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motorola spectra narrowband

Posted: Fri May 05, 2006 1:41 pm
by rydzewski
is there any other way to get the spectra to cover narrow band other then tweeking the rf board*?


or atleast i heard that will work*

Posted: Sat May 06, 2006 12:53 am
by Mike B
Legal 2.5 KHz Tx narrow band analog requires an IDC filter cutoff at 2.5 KHz with a sharper roll off than a 5 KHz wide band. The wide band cutoff is at 3 KHz. The frequency stability is stricter for narrow Tx. There are Spectra first IF filters for narrow band as well as complete Spectra narrow band RF boards. I think all this stuff resides on the RF board (I cannot remember if the IDC is there also). The Astro Spectra can do wide or narrow while the Spectra must be built for either one or the other. Even so, the FCC might not type accept some radios for legal narrow analog Tx (you would need to check with them).

You can still monitor narrow band analog with a wide band receiver, but you will have to crank up the volume. If any of the directly adjacent narrow band channels are busy, the wide band first IF filter will not be selective enough to block them from interfering with or obliterating the frequency you want to listen to.

If you do not want to tweak, then get a narrow band radio and do not hassle with it. I do not know of any magic no tweaking fix for Rx. If you want to stay legal on narrow Tx then there are significant tweaks and issues to deal with.