It would be a great education to fool with an oscilloscope.

If I wanted to sub in a power transformer, what is a suggested transformer. The current out put on the unit is 11.5 volts, with two leads and center tap. 11.5 on each lead and center tap.

A wall wart might do the job.

transformer at wall mart???

I didn't say wall mart. I said wall wart. You know, those sort of cubes that plug into the wall and supply power to various goodies. The older ones are transformers, sometimes with rectifiers. They put out various voltages from maybe 1.5 through 18 Volts at currents up to maybe one Ampere. I have a box of them and often find uses for these things.

You will often find boxes full of "wall warts" at flea markets or habitat recycle stores, etc., with all sorts of voltage outputs, for a buck or two.

Sorry, the old eyes are not what they used to be. I need to do some digging, I think I have some of those transformers also. If I find a 12 v DC, I could replace the current power with one of these?

Can I connect an 12 VDC transformer,and is the capacitor bypassed. Picture attached. Disconnect leads to capacitor and add new transformer.
Current voltage is 11.26 is 12 VDC going to be OK?

I can't answer that directly. The wall wart marked 12V will probably put out somewhat more than that, so you will have to measure and see what you get.

Puts out 12.19, think that will be ok?

Yes but that will change depending on load. Just be careful not to put too much into the radio or you will cause damage.

Hum is gone, all I get now is the sound of power on and off. No AM or FM which I don't really care, I'm hoping to get the intercom only going. I hooked up one of the room speakers and we can also hear the click of the power on thru the speaker. By turning the volume down the clicking sound is reduced. But no activity when the intercom switch is pushed and talk into the speaker. Where to now??

Just checked, I have a buzzing sound on AM around 800, buzz will increase and decrease with volume control. Nothing on FM, but that might be to no antenna, I have a wire connect to the AM, what would be needed for FM antenna?

Hooked up an antenna to the FM, I have a radio that works, but no volume. I'm getting feed back thru the speaker for the intercom, but no volume. What do I look for now.

Took out current power transformer, checked voltage was 12.6, transformer has a center tap, both outputs the same. What would be the average amps for a power transformer, no markings on this one.