[Elecraft] KAT500 Remote Version

[Wes Stewart]

Semantics.   When I say, "It's not necessarily a good one", I mean that just because a match is achieved, it doesn't mean that one should accept the situation.  Even though the L-network offers the lowest loss (it doesn't always) it doesn't mean it is "low loss", in fact the loss can be quite high.  A simple change in transmission line length might be beneficial. 

I can demonstrate that two L-networks in series, using the same component unloaded Qs, can offer (very) slightly lower loss that a single L-network doing the same transformation.  It's often assumed, incorrectly, that the fewer components, the better.  Not true.

--- On Thu, 9/20/12, ab2tc <ab2tc at arrl.net> wrote:

From: ab2tc <ab2tc at arrl.net>
Subject: Re: [Elecraft] KAT500 Remote Version
To: elecraft at mailman.qth.net
Date: Thursday, September 20, 2012, 4:58 PM

Hi,

That's not true. The L network's only solution is the lowest Q possible,
meaning it will have the lowest tuner loss possible and the widest
bandwidth. And if the capacitor and inductor steps are made small enough, a
1.0:1 solution is always possible. The fact that many tuners give up once
the SWR is below 2.0 or 1.5 is merely a shortcoming in their tuning
algorithms. I am having high hopes for the KAT500. Is anything known on how
many bits of L and C resolution is there?

AB2TC - Knut


Wes Stewart wrote
> What Don says is true as far as it goes.  The L-network tuner has only one
> solution, but it isn't necessarily a good one.
> 
> Way back in 1998 when correspondence was via typewriter and snail mail, I
> went around with Dean Straw, N6BV, then Editor of the ARRL Antenna Book,
> about tuner losses.  This was in conjunction with the editing of my paper,
> "Balanced Transmission Lines in Current Amateur Practice" that appeared in
> the Sixth Edition of the ARRL Antenna Compendium.
> 
> Remarkably (coincidence I'm sure ;) it wasn't long before favored authors
> were contributing articles to QST about how to measure tuner losses and
> TLW was written.
> 
> Tuner and line losses really do matter.
> 
> Wes  N7WS