[Boatanchors] 3-phase for BA transmitters?

[Jim Wiley]

Rotary phase converters are commonly used to change single phase to 
three phase power.  All suppliers of machine tools have them in their 
catalogs.  A 10 HP unit should run anything up to a 5-KW transmitter.  
Larger units are available.  Some suppliers are Enco, Grizzly, MSC 
Supply, McMaster-Carr.  Google for more info. Do not use a "static 
inverter" type, they will not work well with transmitter type loads.  
Get a true rotary converter.  Note: It is entirely possible to build you 
own rotary converter from a large 3-phase motor.  Plans are on the 
Internet.  Again, Google for info.


- Jim, KL7CC


On 11/18/2012 12:35 PM, Nick England wrote:
> Has anyone actually tried a Variable Frequency Drive as a way of
> obtaining 3-phase for vintage high power transmitters?
> VFD's are solid state devices that are normally used as motor
> controllers, and they are available as 220v 1-phase to 3-phase
> converters.
> BUT (big BUT) all the ones I have seen say DO NOT switch the load
> (which is exactly what you need to do in a transmitter).
> I'm also wary about xfmr heating from harmonics from these switching gadgets.
>
> Any direct experience with transmitter applications - or a pointer to
> some gadget I've missed that woud be happy in the application - is
> greatly appreciated.
>
> So far the only solution I have seen is a rotary converter
> (motor-generator) for 1-phase to 3-phase conversion.
> cheers,
> Nick K4NYW
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