[Amps] SB-200 circuit breakers

[Tom Osborne]

Hi All

On my SB-200, the front circuit breaker trips after half hour or so of 
operation on RTTY.  If running RTTY, I usually keep it down to 200-250 
watts.  It is the same breaker, the front one, that always trips.  After it 
cools down a bit, it will come back on. The plate current is only running 
about 300 ma or so.

The tubes are fairly new (4 months) and don't run red when operating RTTY at 
200-250 watts.  I also have some muffin fans on top with the lid open to 
take out some of the heat.

In looking at the schematic, the breakers are in the primary of the power 
transformer.  What causes them to trip, heat?  There doesn't seem to be that 
much with the extra fans on top.  73 and thanks
Tom W7WHY