[Milsurplus] 800cps inverter on Craigslist in Portland

[Bruce Gentry]

Consider using an automotive alternator and step up transformer. Most of 
these are at least 8 pole, some are 10 or 12. An 8 pole would have to be 
spun at 12,600 RPM, not at all excessive with engines that turn 4000 rpm 
and belt ratios of 3 or more to one. A 12 pole would  be 8400, even more 
reasonable.  A used 3 hp. 3500 RPM motor from an air compressor with 
appropriate belting would spin it at the required speed.  If you used a 
100 amp 24 volt alternator with the regulator intact, it would produce 
24 or 28 volts DC as well as 20 volts AC at the rectifier inputs that 
could then be stepped up. It would also be more compact than a big 24 
volt power supply and original MG set, and probably a lot quieter as 
well. As an SK who was on this group used to say- "Real radio have Motors"

       Bruce Gentry, KA2IVY



On 11/16/17 2:05 AM, Robert Goff wrote:
> Just noticed this today:
>
> https://portland.craigslist.org/mlt/clt/d/wwii-us-signal-corps-inverter/6383884175.html
>
> Output is 80V, so would still require a transformer for use with GP,
> GO and TBW type gear.
>
> I'm curious what others have done to overcome the 800 cps problem.
> I've looked into motor VFD's, but all the ones I've seen top out at
> 400 or so.  Any brighter ideas?
>
> 73,
> de Robert W7MKA
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