[Test-Equipment] Using an HP 331A Distortion Meter

[Dale H. Cook]

At 10:57 AM 9/4/2014, Barry wrote:

>Does anyone have experience cleaning/replacing the balance pots?  Mine are very touchy.  They appear to be the sealed type and I realize I can most likely pop the back off the piggy-backed one, but not sure about the "front" one and I'm wondering if I'm opening a can-of-worms with this.

 From the parts list this dual control was made by Beckman. Open the 331A up and see what it looks like physically. Odds are good that you can find a suitable replacement. Other manufacturers made dual controls as well - I have some Allen-Bradley Type J examples of dual controls that were used in other instruments but are the wrong values for the 33nA series.

In the 332A and 334A noisy balance pots are not as much of a nuisance because with those DAs you just want to get the balance relatively close in manual mode, then switch to automatic mode and let the instrument finish the nulling.

Dale H. Cook, GR / HP Collector, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcity/radios/index.html