Looks to me like there is an incorrect interconnect cable length. If you are intending to tune both to the same frequency, you should see a single response, not two.
Chuck WB2EDV ----- Original Message ----- From: Larry Horlick To: [email protected] Sent: Tuesday, April 20, 2010 12:38 PM Subject: Re: [Repeater-Builder] Sinclair C-Series cable lengths The cavities were initially tuned individually and the loop positions set for 1 db IL. They were then coupled together using a 18.5" cable and the rods touched up to re-establish resonance. The measured IL is now 2.9. The loop positions were not changed after coupling. When using the RL bridge I do not see one clear notch, but rather a notch that has a bump; kinda looks like 2 notches. This is what I always see even when cavities are factory tuned, so I'm confident that the tuning is OK. On Tue, Apr 20, 2010 at 9:26 AM, Jeff DePolo <[email protected]> wrote: > I have 2 C-Series bandpass cavities, with individual I.L. set > at 1.0 db each. When I couple them together and measure, I > get a total I.L. of 2.9 db. I should see something like 2.1 > or 2.2. I have measured the coupling cable and see < .1 db, > so the cable is good. Anyone have an idea why the loss is so > high when coupled? Most likely they aren't tuned correctly for maximum return loss, and when you cascade them, the resonant frequency is no longer where you thought it was (i.e. a "detuning" effect). Have you measured the return loss of the cavities individually? --- Jeff WN3A ------------------------------------------------------------------------------ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.801 / Virus Database: 271.1.1/2822 - Release Date: 04/20/10 02:31:00
