[Antennas] Multiple dipole spacing

[Les Severson]

Hi Claus,
Link coupling acts like a transformer with primary and secondary AIR wound coils
in close proximity.   It very simply transforms the low impedance unbalanced coax
output of most transmitters to high impedance balanced output to the ladder
line,  like a balun transformer does, but very possibly more efficient.      I
think Johnson and NyeViking are the only tuners on the used equipment market
nowdays that use link coupling but many hams still use this method with their new
rigs by home brewing their own balanced line tuners or by buying an older Johnson
or Nye Viking  "Matchbox".
Claus,  I'm not an RF. engineer.  hi   I just know is that it works great for a
ladder line or
twin lead feed to an all band single wire dipole.
btw,  These old matchboxes generally work fine on the WARC bands by selecting an
adjacent band on the bandswitch and adjusting the capacitance to match.
I suppose the reason tuners are not made this way anymore is because it is much
simpler
and smaller in size to design a tuner with an unbalanced output and to include a
4:1 torroid balun for matching balanced lines.  (I wish some company would make a
modern link coupled tuner)    Also, most hams want to use unbalanced coax
to feed their antennas anyway... It's much easier to run into the shack.  hi
The trouble
with that is,  now they need a different antenna for each band because with
unbalanced coax feed you need a resonant length antenna for reasonable swr. (
unless they use lossy traps) (or some configuration of multiple wires)

I have seldom used baluns over the past 50 years but when I did,  I liked to use
an air wound balun such as a Heathkit  B-1 broadband balun box.  (still available
sometimes on Ebay auctions)   They seem to work fine but a limited to about 200
watts.       I have to congratulate you though on building your own broadband
baluns.  Sometimes they work good ... sometimes they don't.   I'm going to
address this return letter to the antenna group also so you can get the feedback
on my opinions from more knowledgeable antenna experts...    I'm sure you'll find
some that disagree with me
about efficiency and others who will say I'm too much from the "old school"   hi
73 & Good luck,   Les W�OJH










Claus Waldraff wrote:

> Les Severson schrieb:
>
> > line, tuner &
> > balun for excellent all band results.   I personally  prefer a link coupled
> > tuner such as
> > a Johnson matchbox which eliminates the need for a balun.
>
> Can you point out that a bit more specific to me ?
>
> Why is there no need for a balun ?
> Sounds appealing to me as I had some bad experience with broad band
> baluns (home brewed)
>
> thanks in advance
>
> 73 de Claus