May I please have a copy of pinet4 if possible.
On Mon, 10 Mar 2003 09:11:50 EST RFlabnotes@aol.com writes:
> I have just finished a sequence of updates/enhancements to the Pi
> analyzer program which I have developing. The response to the
> initial version
> was far better than I anticipated, encouraging me to put in a little
> additional effort.
> I took care of a few minor computational glitches which pop up
> and hope I caught all of them. I console my guilt for this with the
> that Mr. Gates's operating system contained well known non-trivial
> errors for
> over 25 years, and he has enough support staff to populate a medium
> size city.
> The new version contains three primary additions: an expansion of
> the circuit
> model to 2 full PI-sections, addition of file librarian for saving
> recalling designs, and explicit calculation of phase delays. By
> going to 2
> sections, it is possible to analyze a wider class of networks. I
> have already
> used it to see where a 2-section PI may be advantageous in certain
> cases of
> amplifier tank circuits. Also, by just omitting the output
> capacitor, it
> reverts to the standard Pi-L, whose superior harmonic suppression
> can be
> viewed in great detail.
> This last week I happened to see another interesting but unusual
> for this type of analyzer (this is happening regularly) which is
> close to
> home, as far as this discussion group is concerned. It relates to
> necessity of keeping the cathode of a GG amp as close to ground as
> (electrically.) There have been numerous comments and much
> discussion related
> to this, because the potential for positive feedback is high at
> frequencies. But how can you actually estimate the actual effective
> Z from
> cathode to gnd, especially if there is a tuned grid network inline?
> you look at the Pi-network ( I am assuming the typical grid matching
> backwards, with the load resistance representing your driver.
> Knowing what
> that driver's 'output' terminals represents is not so easy,
> especially over a
> wide band. But you can easily make a number of guesses, at least
> covering the
> extremes, and see what actually get reflected over to the cathode of
> the amp
> through the grid network. This is the impedance that will control
> the main,
> big feedback loop originating from the feedback capacitance, and you
> will be
> able to detect where potential trouble frequencies might lie.
> The librarian simply lets you save and recall your designs in files
> which can
> name, and recall from a file menu on demand. This beats the hell out
> trying to keep a lot of data in spreadsheet format.
> The phase delay calculations are very useful (mandatory, in fact)
> designing things like antenna phasing networks, line stretchers, and
> networks. I actually included this feature because of an ongoing
> which includes a somewhat complex exercise in phasing and delay
> designs. So now you can get an instant readout of the phase delay at
> point from input to output.
> NOTE: Many people (myself included, up to about 6 months ago) rely
> on the
> data and formulas from ON4UN's LF DXing book, for the design of
> networks. Well, there are some significant errors in that reference
> and I
> have approached both the author and ARRL about making corrections -
> seemed at all concerned. If you need to design a line stretcher,
> some of his
> formulas WILL give you the wrong answers. My program will NOT.
> For those who received a copy from my initial emailing last month,
> you will
> automatically receive the new version via email, and it is now named
> Any new requests are welcomed and the new mailing will go out in the
> next few
> Eric von Valtier K8LV
> Amps mailing list
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