8875
 

Are there any replacement tubes available that are pin compatible with the
8875. I have the Dentron 2500.

Thanks,
Mitchell

Dentron MLA-2500 conversion from Eimac 8875
 

"Mitchell" wrote in message
...
Are there any replacement tubes available that are pin compatible with the
8875. I have the Dentron 2500.

Thanks,
Mitchell


The 3CX400A7 / 8874 is a 400 watt triode in this same Eimac family - but air
cooled.
http://www.cpii.com/eimac/catalog/167923.htm

3CX800A7
http://www.cpii.com/eimac/catalog/16964.htm

Bob Alper, W6KT wrote an article in Communication Quarterly (now part of
ARRL QEX magazine) in Summer 1996
Specifically for Dentron MLA-2500 conversion (Dual 4CX400a)

Of course this is a conversion from a triode to a tetrode tube.
http://www.tomstubes.com/tube_conversions.htm

Adobe Acrobat articles (right mouse click and save to disk - faster)

Dual 4CX400a
http://www.tomstubes.com/images/mla_2500_4cx400a.pdf
Single 4CX800a
http://www.tomstubes.com/images/mla2500_4cx800a.pdf

8875
 

I don't believe there is a direct replacement. There is / was, on the web,
a mod to use another less expensive 4CX400A. It was writen by Bob Alper,
W6KT in 1996. It replaces the tube sockets

Seems do be dead now:
http://www.svetlana.com/docs/TechBul...hnoteNo14.html

Goran, SM2YER, lists other mods, but the links were too slow to respond for
me to look at them.
http://support2.overkalix.se/~sm2yer/shack/amp_mla2500/

Ahhhh! Here it is from a Google search 6/9/2006: T R U S T G O O G L E
! !

http://dk9ip.ba-karlsruhe.de/pdf/mla...hnoteNo14.html

Do a search on "Dentron MLA2500 Alper". Maybe it's still somewhere. I have
a soft copy. Here's an excerpt:

The major problem for MLA-2500 owners is that there is no economical source
for the 8875 tubes used as the active amplifiers. For under $350 including
sockets and tubes, the amplifier can be converted to run two Svetlana
Electron Devices, Inc. 4CX400A tetrodes. (The price of a Svetlana 4CX400A is
$140.) .
In performing the conversion, five specific needs must be addressed. These
a

- Modification of the final amplifier tube area.

- Adding a screen power supply.

- Meter switching board change.

- Adding a bias power supply.

- Installing the passive input grid circuit.


73, Steve, K9DCI


"Mitchell" wrote in message
...
Are there any replacement tubes available that are pin compatible with the
8875. I have the Dentron 2500.

Thanks,
Mitchell

8875
 

Hi Mitchell,

The 8875 is its own beast... but you can find them surplus from
guy who mod their original Dentron Amplifiers out. I have a 2500
that I'll some day rebuild with a different tube so who knows... I
may even sell my used tubes on ebay.

You can also post a want over on the yahoo rfamplifiers group,
which is a pretty large group about both rf and audio amplifiers...

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

and the group does both tube and solid state amplifiers...

cheers,
skipp


: Mitchell wrote:
: Are there any replacement tubes available that are pin compatible with the
: 8875. I have the Dentron 2500.

: Thanks,
: Mitchell