issues.
If my memory serves me good enough,japanese tube guru N. Shishido was expert
for that kind of...
Go for it! (I also got few 4cx250b's but not got enough time)
--
message sent by Choky,
Prodanovic Aleksandar
ch...@EUnet.yu
Yugoslavia
kt Chan <ktc...@hk.gin.net> wrote in message
news:3B3875DF...@hk.gin.net...
flaco
> Simillar aproach is explained in Sound Practices;try
>www.soundpractices.com for some info about back issues.
> If my memory serves me good enough,japanese tube guru N. Shishido was expert
>for that kind of...
> Go for it! (I also got few 4cx250b's but not got enough time)
>
How would you run the fan and keep it quiet enough??
Maybe a tank of transformer oil and a pump?
my 2c
flacoman
>--
>message sent by Choky,
> Prodanovic Aleksandar
> ch...@EUnet.yu
> Yugoslavia
>
>kt Chan <ktc...@hk.gin.net> wrote in message
>news:3B3875DF...@hk.gin.net...
>> Please comment why not transmitting tube for audio amplifier?
>> What is wrong?
>> Any home builder out there?
>>
>> Regards
>>
>> K.T.Chan
>> from Hong Kong
>>
>
>
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John Byrns
flaco...@hotmail.com wrote:
> On Tue, 26 Jun 2001 14:52:39 +0200, "CHOKY" <ch...@eunet.yu> wrote:
>
> > Simillar aproach is explained in Sound Practices;try
> >www.soundpractices.com for some info about back issues.
> > If my memory serves me good enough,japanese tube guru N. Shishido
was expert
> >for that kind of...
> > Go for it! (I also got few 4cx250b's but not got enough time)
> >
> How would you run the fan and keep it quiet enough??
> Maybe a tank of transformer oil and a pump?
> my 2c
There are conduction cooled versions of some of these small transmitting
tubes that were used in two way radio base stations. They bolt to a
heatsink with thermal compound just like transistors. I think there is a
version of the 4cx125 like this, I am not sure about the 4cx250 though.
Regards,
John Byrns
Surf my web pages at, http://www.enteract.com/~jbyrns/index.html
TubeGarden
system :)
Happy Ears!
Al B^}
PS I have a fresh pair of Svetlana 4CX250B standing by....
Alan J. Marcy
Phoenix, AZ
PWC/mystic/Earhead
flaco
wrote:
>I
>There are conduction cooled versions of some of these small transmitting
>tubes that were used in two way radio base stations. They bolt to a
>heatsink with thermal compound just like transistors. I think there is a
>version of the 4cx125 like this, I am not sure about the 4cx250 though.
>
>
>Regards,
>
>John Byrns
>
You're thinkng of the Eimac 8873 and 8874... Slightly different
bottles but a distinct possibilty. The thing is with those
transmitting tubes is the high B+ required and the high primary
impedance for the transformer.
my 2c
flacoman
Raymond Koonce
Raymond
kt Chan
Raymond http://www.tmhaudio.com/HE-833%20Ultimate%20Audio.htm
That is what tube audio amp should looks like.
Cool
Regards
K.T.Chan
Pär
> How would you run the fan and keep it quiet enough??
> Maybe a tank of transformer oil and a pump?
> my 2c
> flacoman
Hi, One does not have to run it at full oomp. If one keep the DC
wattage at about one fourth of permissible (still 70W and so about 17W
of output)they should run without external cooling. But I would choose
a 3CX300 instead :-) mvh /Pär
SkrewBall
Small,quiet,and they work well. (and draw minimal current)
kt Chan
SkrewBall
NealK811
filament voltage will burn the tube out and in short order.
The 4CS250 was used in the Mot base stations and in dedicated paging
transmitters by some other company.Mounts up with a BeO thermal link to a large
heatsink or the hull of a ship.
