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40 amp power supply ???

Save yourself the trouble. Dig around on Greed-Bay, or at ham radio swap meets, for a Motorola R-1011 series (either A or B) high- current supply. 0-40V, 0-40A, fully adjustable including voltage and current limiting.

This supply was designed, from the ground up, to provide clean DC power specifically to run radios. The output terminals are filtered, bypass-capped, and shielded. The unit itself is a strange linear/switcher hybrid design that has to be seen in schematics to be believed.

Happy hunting.

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Reply to
Dr. Anton T. Squeegee
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While I don't doubt that chargers such as you describe exist, I don't think it's accurate in the general/typical case. I've only opened up a few dozen, but I've NEVER seen a battery charger with a filter cap inside. Maybe they exist; I just ain't never seen one. Your suggestion is very BAD advice for a newbie. He's gonna be really pissed when his radio goes dark. But that's just my opinion. mike

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Reply to
mike

Hi , I need to build a 40 amp power supply that has an input voltage of 120 volts and an output voltage of 12 volts - 13.5 volts . The power supply will be used for amateur radio so it needs to be quiet . The transformer I want to use will come out of a battery charger . I need to regualte the voltage to DC at the voltages I have specified . I don't want to use a battery charger and a battery for a power source . If anyone has a good design and is willing to send me schematics on it , please send it to me . Be sure to remove no in front of ( nemonet.com.) Thanks , Rick

Reply to
rijo1

The transformers in chargers are usually unsuitable for this purpose. They have a lot of interiour resistance and will also not give the advertized current. Sorry

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ciao Ban
Bordighera, Italy
Reply to
Ban

The transformer is part of the schematic. If someone sent you a schematic with a particular transformer in it, how could you be sure you'd find that in an old battery charger?

Or do you already have the transformer? If so, it would help a lot if you could measure the open circuit RMS voltage on the secondary, and then also the loaded voltage with some load to approximate your worst case scenario. Maybe 0.25 Ohms or so. Note that the power dissipation at "12" Volts is

144/0.24 = 576 Watts. So use a big resistor. Or maybe a bunch of light bulbs in parallel.

--Mac

Reply to
Mac

Rick,

Save yourself a lot of trouble and buy a power supply meant for ham radio use. Astron makes a linear supply that is in your current range. It is quiet, because there is no fan. Ripple is very low. I have their 70 amp supply, and it is built like a tank.

I had thought to build my own, but the transformer from Newark cost almost as much as the whole Astron. See HRO, AES, or TexasTowers for prices. Note that at 40 A, you can easily spend $50 just for the heat sinks.

Tam/WB2TT

Reply to
Tam/WB2TT

Reply to
rijo1

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