Has anyone replaced the 8122's to another popular (reasonable ) Tube.
?

On 3 May 2006 04:12:47 -0700, "JB" wrote:

Has anyone replaced the 8122's to another popular (reasonable ) Tube.
?

This has been discussed quite a bit on the National users group
reflector.
In a word - no...

Some, including an engineer for Svetlana, have tried the 4CX800A
conversation and most have said that it was more trouble than it was
worth since the plate choke, sockets and tank coil have to be
reworked.

You can find lots of 8122's these days on eBay. Someone is selling at
least one set a week on there wth typical going prices of around $135
to $175 a pair. That's pretty cheap. A conversion to 4CX800A's with
the socket costs, etc. will cost you more than that.

Using that scheme, I've now got 4 sets of spares for my 2 NCL-2000's.
One set was found at a local hamfest for $175 brand new in their
original boxes. The other tubes were bought via eBay.

With all of the military and maritime transmitters than have been
built using the 8122, lots of tubes are hitting the surplus market.
The 8122 isn't really rare and is still in production by Burle and a
Chinese company. Yep, the Burle ones are expensive and the Chinese
ones aren't giveaway either!

Doug

Thanks doug I have herd mentioned 4cx250 Reduced power but more
foregiving ? Just wanted to know if anyone has replaced 8122,s with
anything ?

Svetlana in California converted my old NCL-2000 to their 4CX400's but it
was a major task. The RFC choke has hot spots on several bands and they had
to build a separate sub chassis for the tubes. I heard they also tried a
single 4CX800 in another NCL-2000.

There are two off shore copies of the 8122 beside the original RCA versions.
I had a pair of the off shore tubes in a Hallicrafters SR-2000 and they
seemed to work fine.

8122 and the off shore version are available right now some at reasonable
rates. The thing that needs changing is the relay and the RFC choke.
Svetlana had my old amp working on 80 to 10 including 17 and 12. I think
Svetlana closed USA ops and moved 100% overseas altho they do selll thru USA
companies.

Dave K4JRB

One of the cheaper tubes vs. power is the old 4CX1000. It would take some
mechanical work, but that is the fun part. Winding a new choke is also fun.

73, Colin K7FM

On Fri, 05 May 2006 12:42:40 GMT, "COLIN LAMB"
wrote:

One of the cheaper tubes vs. power is the old 4CX1000. It would take some
mechanical work, but that is the fun part. Winding a new choke is also fun.

Now that would be a *lot* of mechanical work as the 4CX 1000 (at 4.8"
tall by 3.37" in diameter) is a lot larger than the original tubes in
both girth and length. Even the 3CX800 is a fair amount larger, but a
whole lot more rugged. With zero watts grid dissapation a lot of
4CX1000s have gone to an early grave from a slight oops! :-))

Of course that brings the choice of staying a tetrode amp with low
drive or going GG. My preference is the 8874, but they are
*expensive*. I keep hoping they last for ever in my old 76A.

The tubes are worth more than the whole amp.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

73, Colin K7FM