handheld voltmeter

Yes, a Radio Shack multimeter should do fine, but if you want something better you might consider Triplett, which has been around forever and makes both analog and digital meters which are widely used by electricians, electronic technicians, and engineers:

http://www.triplett.com/

Also, Simpson was for many decades the leading name in high quality multimeters, although I have no knowledge of their recent products or ownership:

http://www.simpsonelectric.com/

Regards,
-- Al

I've used Fluke for many years without problems. Not the least expensive but very good.

It's easy to find a used Fluke digital multimeter on eBay, and they will last quite a while(accurate/tough/dependable). I've had mine for almost thirty years. Some reviews from users: (http://www.eham.net/reviews/detail/4518) Of course, there are less expensive models too.

The amps I've had that needed biasing required a meter to measure mili-volts, not watts or amps.
Might want to check the manual.

An old analog Simpson with the mirrored scale would be great and bring back memories, but overkill for this application, IMO. I'm gonna go check the auction sites...

Go digital rather than analog if you have old eyes and an unsteady hand like me.