Rob, that is all wonderful theory and I have little to disagree about.
But it is simply a dream for 99% of todays hams and it "ain't gonna happen."
Honestly, when is the last time you have personally seen someone build a
link coupled matchbox that worked more than 2 bands?
I built mine in the late 80s and it worked 80 and 40m.
You guys must have a lot better flea markets than we do.
One could NEVER accumulate all the parts for a multi-band link coupled
matchbox.
Perhaps you believe that if you can't build your own link-coupled matchbox,
you should do nothing at all. I don't.
Despite losses in baluns, you can still put out a great signal with a 1:1
current balun in front of a big asymmetrical matchbox, when feeding into an
openwire-fed dipole.
My philosophy here is one should strive to do the best he can.
We don't all drive Cadillac's or Mercedes.
People who can afford (cost and space) multiple antennas should rather go
that route, but if you can only have one antenna and want to work all bands,
then you must be willing to accept compromise. That doesn't prohibit you
from having a good signal - even when using a balun in front of your
matchbox.
73 - Rick, DJ0IP
(Nr. Frankfurt, Germany)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Rob
Atkinson
Sent: Saturday, February 20, 2016 1:39 PM
To: tentec@contesting.com
Subject: Re: [TenTec] TenTec Digest, Vol 158, Issue 27
> And we should also build or own cars because we can all build better
> cars than what GM and Ford (etc.) are selling us. ;-)
>
That's a specious comment. Cars are not antennas or impedance matching
networks.
> Rob, as perfectly correct as your email was, it is no longer a viable
> solution for 90% of the hams out there today. A couple of guys might
> actually manage to find what they need at hamfests, but there aren't
> enough components available to support the masses.
>
You are equating mass production needs with a few people homebrewing.
> To categorically claim all Palstar and all MFJ matchboxes are bad is
> not fair either.
"fairness" is irrelevant. I'm writing about building a better piece of
gear.
By the way, I have seen their products and in my opinion they are poorly
constructed and a ham can do better homebrewing with old parts purchased
second hand. Period.
> They were designed for the kind of antennas most hams use today, not
> for the openwire antennas of yesteryear.
>
Antennas and feedlines have not changed substantially. Not on HF.
> In order to have a good match to an openwire fed antenna, you need two
> things:
> 1). A means of matching
> 2). A means of managing the Common Mode Current (CMC) which sometimes
> can be hefty.
>
> The old Link-Coupled tuners Rob speaks of were great and inherently
> had an advantage in coping with CMC. But there are way now days to do
> it using today's products.
> It is only a huge challenge if you insist on doing it with 1500w.
> It's all about choice of balun and where you physically locate it.
>
Forget baluns. they stink. They become reactive and lossy in 99% of cases.
They are only useful if you have an engineered system with one where they
transform a resistance and for that to happen you have to
stay on one frequency. If a ham does that they are fine. Have a
nice life on your frequency.
Also, network designs have not really advanced apart from superficial
controls, switching relays, motorized additions etc. to create an automatic
tuner. Link coupling is still the best way to go for a transition from
unbalanced to balanced and vice versa.
Further, you imply a high power capability tuner is not necessary for low
power. On the contrary, it is even more important because high power
capability in the entire antenna system including feedline results in better
efficiency and lower loss, which is very important for low power.
> The recommendation for 4:1 balun (as the only balun) under any
> circumstances is bad advice. The balun should always be a 1:1 current
> balun. Of course if you have an older symmetrical matchbox (Johnson
> or Annecke) you don't need any balun at all.
>
This is correct except that with a link coupled design you don't need any
kind of unun or balun ever.
> Using the 1:1 current balun does not prohibit also using a 4:1 balun
> as a transformer, in addition to the 1:1, but it should only be
> switched in when absolutely necessary.
>
Throw it away. You are always better off using a method that does not
require the use of a balun.
Okay enough. I have things to do. You all do what you want and learn the
hard way like I did, I heard that hams today don't care what they have for a
load as long as their "automatic tuner" can keep their plastic radio from
folding back.
73
Rob
K5UJ
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