DIYbanter - View Single Post - Inexpensive fairly good quality home brew or kit RF power meter

msg

wrote:
I have a need for a power meter for general low band and VHF work. I
would like it to have at least two scales. One, a 0 - 10 W or so
scale and if possible another which would enable it to measure up to
around 125 W as well. The immediate need to satisfy the requirements
of a job we're doing is for an instrument that can measure 1.0 W at
72.0 MHZ. The signal is AM with a duration of .50 sec. and there is
some type of digital alarm transmission which modulates the carrier.
The only way I think that I can do this now is to measure the RMS
voltage accross a 52 ohm dummy load with my Boonton, and then
calculate the power. I feel though that this is clumsy and may be
potentially inaccurate. I'd love to have a Bird with all the bells and
whistles but I really can't afford one. Does anyone know of a home
brew project for doing this or even an inexpensive accurate kit?
Thanks, Lenny.

Some thoughts:

1. find a bolometer head that covers your frequency of interest on
eBay and build the rest of the meter (or perhaps buy the whole
thing if cheap enough).

2. look for old military RF power test sets that included a mess of
attenuators, directional couplers and a bolometer head together
with the meter in a steel case (used to be very cheap and readily
available but perhaps times have changed).

3. build something out of the ARRL handbook.

Michael