On Apr 18, 9:29*pm, msg wrote:
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

Do you have access to a scope that has a decent response at 72 MHz?
That and an accurate dummy load should be enough.