900mhz MCS2000 receive sensitivity issue
Posted: Sun Jul 07, 2013 9:46 am
After a long and successful run using analog Motorola spectras on 900mhz and UHF in my vehicle, I decided to modernize to MCS2000s upon getting a new vehicle. Due to space constaints, I selected model-1 radios and picked up a couple that appear to be ~2002 vintage. Thus far, I have spent most of my time working with the 900mhz MCS2000. After programming and carefully aligning the radio, I was suprised to find that the sensitivity was 5 to 6 db worse than my trusty Spectra. Thinking there was a problem with the radio, I checked T/R diodes and the front-end pre-amp and everything seemed OK. I replaced those devices for good luck with no improvement.
Recently, I have tested several similar-vintage model-1 900mhz MCS2000s with the same result. I have a friend who has a ~1998 vintage model-3 900mhz MCS2000 and that one had considerably better sensitivity, analagous to my trusty Spectra. It appears from the service manual that all the RF design is the same between model-1,2,3 radios. I'm wondering if perhaps there was some type of design change between 1998 and 2002?
Anyone had similar observations or any idea on what I'm experiencing? I know Spectras pretty well but am just getting familiar with MCS2000s.
Thanks,
Randy/N3HFK
Recently, I have tested several similar-vintage model-1 900mhz MCS2000s with the same result. I have a friend who has a ~1998 vintage model-3 900mhz MCS2000 and that one had considerably better sensitivity, analagous to my trusty Spectra. It appears from the service manual that all the RF design is the same between model-1,2,3 radios. I'm wondering if perhaps there was some type of design change between 1998 and 2002?
Anyone had similar observations or any idea on what I'm experiencing? I know Spectras pretty well but am just getting familiar with MCS2000s.
Thanks,
Randy/N3HFK