Steve, I would recommend that you NOT use the Tantalum caps. They have a very nasty habit of shorting when they overheat in the summer. When this happens depending on where the cap is, you may cause a fire in the radio.
Not a pretty when this happens. Charles Miller ----- Original Message ----- From: "Steve Murphy" <[EMAIL PROTECTED]> To: <Repeater-Builder@yahoogroups.com> Sent: Friday, January 19, 2007 11:01 AM Subject: [Repeater-Builder] Spectra time-bomb caps. > Hello everyone, > > A couple of weeks ago, I sent Bob, WA1MIK a message thanking him for > his fine article on recapping the Spectra radios. > > At work, we have a fleet with several hundred 800 MHz Spectra C5 and > C7 mobiles. Over the past year or so, they've been dropping like > flies. I've now gone through nearly 50 Spectras with various > problems, and in all but four radios, replacing the electrolytic caps > and cleaning the circuit boards restored proper operation! There were > many different symptoms, but the one thing that I saw repeatedly were > radios that would work OK when first powered up, and then develop > various problems after running a while. > > Bob's article gives Digi-Key and Mouser part numbers for the > replacement capacitors. I've used the Mouser numbers, and they're > right on target. > > On the last batch of radios that I repaired, I did deviate from Bob's > parts list in that I used a 10uF/25V tantalum to replace the 10uF/16V > factory electrolytics. The reason for the substitution is that the > tantalum cap is physically smaller, making it easier to install, > especially in the tight spaces near the audio IC. The Mouser part > number for this cap is: 74-595D106X9025B2T. > > Another thing worth noting is that in the three 900 MHz Spectras that > I've recapped, the 47uF cap on the RF board was not present. It was > present on all of the 800 MHz and 450 MHz Spectras that I've worked on. > > Thanks again to Bob for his article, and I hope that this posting > might help someone else. > > 73/GL > > Steve N8NM > > > > > > > Yahoo! Groups Links > > > > >
