last revised: Friday, December 15, 2006

Some update notes from Rick Zach:

Plan-B was the choice.

Plan-A:     Deploy a split-site 6-meter repeater system       ( original plan )

Split-site pros:
The bottom-line advantage is excellent performance if deployed properly.

A split site repeater system uses one mountaintop for receive and another completely separate site for transmit. In most cases, six meter repeaters need to use "split site" operation because of two key attributes relating to 6-meter duplexers. 

• Due to their size and complexity, six-meter duplexers are hideously expensive.  Considering typical ham budgets, these are rarely used. 
  ($4500 list, $3500 dealer cost).
• If the system does not use a duplexer, using two separate antennas on one tower requires an unmanageably huge vertical TX & RX antenna separation that would be longer than the height of most towers.
• The use of split-site repeaters solves both of these messy problems

Split-site cons:
The downside of split-site repeaters the need to use a 440 link system between the 6M receiver and 6M transmitter that are usually located on separate but nearby mountaintops similar to Belknap and Gunstock.  The split-site challenges are:

• The need to identify two viable sites
• Deal with two benevolent landlords who are willing to support CNHARC from the public service perspective
• The need to gain physical access to maintain what are essentially two separate repeater systems that operate as one
• Increased parts count on antennas and other equipment
  
   

Split-site hardware already obtained at no cost to CNHARC

This is a portable repeater called a GE Custom MVP.  This will provide the 6-meter receiving capability along with the 5-watt 440 link going to the 6-meter transmitter site. This tiny package is completely self-contained, includes a simple repeater controller, and draws so little power that it can run on emergency batteries. In a perfect world, and due to it's small size this would be the ideal Gunstock 6-meter receive site package.  This could be located in the ski patrol shack or Panorama Pub with minimal physical impact or electrical utility drain to the landlord.

Two GE MASTR-II repeaters This is the business-end of the 6-meter repeater system that contains the 6-meter transmitter and UHF link receiving gear.  The bottom box is the 6-meter transmitter and the top box is the UHF receiver.  As a practical matter, the top box is (in reality) a full 440 repeater system so that members with 440 gear can use the six-meter system and six-meter users will also be rebroadcast on 440.  Pretty neat! This complete package will undoubtedly need to be re-installed into a larger rack like the one shown below.

Plan-B    deploy a single-site 6-meter repeater system   

For the economic and technical reasons mentioned above, single-site 6-meter repeaters are somewhat rare.  Due to an incredible find of a 6-meter duplexer at the spring HossTraders 2004, we now seem to have a 6-meter duplexer but this may require a re-thinking on how we deploy the project.

1. No doubt about it, the 6-meter duplexer is HUGE at over 86" high plus the length of the tuning rods!
2. The duplexer will require some metalworking modifications by skilled CNHARC folks.  Other hams who have done this before are willing to tell us how they did it, step-by-step.  It is do-able!
   
    

Single-site hardware already obtained:

Yes, we now have duplicated equipment available to CNHARC so we need to pick and support "the keeper".  Some equipment has already been donated (plan-A) and other equipment will be donated at no cost if that plan is selected (plan-B).
 

	Yes, this is BIG!  Rick, K1RJZ  stands 5' 11" and the duplexer is over 7ft high not counting the tuning rods that will extend another few feet. On the other hand, the 5' 8" GE cabinet installation will remain the same with either plan as the gear inside will be essentially identical. The 440 UHF repeater gear is on the bottom and the 6-meter gear is on top. The reason for the 440 gear is that a 440 control link will be needed per FCC Rules.  Since we already had the 440 repeater donated by channel-5,  the combined 6+440 repeater system is a very small upgrade.  The 440 duplexer area is located right above the power supply on the bottom of the rack.
	Another HossTraders find was this 6-meter dual-dipole "trombone" antenna which side-mounts to a tower.  The previous owner already had it tuned to 53 MHz. Frank, WA1ZDV is checking the resonant frequency of a different and very heavy-duty 6-meter ground plane antenna that was made available to us. It we go with Plan-A (dual site), both 6-meter antennas will be used.   The Plan-B deployment (single site) will use one of the 6M antennas but not both. The UHF repeater system antenna is a rather small Hustler G6-450 which looks very similar to a typical VHF marine antenna.
	This is the NHRC-5 repeater controller that will manage the entire operation. There will be no difference here whether split-site or single-site operation is used. Voice ID may help us "PR-wise" in promoting landlord access to the very best site. Details here

So folks,  there we have it . . .

Plan-A with split-site operation

Plan-B with single-site operation

Not only has the equipment has been obtained, we have both configurations available to us at pretty much no cost.  The UHF PA hardware fixes are already being taken care of by Ed, N1EO.  Rick, K1RJZ is taking care of the system integration and tune-up. Frank, WA1ZDV is checking antennas.  Others with metal working skills may be able to contribute to the six-meter duplexer mods. And of course we need a few fearless tower climbers!

Both Plan-A and Plan-B are do-able from a hardware and technology perspective with the key driver being who can obtain what site or sites on behalf of CNHARC.  We need a "great" site or sites.  Obtaining a site that is "just OK" may defeat the primary project goal of wide area coverage in mountainous areas like the Lakes Region.  One theoretical option may be a solution of using Plan-A with Belknap TX + Gunstock RX or a Plan-B using just Gunstock or just Ossipee. 

At this point we need to seriously explore what sites are available to CNHARC and make a very professional presentation to the prospective landlord(s).

If the absolute best sites are obtained, this system will provide a new and very unique service to the area!
 

last updated: Friday December 15, 2006

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