On Feb 24, 3:31 pm, Owen Duffy wrote:
"harry" wrote in news:1172334927.954451.290220
@q2g2000cwa.googlegroups.com:

I have recently purchased two different VSWR Bridges.

One was made by Johnson.

The second is a clone.

Both use a fifty ohm resistor in series with the signal path. This
strikes me as a lossy setup. Is there a theory of operation posted or
a text which can explain the operation of the bridge?

The bridge is indeed a simple bridge with a single null indicator. It is
for use with less than 1W of RF, and is not intended to be left inline.

ftp://bama.sbc.edu/downloads/johnson/250-24/

Owen

Owen. thanks for the link on the BAMA server. It cleared up a lot of
questions.

What threw for the loop was the coupler has to be removed one the
measurement is completed.
I had assumed (and you know what they say about that word) it was like
other couplers and
remained in circuit.

I had not tried either one since obviously the 2 watt resistors were
going to go poof, if used
like its more modern cousins.

I apologize to all for the lack of info and will be more diligent in
the future.

Harry