[Milsurplus] 60/400 cycle indicator use?

[Ben Dover]

At 04:25 PM 4/8/2006 -0500, you wrote:
>de N4TGC Eric
>
>I have a couple of little "JBT" brand model 15-FHAC 'meters' that have 
>vibrating reeds for 60 & 400 cycle current.  Are these direct-reading off 
>the line, or is there a current/voltage-limiting network needed?  TIA    e 
>
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Howdy, Eric.

I have one of those that I obtained to use in a control panel for my mil
surplus gasoline generator (if you're under about 5 KW, Uncle Sam didn't
much believe in controls or instrumentation...   painfully so!).

I just hung the meter from one phase to the neutral wire (110 VAC) without
any sort of current limiting. If you check the meter with an ohmmeter, you'll
find the internal resistance is high enough to limit current flow without
any external help needed.

All that's in these things is an iron core coil, and one end of the core is
coupled to metal reeds that are mechanically resonant at 60 and 400 Hz.

BTW... hook it up the way you would a VOLTMETER, and NOT like an ammeter.


Mr. T., W9LBB