The particular radios I mentioned (UHF) were all designed for 25 kHz channel spacing, with correspondingly broader filters than current models... Com-Spec sells replacement filters, both singly and in kits for specific radios, to retrofit them for 12.5 kHz spacing.
For example, the stock Johnson PPL 6060 has a 4-pole 10.7 MHz crystal filter with a 13 kHz bandwidth (3 dB?) and a 4-pole 455 kHz ceramic filter with a 20 kHz bandwidth. Com-Spec sells a replacement 10.7 crystal filter set with a 3 dB BW of +/- 3.75 kHz, and a 455 ceramic with a 6 dB BW of +/-4.5 kHz. Just wondering if it was worth doing or not, particulary for a GMRS repeater & the potential for FRS interference. ----- Original Message ----- From: "Dick" <[EMAIL PROTECTED]> To: <Repeater-Builder@yahoogroups.com> Sent: Sunday, February 25, 2007 4:04 PM Subject: Re: [Repeater-Builder] Narrowbanding > George: > > What do you mean by narrowbanding? > What's the current FM deviation on the radios? > Way back when, it was called narrowbanding when the FCC changed > from +/- 15 KHz to +/- 5 KHz FM dev. > > 73, > > Dick W1NMZ > > ----- Original Message ----- > From: "George Henry" <[EMAIL PROTECTED]> > To: <Repeater-Builder@yahoogroups.com> > Sent: 25 February, 2007 12:04 > Subject: [Repeater-Builder] Narrowbanding > > >> Has anyone narrowbanded a Mitrek, MastrII, or Johnson PPL6060 with >> Com-Spec's narrowband filter kits? Is it really worth doing? >> >> $25 per radio is $25 I could use elsewhere, if not. >> >> >> George, KA3HW / WQGJ413 > > > > > > > Yahoo! Groups Links > > >
