rtc, Eric and Skipp, I remember one of the Kenwood repeaters I serviced few years back, the 720 I think.
It was advertised as 50 watt repeater/base station. After looking at the final with only 1 transistor it had done as rtc stated; the PC board had gotten so hot it blackened/charred the PC board. After further study of the spec sheet found little beared? spec..."for continous duty turn power down to 15 watts". Had to look hard. Always need to read the fine print. Also there was so much stuff in that unit to do the simple FM rx/tx functions. That is typical of Japan. 73, ron, n9ee/r >From: rtc_0001 <[EMAIL PROTECTED]> >Date: 2007/07/14 Sat PM 11:03:19 CDT >To: Repeater-Builder@yahoogroups.com >Subject: [Repeater-Builder] Re: Motorola R1225 versus Kenwood TKR-750 > > >It's not so much a defect as it is asking the rptr to do more than it was >designed for. It may be a 45 watt PA but in rptr use, medium to HD rptr use, >drop it down to about 25 to 30 watts out of the PA. Enjoy what you get thru >the duplexer. Asking for more will melt the PA. >The earlier units had a temp controlled fan that only came on when the PA was >about to melt. The next generation of power supplies came with a switch to >turn the fan on permanently. >You will probably be able to fix them without the manual. Most of the time the >PA transistor collector got hot, melted the solder & the chip caps moved (slid >down the pcb due to gravity). >I repaired these on a regular basis without needing new parts unless the >damage literaly burnt the pcb around the collector lead. I removed the chip >caps, removed the solder on the collector tab & trace & resoldered it all back >in with silver solder. This, along with turning the factory output down, >made them last a long time even under HD casino use. >I think it took me maybe 45-60 mins to get it all apart, fix it, reassemble, >reinstall. Lots of times I did it in place at the customer's premises. rtc > > > >> -----Original Message----- >> From: Repeater-Builder@yahoogroups.com >> Sent: Friday, July 13, 2007 11:08 AM >> To: Repeater-Builder@yahoogroups.com >> Subject: [Repeater-Builder] Re: Motorola R1225 versus Kenwood TKR-750 >> >> Hi Eric, >> >> <SNIP> >> >> I just pulled three 1225 uhf repeaters from two different locations >> and they all have the same failed tx pa problems. Wonder if there's <BR>> a >> minor pa defect problem (like there was in early version one tkr <BR>> >> repeaters) or it's just bad customer karma time. I've got to find >> a service manual before we open them up... >> >> cheers, >> skipp > Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
