Hello Scott, Mike, and Jim. Thank you for taking the time to Reply, i am grateful for all the info supplied and will be studying the answers given. I should have stated in the original post that i am in Austraila, and the Repeaters that were mentioned are in commercial service full time. I have a small unit comprising of two Mobiles with a duplexer tieing them together to a common Aerial and although the receive audio is presentable the TX seems to me to be pretty substandard. When the controller is enabled for Simplex the Audio being repeated is very good indeed, all most perfect but when it is being relayed straight thru it is pretty awful. I thought it might just be the way i have set this up but sticky beaking on the input / Output channels of the Commercial Ones in service here seem to have the same problem.
Hopefully with the info given i will be able decipher what the issue is with my setup and sort out a solution. Thanks again to all concerned, Regards Chris S. In Repeater-Builder@yahoogroups.com, "Jim WB5OXQ inb Waco, TX" <wb5...@...> wrote: > > If I remember I will record a net on one of my repeaters and put it on > youtube. The repeaters I set up are so natural you can barely tell the > repeater audio from the input audio. My current repeater is a Motorola MSF > 5000 using it's stock controller and the audio is quite good. I usually > retard the repeated audio about 1 tenth of a kc in deviation so there is less > chance for clipping which results in muddy audio. > WB5OXQ > ----- Original Message ----- > From: Mike Morris WA6ILQ > To: Repeater-Builder@yahoogroups.com > Sent: Thursday, July 02, 2009 10:55 AM > Subject: Re: [Repeater-Builder] Repeater Audio samples > > > > > > At 03:22 AM 07/02/09, you wrote: > >Hello, > >Was Wondering if anyone had a link to a site that had samples of > >talk thru Repeater traffic that would be considered good quality audio ? > >Maybe i am expecting too much but any of the ones around here that i > >have heard seem either Muffled or very Shrill, Listening on the > >input frequency the Audio seems quite reasonable but the Transmit > >Audio doesn't sound the same and seems a bit average. > >I realize that the Audio will vary due to the normal constraints of > >Radio atmospherics but i was hoping for something that doesn't sound > >like a very cheap tiny AM broadcast radio > >I would be really interested in discovering just how good normal > >Analogue speech can sound when it is being passed through something > >that is properly setup. > >Apologies if this has been answered before, i searched but couldn't > >find anything specific. > >Any info gratefully received, > >Cheers, > > Where is "around here" ? > > From what you are saying it sounds like whomever set up the > repeater(s) does not understand de-emphasis and pre-emphasis. > From the article at > <http://www.repeater-builder.com/tech-info/flataudio.html> ... > > >Another problem that rears its ugly head unless you know the equipment > >you are working on intimately... If you pick off raw (i.e. not > >de-emphasized) audio from the receiver discriminator and pipe it into > >the microphone jack of a transmitter you will end up with an extra > >level of pre-emphasis (commonly called "double pre-emphasis") that > >will cause the audio to sound very tinny or shrill (take your home > >hi-fi, tune to a talk radio station, center the bass and the treble > >controls, note the audio characteristics, then crank the bass control > >to minimum and the treble to maximum - and mentally double or triple > >the overall effect). On a true FM transmitter you can sometimes > >bypass the pre-emphasis network, on a phase modulated transmitter > >there is no way around it without adding a de-emphasis network in > >front of it to compensate. This is why many repeater controllers > >have a built in de-emphasis network that can be jumpered into the > >circuit or jumpered out as needed. > > > >Likewise, picking audio from the receiver after the de-emphasis > >network (in some receivers that point is after the volume control and > >the audio muting part of the squelch circuit) and piping it into a > >true FM transmitter modulator can produce audio with extra amount of > >de-emphasis (commonly called "double de-emphasis") resulting in a very > >muffled, bassy sound with no high frequencies (same example as above, > >but crank the bass control to maximum and the treble to minimum - and > >mentally double or triple the overall effect). > > > >Either of the above two situations is instantly recognizable by an > >experienced ear. > > Mike WA6ILQ >
