Bart Kus me at bartk.us
Fri Jun 26 15:29:52 PDT 2020


Upon further review of the mounting hardware, I appear to have 
"misunderestimated" the required Unistrut.  My original thinking was to 
bisect 3 10ft Unistrut sections and use 5ft pieces top+bottom to form 
the 3 required dual-offset arms.  I have since studied the Rohn 45G 
specs, on page 12 here:


The tower is 1.5ft wide, so a 5ft piece of strut would only have 1.75ft 
of stick-out at the very end, which would also need to come in a few 
inches to hold the 2" mast pipe towards the end.  This is packing things 
too tightly.  We need to clear some guy wires up there, and more 
separation in general would be better.  Since we need more stick-out, we 
can no longer simply bisect the 10ft sections, so the count of required 
strut needs to be doubled from 3 to 6 sections.  Furthermore, due to the 
longer stick-out and the requirement for microwave gear to be steady and 
not wobbly, we need to use more rigid Unistrut.  This is available in 
the form of back-to-back welded channels.  At a 2.5ft stick-out for 
example, the back-to-back channels exhibit 2.6x more rigidity than 
single channels.

I have created a new Blyn spreadsheet here:


Which doubles the Unistrut count and also specifies the more rigid 
strut.  The keen-eyed will also notice a change from U-bolts to 1.25" 
pipe clamps.  There is no cost difference there.

I am aware of the thread arguing for the removal of a sector from the 
site, but I don't think the foundations of the arguments are valid, so 
this revised proposal keeps all 3 sectors.

My vote for this revised proposal is: Yea.


On 6/24/2020 11:11 AM, Bart Kus wrote:
> Hello,
> I've put together the spend request to deploy HamWAN coverage to Blyn 
> Mtn:
> https://docs.google.com/spreadsheets/d/12lho76dJUSlXiJRy0UzYlnG66JHQeDzPMBZUxxYs3DY/edit?usp=sharing 
> The site is at (48.006678°, -122.972668°), has a 110ft Rohn 45G tower, 
> will provide a high speed link between SnoDEM and Victoria, as well as 
> providing regional omnidirectional coverage.  Once HamWAN is 
> installed, my understanding is there will be some DMR repeater(s) 
> going on the air there.  There is already a corresponding dish @ 
> SnoDEM for this site, and has been for years.  We've also got 
> confirmation that we'll be able to get a dish installed @ Triangle for 
> the Victoria end.
> 24-hour director voting period for this starts now.
> My vote for this is: yea.
> --Bart

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