[Milsurplus] TCM-2

[Kenneth G. Gordon]

On 5 Jul 2017 at 12:21, Richard wrote:

> That's pretty close.  My TBW, with guaranteed output of 100 Watts, (from 
> memory) measures 190 Watts.

Ah. That is interesting...

>  Two 803's should be at least 380 Watts.

Yes. I agree. Depending on applied voltages. 

According to the spec sheets on the 803, a pair should output 420 watts (at 700 watts input, 
350 watts per tube) at 2kV plate voltage, but that is under ideal conditions...which don't really 
exist. Your 380 watts is more reasonable.

One thing I find very interesting is that what appears to be the plate bypass capacitor in the 
TCM is a really HUGE broadcast-transmitter quality ceramic-and-mica cap good for 10KV. 
Seems way overkill to me, but I suppose I'll figure that out eventually.

> Noting that the TBW has no parasitic suppressors,

Neither does the TCM... however the tubes DO reside in shield cans which cover much of the 
bottom 3/4 or more of each tube.

> the 803 is probably 
> more stable and a better choice than the 813 and other beam-power tubes.

Again, yes, I agree. The data/spec sheets on the two tubes are very different, that for the 813 
including all kinds of warnings about how it should be used. There is none of that for the 803.

I have several what look like NIB 803s here, all of which have very heavy cermic bases, and 
all are marked for the Navy.

Well, if I am able to do with this TCM what I would like to do, we'll see what we learn.

It will be fun anyway.

Ken W7EKB

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