what did i find?

[gwedo2000]

hello all this is my first post. hope some one knows what i got.
the tubes are 12ax7, 2 - 6f6g
big transformer = utc type a19
small transformer = triad a-31x interstage transformer
well thats about all i can tell ya about it.
thanks.

 

[luckyed]

Welcome. It looks cool but I do not know what it is though. Do you have more photos?

 

[cademan]

Hi, and welcome! It looks like a basic audio amplifier without the power supply!

Do you want to see if it works, or have you gotten that far yet?

A power supply would be a simple build. Can we see some of the underside and side connections?

 

[BwanaJim]

Any pictures of marking's/ label's?
And welcome to the greatest audio site on the web !!!!!!!!!

 

[gwedo2000]

ok i got more pics uploaded. no labels no stampings no name just whats on the transformers.

 

[gwedo2000]

the big cap has been cliped on the dual side and it looks like there was a switch on the back of the pot at one time

 

[Cadillac Kid]

Looks like a home brew push-pull design.

 

[gwedo2000]

i was told it came out of a grade school when they were remodeling the office

 

[ke4mcl]

i say homebrew push pull mono amp with external power supply that you are missing. the transformer should have a part number stamped on it. maybe a letter and a coupled of numbers. looks like a UTC transformer. you can google "UTC" and part number and may get hits on it.

 

[audiodyssey]

The UTC A-19 is an interstage transformer, single plate to 2 grids, 15K ohms to 80k ohms, 2.3:1 turns ratio with a frequency response from 40-20k. I'd say what you have is a pre-amp of some sort, probably microphone. The a-31x is plate to single or push pull grids, Pri=10k Sec=90k (ct) 1:3 100-10k. I can do the research, someone else can tell you what its for...

 

[similost]

. I'd say what you have is a pre-amp of some sort, probably microphone. .

THis is what I am leaning towards myself. Especially after hearing it came out of a school, and the fact is has a 1/4"input on the front... Probably used for making the daily announcements and getting everyone to say the pledge first thing in the morning..

 

[gwedo2000]

thanks for the help so far, so can i turn it into somthin' usefull, does anyone have a schematic that uses those tubes so i can convert it.

 

[cademan]

The 6F6 is an output pentode tube where pins 3 of both tubes are the plate connectors to the output transformer, with center tap.

I still think it's an audio amplifier (don't hurt me, its just what I believe I see). A 1/4 inch jack isn't always used as a microphone input.

 

[jaymanaa]

What's the stuff I see in the background? Maybe one of those pieces is the power supply?:scratch2:

 

[MelodyMaster]

i say homebrew push pull mono amp with external power supply that you are missing. the transformer should have a part number stamped on it. maybe a letter and a coupled of numbers. looks like a UTC transformer. you can google "UTC" and part number and may get hits on it.

Since it came from a public school I'm thinking it's a paging amplifier, public address system. It would be in a rack with separate power supply, and a routing switch for source and destination, including general address. The latter would have the line transformer and preamps. This is definitely the power amp, (including grid driver transformer) not a preamp. The output transformer for the 6F6's will be the PA line transformer elsewhere in the rack.