Bill, Maybe you missed this from yesterday:
"Yes, a 4 dB pad in line with the antenna would be bad for receive. I'm no good at making ascii diagrams and didn't have time to make a real circuit drawing, so my word picture wasn't clear enough. I suggested the extra coax be placed between the T/R relay and the input of the amplifier. That way, the receive path is isolated from the extra coax. The amplifier most likely employs a DPDT coax relay (or equivalent pair of SPDTs) to put it in the circuit only during transmit. The amplifier has to be bypassed during receive or one would have to "listen backwards" through it. The extra coax goes between the VU5K side of the DPDT transmit path and the amplifier input stage. There is already a piece of coax in the circuit between these points that is only active during transmit. One simply needs to replace the short piece of coax already in the circuit with a piece that is "4 dB longer". I hope the above is a little bit more descriptive." Cheers, Mike - W8MM -----Original Message----- From: Bill Ockert - ND0B [mailto:n...@ockert.us] Sent: Tuesday, August 14, 2012 10:48 PM To: Mike Valentine; flexradio@flex-radio.biz Subject: Re: [Flexradio] Flex 5000 VU module Not quite that simple Mike. Without relaying the attenuator will also be in the receive path. 73 de Bill ND0B _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
