What Rick said, plus: there was a higher power version produced - the KW109.
This quote from G3RZP on another forum:
"The KW109 design is not well suited for really high power - say above
500 or 600 watts. All the Z match type tuners have the problem that the
working Q is totally uncontrolled, so some antennas can lead to very
high voltages and circulating currents. This is why the KW109 was
produced - an uprated KW107/ KW E-ZEE match. These couldn't the handle
the KW1000 linear amplifier output into many loads - the KW1000 has a
pair of 572B with 2400 or so on the anodes. Even the KW109 had problems
when paired with a KW1000 and some antennas.
I was development engineer at KW back in the 1970s, so I learnt some of
the weaknesses in the products."
But, if you don't exceed its capabilities and you can live with swapping
the ladderline between the two sets of terminals, it's OK.
Steve G3TXQ
On 18/02/2011 17:51, Rick - NJ0IP / DJ0IP wrote:
> Tom,
>
> First of all, if I say "yes", Gerry will jump in my case! ;-)
>
> This is a clasical Z-Match - the 2-coil version.
> It is the high power version built about 30 years ago (or more).
> It was designed for openwire from the get go and is pretty good for matching
> typical open wire antennas.
> Like the Viking, it adds selectivity, which is useful for the receiver and
> for suppressing harmonics.
> However with today's good receivers (the good ones), you don't need it for
> that reason.
>
> It has no bandswitch, so that is one less source of trouble.
> Instead it has two sets of connections for the openwire.
> You have to move the feedline back and forth to change from 80/40 and
> 20/15/10.
> However, if you have some wild impedances, it can happen that you need to
> use the other input - generally only true when working 40m or 20m.
>
> It also tunes the WARC bands, matches them quite well.
> Which input 30m uses depends on the antenna. Can go either way.
>
> Sounds good up to this point.
>
> However, when you get impedance extremes, this box has an awful lot of loss.
> They were condemned by many people because of this.
> As long as you know that and make sure your antennas are never more than
> about 1000 Ohms, they work OK.
> You do that by changing feedline lengths.
>
> The answer to your question depends on the price.
>
> A better box in my opinion is the big MFJ Symmetrical matchbox.
> If the auction price comes anywhere close to that, go with the MFJ.
>
> Maybe Gerry has some other reasons why not to use a Z-match.
> I'm sure Steve is quite familiar with it; probably more than the rest of us.
>
> At the end of the day, there is theory and practice.
> I have the low power version, the KW EZEE Match, and I'm not parting with
> it.
> I haven't used it for 20 years, but I'm keeping it as a backup symmetrical
> matchbox.
>
> When I was using it regularly, I used it with:
> - 2x 13m doublet
> - 2x 17m doublet
> - 2x 20m doublet
> - 84m Horizontal Loop
> - 42m Horizontal Loop
> - Vertical Dipole (2x 5m)
>
> Our club(s) turned in lots of good field day results with these antennas
> (especially the loop), using that Z-match.
> I had lots of successful mini-expeditions with these combinations.
>
> There are better matchboxes.
> Some are expensive, others are not to be found (because nobody parts with
> them [think "Annecke"]).
>
> 73
> Rick
>
> -----Original Message-----
> From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
> On Behalf Of tom stewart
> Sent: Friday, February 18, 2011 11:48 AM
> To: TenTec@contesting.com
> Subject: [TenTec] KW 107 Supermatch
>
> Is this a good tuner for balanced lines? Is it worth pursuing?
>
> Thanks- Tom N7ESE
>
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