Richard,

It would seem a short might reduce some end capacitive effects when
compared with an open circuit. However it would not help in the case of
'minor' frequency dependent changes in coax inductance.

Thanks,
Dan

Richard Clark wrote:
On Thu, 15 Mar 2007 14:37:28 -0700, dansawyeror
wrote:

The reference coax is coiled on the floor. Is it possible this created
an inductance which affects phase?

Hi Dan,

There is a vastly simpler way:
1. Measure to a short circuit.

73's
Richard Clark, KB7QHC

Hi Dan

What would happen if you closed the coax shield around the open end of the
coax?

Jerry


"dansawyeror" wrote in message
...
Richard,

It would seem a short might reduce some end capacitive effects when
compared with an open circuit. However it would not help in the case of
'minor' frequency dependent changes in coax inductance.

Thanks,
Dan

Richard Clark wrote:
On Thu, 15 Mar 2007 14:37:28 -0700, dansawyeror
wrote:

The reference coax is coiled on the floor. Is it possible this created
an inductance which affects phase?

Hi Dan,

There is a vastly simpler way:
1. Measure to a short circuit.

73's
Richard Clark, KB7QHC

On Fri, 16 Mar 2007 06:45:48 -0700, dansawyeror
wrote:

It would seem a short might reduce some end capacitive effects when
compared with an open circuit. However it would not help in the case of
'minor' frequency dependent changes in coax inductance.

Hi Dan,

A short "might reduce some?" That is rather an understatement.

"It would not help... 'minor' changes?" That is even worse.

Trying a short in place of an open would have taken less time, and
proven these two statements are wrong. A short is also an excellent
way to measure Ohmic loss in the cable. If you read your user's
manual for your vector network analyzer (assuming it has one), you
would find that a short is the preferred method. Also, for vector
network analyzers that do not have built in correction, it is also
expected you repeat the measurement with a Zc load. Then, and only
then do you proceed to doing it with an open (which will reveal the
extent of fringing).

I wouldn't do an open anyway. Instead, I would measure a load
constructed to mimic the measurable (you must have some idea what it
is you are going to be measuring, don't you?) and put it in a shielded
enclosure. Then move this text fixture to the vector network analyzer
and repeat to see the effects of the line.

73's
Richard Clark, KB7QHC