[Drake] Drake L7 psu

[Chris Pedder]

Hi,

As a precaution, and not out of necessity, I am in the process of 
rebuilding the L7 psu with new caps, diodes etc. Rather than reinvent 
the wheel I have obtained a printed circuit board from a US supplier.

Looking at the board I notice a couple of things. The original used 
two strings each of 7 diodes, rated 600v PIV. The new board maintains 
this number even though the replacement diodes are 1000v PIV. 
Overkill perhaps, but diodes are cheap and better too many than too few.

The new board retains the old practice of using equalising resistors 
across each diode. I did this 30 years ago but understood that it was 
no longer necessary and, indeed, not desirable. Is this the general consensus?

It would be helpful to get rid of the heat from the pair of 50K 
50watt bleeder resistors in the psu. This would mean the loss of 120v 
cutoff voltage which also drives the 'transmit agc'. I'm happy to 
rely on the 100K across each electrolytic to bleed the HV, albeit 
slowly, but is this wise?

Are there any other 'improvements' that I might incorporate while I 
am at it? (Soft start is already on the list)

Thanks

Chris G3VBL