|[AMRadio] small power transformer needed|
John King via AMRadio
amradio at mailman.qth.net
Mon Jul 14 14:42:13 EDT 2014
I need a physically small power transformer to build a small bias supply for my Hallicrafters HT 33A amplifier with Eimac 8295 which is a direct replacement for the original Penta PL-172. The original filament transformer had a bias winding that would produce -200 vdc from the rectifiers. The original filament/bias transformer COOKED and was replaced with a filament transformer without a bias winding.
The bias variable circuit varies the bias between -95 vdc and -125 vdc. I am looking for a PHYSICALLY SMALL power transformer that will supply the AC voltage to give me a rectified -200 vdc from a bridge rectifier. Low current rating is not a problem because the tube runs in class AB1 or AB2 depending on user's choice.
If I can't find such a physically small transformer that produces rectified -200 vdc with a bridge rectifier, I might be required to locate two small filament transformers and run the (secondaries) in parallel off of 6.3 vac ( now becoming primaries) and series the 120 vac primaries they becoming a secondary to transform 6.3 vac to approximately -220 or so vac. which can then be rectified with a bridge rectifier to provide the required negative voltage to the circuit that makes the bias variable.
Does anyone have the physically small transformer that would perform the aforementioned chore or a pair of identical small filament transformers that would do the job? Please email me and let me know. Thanks and 73, John, K5PGW
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