[Collins] Bucking Voltage

[Dr. Gerald N. Johnson, electrical engineer]

Those filament windings are rated at 3 amps. Even though the power
supply has a 4 amp fuse, I suspect 3 amps is about what it draws key
down CW. Less average on SSB.

A transformer winding doesn't fail like a fuse at 125% of rated current.
It just runs hotter. That makes the paper insulation age more rapidly.
Power companies with oil filled but paper insulated transformers figure
that intermittent loading to twice their rating only cuts the life to 20
years from 40 years.

The up side of dropping the primary winding voltage is that the primary
current is reduced, and the core losses are reduced. The primary current
has smaller peaks from core saturation. That's a great benefit towards
longevity.

Some only need 5 volts drop, some need 10 volts drop, it depends on the
local utility and the loading at the time the supply is being used.

73, Jerry, K0CQ, Technical Advisor to the CRA.

-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
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