With tuning the cavities /duplexers should we use 50 ohm pads or something else in line with the items when we tune them on service monitors Thank You, Ian Wells, Kerinvale Comaudio, 361 Camboon Road.Biloela.4715 Phone 0749922574 or 0409159932 www.kerinvalecomaudio.com.au -------Original Message------- From: iain.philipps Date: 26/08/2009 15:57:13 To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Cavity/duplexer connection cables --- In Repeater-Builder@yahoogroups.com, John Sehring <wb...@...> wrote: > > There seems to be confusion & mystery in the crowd of radio buffs that I han out with (not in this group!) on the subject of connecting cable lengths for cavity & duplexer use. I've heard that the manufacturers of such devices also tend to be mum on this.
These sets of cables are generally known (where I come from) as "critical length harnesses". > It seems to me that if these devices are tuned up to perform their function(s) (notch, peak, bandpass, bandreject, etc.) with 50 ohms of pure R in & out as source & load Z, cable length ought not make a difference (within reason, I'm not talking long cables with significant losses) to their performance. > > Is this so? Am I missing something? Thanx! Common sense would say you're right on the money. However, I think that common sense only applies if the velocity factor of your cable is 100%. There's also something to do with the "shape" of waves travelling along it, and voltage/current minima and maxima, I suppose :-)
