Jim,
I questioned the LMR400 for an "over-engineered" system, but you already
explained that for some reason it costs less than RG213/U where you are.
(This is a mystery, but I don't live in Canada!)
For an "over-engineered" system, I'd probably use RG214/U. Equivalent
shielding (>90 dB through the HF spectrum), more rugged, will last longer in
many environments. Loss slightly higher than LMR400, but inconsequential
unless you're running many hundreds of feet (difference is only about .15
dB/100' at HF), I'd take it for the increase in reliability. And here in
the States, it's readily found for < $1 ($USD) per foot.
If I were in Vancouver, I'd be tempted to line up some of the materials
which are obviously more costly there and have them delivered to someone in
Seattle, then drive down and fetch them!
73 & happy engineering!
Steve, WB2WIK/6
"If everything seems under control, you're just not going fast enough." -
Mario Andretti
> -----Original Message-----
> From: Jim Smith [SMTP:jimsmith@shaw.ca]
> Sent: Friday, November 22, 2002 5:05 AM
> To: towertalk@contesting.com
> Subject: Re: [Towertalk] Obssessive-compulsive Anal Paranoid Builds
> Over-engineered Roof-top Guy Anchors
>
> Well, I threw this out there thinking that maybe a few people might be
> interested enough to bother wading through it. Seems that some TTers
> can't resist commenting on the agonies of their peers. Summary of
> comments follows:
>
> A mechanical engineer stated that this was the funniest thing he has
> ever read on TT. I believe (and I sure as hell hope I'm right) that he
> meant that he enjoyed the story as opposed to the design being so
> ridiculous that he was helplessly carrried away in laughter by the
> hopelessness of the design succeeeding.
>
> A W0 asked if an intro to a patent attorney would interest me. I can
> only presume that my convoluted description is reminiscent of USPTO
> patent applications. (Actually, I know them to be far worse. "Said
> antenna is revolvably connected to said mast. ") The funny thing about
> this comment is that I am paying the carpenter from some of the money I
> received from a local company for whom I did some patent work. (30,000
> patents reviewed for relevance. Wrote a significant portion of their 80
> page core patent application. Application filed a few days ago with
> USPTO. A substantial part of the reason why the C4 isn't already up
> there.)
>
> A K4 tells me he got LMR 400 for 30 - 35 cents/ft on e-bay. I have
> never bought anything on e-bay (see the word "paranoid" in the title).
> e-bay is in a foreign country. $0.35 there translates to $0.56 here,
> not counting shipping. What happens if the stuff is full of water?
> What recourse do I have? I am very suspicious about dealing with
> unknowns in foreign countries.
>
> A K9 in Florida expressed concern about the lack of attention paid to
> lightning issues. Fortunately for me, lightning simply isn't an issue
> here in Vancouver and can be ignored.
>
> The same K9 expressed concern about the viability of the 1-1/4" tubing.
> Hmmm...... When I wrote the story I realized, for the first time, that
> I had made an assumption about the tubing that I hadn't checked. The
> length of the tubing between the first lag bolt and the shackle to which
> the guy turnbuckle will be attatached is about 18". Didn't seem like
> much to me but didn't do the calculations. I very much appreciate that
> someone would read the story sufficiently thoroughly to notice and,
> having done that, take the trouble to point that potential oversight out
> to me. Thank you Roger.
>
> I don't think I mentioned it in my description but the existing 25 ft of
> tower is, at the moment, self supporting with no guys whatsoever. The
> first 7 ft are rigidly attached to the beefed up building as described
> in a post to TT (Tower Building 201 or How I Beefed Up A Wall To Which A
> Tower Is Bracketed 2002/09/03). We had the biggest wind of, I think, 25
> years a few months ago. Two ft diameter trees laid right over on the
> ground less than 5 blocks away. The top of the tower swayed maybe a
> couple of inches. Be that as it may, the C4 has much higher wind
> loading and the adequacy of the guy anchor tubing needs to be checked.
> If it isn't adequate, well I might go to a higher strength tubing, I
> might use solid bar stock or, I might go to a larger size. In any
> event, I acknowledge that I haven't done my homework on this part but I
> promise that I will.
>
> A WA3 suggested I could pick up another dB if I put the connectors on
> properly. Well, harrumph, I believe I've been putting connectors on
> properly since before he was born. Then again, maybe he knows
> something I don't (an astonishingly large number of people are in this
> category), particularly with respect to LMR-400. Anything different
> about this stuff compared to connecting RG-8 to PL-259s?
>
> Someone who didn't give his call (naughty, naughty, Ken - ham etiquette
> requires calls) wondered why I didn't choose 9913. Apart from local
> availability questions, I was scared off it by a number of posts on TT
> referring to its tendency to suck moisture through the outer sheath
> which would then condense inside. I gather the Brits refer to it as
> "hosepipe". Do a search for 9913 on TT for details.
>
> I really appreciate all the comments/questions. What a marvellous
> resource
>
> 73 de Jim Smith VE7FO
>
>
>
>
>
>
>
> _______________________________________________
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