The AM Forum

Can anyone say what this is from?
The tag says MR052303 and 50A and 14.4V no load. The transformer has two 18VCT windings. They are connected in parallel and the rectifier is full wave center tapped circuit.

This stuff also came with it. ATR inverter, probably a vibe type. Need to open it up and see if an upgrade is in order as it seems oversize and heavy for that size transformer. Says 150V cont / 175W int.

Interesting old HF marine radios - AM mode too, 3 of them. Two Pearce-Simpson Bimini 550's and a 40. All have solid state modulator and B+ inverter, and ss receivers. The TX is all tube from oscillator to class C stage 12JB6. Just thinking about a low power AM set. They are channelized with crystals but that shouldn't be too hard to deal with using a DDS VFO for favorite frequencies. No idea what range the radios can cover so need to look up the old HF marine frequencies. These also have an AM BC receiver built in. The ANT TUNE switch goes to a loading coil between the pi network and the external antenna connector. A lamp on the front panel seems to indicate antenna current.

Two Ray Jeffeerson marine HF radios also. One is the model 4150, the other  a 490 having fewer features.
The 4150 has no bottom cover so the pron is from it. There are supposed to be three 12JB6 in there, but they have just one. There is a built in antenna loading coil with a tap for each channel position. This ones are also high level modulation.

it would be nice to find schematics for these too. Either way this stuff can be put to use or would be a decent source of parts.

Most of those radios cover 2 to 3 MHZ. The higher power sets like your Ray Jeff sometimes had the "High Seas" channels on 4 or even 8 MHZ. Always in the last two or so channels. They are designed to match low Z antennas, around 12 ohms or so. You can ditch the loading coil. Two issues with all of them: poor harmonic suppresion and no neutralization. They all use a Pierce oscillator with no uned circuit. To use a DDS vfo you will have to reconfigure the oscillator into a buffer amp and neutralize the PA. In the end it's usually not worth it. The receiver can be made tunable by taking turns off the BC band oscillator and antenna coils. I spent my first ten years in radio working in the marine electronics field servicing these, before they were banned by the FCC. Over the years I have put many on 75 AM and used them mobile.

That's some very interesting history on them and explains why there is little info on some of the frequencies they are crystalled for.

There is another Ray Jeff, a lower model the 490 but the same size, which was converted to have 3880, 3885, and 3890 KC including RX and TX crystals. That particular set however has a few burned up components, and only one RF output tube socket, smaller power supply, etc.

These are all 12-volt DC plate modulated AM sets with the HV supply and the modulation transformers both driven by push pull power transistors, so there is something for parts including the nice sections of coil, but otherwise somewhat of a pile of junque. I don't think I'll do any conversions for ham, no time, too many projects already waiting.