Watt meter calibration

[W4ZDI]

I have a nice Swan WM-3000 watt meter that I'd like to have calibrated.

Can anyone recommend a service center or repairman they trust?

Thanks,

Pierce
W4ZDI

[WB2WIK]

I was hoping someone local to you would reply, but didn't see that yet.

If nobody does, I'd be happy to cal it for you. Just include return postage (whatever it cost you to ship it, it will cost the same to return it) and allow a few days.

Of course, the cal assumes there's nothing wrong with the bridge. I assume you've been using it and it works okay, but you just want to confirm calibration?

(If you haven't been using it, use it first.)

[W4ZDI]

I was hoping someone local to you would reply, but didn't see that yet.

If nobody does, I'd be happy to cal it for you. Just include return postage (whatever it cost you to ship it, it will cost the same to return it) and allow a few days.

Of course, the cal assumes there's nothing wrong with the bridge. I assume you've been using it and it works okay, but you just want to confirm calibration?

(If you haven't been using it, use it first.)

Thanks for the generous offer. I was told last night of a local ham who can take care of this for me. I will call him first thing Monday.

Pierce W4ZDI

[WB2WIK]

Thanks for the generous offer. I was told last night of a local ham who can take care of this for me. I will call him first thing Monday.

Pierce W4ZDI

I'm glad you found a local. Much easier, and no risk of shipping damage.

Go watch what he does, it should be interesting.

[WA7KKP]

Calibrate it yourself -- it is very easy to do . . .

First method is to use an RF ammeter (2 or 3A full scale, depending on the power you have) and put it in series with your dummy load. Use a Cantenna or equivalent (no light bulbs here). With a properly tuned transmitter, key up and determine power by Ohm's law P = I^2 x 50.

Second method is using a good grade calibrated oscilloscope, and measuring the voltage across the dummy load. Again use Ohm's law P = E^2 / 50 to determine power.

Adjust your meter to match.

You'll find out that these meters can vary widely in reading, depending on how good the match is to the antenna. I would believe it only with a very large salt block nearby.

Gary WA7KKP