Hey hi all I have a very nice RCA model 7311 record player. This is the type with no mini amp so it has to be pluged into the back of a radio. I was wondering what year it was made so I could pick up a period radio (with jack) to use it with or is there a cheap littel amp (with speaker)I could pug this into to play my 33 rpm records...

If the cartridge is still good, you can use any radio from your collection as an amplifier for the phonograph. It will be easiest with a radio that contains an appropriate jack. Many RCA radios had phono jacks on the rear. However, you can connect to most-any radio with a conventional type amplifier by connecting the center pin of your phono cable to the IF or 'high' side of the volume control, and the outer contact of your phono cable to the B- or 'low' side of the volume control (the two outer terminals). If the radio is an AC/DC radio, it would be best to connect through two .02-.05 MFD capacitors to isolate the radio from the phonograph. Shocks will still be possible (and are possible with any radio, actually), but will be less severe. It is best not to touch any metal parts on the phonograph while standing on or touching a conductive grounded surface (such as a concrete floor, any wet floor, metal, metal pipes, radiators, sinks, stoves, etc.).

If you are using one of the early radios where the volume control is in the RF circuit, you will have to wire either into the detector tube, or, if the amplifier has two fully dedicated stages, into the 1st amplifier tube. An external volume control will have to be provided.

Also, another method, if there is room within the phonograph, would be to install a small transmitter that would allow you to receive the music on your phonograph from any radio (but with lower quality compressed audio). Many phonograph motors draw an appropriate current to light a 6SA7. Some draw less, and would better light a 12SA7. Start with a 6SA7 and then try a 12SA7 in series if the 6SA7 won't light, or simply power a 6SA7 from a small filament transformer (you can also use the miniature version of these tubes, 6BE6 or 12BE6). Build a small oscillator circuit that will tune over a good portion of the broadcast band. You can use any good AA5 oscillator design that uses one of the above tubes (and not an external oscillator tube). Feed the audio of your phonograph into G3. Also build a power supply for the transmitter using a solid state rectifier, two 47MFD 200 WVDC electrolytics, and a 22K resistor. If you do not use an isolation transformer, be sure to isolate the tone arm return with a .05 MFD Y type safety capacitor, and use a polarized AC plug with the wide prong on the B- side of the circuit, if you are concerned about shocks.

T.

T.

Also, if you want an easy, cheap isolation transformer, you can purchase two of the smallest 12V transformers from Radio Shack and wire their secondaries together. The first one can also power a 12BE6 or 12SA7, and the second will supply your isolated 120VAC. Also, www.tubesandmore.com sells a complete transmitter kit that comes with an isolation transformer, and can be wired smaller to fit inside of your phonograph.

:Also, if you want an easy, cheap isolation transformer, you can purchase two of the smallest 12V transformers from Radio Shack and wire their secondaries together. The first one can also power a 12BE6 or 12SA7, and the second will supply your isolated 120VAC. Also, www.tubesandmore.com sells a complete transmitter kit that comes with an isolation transformer, and can be wired smaller to fit inside of your phonograph.
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