UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Williamson amplifier. Winding an output transformer.

thermion · 9th Aug 2022, 8:28 pm

Yes, that’s very similar, I recognize the gold colour too.
Now I’ve taken some measurements this afternoon, & the results below.
Resistance tests;
Anode to Anode 203r
CT to anodes equal @ 105r
Screen to screen 94r
CT to screen taps unequal. 1@54r the other is 40r
Voltage test. 10V AC on secondaries. With 3 sets of windings in series, 3+2+3 parallel sets;
Anode to anode 340v balanced ok @ 170v per side
Screen to screen 147v balanced ok @ 73.5v per side
With 5v ac anode to anode leakage current 0.08 mA.
So the turns ratio with 3 groups of secondaries in series is 34:1, squared is 1156, into a 10k load gives 8.6 ohms. Is that right?

9th Aug 2022, 8:28 pm	#22
thermion Tetrode Join Date: Dec 2011 Location: Cheshire, UK. Posts: 89	Re: Williamson amplifier. Winding an output transformer. Yes, that’s very similar, I recognize the gold colour too. Now I’ve taken some measurements this afternoon, & the results below. Resistance tests; Anode to Anode 203r CT to anodes equal @ 105r Screen to screen 94r CT to screen taps unequal. 1@54r the other is 40r Voltage test. 10V AC on secondaries. With 3 sets of windings in series, 3+2+3 parallel sets; Anode to anode 340v balanced ok @ 170v per side Screen to screen 147v balanced ok @ 73.5v per side With 5v ac anode to anode leakage current 0.08 mA. So the turns ratio with 3 groups of secondaries in series is 34:1, squared is 1156, into a 10k load gives 8.6 ohms. Is that right?