Dan, The "cheap stuff" would be better labeled "inexpensive," since it is
an excellent and economical transmission line when used properly and kept
clean so that water "beads" up on it. Dry, the 4 models of it range in
loss from .09 to .13 dB loss per hundred feet at 4.0 MHz and in a cloud
burst would indeed be more lossy, but clean, it is a minor inconvenience,
non-existant most of the time.
You could about equal that loss by going to 7/8" hardline, and improve it
with 12 AWG open wire ladderline by perhaps .04 dB or so per 100 ft,
depending on the condition and type of the wire used.
The max. DC resistance of the cheapest Window type out there (18 g solid
30% CCS), measured by your protocol (1000ft), would be about 22 ohms
under perfect conditions, so the 31 ohm figure is reasonable; the largest
size is 14 gauge stranded CCS, and would be about 19.5 ohms, both figures
interesting and some 4 to 8 times greater than bare copper, and useful
for continuity checks, but not for RF at HF.
The 6 dB loss, wet, at 4.0 MHz (assuming the 40 was a typo), is
meaningless without data detail and conditions, and makes one wonder,
...in "addition" to what?
Good luck with your project,
Press Jones, N8UG - The Wireman, Inc., 261 Pittman Rd, Landrum, SC 29356
<Press@thewireman.com> or <orders@thewireman.com>
800-727-WIRE(9473)(sales)
Tech help 864-895-4195, fax 864-895-5811.Full catalog, images,
descriptions, coax specs, ordering, at http://www.thewireman.com and
super deals, specials, close-outs etc., at THE WIRELINE. Check the
CALENDAR to find us at a hamfest!
<Anybody know what the loss of 450 Ohm ladder line at 3.8 Mhz is , the
cheap stuff with square holes like you get at Ham Radio outlet a 500 ft
run. I have measure the DC resistance of 31 ohms for 500 ft shorting
out one end and measuring the loop. I have see test results at 40 Mhz
when wet there a additional 6 db for 100 ft. I replacing mine now with
#12 copper wire and wonder how much I will gain>
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|