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Powering downconverters




I am trying to devise a better way to power 2.4 Ghz downconverters for
AO40 reception during battery-powered portable operation.  110V AC to
run the wall-warts is not available.

I need to power either a Drake 2880 or Transystems 3731.  Both use 
bias-t's to inject DC power into the feedline.  My DEM preamp is quite 
happy with a 12V supply.

Here are the choices I've come up with:

- Small dc-ac inverter to power wall-wart.  Works (used this for Field 
Day), but it is inefficient  and kills the battery too quickly.

- power off the 12-14V DC runing the rigs.  *may* work (I haven't tried it 
yet), simplest.  Reading the docs on the Drake 2880 and Transystems 3731 
converters, they seem to be happier at 18V.  I assume folks using 
preamp-power supplies built into their radios are doing this.

- Batteries - I'd have to build a large pack of AA's or NiMHs; I don't 
think 2 9V cells in parallel would handle the 180 mA draw.

- DC-DC converter (nominal 12V in 18V out).  Anyone have a schematic?

73 & Thanks in advance,

Steve
KS1G

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Stephan A. Greene     sgreene@patriot.net        ks1g@amsat.org
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