Bottlehead Forum

General Category => Technical topics => Topic started by: jmv on June 05, 2012, 06:37:54 AM

Title: 71A Circuit?
Post by: jmv on June 05, 2012, 06:37:54 AM

I can't find the thread atm, but I recall that Paul Joppa recently posted about using the 71A tube in a battery-powered circuit.  Apparently they were common on old farm radios and ran off a 6 volt battery.  I happen to have a couple of 71As lying around, and I'll like to try them in a battery-operated setup.   Anybody have any insights here, or a place on the web you could point me to?

Title: Re: 71A Circuit?
Post by: xcortes on June 05, 2012, 07:39:29 AM

The filaments are 5v low current and meant to be run off batteries. IIRC the datasheet OP for 750mW is 180v p-c, 40 v bias and 20mA so you can use batteries but many of them.