The output xfmr and power supplies would be expensive and a big challenge,plus
which, the trend in tube power amps is to less output power.
wb0...@prodigy.net
Pär wrote in message ...
>---cute cut---
>> How would you run the fan and keep it quiet enough??
>> Maybe a tank of transformer oil and a pump?
>> my 2c
>> flacoman
>---cute cut---
>Hi, One does not have to run it at full oomp. If one keep the DC
>wattage at about one fourth of permissible (still 70W and so about 17W
>of output)they should run without external cooling.
Can't do this without wrecking the filament seals. Most xmitting tubes need
the filament seals to be cooled, even with no B+ applied.
73 John
kt Chan
pipe....?
Thanks
K.T.Chan
Pär
Uhu... There I learnt something. Thought it was possible coz a 3cx300
could be run without a fan as long as the proper socket is used (and
air is fre to flow with convection through the socket AND the plate
dissapation is kept low). 4cx250 and 3cx300 are not that different
(take or leave a grid or so :-) ). mvh /Pär
wb0...@prodigy.net
Pär wrote in message ...
>could be run without a fan as long as the proper socket is used (and
>air is fre to flow with convection through the socket AND the plate
>dissapation is kept low). 4cx250 and 3cx300 are not that different
>(take or leave a grid or so :-) ). mvh /Pär
To quote the RCA Tube Handbook HB3, data page for the 7203/4CX250B:
" If an air-system socket is not used, it is essential that adequate cooling
air be directed over the base seals, past the envelope, and over the
radiator... at higher ambient temperatures and altitudes, the air flow must
be increased to maintain the respective seal temperatures and the plate
temperature within maximum ratings."
I don't see any way that you could effectively liquid cool these tubes.
Freon, etc., will probably instantly crack the ceramic; immersing the tube
in oil would probably result in hot spots in the radiator and the seals.
Jeez, just air cool it - 'tain't that hard!
The 3CX300 may have a lower rated filament current; I don't know. But
*generally speaking* you must make sure that there is adequate airflow over
the pin seals on xmitting tubes (except lower power tubes and tubes with
bases like 811s, 572Bs, 807s, 6146s, 2E26s, etc).
73 John
73 John
kt Chan
the reason of air cool tubes are not considered.
Would like to see if there is any way to make a muffler for it.
K.T.Chan
Ned Carlson
wrote:
>On Tue, 26 Jun 2001 11:13:01 -0500, jby...@enteract.com (John Byrns)
>wrote:
>
>>I
>>There are conduction cooled versions of some of these small transmitting
>>tubes that were used in two way radio base stations. They bolt to a
>>heatsink with thermal compound just like transistors. I think there is a
>>version of the 4cx125 like this, I am not sure about the 4cx250 though.
>>
>>
>>Regards,
>>
>>John Byrns
>>
>You're thinkng of the Eimac 8873 and 8874... Slightly different
>bottles but a distinct possibilty. The thing is with those
>transmitting tubes is the high B+ required and the high primary
>impedance for the transformer.
>my 2c
>flacoman
There's also a a conduction-cooled 4CS250R and 8560AS,
and a similar GEC equivalent IIRC.I think all these use beryllium
oxide insulators, so don't run around filing the insulators down
on a bench grinder!
I suppose you could cool a 4CX250B or other external-anode tube via
methods such as oil cooling, I suppose commercially available
dilectric oil would work (as opposed to motor oil which usually
contains detergents & additives). Some transmitting tubes just have
threads on the anode which can be connected to radiators and
can be cooled by a number of methods.
A 4CX250B used at lower voltages actually uses plate loads that
aren't way out of line, with Va 1000V and Vg2 350V, the book calls for
only 3500 ohms, and a pair puts out about 240W.
http://www.triodeel.com/4cx250.txt
Ned Carlson Triode Electronics "where da tubes are!"
2225 W Roscoe Chicago, IL, 60618 USA
ph 773-871-7459 fax 773-871-7938
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