Tag: homebrew

Oak Hills Research QRP RF Power Meter (WM-2 QRP)

The Oak Hills research produce a very nice QRP power meter kit, the RF power meter WM-2 QRP is produced with a high quality case and silkscreened and masked PCB and a large moving coil meter.

Meter Highlights

Operates from 300 KHz to 54 MHz

Measured power range from 100 mW to 10W FSD with an accuracy of 5%

I built one a few years ago, and found it very helpful when measuring QRP power from the FT817 and Ultimate 3 QRP kits.

The kit comes with everything you need, instructions are provided in the pack and takes a few hrs to build. The kits are available online and currently cost $129.95 and can be provided with BNC or SO239 sockets.

You can calibrate the meter without the need for any special test equipment.

Ive included some pictures of the completed meter, and think you will agree it looks very professional. Power is provided by a 9v battery or external supply.

Oakhills QRP meter

Oakhills QRP meter

14 MHz 2e Homebrew Quad

Homebrew 2e Quad for 14 MHz

The project was to build and test a 2e Quad antenna for 14 MHz, I wanted it to be lightweight and portable. The antenna had to be packed away in the car after a contest, so some parts of the antenna had to conform. The boom could be no longer than 3.5m, and the spreaders must be retracted for storage.

Cost should be under £100 for all the parts delivered.

The design uses fiberglass fishing poles, each pole is 4m fully extended. The project uses 8 poles. The poles will be fixed to the centre clamp using exhaust brackets, as they come complete with “U” support bracket. The size of the exhaust clamps will depend on the size of the roach poles.

The aerial will be 8m long, and 5m wide (see diagram) and the feed point will be at the bottom of the driven element. You may require some matching at the feedpoint, although mine was close to 50 Ohms.

You can find many online quad calculators, one that worked well for me is located here.

Here you will see the basic quad element, the basic construction is the same for both the driven and reflector. Here you will see the basic layout.

quad

 

 

Photograph of parts required. (Click to expand pictures)

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Having fun with the Quad and linear amplifier. QRO HF portable

© 2015 Dave, M0TAZ