Jeff No question about that - cable lengths between the duplexer cavities is critical and just as critical are the lengths between the duplexer and the Tee that feeds the antenna. Your test equipment is unquestionably more sophisticated than my tracker but I wonder about the figure you recorded for the BP BR pass attenuation at .0953. That seems awfully low. I would expect to see something in the whereabouts of .5 db. While your pix indicates that the composite pass curve isn't significantly affected by the cable length from duplexer to pass cavity, they sure as hell show how significantly the reject curves are sensitive to cable length - one significantly and the other dramatically. Because of the division scale you used you aren't displaying any changes that take place w-a-y out of band and Murphy's law being what it is, this might be significant in certain situations. It can get even more curious than the reject curves you display. For example, the 9 1/2" cable that Lloyd initially scheduled between the duplexer and the pass cavity produced a slightly asymmetrical curve slightly steeper on the high side with a quasi-pass spike to -40db at 342.4 Mhz with little rise from the noise floor on the high side through 540Mhz. But when he lengthened this cable to 19 1/4", the low side quasi-pass spike shifted to 362.9 Mhz on the low side and a new -40 db quasi-pass high side spike appeared at 508.1 Mhz. Go figure. I don't much care for right angle connecters either although I don't have any solid evidence to support it.. I much prefer in-line stretchers which permit more subtle changes. Bruce K7IJ In a message dated 7/27/2007 6:00:59 P.M. Pacific Daylight Time, [EMAIL PROTECTED] writes:
> According to Lloyd, the cable length between a duplexer and > an inline > cavity filter and the receiver makes little or no difference. Steve, Was the question posed (or probably misunderstood as being) whether the cable length between the receiver and the filter being critical, or the cables between filter sections being critical? If the latter, then I would have to humbly disagree with the answer, as theory and personal experience, as well as the results of the test earlier today, has been to the contrary. --- Jeff ************************************** Get a sneak peek of the all-new AOL at http://discover.aol.com/memed/aolcom30tour
