On Fri, 4 Feb 2005, Marc Nicholas wrote:

> That's what prompted the question -- there must be a relatively simple
> tunnel diode circuit that can be used. But there's no technical details or
> schematics on that site.

If you want go/no go you can use a microwave bipolar transistor 
polarised into class B as active detector. This works well. I used 
2SC2570 (ft=5GHz). The base was a lambda/4 wire stub (~6cm at your 
wavelength) and the collector was decoupled to get dc. The device will 
react to all 2.4GHz sources, such as microwaves, phones and video/audio 
links. There is also a 'microwave sensor' that uses a LM358 opamp (whose 
input stage apparently rectifies microwaves to some extent).

If you want to measure I would look at Analog's log-amps which can be 
had for as little as $7 in ones and accept rf input directly at your 
frequency, providing db-proportional output.

Imho, without using a band limiting circuit and a spectrum analyzer the 
output from your meter will not mean much (unless you are trying to 
optimize an antenna in 1:1 receive mode). There are a lot of sources at 
and around that frequency band.

good luck,
Peter


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist