Re: {Collins} 30L-1 / 572b

Ulrich Schneider wrote:
Hi to the list,

I just bought a matched quad of 572B made by Svetlana from Keith (K5SVC) via
his ebay advertisement. I am enthusiastic about their behaviour in my 30L-1:

All parameters seem to be just fine, no adjustment was necessary at all!
Other than the 811, their plates do not start glowing with just 100W(!) CW
output and in addition to that the power has increased from around 600W to
more than 700. I do not attempt to challenge the amp beyond that but this is
really convincing to make the change, especially considering the high plate
voltage I have, which is around 2000V in idle!

As a summary it is highly recommendable to exchange the 811 to the 573B also
where the price of approx. 200 USD is very reasonable.




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Hello Ulrich,

I also use the 572B's and from the same source. My high b+ runs 2100 vdc since I changed my diode/capacitor boards. I used the board offered by Bill Noonan, W6BN, that replaces both of the original Collins boards. See link at end of message. My line voltage here in Indiana runs 248 volts most of the time.

I am in the process of constructing a external relay control for the line ac source. This will allow me to leave the rocker switch in the "on" position. They are hard to find and even more difficult to replace.

Smith Bradford

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