On Wed, 07 Sep 2011 09:19:56 -0700, Jeff Liebermann
wrote:

Well, do the math. The front end of the service monitor is 50 ohms.
The fuse is probably 0.1A.

I don't suppose the reference to a "picofuse" is literal to amperage
(pA), but the introduction of a 0.1A fuse is equally a supposition (I
suppose, because from my experience with precision power measurement
equipment, they often used a commercially available, specialty fuse
rated at 10mA - a Wollaston wire).

Power to blow the fuse is:
P = I^2 * R = 0.1^2 * 50 = 0.5 watts = +27dBm
P = I^2 * R = 0.01^2 * 50 = 0.005 watts
I'll guess a 10dBi yagi and a 3 watt (+35dBm) HT into a 0dBi rubber
ducky.

[Q]: How close to the antenna can you use the HT before you blow the
fuse?

Getting too close (less than 5 to 10 wavelengths, and for "gain"
antennas, 20 wavelengths or more) negates directivity.

Go thee unto:
http://www.terabeam.com/support/calculations/som.php
....
I get: 0.0003 miles = 1.6 ft

Which is extremely suspect.

Drivel: Yes, I know we're close to the near field and the numbers
aren't very accurate.

Which makes the exercise rather pointless.

73's
Richard Clark, KB7QHC