{Collins} 30L-1 strange looking power supply board



Just beginning my next project, to recondition another 30L-1.  This is the one I've been using for a couple of years... I bought it as a working unit and opened it up to install the tubes (Svetlana 811A) and give it a once-over before bringing it up on a variac, but didn't really inspect it very closely and in those days wouldn't have really known what to look for anyway.  All seemed OK so I put it into service and have been using it as I said for a couple of years.

Its output is a bit low (500 watts PEP max) and its linearity on the scope isn't the best, so since I just finished my other 30L-1 and put it into service (see the threads about step-starts and relays and such over the last week or two) this one is next on the bench.  Opened it up and finally took a close look.  Let's just say it works a lot better than it looks.

The power supply board looks strange.  It's a single board rather than two boards as original equipment, but it mounts component side up rather than component side down like the Young Kim and K4LAJ boards do.  It has six blue radial lead can capactors, each of which is 3.25" high (much higher than YK/K4LAJ).  Looking down at it from the front of the amp, on the right edge is a row of white resistors marked 100K 2W (although they look much too small to be 2W).  The board has some prominent burn marks in the area of those resistors.

This may be an optical illusion but the board looks sort of trapezoidal in shape rather than rectangular with square corners.

Any ideas what this might be?

Rick WA1RKT



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