> Paul said:
>
> >Seems to me that KW electronics built 4000-5000 of the KW107 EZ matches
> >I owned several of these myself. These were very popular in earlier times.
> >Whats to catch fire !! Maybe you can clarify.
>
> I worked in development at KW Electronics back in the 1970's.....interesting
> job, but financially very unrewarding.
>
> The problem with the Z match is that because the working Q is very dependent
> upon the load impedance, the circulating current can be very high, leading to
> very high voltages. The KW107 EasiMatch had problems with this, which was why
> the KW109 Supermatch was introduced, with larger capacitors and larger gauge
> wire on the coils. A favourite of the KW107 when the KW1000 linear was used
> was for the coils to unsolder themselves and drop into the bottom of the
> cabinet, often with interesting results for the loading cap in the KW1000!
> (The loading cap was a bit marginal for high SWR) If you had the 'magic'
> length of feeder from the KW trap dipole, it could just about get by. Some
> load impedances, even at the 100 watt level, could distress the KW107 ( and
> its earlier counterpart, the KW103). Even the KW109 had some loads that it
> didn't like at high power, and it could arc nicely. Another facet I didn't
> like was the lack of a DC ground on the antenna - I don't like antenna systems
> with no DC ground to drain the static off.
>
> Certainly the Z match was (is?) popular, but one shouldn't be deluded that it
> doesn't have its problems. Unlike the 3 variable T match, you don't get any
> options on trying to reduce working Q. Every time the working Q doubles, the
> circulating current doubles, and the dissipation in the coils goes up by a
> factor of 4. The capacitor voltages go up by a factor of 2 as well. Doesn't
> take much in the way of Q increase to get really high voltages......
>
>
> 73
>
> Peter G3RZP
>
>
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