[Milsurplus] [Boatanchors] 19 Set Power Supply

[J. Forster]

The point is that if the line fuse blows due to a failing 6X5 (H-K), and
someone overfuses it, the transformer assembly DIES.  IMO, a poor design.
A bum tube should not kill other things.

FWIW,
-John



> I think technically the circuit is sound however the unit uses 4 6X5-GT
> valves. Two are used for the receiver B+ at 265v, below the 450v choke
> input filter rating. The HT2 (xmtr) is 540vdc but is divided between two
> cascaded 6X5 full wave rectifiers so each valve handles 270v. The
> heater/cathode rating is 450vdc, above the actual applied voltage. I
> think the main problem is using a 6X5 in the first place. It has a
> reputation of shorting internally and converting solid copper into
> copper ions inside the xfrmr housing.
>
> I bring it up on a variac just to prevent any surge. It hums loud but
> not as noisy as the dynamotor spooling up and there's no delay going
> from rcve/xmit/rcve.
>
> Bruce   ve7mt
>
> J. Forster wrote:
>> Mine are not to hand so I can't tell you the S/Ns.
>>
>> I'm not so sure bringing it up on a Variac is the issue. One of the
>> tubes
>> in the HT2 supply has about 300 V, heater to cathode. IMO, that's asking
>> for trouble. Silly design.
>>
>> The main failure mode seems to be arcover in the HT windings of the
>> transformer also. I have one mostly reverse engineered and will get one
>> rewound eventually.
>>
>> Best,
>> -John
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