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[Amps] New PINET Software

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Subject: [Amps] New PINET Software
From: nospam4me at (skipp isaham)
Date: Fri Mar 14 22:34:55 2003
May I please have a copy of pinet4 if possible. 

On Mon, 10 Mar 2003 09:11:50 EST writes:
> I have just finished a sequence of updates/enhancements to the Pi 
> Netwotk 
> 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 
> ocassionally, 
> and hope I caught all of them. I console my guilt for this with the 
> knowledge 
> 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 
> and 
> 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 
> application 
> 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 
> the 
> necessity of keeping the cathode of a GG amp as close to ground as 
> possible 
> (electrically.) There have been numerous comments and much 
> discussion related 
> to this, because the potential for positive feedback is high at 
> unexpected 
> frequencies. But how can you actually estimate the actual effective 
> Z from 
> cathode to gnd, especially if there is a tuned grid network inline? 
> Answer: 
> you look at the Pi-network ( I am assuming the typical grid matching 
> circuit) 
> 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 
> of 
> trying to keep a lot of data in spreadsheet format. 
> The phase delay calculations are very useful (mandatory, in fact) 
> for 
> designing things like antenna phasing networks, line stretchers, and 
> delay 
> networks. I actually included this feature because of an ongoing 
> project 
> which includes a somewhat complex exercise in phasing and delay 
> network 
> designs. So now you can get an instant readout of the phase delay at 
> any 
> 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 
> phasing 
> networks. Well, there are some significant errors in that reference 
> and I 
> have approached both the author and ARRL about making corrections - 
> neither 
> 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 
> PINET4. 
> Any new requests are welcomed and the new mailing will go out in the 
> next few 
> days.
> Eric von Valtier K8LV
> _______________________________________________
> Amps mailing list

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