[ARC5] A pair of questions

[Michael Hanz]

I think Craig was simply listing two of the 400Hz rotary inverters that 
could be used for the SCR-269.  The ones used in 28v aircraft were 
MG-149(*) units and supply 500w at 115vac and 250w at 24vac for compass 
and navigation purposes, as well as countermeasures equipment.  There 
were normally two of them to provide redundancy (see photo below of two 
in a B-29).  They are roughly the same physical size as the ones for the 
ART-13.  The overhaul specification for the MG-149H says that the no 
load input current at 28vdc input should not exceed 12 amperes, but the 
ones I have run a bit less than that without a load.  They do supply 
more loads in a typical aircraft installation than the smallish 115VAC 
400Hz power required by an SCR-269 (or ARN-7), though.

  - Mike  KC4TOS



On 11/14/2017 8:27 AM, David Stinson wrote:
>
> Is the SCR-269really that power-hungry?  It’s a radio compass.
>
> I’ve never worked on one, but 20 Amps run for a receiver dyno?
>
> I don’t think I’ve found a receiver dynamotor, save those for
>
> the RBM, that required anything near that.
>
> Is it possible something else is going-on here?
>
> Maybe I missed something in the thread?
>

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