Re: {Collins} 30L-1, keyed down current @ no excitation.



You should not run your 811A's at 200 mA. Even at 110 mA they are running close to their rated power. If everything else checks out OK on the finals and bias supply, then use a higher value for R28. Experiment to see what value of R28 get's you to around 110 mA key down idle plate current. And I would definitely use a 2W resistor for R28.

Gaylord
WB7ODD

----- Original Message ----- From: "Bent" <bjoe@xxxxxxxxxxxxx>
To: <collins@xxxxxxxxxxxxx>
Sent: Saturday, February 18, 2012 10:53 AM
Subject: {Collins} 30L-1, keyed down current @ no excitation.


Hello All

Until now thanks to all who had responded on this issue.

I do not know whether this theme is fully clarified.
I am not quit sure.

Based on the responses am not able to conclude something.

It seems for me, based on different generations of instruction books that R28 should be 39 Ohm.
Maybe this is still an open question.

Is someone able to draw a final conclusion about the correct key down current if R28 is 39 Ohm ?
In my case I measure -157 VDC on the ANT Relay connector at 1800 VDC.

Is 200 mA instead of 110 mA OK for normal SSB use ?

If the current increases to the doubble the power increases four times as far as I know.
And that generate heat.
Where does this extra heat occur in the circuitry, tubes ?

Thanks again.

Br.
Bent
OZ5ZD





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