[BC] 7/8" vs 1-5/8" line for 2kW FM

[Edwin Bukont]

Brain trust
 
I am trying to decide which direction to advise on in a project.  The question is, do I want to use 7/8" (lower cost) or 1-5/8" (lower loss) for an @ 450-500' run from transmitter shack to antenna.
 
The station is a Class A.  Transmitter can do 3.5kW, so the higher loss of the smaller line is not an issue.  I suspect the smaller line was used originally for several reasons of cost, size (tower load) and maybe to allow a more fringe signal friendly TPO calculation for making up the loss of the line.  Fringe coverage and closer building penetration are important to this project.
 
 The question is, given that 7/8" foam line is now out of production, how much longer do we think 7/8" air line will be available?    I am concerned that continuing to rely on 7/8" is going to present a servicability problem in the future.  That is why, despite the higher cost, I think the lower loss of 1-5/8" line, and the more likely continued availability of the line, make its' cost justified over using 7/8" air line.  Am I incorrect?
 
We are also interested in a used communications shelter of @ 12'-20', used major brand SS transmitter, used 10-15kW single-phase bottled gas generator, 7/8" (STL) or 1-5/8" air line.  The STL transmitter end is a way short tower, so mimimizing Rx loss is important. 
 
We would be interested in @ 450-500'  of used guyed tower, sufficient to support Shively 6810 4 bay or siimiliar, galvanized rather than painted if possible.
 
Thoughts?  Off-list reply is fine
 
Thank you
 

Edwin Bukont CSRE, DRB, CBNT 
V- 240.417.2475; F- 240.368.1265 
Genuine StudioHub+ Dealer