Well, everyone, I have finally figured this out. and it turned out NOT to be anything anyone had suggested.
After trying two other PA assemblies and seeing no improvement in receive sensitivity, I decided to try a different RX filter hybrid. When I removed the one in the radio, I noted that it was not securely plugged into the VCO assembly. I changed it out anyway, and made certain that the RF cable was well plugged into the VCO board. The plug did not fit tight (like the other RF connections in the radio did) but it stayed connected, so I put it back in the car and tested my repair. VOILA!! Receive is now on par with the GTX and MaxTracs I have tested the Spectra against. I have no idea why the RF interconnect cable became loose and/or disconnected, or why the connection felt "different" (i.e., more loose) than the others in the radio, but I'll keep an eye (or should I say, EAR) on the receive performance, and if it deteriorates again, I'll take the radio apart and see if I can tighten the RF connection on the VCO board somehow. Thanks to everyone who gave me suggestions on how to troubleshoot this situation! Hope to see some of you at Dayton. You won't be able to miss me - I'll be wearing a floppy brown felt hat and armed with a 900MHz GTX portable! Mark - N9WYS From: Mark To: ar902...@yahoogroups.com ; 900...@yahoogroups.com ; Repeater-Builder@yahoogroups.com Sent: Saturday, May 09, 2009 2:41 PM Subject: Spectra RX sensitivity questions I have a Spectra converted for operation on the amateur portion of the 900 MHz band. This thing seems to be somewhat deaf - it barely opens squelch while the same signal on a GTX (either handheld or mobile) is much stronger, and when squelch is open, the signal; is markedly "weaker". Is there something I can do in software (i.e., alignment) to improve the RX sensitivity, or is this a filter issue, or what? Mine is not the only one I am aware of that exhibits this problem. Thanks, Mark - N9WYS
