> I'ts been interesting reading the various information and mis-information
> about tuners on here lately.
Thanks, Puck. Very good material. I have only one or two things to
add from my perspective.
> series inductor. In most cases you could match antenna impedances
> ranging from 25 to 150 ohms with these adjustable PI network output
It is interesting to note that a whole lot of the older transmitters
had Pi networks that matched much greater ranges than that, for
example, my Knight Kit T-60 transmitter spec'd out at 10-600 ohms
matching range right from the box.
> improved harmonic attenuation. It was found that the basic T network did
> much the same thing without the need for the more costly dual section
> capacitor so the T's pretty much replaced the Ultimate and SPC.
I was not aware that the Ultimate and SPC were forerunners of the T
match, the Handbook articles seem to indicate that they are an
improvement on the basic T match designs. In fact, I use an old
Murch here, which was the Ultimate design, but then modified it for
the SPC design, to get a better "bandpass" filtering through the
tuner for my receiver front end. It works far better than any T
match I have ever had in my shack (and I have had many, hi hi).
I believe that the SPC design, at the least, gives a narrower
match in freq range (desireable for me) and also better attenuation
both above and below the operating freq (desireable for me), thus
helps my receiver front ends cope with local RF that is not very
close to my received frequency. I really like this feature, and
will not use a standard cap-tee for that reason.
I recall an article in QRP Quarterly last year about measuring
tuner loss, and think it indicated that the well designed Pi
Network may even be a better bandpass / low loss design for
tuners than the SPC, and find that my copy is not in my shack.
Darn.
Clark
WA3JPG
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