On 4/16/2012 7:30 AM, Jim Lux wrote:
> I think it's in a zone of "cost to build yourself, counting time" and
> "buy retail" where it just doesn't pencil out.
Jim, we're at cross purposes here.
Somehow, you're missing the point that my primary beef with commercial
products is not their cost, but simply that their designs are so bad
that they are essentially useless. The technical basis for this
statement is developed in considerable detail in several pieces that are
on my website.
With almost no exceptions, there are virtually no technical specs on
so-called "baluns" beyond power rating -- the only exception I've seen
is for a few of Array Solutions' chokes, for which impedances at a few
frequencies are published, but they're strings of beads, they aren't
very good chokes. By contrast, the response curves of the W3NQN filters
ARE published, and anyone who has built high performance filters knows
that engineering that goes into building them makes them worth the cost.
Except (possibly) for protection from freeze/thaw cyless, there is no
good reason for a common mode choke consisting of winding multiple turns
of coax through one or more cores to be in a box at all! The "labor"
consists of running the coax through the core(s), and if there are
multiple cores, lashing them together with ty-wraps. If they're on a
wire dipole, or on coax coming from a vertical, you're done. If they're
on a typical beam, the coax at both ends of the choke simply must be
mechanically secured to the boom. The only reason for putting this kind
of choke in a box is so that you can sell it to someone!
The lower cost bifilar-wound chokes I've designed that DO require some
sort of packaging, but I'm not at all convinced that they needs to be in
a BOX. What IS needed is a means of adding SO239 connectors and strain
relief so that they can be patched into an existing transmission line.
My neighbor, W6GJB, who is much better with mechanical design than I am,
worked up a nice method that uses PVC plumbing parts to hold the
connectors.
I'm quite willing to pay good money for good products -- there are two
K3s and two Ten Tec Titan amps on my operating desk in an SO2R setup,
and both have W3NQN filters between K3 and power amp that were purchased
from Array Solutions. Thanks to 40+ years employment in engineering,
technical sales, and consulting, I have a pretty good grasp on the cost
issues you've outlined, and I have no quarrel with them.
73, Jim Brown K9YC
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