[Amps] YC-156

[David Kirkby]

Norman Hockler wrote:

> Charlie,
>
> I do not know the history of the YC-130 but the YC-156 ( 3CPX5000A7) 
> is as rugged a tube as you can find.
> This tube ( a high mu triode) was designed by Eimac for the medical 
> business as the output Tube for MRI machines.
> I can guarantee it would take an awful lot to blow this one up.   Ask 
> some of the Hams that have built amps with them.
>
> Norm  N8NH


I heard from a ham, who did not want to be named, but his company made 
amps using the 3CPX5000A7 (which is identical to the YC-156 apart from 
some tests performed as Eimac on it).  He told me they run the tube up 
to produce 40kW and left it all weekend like that. On Monday, the tube 
had blackened badly, but was still producing 40kW CW.  The amplifier was 
then tested and found to meet the specification. (Whether the tube was 
run at 40kW in the amp, or on a test bed I can't recall).

There's a copy of a letter from Reid Brandon at Eimac
http://www.g8wrb.org/yc156-amp/pulsed.txt

confirming these tubes use the same cathode and grid structure as the 
3CX15,0000B7 which has a 15kW anode dissipation.

So the fact the tube has the same guts as a 15kW tube, and that someone 
else has told me one produced 40kW all weekend without failing, I find 
it hard to believe there is anything wrong with that tube.

Although it would not be reccomeneded, my guess is that if you could 
keep it cool enough (and I rekon my fan will put 1000cfm thru the tube), 
you could probably rate it like the 3CX15,0000B7. That is pure 
speculation of course. But if the grid and cathode are the same as the 
15kW tube, and you could keep the anode cool, I suspect it would take 
quite a bit of punishment.

BTW, I hear the YC179 -  picture at
http://www.g8wrb.org/data/Eimac/pictures/YC-179.jpg
is the same too, except that the grid ring has the holes in different 
positions to make fitting one in place of the other difficult. If you 
could get a properly dimensioned drawing of each, I guess it would be 
possible to drill the chassis so it would take either tube without 
problems. But the YC179 is designed not to be physically compatable with 
the YC-156.

There are data sheets for the YC-156, 3CPX5000A7 and the 3CX15,000B7 on 
my web site. I've not seen a data sheet on the YC179. Does anyone have 
one ???


The 3CX5000A7, is not the same at all.

-- 
Dr. David Kirkby, 
G8WRB

Please check out http://www.g8wrb.org/ 
of if you live in Essex http://www.southminster-branch-line.org.uk/