On Feb 16, 2010, at 9:57 PM, KE4ZDG wrote: > Hey folks, > > I'm working on a GE Mastr II high band repeater. Someone gave me some > crystals that were made up for 146.010 RX. I installed one in an EC ICOM and > the best I can adjust for is 146.0064, which sounds really scratchy when I > inject a >3k deviation signal on 146.010. When I tune the monitor down to > 146.0064, the RX audio cleans right up. > > I've backed out the screw until there's no more threads left in the ICOM. Is > there a capacitor I can change or add to give me a little more tuning range > to the ICOM? I just need the crystal to go up a hair more (400 Hz on the > crystal freq). > > I know I'm promoting cheapness by not buying another crystal, but the club > doesn't have much money to spend. > > Thanks, > > Jared
Just to comment on the "cheapness" part... you do realize you can re-rock an ICOM yourself? The crystal will run about $20-$25 last I checked from any of the reputable crystal houses. It won't be temperature-compensated or "burnt-in" and you could experience some frequency instability, but they usually work and settle down after anywhere from 6 months to a year. (Just visit the repeater every couple of months and check it.) I think I paid less than that once, even. Most folks here will recommend not being this "cheap" and having the whole ICOM sent in, full compensation, all that stuff... but for "non-critical" repeater stuff I've slapped ICM rocks in an ICOM and run with it. Especially for "test" crystals for use in the basement test lab, etc. $20-$25 is BEYOND cheap when the full price of a good, working, repeater system is factored against it. Of course, I think the full crystal and compensation are cheap, but I wouldn't put a repeater anywhere near a crap duplexer/antenna setup, having seen what good ones do for the system. Any pair of radios can be a repeater. The antenna system including duplexer, feedline, connectors, and antenna (plus lightning protection) makes it perform. You've also read the appropriate LBI manuals on the Repeater-Builder site and articles about EC ICOM's and how they require a 5C ICOM installed to drive their compensation voltage, right? Just checking. A lot of people will swear that you need 2C ICOMs for repeaters and then don't read the LBI's that a 5C ICOM will hold 2PPM within a very broad temperature range... and any 5C will compensate an EC. Only outside of that range in the chart in the LBI is the 2C even a necessity... so if the repeater lives in any kind of temperature-controlled environment... Anyway... my $0.02 and another buck will get you some Via instant coffee. :-) -- Nate Duehr, WY0X [email protected] facebook.com/denverpilot twitter.com/denverpilot
