[K4RY] moving the K4RY shack -- again

[Kris Kirby]

On Wed, 6 Jun 2012, John Hung wrote:
> I don't know the constraints yet, but my advice is it is better to 
> first ask for the sky, and be told we have to scale back.  Otherwise, 
> we might miss an opportunity.
> 
> Remember, we are being moved by people who are not radio persons, so 
> the scientific issues are lost on them.

Expensive things like cutting holes in roofs, sealing and so on tend to 
dissuade. Call a local radio shop and explain to them to situation, and 
get them to quote you on removal of the existing antennas and structures 
and re-erection in another location. Oh, and you're going to need new 
feedline$ to replace the one$ that are cut. Simple stuff like RG-213 is 
going for ridiculous numbers today due to the cost of copper. 

LMR400 or any LMR cable is unacceptable; you're in a duplex environment 
(transmitting on one band and receiving on another simultaneously) and 
the resulting signal degradation isn't worth it. LMR coax has a 
dissimilar metals issue between the braid (copper/tin) and the shield 
(aluminum) which produces microscopic diodes between them, and worse, on 
the antenna side of the equation. The result is that ANY RF can excite 
those diodes and create noise, not just the HF/VHF/UHF transmitter 
attached to it.

Get your current loss figures figured out, and use that as a baseline. 
Ask for not less than your current loss. Changing from fifty feet of 
RG-213 to a 150' distance may require half-inch hardline to meet or keep 
the same loss figures. Tessco has half-inch Andrews Superflex at $4.30 a 
foot. And you're going to need connectors, and grounding kits, and 
lightning suppressors (Polyphasers). If you use Andrews heliax and 
Andrews heliax connectors (do not mix heliax connectors between brands), 
Andrews warranties the installation for ten years. Lastly, one must 
supervise the installation labor; 1/2" LDF-4 is $3.00/ft and has a 
minimum bend radius of 5" -- do not exceed that number, or kink the 
coax. If you do, the loss figures go out the window, because the cable 
has to be cut and a splice installed. The splice is typically worth 1dB 
of loss (connectors are .5 dB). Finally, depending on fire codes, you 
may have to buy Plenum-rated cables. Fire-retardant coax is a special 
order item; not typically stocked and may have costs above normal. 
LDF4-50 in fire-retardant is $3.60 from Tessco at this time. 

If the club volunteers to do the labor to a better location, that's 
fine, otherwise bring up history and the long-standing relationship 
between the club and the university. Start digging through the club 
archives for letters from or between the club and the university.

Also, remember to bring up that the new site may require mitigation of 
noise from motor controllers, and cannot share any space with elevator 
equipment per NFPA codes. 

--
Kris Kirby, KE4AHR
Disinformation Analyst