On paper I agree but what about real world? Topbanders seemed to do quite
well with the old 43 mix and the resultant lower impedance.
How much is good enough?
That's a good point.
It seems we tend to go to extremes of black and white and abandon common
sense or reasoning in everything we do these days. That pattern has crept
into some very simple things, perhaps so one answer fits all and no one ever
says "it depends".
I havent changed any of the 43 material in the house since they removed
the noise from each consumer device; some have been in place for over 30
years going back to the prior QTH. As new stuff is added I use 31 mix,
seems to work the same.
I've never been a big proponent of peppering a system with beads, because
often a common-mode series impedance by itself is the least efficient way to
do mitigation. It takes a terrible CM signal levels to cause problems, if
connectors are good and the antenna is a reasonable distance away. If the
antenna isn't a reasonable distance away, then correcting the source is
often better.
It's really a big soup of things, and I think some of this has gone beyond
sensible solutions. I lived years without problems without any ferrite
cores, BUT I grounded feeders sensibly and looked at the system. It all
about ratios and changes in CM impedances.
Once something fixes something, it all seems the same. After all, fixed is
fixed.
Correct me if I am wrong, but it seems we think noise all comes from common
mode and if we add increased suppression things get better and better with
nearly no limits. We become almost anorexic with suppression. What really
happens is once antenna noise dominates, which can even happen without any
suppression at all in many systems, all the rest is a wasted effort. In
other systems once the feedline has reasonable suppression, direct radiation
takes over. We can add a billion beads to the feeder and nothing changes.
There should be more focus on telling people how to find problems, and less
on treating every system the same.
I was visiting a friend and he told me stories about building massive bead
strings a few feet long on Yagi antennas!! Someone should stop the bead
madness enveloping us, and get us back to rational thought.
73 Tom
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Topband reflector - topband@contesting.com
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