In a message dated 31/03/05 23:06:29 GMT Daylight Time, [EMAIL PROTECTED] writes:
I'm thinking external T/R relay is the smart move. If the relay is rigged to rest in the transmit position, when the transverter is powered off, the out of band signal will land in the PA output, I suspect the output of the PA module is a big strong MOSFET or bipolar, that can take a few volts on it's drain (or collector) when it's biased off. When I add a "real" amp, the plate of an 8877 can take big voltage ;-) ------------------------------------------------------ External T/R relays to isolate the unused antenna feed and dump any unwanted energy into a dummy load with some form of interlock to prevent transmission until the feed is enabled would be the cheapest option by far to resolve the problems with damage to the XV-50 RX front end. The commercial systems I worked on had ferrite isolators in the TX antenna feed to stop exactly what you talked about, i.e. TX power from another TX coming back down the feeder into the PA as this could generate unwanted RF products at the PA. The ferrite isolator works as a directional coupler, allowing TX power towards the antenna, but any energy coming back from the antenna towards the PA from another source is dumped into a dummy load. Not normally needed for ham equipment working in simplex, though essential with systems on busy sites working in duplex such as repeaters. Used universally with transmitter combiners into a single antenna. Bob, G3VVT _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
