Oak Hills Reasearch WM2
There are a couple of pieces of equipment that I would not be without. One is the MFJ 259B Antenna analyzer and the other is the Oak Hills Research WM2 QRP WattMeter. Ham radio would be less fun without these two. After I built the Elecraft K1 it quickly became clear that the watt meters that I was using were woefully inaccurate below about 20 watts. When I saw mention of the WM2 on the Elecraft e-mail reflector, it looked like it would be worth checking into. Very glad that I did! This little kit is well executed and a joy to use when completed.
Oak Hills Reasearch WM2
The front panel is attractive, uncluttered and easy to read even under less than ideal lighting conditions. There are three power ranges and the forward/reflected switch. The meter face is done in a very high contrast black and white, much better than a couple of the meters, here in the shack, which tried to get fancy with multicolor schemes which simply do not remain easy to read in low light.
Oak Hills Reasearch WM2
The only control on the rear panel is the internal/external power selector. The kit comes with SO-239's but OHR sells a conversion kit for changing over to the, QRP standard, BNC connectors. Everything in my shack uses SO-239s except the K1 so I chose to stay with the default.
Oak Hills Reasearch WM2
As you can see, there isn't a great deal to a simple meter like this and this one would be a very good choice for a first time kit builder. The circuit board does not have though plated holes like the Elecraft boards, however, it is entirely adequate for this task and the silk screening is easy to read. Calibration of the meter requires only a DVM and is an easy procedure to follow.

A very important factor in the choice of any piece of equipment that I buy is customer support. I had a small problem after the meter that I built had been in service for awhile and a call to OHR service had a new integrated circuit in the mail the same day, nice people to talk with and very helpful. A big plus in my book!

If you would like to have accurate power level readings for your QRP rigs, this OHR WM2 gets my hearty recommendation.
Oak Hills Reasearch WM2
The early manual that I have contained a small error which I noted below. I am told that OHR quickly fixed the problem and all current manuals contain the correct formula. The note below would only be relevent if you have an older manual, like mine.
Oak Hills Reasearch WM2
As a minor aside, there was an error in the manual that users should be aware of. The formula for calculating SWR is not correct:
SWR formula