Hi Puck!
> Maybe the Ultimate and SPC were not forerunners of the T but I never saw
> a T until after that Murch Ultimate came out. Other manufacturers came
I will ask around, that is a good question. That is a good way to
find out. Anyone know the history of the general cap-tee match? I
had assumed it predated the Ultimate and SPC since I thought that
both of them touted the bandpass design as desireable over the
cap-tee high pass response. I may be mistaken.
> As to harmonic attenuation, that's hardly a concern these days as most
> rigs are quite adequate in this area. A PI or series inductor L are both
Ah! You don't live here in Irvine for sure. Hi Hi. I have quite
an RF environment here and untuned antennas that are large.
> loss pass in nature and would be better than a T or an Ultimate which are
> both high pass types. The SPC is basically an Ultimate with that third
> cap relocated to give more of a band pass rather than high pass effect.
That is just what I need in most cases. I have very, very strong
stations on the AM BC band, and other hams local to me. I have a
500 foot horizontal loop up in the trees at 50 feet. Most every radio
I put on there dies under the RF that comes off the coax. Even
Kenwood 940's and the OMNI VI crunch to some extent.
> I'm sure you're right about the PI networks in the old tube rigs. I just
> pulled some numbers out of the air. My DX 20 would load power into
> everything from a light bulb, to a window screen to a short piece of wire
> lying on the floor. It even worked quite well on an off-center fed
> dipole I had fed with 75 ohm twin lead.
I remember those days of 75 ohm twin lead! I am sometimes tempted
to just take the pi network components out of my T-60 and build a
little tuner for myself out of them.
Actually, I have been thinking of taking my Heath SA 2060 tuner
and making it a pi net tuner by adding more capacitance to the
variables with switches. Just need to find the QRP Quarterly
article to firm up my own suspicions. Your points about the L
network are well taken, one less component is pretty much one
less component to dissipate RF :-) . I have never used the 238
so I have no experience with them.
Clark
WA3JPG
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