I was hoping to get info on putting a gm300 to the 220 mhz band so that I can take advantage of the channel steering capabilities of that radio as a remote base.
Sent on the Sprint® Now Network from my BlackBerry® -----Original Message----- From: "Bill" <[email protected]> Date: Tue, 24 Nov 2009 19:28:06 To: <[email protected]> Subject: [Repeater-Builder] Re: Motorola Spectra 900's You and I need to talk (I type too slow). I too have wanted a spectra on 220 mhz. Had not thought about the 1 pf cap trick. . bill . jawjabillatl---bellsouth---net . . --- In [email protected], Mel Swanberg <wa6...@...> wrote: > > Well, maybe I've actually managed to do something different... > > I've been adding a 1 pf chip cap (0603) between the oval shaped pad in the > filter, and the edge of the filter sectiont. One cap for each section. This > lowers the frequency down below 900, and then I use a dremmel with a sharp > bit to walk the filter back up in frequency. This is all done while watching > a sweep of the filter on a network analyzer. > > I've not really attempted to narrow the BW of the filter at all, just shift > it down some. > > As to the VCO, that's where the conductive ink comes into play. Just dab some > in through the slotted window, no need to remove the cover. The microstrip > resonator needs to be about a 1/4" longer. The conductive ink pens work just > fine for that. > > I have a web page up on converting the 406-433 spectras to 440 that has some > useful pictures on how I go about retuning the filters. Just add the 1 pf cap > to the process, and it's otherwise the same. > > http://mysite.verizon.net/res8teuc/Range1spectra/Range1Spectraver1.1.htm > > Maybe that, and my comments above, will prove helpful until I can put up a > similar article on the moving the 800 and 900 Spectras down. > > My next project? See if I can get a VHF Spectra to receive on 220. > > Mel - WA6JBD > > > > Well, you have me curious also, maybe > > I took the dark path for tuning the front end filters. > > I had to resort to silver paint (not cheap), a grinder, and > > a little blood and guts to tune those puppies. What's > > your story...... > > . > > bill > > w4oo >
