On Fri, 22 Mar 2002 07:45:43 -0500 Pete Smith <n4zr@contesting.com>
writes:
>
> Basically, everyone said that you can just trim back a little and go
> with it. K1VR suggested 1 foot per year stored outside, while others
> said just to look at the end and trim till everything looks clean and
bright.
K1VR: Trim until clean and bright is the best answer. The reason I
suggested one foot per year stored outdoors is that sometimes a ham must
guess about whether he wants to buy some cable and cannot start trimming
back until he finds "clean and bright". For example: You absolutely
positively need 188 feet of hardline. Someone is selling 190 feet, stored
outdoors for 10 years. Should you buy it? No, unless you can trim back to
"clean and bright" and then substitute RG-11 for the now trimmed back,
missing length.
One tip, learned from experience. Don't forget that cable TV hardline is
75 ohms. If you are going to use an asynchronous transformer (normally
attributed to K1XX for the design), you will be adding RG-11 and RG-213
to each end, to start and end at 50 ohms impedance. Thus, you can
tolerate a shorter piece of hardline in between the two K1XX
transformers.
In fact, one of these days I'm going to trim 15 feet of excess hardline
out to my 80 meter verticals, made unnecessary by the presence of the
K1XX transformer out in the field. After all, that' s 15 feet of extra
loss in 0.500 inch hardline at 3.5 MHz . . .
Fred Hopengarten K1VR hopengarten@post.harvard.edu
Six Willarch Road * Lincoln, MA 01773-5105
781/259-0088 *eFax 419/858-2421
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