At 10:27 AM 11/30/04, you wrote: >Mike, I thought there was some reference to a signal generated by the >oscillator crystal in one receiver getting into the other receiver and >causing a problem.
Maybe you are remembering the Cactus Radio writeup on Mitreks where they mention that the 406-420 models have a problem when duplexed with the RX multiplier getting into the TX multiplier and creating spurs. >I have not been able to find ref to it in a search of the messages. >Perhaps it is only a concern if two receivers are operating on the >very same frequency as with voting. Even then you wouldn't have two voting RXs at the same site in the same rack. The nearest situation I know of to that is one site that has two RXs in adjacent buildings - only because the hardware was lying around, already crystaled up and on channel, and all it took was the labor to install, and it cut the mobile flutter in half...) >I understood there was a recommendation for using a high >side crystal frequency in one receiver and a low side crystal >frequency in the other. >Might it have implied that the receivers might pick up the >"wrong" input signal as interference? Don't remember that.... Most well designed radios don't have that much LO or injection leakage (as long as all of the shields are in place)... >Hardly any repeaters up here in the boonies are set up to >use PL tones. I see only one repeater in Nova Scotia is >listed as requiring PL tones. >Perhaps our two repeaters should be the second and third! :-) Not unless you have a problem that requires it. Try it and see. >I know were do have some problems at times where one >repeaters output signal causes the other to come on. But >it only happens once in a while. Probably a random mix.... >Just wanting to cover my bases! >I appreciate any advice. I'm sure that the list members will contribute. >Bruce Mike WA6ILQ >----- Original Message ----- >From: "Mike WA6ILQ" <[EMAIL PROTECTED]> >To: <[email protected]> >Sent: Tuesday, November 30, 2004 5:20 AM >Subject: Re: [Repeater-Builder] need input on changing Mitrek oscillator >crystal > > > At 02:52 PM 11/29/04, you wrote: > > > > >I have read a few comments in the past about the need for changing > > >the crystal from one side of the operating frequency to the other in > > >a Mitrek. > > >I am not sure I will be wording this properly so please be patient. > > > > > >I will have two repeaters at the same site which are Mitrek > > >conversions. > > >One repeater is on 145.210 MHz (neg. offset) and the other repeater > > >is on 147.240 (pos. offset). > > >At present the 145.210 repeater is not a Mitrek but when I am > > >finished the conversion it will be replaced by the second Mitrek. > > > > > >I would appreciate comments re experiences (ie problems) encountered > > >if both receivers have the same frequency crystal. > > > > > >thanks > > > > > >Bruce, VE1II > > > > The standard 136-174Mhz Mitrek configuration uses high > > side injection, with a 10.7 MHz IF. As Neil pointed out, I had it wrong... it's low side. > > And remember, the 147.24 repeater will be listening > > to 147.84, and the 145.21 repeater will be listening to > > 144.61 - with over 3mhz of RX to RX separation I don't > > see a problem at all. > > > > And if you are referring to the two repeaters being on > > the same channel simultaneously, well, that's what > > two different PL tones are for - set up repeater 1 on > > tone A and repeater 2 on tone B. > > > > Or am I not understanding the question? > > > > Mike WA6ILQ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
