[Collins] Help 75A4

[Dr. Gerald N. Johnson]

On Tue, 2009-02-03 at 14:20 -0500, Greg Mijal wrote:
> I think for this meter fix I would put a high impedance volt meter or O 
> scope across the terminals of the meter and see if there was voltage there 
> when the meter stops reading.
> 73's
> Greg
> WA7LYO
> Kinston NC

Be very careful with the oscilloscope. The meter circuit is not
necessarily grounded on either side. Its in a bridge circuit in s-meter
mode using an IF tube as a DC VTVM reading AVC voltage. And the full
scale drop to a typical 1 ma meter is 0.1 volt.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer