"Richard Clark" wrote in message
news
On Tue, 5 Oct 2004 12:26:06 -0500, "John Smith"
wrote:

You should get 1.0 @ 180° (the definition of a short).

Well, that's not possible when feeding a length of RG58 at 400 MHz, is it?
Remember, I said that there was about a 5 foot length of RG58 between the
directional coupler and the load. How can one get 1.0 reflected to the
coupler when the load is a short? That requires zero loss coax.

Hi John,

As Wes suggests, butt up the load against the directional coupler
output and eliminate this arbitrary loss of the 5 foot RG58. It
should also shift the readings too (you are simply walking around the
circle of constant SWR). One question that would be obviated in this
process (but I have to ask anyway) is WHERE was this short you
applied? At the output port of the coupler, or at the end of this 5
foot RG58? (Same question applies to the calibrated load).


I used a 66 inch piece of RG58 between the directional coupler and the load.
It was at the load end of this piece of coax that I calibrated with a short
and made the load measurements.


The other measurements that you reported in response to Wes indicate
you have tracking ports (even if they are off by 4dB). As I said, it
seemed unlikely this would be a problem and it confirms the
out-of-octave specification.

73's
Richard Clark, KB7QHC