Palomar 450HD

skywalker GB · Post by **skywalker GB** » Monday 11th Jun 2007, 4:39

hello, I have a 450HD a few months old, having some problems... i noticed for awhile the modutation led under the power level switch (center switch) was no longer lighting when transmitting. now the relay has a problem. Too see if my output transistors were ok I made a small hole in the relay cover, pushed it closed manually and keye'd my driver. amp showed 200 watts dead key. for some reason the relays not energizing. if i power amp on and off while keye'd up it transmitts for a split second. seems the rf just doesnt hold the relay closed. this amp appears to be contructed in a way thats not easy to get at the circuit board short of lifting the finals. Maybe I'm missing something there. Any advice on all this will be much appreciated! thanks, skywalker, central cali coast

nomadradio · Post by **nomadradio** » Wednesday 13th Jun 2007, 15:29

Umm, you keyed your, uh, "DRIVER"!!!! ? ? ?

The keying circuit was built to tolerate only barefoot-radio drive. You have probably blown out the keying transistor that senses the radio's carrier and activates the relay.

With a light touch, the leads can be snipped flush with the body of the old part, and a new one lap-soldered to the old leads. Lots less trouble than removing the entire pc board. It was designed to be easy to build, NOT easy to take apart.

And if your touch isn't light enough, one or more of those protruding leads will just come out of the board.

Pretty sure the type number is PN2907A

73