Yes, you must re-tune the oscillator by the book (LBI, actually) when you change frequencies.
One of the easiest ways to check for oscillation and adjust the channel frequency is to set your service monitor to receive the local oscillator frequency. Place the monitor's pickup antenna close to the crystal oscillator. You should see a signal at either +11.2 MHz or -11.2 MHz from your channel frequency, depending upon whether you have high-side or low-side injection, respectively. Once you get the oscillator working per the LBI steps, tweak the variable capacitor on the channel element to warp the local oscillator to the exact frequency and repeat the tuning adjustments. You should now be able to tune the RF assembly at the channel operating frequency. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Mathew Quaife Sent: Monday, January 01, 2007 9:27 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Bowmar Crystals Ordered, all the RX not working for GE EXEC II mobiles Ok, gonna sound stupid here. The xtal that originally came with the unit was set for normal frequency range. Does everything have to be redone when you go with a high side xtal? At this point it will not receive even with a 5 watt ht next to it, aside the 0 dBm my service monitor gives it. Mathew Chuck Kelsey <[EMAIL PROTECTED]> wrote: You did re-tune the oscillator section, didn't you? Chuck WB2EDV ----- Original Message ----- From: Mathew Quaife <mailto:[EMAIL PROTECTED]> To: Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder@yahoogroups.com> Sent: Monday, January 01, 2007 11:44 AM Subject: Re: [Repeater-Builder] Bowmar Crystals Ordered, all the RX not working for GE EXEC II mobiles Thanks Chuck, that is what they sent me, so your math is just fine. Then there must be something I am missing. I can take one of the old xtals and they work out just fine, so I know the receivers are working. Might I ask what the formula you used was? It's been a long time since I have calculated a crystal freq. so just need the formula configuration. Mathew Chuck Kelsey <[EMAIL PROTECTED]> wrote: If my hasty math is correct: 144.81 low side = 14.845555 144.81 high side = 17.334444 434.875 low side = 16.39537 434.875 high side = 16.521296 Chuck WB2EDV ----- Original Message ----- From: "n9lv" <[EMAIL PROTECTED] <mailto:n9lv%40yahoo.com> > To: <Repeater-Builder@yahoogroups.com <mailto:Repeater-Builder%40yahoogroups.com> > Sent: Monday, January 01, 2007 10:40 AM Subject: [Repeater-Builder] Bowmar Crystals Ordered, all the RX not working for GE EXEC II mobiles > Hope someone can help shed some light here. I ordered xtals from > Bomar (3 week wait) for the GE EXEC II mobile radios, 6 for RX for > 144.810 and one RX of 434.875, all high side injection. None of them > are working at all. At the same time I ordered tx xtals for the same > radio, they all work just fine. What might I be missing here, or did > they just cut them all wrong. > > Mathew > > > > > > > > Yahoo! Groups Links > > > > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
