Please use the comment section below to reply.  How many of my readers used a dynamotor to power the finals of their mobile transmitters?  Let me broaden that question; how many have even heard of a dynamotor?

Back in the days of vacuum tubes the finals of most mobile transmitters required 600 to 900 volts.  A 6146 final usually ran at 800 volts.  Most vibrator power supplies did not supply sufficient voltage or current to run the final so a separate power supply was used to provide the voltage and current necessary to run the finals.  The most common type of supply was the dynamotor.

The dynamotor is also known as a motor-generator.  They have many uses including the changing of AC to DC, DC to AC, power isolator, positive ground to negative ground, lower voltage to higher voltage, and higher voltage to a lower voltage.  The dynamotor is nothing more then an electric motor connected to an electric generator.  In the case of the ones we used they were a 12 volt (some times 6 volt) DC motor connected to a high voltage (800 volts + or -) DC generator.

To provide the high voltage for the final when the PTT button was pushed a relay was used on the dynamotor input.  The relay transferred the battery power to the dynamotor input.  The dynamotor output was wired directly to the power plug for the transmitter’s high voltage input.

In some ways I miss pushing the PTT button and hearing the clack of the relay and the whir of the dynamotor wait for about a second for it to stabilize and then start talking.


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