I would imagine that inside that piece of PVC pipe is a row of fairly
conventional toroidal cores with a piece of coax running through them. Lots
of places sell them. Several design choices for the mfr in terms of what
material to make the core of, what kind of coax, what dimensions for the
core, how to mount it.
The supplied picture in Japanese provides almost no information on what
those choices are, or the resulting RF performance. It might work well, it
might work poorly, it will almost certainly do something. (probably not with
the bandwidth or performance that the seller might hope, though.
As Tom pointed out, some mfrs claim performance that defies rational
expectation, basing their optimistic estimates on "designed to" or the
results of poor measurement technique. While, as a RF professional, I'd
love to see real, calibrated test data on ham products, I'm also a realist,
and recognize that I don't want to pay for it, so I'm willing to accept
whatever the actual performance is, based on a knowledge of the internal
design (or other factors) and ignore the manufacturer's claims.
There's nothing special, electrical design wise, in most ham products. What
you're really paying for is that someone else figured out which components
to buy, bought a bunch, assembled and (hopefully) tested them. And this is
worth a fair amount. I don't have to stand in the rain at the TRW swapmeet
for 10 years scrounging up parts, agonize about the optimum way to solder
PL-259s, etc., and I can get on with other things that are more interesting
to me, specifically. I have a limited amount of time to spend on ham radio,
so the convenience of preassembled componentry is valuable to me. To
someone else, with different amounts of free time, or with different
interests, a preassembled ferrite toroid stack choke isn't worth it. Heck,
I'll bet there's someone out there who's contemplated making their own
coaxial cable from copper and plastic. I know people who make their own
open wire line and vacuum tubes... more power to them.. it's what makes ham
radio fun and interesting.
To return to the original question that Doc asked, whether the product is
worth the price being charged. It is a very good question, and one that is
impossible to answer with the information given. No information is given
about what's inside the box, no test data or claimed performance is given
(so you can't guess what's inside the box). All you could do is buy one,
with a right of return, try it, and make the decision then.
Jim, W6RMK
----- Original Message -----
From: "doc" <kd4e@verizon.net>
To: <towertalk@contesting.com>
Sent: Sunday, February 20, 2005 7:02 AM
Subject: Re: [TowerTalk] RF Inquiry HI-Q Filter CF5KV?
> So, would it be fair to say that there is no good reason
> to believe that this product will actually have any
> effective impact on rfi, swr, or anything else of
> interest to Hams?
>
>
> >>What are the collective thoughts about the design efficacy
> >>of this device (author's sloppy spelling aside)?
>
>
> --
> Thanks! & 73, doc kd4e
>
> ~\~
> |--------------------|--
> | QRO in WCF! | ||'""|""\__,_
> | _____________ l ||__|__|___|)
> |(@(@)""""""""**|(@)(@)***|(@)
>
> West Central Florida 100% Linux. Suse 9.2
> Halli, Heathkit, Homebrew, SBE, TenTec, Yaesu
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> Linux-Incompatible hardware is defective!
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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