[NLRS] 24 VDC power for a Rover

[Steven H Sawyers (na0ia)]

At Aurora, KM0T described using a small switcher to do 12 VDC to 12 VDC 
boost and placing this in series with the auto battery. I think it was 
originally a 5 VDC to 5 VDC part. The switcher must have an isolated ground 
so it is will allow the boost configuration. This may be what you were 
thinking of. Perhaps he can email you the presentation.

If you are just running a relay box, you can probably use a second battery 
above the standard auto battery and just run on battery. Or have two and 
charge one while the other runs down. The one on charge is actually in 
parallel with the auto battery so it cuts the voltage drop to the radios. 
That is what I did on the Red Rover a year ago. This give you the option of 
having some 24-28 volt amplifiers.

As mentioned in the other posts, you can also buy some small switchers new 
that will do 12 to 24. But some of the chips get a little expensive by the 
time you get the inductors and do the filtering.

A number of other options:

I was searching ebay several months ago for DC DC converters and bought 
some 12-24 volt ones for about 10 bucks each. They do about 7 amps. They 
need a heat sink but I think I can handle that.

This spring, I got all excited about DEM announcing new 48 V amps, so I 
found a 24 to 48 volt parallel switcher rack that puts out 35 amps on Ebay. 
These are switchers, but specs were real good and the manufacturer put big 
toroids and some filter caps on the input and output of the rack.

Then I needed a large source of 24 VDC, I went to our local auto electric 
repair and had them build me up a 24 Volt alternator. They got a kick out 
of it because it was out of the ordinary. This is in one of the old GM self 
contained alternator bodies from the late 70s. It takes a new rotor and 
regulator and cost me about $145. You just get a belt to turn it and run 
the ground and output to a stack of batteries for the 24 volts and you are 
done. I have figured out how to put a second sheave on an engine idler 
pulley, but have not taken the time to do the install under the hood. This 
will give a steady 800 watts 24 volt power. The battery will handle the 
peaks. I thought about stacking 2 for 48 volts, but the alternators have an 
internal ground so cannot stack them electrically. Plan is to drop the belt 
and pull the batteries when I am not running as a rover.

This is all waiting till DEM releases the Amps and I can afford them.

Interestingly enough this will also work the 400 watt aircraft HF amp and 
tuner that I have on the shelf for when I have time.

Watch out for the HP / California Microwave amps - they want NEGATIVE 24 
volts. Again on Ebay, I got some isolated 24 to 24 modules and will build 
up a  couple of them in parallel for the 5.7 GHz Amp. So I can take my plus 
24 DC to minus 24 DC.

There are a lot of other possible combinations. But this should give you 
few options/ideas.

BTW I missed Central States - combination of work and father-in-law in the 
hospital. Did DEM have any info on the new amps?

Steve