I wonder if anyone can offer some advice please? I've just put together a KPA-500 linear amplifier kit and everything seemed to work fine until I switched from standby to operate when I get a 270v ERR message, which needs a hard reset.
The 60v line is present (68.5v) and the interlock works as it should do. I've checked and there is no 270v line present for the PA T/R switch reverse biasing - grey wire on PSU. That is until the grey wire carrying the 270v line from the PSU, which connects to P2 on the PA board is unplugged and then I can see the required +270v. Clearly the PSU is working. As soon as I reconnect the grey wire to P2, the volts disappear and R17 on the PSU board starts to get hot. I've found a circuit diagram for the KPA-500 on the WB4KDI web site: http://www.qsl.net/wb4kdi/Elecraft/index.html Here it shows R17 in the 270v bias circuitry as a 10K rated at 1W. However, R17 in my PSU is actually a marked 1K rated at 1W (measures 998 ohms) Is this the problem? Wrong resistor fitted in the factory? I dunno whether this actually is the problem or whether Elecraft have changed the circuitry since that earlier circuit diagram referenced above was made available and the fault is elsewhere. Sadly, there was no circuit diagram in the handbook provided with the KPA-500. Any thoughts please? Thanks in advance! 73 -- Steve Wilson, G3VMW Bramham, Wetherby, West Yorkshire ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
