Further travails with the Phase Angle Voltmeter: The synchro problem

[COWBOYME]

Okay, frustration is setting in. It seems like every time I go near the PAV meter, the dramatic music cues up. After my last brush with this equipment, I determined to figure out how it works and what it actually can measure. I scrounged up an old manual for our dreadfully obsolete unit (NAI 213C) and set about learning. However, I keep getting bloody noses almost every time I scrap with it.

Here’s my present problem: we are testing synchro output from a servo. Our Technical Order calls for us to set up the null position and then rotate the servo 10 degrees in each direction. The PAV meter should read 2.0 V with a .1V tolerance. The needle should indicate the proper deflection (CW/CCW). The deflection is good but we are only getting ~1V. If I switch over to the TOTAL function the meter acts as a common voltmeter and the correct voltage does register (W/O deflection). This is corroborated by a DMM set up on the output jacks. I feel like this problem has more to do with the learning curve than the equipment but can’t really be sure. We have tried two separate PAV meters with similar results. What could be the possible causes of getting a reading in PAV mode that is half of the voltage measured by the voltmeter?

 

[VEBill]

Loading (input Z)?

 

[COWBOYME]

VE1BLL,

I'm not sure exactly what the impedence is. We are tapped into leads coming from a test stand, not directly from the synchro. I might be out of my league on this one.