Well, if that is the case, when in the tune position, then I must have been very lucky. I have never looked or considered the issue. The dynamotor voltages are combined for the full 1100v. In tune position, a lesser voltage is applied to the final. I plead ignorance in this case. Dumb luck, perhaps? I just looked again at my a.c. power supply design. Indeed, I do apply both voltages simultaneously and the transmitter sorts out the stacked voltages in tune and operate. My error it would appear... So please amend my start up procedure and apply both voltages.... in the tune position. Above and beyond, I may have to interlock the two voltage sources in my supplies as they are fused independently. If the high B+ fuse were to blow, the 400v is still there. It has happened with nothing (apparently) untoward happening. But... never the less....

Jeep, when you apply the 400V prior to the high voltage, what are you doing with respect to the 813 screen voltage. I’ve always been of the understanding that applying drive and screen voltage to a screen grid power tube without plate voltage applied should never be done because it would cause the screen to draw heavy current and quickly destroy it. Typically the screen voltage would be obtained by a voltage divider from the plate HV circuit to avoid the possibility of leaving the screen at potential without plate voltage present.

Chris B. AJ1G Stonington CT

Sent from my iPhone

On May 17, 2023, at 10:52, Jeep Platt <[email protected]> wrote:

I just sold an on the air ART-13 and ARR-15 receivers for $1k. The ART-13 was complete and virtually new condition. The ATC (Navy designation) and the ART-13, both T-47s, are virtually the same. I would shoot for the easiest one to get on the air. I might also recommend an a.c. power supply, to begin with. That will allow sequential application of voltages; filaments first, the 400v, then the 1100v HV.

Things to sequentially check:

All tubes light up.

Autotune works and properly "homes". ( no home, no TX key).

Apply 400v and check grid drive.

Finally, apply HV and check for power out.

If you need initial dial settings for test on 75 meters (can provide).

You will need between 700 and 1100pf of loading to tune 75 meters at 50 ohms.

Been there, done that, at least 8 times.... It can be done.

Jeep K3HVG

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