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Update 7-30-2008 : All Gunstock repeater output traffic is now mimicked on 51.74 from Hopkinton, MA. A Hopkinton remote receiver on 51.24 will be installed later this summer to enable extended southern coverage down to the Cape Cod Canal. This will enable NWS Gray ME to communicate with NWS Taunton, MA as well as many other Skywarn spotters.

The existing, on-site Rohn-25 was purchased from WMEX radio which was recently sold. The antenna base is only 5-feet above the building roof.

The very rare lowband duplexer was previously used by Boston Gas.  It was purchased at Hosstraders in 2005.  Original list price:  $4500

The lowband GE MASTR-II repeater was acquired via eBay and was previously used by the Arizona Highway Patrol on Roof Butte on an Apache reservation in northeast Arizona.  The repeater is now going from baking to freezing !

The heavy duty backup batteries came from a retired UPS system formerly used at the ch-5 Doppler RADAR site.  The new UPS uses different voltage batteries so these "old"  batteries were only six months old!

The brand new Heliax cable came from a new microwave system being installed by ch-9.  These were the leftover short ends and the length was perfect for our needs as we had a short run.

The Motorola cabinet that holds the GE repeater was part of Operation Wolfpack. Click here for details.

Different TX and RX PL's are used to prevent the repeater from talking to itself.  The user transmits on a PL of 71.9Hz. The RX PL of 100.0 Hz is optional and is only used to reduce unwanted noise on the channel.  This is very important in the Boston area due to the ch-2 TV transmitter but may be of little use in New Hampshire.  Not all ham-built radios can support different TX & RX PL tones (some do) but all commercial radios can.

Testing on day-one reached south to Framingham, MA using a non-directional antenna (full quieting) and later in the day, Rhode Island. A coverage map is below.

Repeater Voice ID's by:

• Long ID with "Gunstock":  Peter Mehegan, ch5 Chronicle reporter
• Short ID: JC Monahan, ch5 meteorologist
• PL ID:  Natalie Jacobson, ch5 former anchor
• timeout:  Mary Richardson, ch5 Chronicle host

The previous "audio crunchies" issue was traced to a few loose connections that have been corrected.

Due to the highly skilled mechanical work (actually major surgery) of N1VE, NY1H and N1LT, this now-shortened commercial duplexer could be properly tuned up on ham freqs.  This gives the phrase "duplexer tuning" a whole new meaning !

Without CNHARC's amazing and highly-diversified skill-set, none of this would have been possible!
 

This is an extremely rare six-meter duplexer.  It was originally set-up by K1RJZ but some pesky repeater receiver desense symptoms remained.  Rick's work was double-checked by W1BRI and was already found to exceed factory specs at 53.77 MHz.  The culprit was that most testing of the repeater and duplexer was performed at a safe 20-watts.  However, the 110-Watt GE PA did not like to operate at 20-watts and thus created spurs. Increasing the power to a full 110-Watts made the problem go away.   None of this could have been proven without a 90-minute proof of performance battery of tests by Bryan, W1BRI using some fairly exotic borrowed test gear.  (HP 8712C Network Analyzer and Agilent 4407B Spectrum Analyzer... about $70,000 worth!)