Discussion in '"Boat Anchor" & Classic Equipment' started by W8TMT, Nov 5, 2019.
This "transformer thread" has most certainly been "transformed"
Late 60's a retired railroad telegrapher and one of a few excellent ham mentors, perhaps 60 years old with a wooden leg, carried his hamfest beer in a "tupperware" container. I still remember when one of the teen YL's (yes, there used to be many of them at hamfests) asked, "Mr Simpson, what do you have there?" Without missing a beat he replied "specimen". The things one remembers from 50 years ago.
Likely powered a solid-state audio amplifier.
Based upon the voltages ( 70 VAC, etc. ) I might guess that someone was using this as part of a Public Address Amplifier ( 70V is a common theme for many in use today, yet the transformer voltage may be a bit high for producing the correct power supply voltage with good efficiency ). Because it has cloth-covered ( or very dirty ) leads, you might look closely at them to see if there is a shellac or other more-brittle coating on the wires than the enamel frequently used today. Even with enamel, sometimes transformers are sometimes found to be arcing internally under conditions of high humidity. These can sometimes be rewound or dipped to restore integrity, and verified with the judicious use of a 'megger'. Ask the 'elmers' in your local amateur radio community, or an experienced electrician about the use of a 'megger' before considering a purchase of this sort of equipment. There are safety precautions involved, and keeping this sort of test equipment where children might access it is a recipe for disaster. For those who are curious about 70V public address amplifiers- start by looking at the electronic audio component "L-Pad". Many public buildings have speakers in the suspended ceilings which include small transformers for matching to 70V systems. The manufacturer 'Peavey' has delivered amplifiers for these over many years. I have no fiduciary ( money ) interest in Peavey, just some experience with the service of their amps and changes to connected speaker configurations. An in-circuit electrolytic capacitor tester or oscilloscope 'octopus' jig would be a good investment if you plan to re-use components such as the transformer in your post. Please be certain that you understand the math so as to be aware of the voltages produced, and take appropriate precautions for insulation and fire-safety.