While Tim and Phil were working on the FPCARC repeater (146.715) the other day, there was mention that the duplexer might need to be check-ed out, since receiver sensitivity was not very good. Actually, there are a number of things that probably need to be looked-at, as soon as time permits :
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- The Duplexer – hasn’t been swept in a number of years. We’ve prepared one of our spares on the 146.715/146.115 pair that is ready to install at the site, while we take-down the old duplexer and put it on the bench.
.. - The tuning of the VXR-7000 repeater – since we’re operating about 4Mhz outside of the Commercial band (150Mhz), the receiver might need to be re-aligned for the low end (146.115) in order to achieve maximum sensitivity, without causing IMD3 to be unreasonable. If the replacement duplexer doesn’t appear to be giving added performance, then we’ll remove the VXR-7000V and ask Mr. Schwartz (WS1C) to put it on the bench and re-align the receiver based on the detailed instructions in Icom Service Manual.
.. - The coax and antenna should probably be swept with an analyzer – although Tim already did that previously with a ham-grade instrument, we’ll probably “take a picture” of the antenna/transmission system with the Agilent N9330B in the next couple of weeks, so that we can establish a baseline performance standard of the current antenna system.
.. - Any or all of the above could be contributing factors, so we’ll attack them one-by-one, staring with the replacement Duplexer, which has already been swept and certified.
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This author has now taken an interest in contributing to the improved health of the FPCARC repeater – for a number of reasons.
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- First and foremost, I really like the guys in that club – stand-up quality, honest talk, pure in heart – a great group to fellowship with.. all are former professionals, so there’s no “one-upmanship” or power positioning going on as in other groups,
.. - Second – they do good work, whether for the children in the County thru the Cadet program, or with the Boy Scouts – these guys (and gals) want to serve – and they do it with a humble heart.
.. - Third – many of the FPCARC members are now also certified members of either FEMV, or the Hospital ARES Volunteer organization – the only two officially sanctioned and operated programs by the County and Florida Hospital, respectively. Others make wild claims to be “affiliated” or whatever other words, but their claims are hollow and misleading at best. FPCARC members who are volunteers of FEMV and the Hospital volunteer groups are credentialed, background-checked and listed on the rosters of those respective organizations – all good things in this post-9/11 world.
.. - Fourth – the FPCARC repeater is graciously hosted by the Florida Hospital, Flagler – and has been for a number of years. This organization understands the benefit of having Amateur Radio in their emergency operations plan – and the practice it in their involvement with their volunteers. Although they never expect to use our services (due to the numerous backup systems that they maintain), they understand that it is a possibility and want to keep our skills (and theirs) sharp in case that day comes. Given their high expectations of us, it is incumbent on us to insure that the repeater operates to its fullest potential, given the height and geographical placement.
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I would expect that the efforts would take the next couple of weeks – this author is traveling until the 10th of March, but many activities will be possible in the interim.
