Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Hebert on January 20, 2020, 05:24:44 pm

Title: Silvertone 1331 power transformer
Post by: Hebert on January 20, 2020, 05:24:44 pm

I am wanting to build this amp from the schematic and from photos of the insides of the amp.  the transformer in question does not have 5v wires and the heater wires go directly to the rectifier tube rather than to a lamp. the ac wires are 270 v.a.c. and it also states 39 m.a. (which seems really low).  I need to find a good transformer that fits the needs of the circuit. also, how much can you fudge these numbers and still have it work with a circuit? thanks

Title: Re: Silvertone 1331 power transformer
Post by: sluckey on January 20, 2020, 05:33:18 pm

I would use the Hammond 269AX

Title: Re: Silvertone 1331 power transformer
Post by: Hebert on January 20, 2020, 05:51:48 pm

Quote from: sluckey on January 20, 2020, 05:33:18 pm

I would use the Hammond 269AX

thank you, that one is quite close at .3V @ 2Awith R.M.S. of 250V C.T. @ 115ma. Is the higher ma fine?

Title: Re: Silvertone 1331 power transformer
Post by: sluckey on January 20, 2020, 06:06:15 pm

Hammond 269JX is a much better choice. I was too hasty with that first suggestion.

Title: Re: Silvertone 1331 power transformer
Post by: Hebert on January 20, 2020, 06:13:38 pm

Quote from: sluckey on January 20, 2020, 06:06:15 pm

Hammond 269JX is a much better choice. I was too hasty with that first suggestion.

thanks again. I guess I don't know how to choose an output transformer either. Is there a calculation for determining this?

Title: Re: Silvertone 1331 power transformer
Post by: sluckey on January 20, 2020, 06:29:41 pm

I would use a Hammond 1760C

Title: Re: Silvertone 1331 power transformer
Post by: Hebert on January 20, 2020, 06:41:16 pm

Quote from: sluckey on January 20, 2020, 06:29:41 pm

I would use a Hammond 1760C

thank you