Building The OHR WM-2 QRP Wattmeter Kit.

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[nrrful]

great, another interesting video and project. Thank You...i also agree that it is the seller or manufactures responsibility to make sure all the parts are included.

[stanaeut]

Ok.... that is another kit I want
Thanks for showing your build. Love your channel.

[ElektroLUDIKITS]

To scrap insulation I use a piece of sandpaper that I bend around the wire. It is a little bit longer but a little less risky too. :D

[paulgrodkowski]

Very nice quick easy to understand Video ! Thank you for posting !

[gokt]

Great bit of kit, I built mine some years ago and found that you had to be careful when picking it up, not to squeeze the front and rear panels together. I reinforced it by adding two aluminium tubes with self tapping screws along the top, from front to rear. Because I use it for my K1 and K2, I paid extra, for the BNC kit, I also added an led to indicate power ON, I was forever forgetting to switch it off ! Great vid as usual, always watch your stuff Gil, 73 GW4OKT

[hectorpascal]

It's a drop in 25.4 mm square flange BNC female, exactly replacing the SO239. The supplier often advertises on eBay, so check ebay.com or ebay.fr listings.

[hectorpascal]

Nowadays much "enamelled" wire uses a self-fluxing polyurethane coat. A soldering iron temperature of 400°C+ is needed to burn it off. It's always worth testing unknown wire before scraping. But don't breathe in the fumes. EVERYBODY soldering should have a portable fume extraction fan to avoid breathing in lead, burned rosin flux etc.

[stevejones]

Nice build Gil you are getting better all the time. Cannot understand why we still use so239, s BNC, s are a lot easier to use especially if you have a good ratchet crimping tool. I think they are much neater and give a better connection.
Keep up the good work mate.

[warplanner]

Bonjour, Gil! Late to the dance here but wanted to make two points:

Firstly, the multi turn pot for R6 is to accommodate the adjustment of the voltages (2.56, 0.800, 0.25) for the three ranges. The older WM-2s had a single-turn R6 similar to the other pots in the circuit.

Secondly, while the WM-2 is a terrific power meter for QRP levels, I found mine to be in variance with my **calibrated** scope and possessing confidence in my scope's calibration, I used that to "re-calibrate" the WM-2. (See link below.)


I used an FT-817 at 30 meters (10, 100 Kc; middle of 2-30 Mc) as a power source with the 5.0, 2.5, and 1.0 watt levels for the 10-watt range and the 1.0 and 0.5 watt levels for the 1-watt range. For the 100 mW range, I used an attenuator on the 0.5 watt level (-7 dB = 0.099 watts; -10 dB = 0.05 watts).

The calculation is simple (from the link above and simple algebra: P = Vpp^2/400 for a 50-ohm system.

Cautionary note: All this is out the window if folks are not as compulsive as I am; I burn up more rolls of solder than logbooks and repair and restore test equipment and my wife considers me certifiable.

[ronleblanc]

Beautiful build .use to build heath kits long time ago.ordered one of those qrp tuners but noware does it tell you no instructions...not impressed found some info on line bad pictures..i built it but i think i have to many windings on toroid coils like your vedios very mich ve1 bhm

[Digiu]

Nice video Gil ! I really want one like these for quite some time.
May I ask where in Europe did you buy the kit ? Or is there some french supplier ?
Mni 73 ! Patrick, ON4CDJ

[FNP]

What melted the band and menu buttons on your K1?

[Michael-ndgh]

I loved my ZM-2 and I love my WM-2, but they're not from the same company :)

[salvadorsolavidal]

MUCHAS GRACIAS POR ESTE EXCELENTE VIDEO, HE USADO UNO I FUNCIONA CORRECTAMENTE

[dltarvin]

Thank you for this video. I am considering buying one of their qrp radio kits. Do you have any recommendations of what add-ons I should get with the kit?

[sonnytee]

Hi Gil, love your channel! I’m living here in France not to far from you ... can you tell me where I can take the Amateur Radio test in English? I speak French but would prefer to do the test in English, any help would be appreciated...

[dansloss]

Is a dedicated watt meter like this necessary? For example, with a QRP-guys 12W dummy load/power meter ($10) and a volt meter, you can calculate the power (volts squared divided by 100). It's tiny, too - and it uses a BNC connector. Thanks for your videos, Gil.

[DonDegidio]

Hi Gil,
As usual, another fine build video. Great no real problems with the build. Time to have fun. 73 WB3BJU

[MichaelLloyd]

I like OHR's kits. I have built a few of the WM-2's. I slightly modify them by adding sockets for the opamps (because if you plug the power connector in hot it can short and wipe out the opamps, more than once), pin header and jumper for the calibrate jumper, and in one kit I installed a pot with more turns and mounted in a hole on the back of the case for one of the pots to simplify calibration. OHR doesn't supply a PDF file for the instructions and schematic so I can't look up which pot I changed out. <edit> R6 is the pot I replaced