looking for swr/power meter kit

[KJ4LTC]

Anyone know of a good kit thats not for qrp use only??

[VK2TIL]

You could easily modify many QRP kits by only changing the coupler.

Suppose the kit uses 10 turns on a toroid. That gives a 20dB coupler since the coupling ratio is proportional to the square of the turns ratio.

10 squared = 100; 100 times is 20dB.

So, say, 10 watts on the through line produces 100 milliwatts to the detection circuitry.

Suppose we now wind 32 turns on the toroid. 32 squared = 1000; 1000 times is 30dB.

Now 100 watts on the through line produces 100 milliwatts to the same detection circuitry.

It only remains to add a zero or two as appropriate to the analog meter scale; this could even be done "mentally" by remembering to multiply all power readings by ten.

SWR is a ratio so no change to the SWR scale would be required.

If the original coupler has more or less than ten turns, use the above simple maths to calculate a new coupler; for instance, an original 12-turn coupler will require 38 turns for a x10 change.

A x10 change is not mandatory; it can be anything but x10 gives simple meter re-scaling.

And, if the extra turns won't fit on the core used originally (the NorCal kit uses a "pig-nose" core for its "Stockton" (Sontheimer & Fredrick actually) coupler and 32 turns might not fit) just use a larger core or, in the case of the NorCal coupler, two small toroids or beads of the same material.

[KS2G]

Kind of pricey ($159) but Ten-Tec has one:
http://www.tentec.com/index.php?id=330

But, for that price, I'd recommend the factory-built Autek WM-1:
http://www.autekresearch.com/wm1.htm

73,
Mel - KS2G

[G3TXQ]

I can highly recommend the LP100 kit:
http://www.telepostinc.com/lp100.html

There's no need to play with turns ratios - the standard coupler covers 50mW to 3kW.

There's also an excellent Yahoo support group:
http://groups.yahoo.com/group/lp-100/

But not cheap

Steve G3TXQ

[KV6O]

Ditto on the LP100 - I use it for everything from my legal limit amp to measuring power out of the K3 xtransverter port (in direct mode w/o the coupler).

Steve
KV6O

[G3TXQ]

One of the nice things about the LP100 is its ability to operate as a digital field strength meter. It interfaces easily to other software to automatically produce polar plots such as this:



Incidentally, the "skew" in the rearward pattern was caused by a common-mode issue I was investigating.

Steve G3TXQ