[Boatanchors] Baking Transformers

[John Lawson]

On Mon, 2 Nov 2009, Mark K3MSB wrote:

> Recently acquired an SB-200 parts unit from a 10 year stay in a pole barn.
> Power tranny tests OK for shorts and continuity etc.


   You might want to consider removing the rectifiers, and putting a 
suitable power resistor across the HV leads, then running the unit up on 
the variac at a percentage of full input power, and let the transformer 
bake itself. The resistor will load the HV, and the remaining tubes will 
load the filament windings.

  I've used this method several times on large HV power transformers; 
afterward they all showed perfect on the hipot tester.


   Saves putting the rig in an oven and endangering the "soft" parts, 
drying out already-old rubber, etc...


   Just my 200 millidollars...

Cheers

John KB6SCO


PS: the filter caps are most likely toast - kits are available, or Digikey 
or Mouser have (much smaller) replacements, and I took the opportunity to 
use units with appreciably more capacity.