[Milsurplus] My TCK-4 - more info

[Kenneth G. Gordon]

On 15 May 2017 at 15:53, WA5CAB at cs.com wrote:

> OK.  Too bad about the CFI.

Yes. I sure think so too. :-(

> I might have guessed that the added switch went to the keying relay except that there is already a 
> switch for that.

I have so far guessed that it has something to do with the bias on the final stage. Perhaps he 
fixed it so that it would act as a linear amp, but didn't intend to use that feature often. I'll figure 
it out eventually. Or maybe it is to turn the filaments off for one of the finals.
 
> The 5U4/5R4 is probably the 500 VDC supply.  You may find that he followed the original rectifier 
> schematic fairly closely.

That is what I am thinking. For one thing, he has the Low Power-Test-High Power control 
installed on that added panel with the key jacks and the test switch. That would require wiring 
directly to the power supply.

An additional power supply of some sort, using an unusually large transformer, fairly 
low-voltage filter caps, and top-hat silicon rectifiers now occuplies the space where the CFI 
originally sat. I suspect this is the 115 VDC supply, but I can't quite figure out why the 
transformer is so large. I would estimate its power capability (on the basis of the core size) to 
be at least 750 watts, possibly as much as a kW. If that supply is, in fact, the 115 VDC 
supply, IMHO the transformer is WAY over-kill. It is out of proportion to the rest of the circuit 
components. Maybe it was all he had.

Or maybe he "oversized" his power transformers in the interests of reliability. The HV 
transformer is simply huge too. In fact, it looks to me very much like an old "pole pig".

> Note that the filament transformer, T108, was always in the transmitter.

Yes. I knew that much at least. ;-)

Thanks,

Ken W7EKB

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