Rex wrote:
On Fri, 10 Mar 2006 01:55:19 -0800, "Joel Kolstad"
wrote:

At work we have these "do-hickeys" that look like a regular "tee" connector.
However, it's meant to be used such that a signal passes through the "top"
of the tee while the "leg" of the tee "picks off" the signal some 10dB or so
down from the input. (The insertion loss is some fraction of a dB.) The
pick off seems to just be a wire tip coming out of the backside of the
connector (just capacitively coupled?); there's an adjustable sleeve that
lets you position this tip closer or further from the through line; moving
it closer creates better coupling, but also tends to decrease frequency
flatness. The cool thing is that all ports drive 50 ohms, and the
pick-off's output is surprisingly flat over more than an octave.

Any ideas? It's definitely not constructed the way I'd build a directional
coupler -- even though it performs a somewhat similar function --, nor a
"magic tee" (although I've only seem magic tees in the form of waveguides
and transformer-based affairs for HF).

Here's a link to one manufacturer
http://www.microlab.fxr.com/pdf/HX,HY,Hzseries.pdf

As on their page, I've always called them samplers.

The picture shows the probe end of an electromagnetic coupler with a
wire loop to ground. The electrostatic version looks like the head of a
nail sticking out of the teflon.

Yeah. for 50-12000 MHz. 6m and above and not much use for HF, then.
Good thing they've got a feedback E-mail address, but I suspect that
they'd want lots'o'$ for a one-off modification.

--
"If God had intended us to vote, he'd have given us candidates."

"Mike Andrews" wrote in message
...
Yeah. for 50-12000 MHz. 6m and above and not much use for HF, then.

I suspect you could make your own for HF without too much difficulty by
modifying something like a SO259 tee along with a standard PL259 connector.

On the other hand, for HF you can make pretty decent directional couplers
using transformers and get a significantly flatter response if you're looking
to accurately measure signal levels.