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Philco 90 filament section on PT bad
#23

Skip, make sure you are measuring the transformer voltage directly at the transformer leads. If you are connecting the voltmeter probes after the clip leads or ammeter, you will see a large voltage drop as the leads have significant resistance. You could easily see a drop of 1 volt when passing 8 or 10 amps through a typical clip lead.

With a 2.5 v supply it is very critical to have a minimum of resistance in the connections and wiring, which is one reason 2.5 volt filaments were abandoned in favor of 6.3 v tubes in later sets.


Messages In This Thread
Philco 90 filament section on PT bad - by Skip - 04-02-2016, 01:08 PM
RE: Philco 90 filament section on PT bad - by OZ4 - 04-03-2016, 11:02 AM
RE: Philco 90 filament section on PT bad - by Mondial - 04-03-2016, 01:15 PM



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