Hi guys .just been following this thead .When you talk about 1/4 wavelength is there a formula available to make these coax lengths. I found a calculator and I am wondering if this is the right one http://www csgnetwork.com/freqwavelengthcalc.html Going off that 1/4 wavelength for my coax's should be 0.15 meters or 6 inches which is very short. Does this 1/4 wavelength work between the transmitter and the diplexer as well as interconnection cable length or should we have a different length for it . Thank You, Ian Wells, Kerinvale Comaudio, 361 Camboon Road.Biloela.4715 Phone 0749922574 or 0409159932 www.kerinvalecomaudio.com.au -------Original Message------- From: ka1jfy Date: 18/09/2008 6:41:57 AM To: [email protected] Subject: [Repeater-Builder] Re: Cavity interconnection cable length One of our engineers had a factory tour of EMR. They did NOT calculate critical cable lengths, rather they had a pile of various length cables that they swapped in until it met specs. They were NOT optimized.
That same engineer finally got a SWAG from them that the loops in the EMR cavities are approximately 1/10th of a wavelength for calculation purposes. That figure seems to have served us well over the last few years. I'll ask whether I can publish the spreadsheet that we use for those calculations. We use an HP 8711C network analyser to setup the cavities for our UHF radio system, and various other users [VHF, UHF, 800]. Walter, KD7BJJ --- In [email protected], "kb9bpf" <[EMAIL PROTECTED]> wrote: > > Hello, > > Many writings about the optimum length of cavity interconnecting cables > mention that the length of the coupling loops needs to be taken into > account, but they don't get any more specific. > > Does that mean the length of the conductor in the loop (circumference > if it were round) or connector-to-end length (diameter if it were > round) or something else? > > I find it pretty easy to get the cables cut to a pretty precise > electrical 1/4 wavelength but this loop length thing leaves me guessing. > > 73 > Brad KB9BPF >
