Is measuring the resistance across the two posts of a meter the correct way to test the meter? I disconnected one wire and measured the meter in my Drake R4B. My digital meter read "OL." I'm assuming this means there's an open in the coil. If so, is there a cure? Are these meter replacements for the R4B available? Where?

Thanks.

Unless you use an appropriate series resistance, it is possible to burn out sensitive meter coils with the small current that the ohmmeter puts out in the resistance-checking mode. So, no, checking meters with an ohmmeter is generally not recommended (especially sensitive voltmeters; current meters have a shunt across the meter terminals).

Don

My guess is that the meter quit working for some reason?
Did the meter work in any of it's functions?
Near the bottom of this page is a list of repair sources for the Drake meters;
http://www.wb4hfn.com/DRAKE/DrakeArticles/TechTips/DrakeTechExchange.pdf

Other than that, I'd look for a parts rig on eBay.
I would also check with any Drake Yahoo user groups. There are probably more than a few.
The ones most closely relating to your Drake and/or having the most members are the best bet.

Mike K7MH.

I bought the radio at a hamfest and checked it out on a variac at home. No meter movement on the receiver. Tried again at night. No meter movement. Don't know the history of the radio. So, you think it's the meter and a search for a replacement is the solution?

Did you substitute your DVM as the meter and see if you get any indications?
A DVM doesnt put out a dangerous voltage, just an analog VOM.

Carl

No I didn't try the DVM to take the place of the s meter, but will. By the way, my earlier tests were done with the DVM. Haven't used an analog meter is some time.

I do the test and let you know what I found out.

The correct way to test any meter is: (according to the old engineer who taught me)
First see if you can find what it's current range is supposed to be. (makes it easy).
From now on "meter" means "unknown panel meter".
Next put a fixed resistor in series with a 1.5 volt battery (higher voltages mean much more caution) - the resistor should limit the current to what the meter spec says is full scale.
If you don't know the spec start at 50 microamps. Then put a pot (1K or bigger) in series with the fixed resistor back to the other battery terminal.
Put your VOM in series with one post of the meter on a current range.
Put your DVM across the both meter terminals.
Turn the pot all the way down.
Hook the VOM and meter to the pot wiper and it's "all the way down" terminal.
SLOWLY Turn up the pot. Watch the meter to see if it moves the correct direction.
If the meter does not go to full scale, then disconnect the battery and decrease the value of the fixed resistor - Turn the pot back down.
Reconnect the battery.
Repeat until you get full scale on the meter.
Record the DVM millivolts & VOM current.
Remove the meter and record the current through the DVM only.
Subtract this from the total current recorded earlier.
You now have the current that is full scale on the meter and you know the internal resistance of the meter. (Ohm's law). with this knowledge and a handfull of resistors you can substitute the meter for any meter that has the same or greater current range.

Meters can be repaired.
If it was dropped, your local jeweler can put it back on the pivots.
If a wire broke off when someone over-torqued the post on the back, it can be re-soldered.
I would not open one with the radioactive sign on the back (glow-in-the-dark-face) but otherwise remember the weakest point fails first, and it may be easy to see.
You have something we never had - digital cameras !
Pat

What you should do is set the ohmmeter first to its highest range, like megohms, then connect it to the meter. If the meter doesn't deflect, switch down a range until it does. The digital ones apply a constant current and display the voltage. Most analog ones apply a constant voltage through a resistance and display the current on a weird log-like scale. You start at the high range first where the meter is only applying microamps at most.