19 set AC power supply

[Bob Carriere]

.... now I can waste more time when at work....... with more to read !!!!


Maybe a dumb question but instead of converting the power supply is it not simpler to just use a large size 110 volts AC to 12 volt DC power supply..? and keep the radio original..!!!

In fact a few military surplus power supply models were floating around not to long ago..?
....and one floated to the barn.

I understand that most battery chargers do not provide a pure enough 12 volt DC output but surely that could be improved with a add-on circuit of large condenser to fill the square wave gap output of the chargers.... !!!!

Love those diagram from Roberta.....thanks.

Bob

[Mike K]

Originally Posted by Bob Carriere

.... now I can waste more time when at work....... with more to read !!!!


Maybe a dumb question but instead of converting the power supply is it not simpler to just use a large size 110 volts AC to 12 volt DC power supply..? and keep the radio original..!!!


Bob

Yes you can do that but the genemotors are rather power hungry . You would need a hefty 12V power supply capable of dissipating the heat involved . For a Mk 2 set , over 10 Amps continous . The genemotors are actually pretty good for HT voltage stability , the mechanial forces of the armature spinning around provide a good voltage regulation , eg they don't want to change speed quickly.

Some people just use a heavy truck battery in the radio shack.. And keep it well charged . The only thing is , the loud whining of the genemotor is a pain .

The other way, building a AC supply will give you a nice regulated high voltage for the transmit side if you use a reguator tube in it , if you don't , the HT voltage will change with load eg keying of the transmitter. If you are only receiving, then its not so critical. You an build them cheap from salvaged parts ..hamfests are a good soure of bits for projects . Old TV's provide chokes and bits too .

Sometimes, the output pass transistors of mains 12V supplies can be blown up by high voltage spikes eg from a vibrator HT supply running from it.

It depends on what you are planning on doing with the sets. MIKE

[Bob Phillips]

Many thanks for the schematics Roberta. My purpose is to build an AC supply to run the receiver - which has relatively low power consumption requirements. Lots of ham radio operators did this in the "old days " and I would like to set a radio up as a receiver only in the basement.

[universalgrl]

The 19 set needs 12 volts to heat the filiments in the valves.
250 volts to operate the receiver and 550 volts to transmit. If you bulit a mains pwr supply in the case have a frame built up that can slide in the box. I would modify the schematic to inculde an indicator light (12v) and maybe a fan for cooling.
The MK II needs 10 amps constantely regardless of receiving or transmitting, the MK III runs at a much lower amperage till you key the mike.

[universalgrl]

Don't forget the output pass transistors in your pwr supply will blow protecting the .25 cent fuse.

thats a joke for all you non avionics types.