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Re: [Amps]  4CX5000A in common grid  circuit

To: Markku Oksanen <markku.a.oksanen@kolumbus.fi>, "amps@contesting.com" <amps@contesting.com>
Subject: Re: [Amps]  4CX5000A in common grid  circuit
From: peter chadwick <g8on@fsmail.net>
Reply-to: g8on@fsmail.net
Date: Mon, 06 May 2013 16:31:55 +0200
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Markku,

Once you have the data sheet, it is easy to determine the values of gm, Rp and 
mu from it, especially as mu = gm times Rp.

73

Peter G3RZP


========================================
 Message Received: May 06 2013, 02:43 PM
 From: "Markku Oksanen" <markku.a.oksanen@kolumbus.fi>
 To: "g8on@fsmail.net" <g8on@fsmail.net>, "amps@contesting.com" 
<amps@contesting.com>
 Cc: 
 Subject: RE: [Amps]  4CX5000A in common grid  circuit
 
 Peter
 I am currently at the "station" some 160 km from the nearest large university 
library ( in Helsinki/Finland) that could have the below book or the paper 
could be found. SO, I would really appreciate your effort if you could scan the 
pages for me.
 I will naturally have a further question or two before this all can be 
committed to MS EXCEL.
 I have been playing with formulas that look like the ones below, however Rp 
and mu I have not had to way to estimate, so  results are kind of useless.
 Thank you in advance
 MarkkuWW1C
 
 > Date: Mon, 6 May 2013 10:00:00 +0200
 > From: g8on@fsmail.net
 > To: markku.a.oksanen@kolumbus.fi; amps@contesting.com
 > Subject: Re: [Amps]  4CX5000A in common grid  circuit
 > 
 > Hi Markku,
 > 
 > Have a look at 'Single Sideband Principals and Circuits' by Pappenfus, 
 > Bruene and Schoenike - the 1964 edition. Or better, see if your local 
 > library can get you a copy of the article.
 > 
 > E.L.Chaffee, A Simplified Harmonic Analysis, Rev. Sci. Instr., pp384-389, 
 > October 1936.
 > 
 > If need be, I'll scan the pages from Pappenfus for you.
 > 
 > The main difference between estimating gain in grounded cathode and grounded 
 > grid is that you  need to take into account the negative feedback.
 > 
 > The gain in Class A is given by {RL/(Rp + RL)}{mu + 1} = {RL/(Rp + RL)} 
 > {[gm.Rp] + 1}: in other classes, the variation in gm over the cycle will 
 > have some effect.
 > 
 > For a tetrode or pentode, Rp is fairly high.
 > 
 > 73
 > 
 > Peter G3RZP
 > 
 > 
 > ========================================
 >  Message Received: May 06 2013, 06:51 AM
 >  From: "Markku Oksanen" <markku.a.oksanen@kolumbus.fi>
 >  To: "g8on@fsmail.net" <g8on@fsmail.net>, "amps@contesting.com" 
 > <amps@contesting.com>
 >  Cc: 
 >  Subject: RE: [Amps]  4CX5000A in common grid  circuit
 >  
 >  Hi Peter, All
 >  First, it looks like my posts don't go to the list at all for some reason 
 > but naturally reach direct emails.
 >  
 >  What is mean by muu here is "muu" in the sense it appears in discussion and 
 > formulas for triode GG power gain.
 >  
 >  I believe I am making this a bit more complicated than necessary by trying 
 > to calculate the Tetrode GG power gain from first principles but I would 
 > finally like to understand how this works compared to a simple, high muu 
 > triode in GG.
 >  Not being familiar with the Chaffee analysis, (google helped none), could 
 > you point me to the correct direction here.Going through the motions with 
 > the characteristic curves is not a problem, just an other little interesting 
 > task in this project.
 >  The main reason for GG thinking for this tube was simplicity and perhaps 
 > additional better IMD from inherent RF feedback  in GG setup.  And I have 
 > build grid driven amps and would like to do something different....
 >  Thanks for the help!
 >  MarkkuWW1C
 >  
 >  > Date: Mon, 6 May 2013 00:20:30 +0200
 >  > From: g8on@fsmail.net
 >  > To: markku.a.oksanen@kolumbus.fi; km1h@jeremy.mv.com; 
 > villelintervo@hotmail.com; amps@contesting.com
 >  > Subject: Re: [Amps]  4CX5000A in common grid  circuit
 >  > 
 >  > I'm not sure what you mean here by mu.
 >  > 
 >  > mu is dVp/dVg. Gm is dIp/dVg and ra is dVp/dIp
 >  > 
 >  > so mu is Gm times ra.
 >  > 
 >  > 
 >  > So for any given screen voltage, you can figure the mu, because at a 
 > given grid voltage, Va has increased or decreased (depending on phase) with 
 > control grid voltage and you can then figure out the plate current. 
 > Likewise, you can fix the screen volts and calculate the plate current at 
 > various points in the cycle and then apply Chaffee analysis. 
 >  > 
 >  > OK, it's long and messy but can be done by hand from the characteristic 
 > curves......
 >  > 
 >  > 73
 >  > 
 >  > Peter G3RZP
 >  > 
 >  > 
 >  > 
 >  > 
 >  > ========================================
 >  >  Message Received: May 05 2013, 09:38 PM
 >  >  From: "Markku Oksanen" <markku.a.oksanen@kolumbus.fi>
 >  >  To: "Carl" <km1h@jeremy.mv.com>, "g8on@fsmail.net" <g8on@fsmail.net>, 
 > "Ville Lintervo" <villelintervo@hotmail.com>, "amps@contesting.com" 
 > <amps@contesting.com>
 >  >  Cc: 
 >  >  Subject: RE: [Amps]  4CX5000A in common grid  circuit
 >  >  
 >  >  Hi
 >  >  I have all the components to build the grid supplies to fit the need, 
 > screen to +1600 V if necessary.I know the DC operating conditions need to be 
 > about the same no matter what the RF configuration is.
 >  >  I would still hope to find the a way to calculate the power gain in GG.I 
 > have a hard time finding the a way to translate tetrode (grid to screen 
 > grid) muu to equivalent triode muu.Or perhaps this is a silly question.
 >  >  Thanks
 >  >  MarkkuWW1C
 >  >  
 >  >  > From: km1h@jeremy.mv.com
 >  >  > To: g8on@fsmail.net; villelintervo@hotmail.com; amps@contesting.com
 >  >  > Date: Sun, 5 May 2013 09:41:01 -0400
 >  >  > Subject: Re: [Amps]    FW:  4CX5000A in common grid  circuit
 >  >  > 
 >  >  > That is a typical British understatement (-;
 >  >  > 
 >  >  > But also typical of many European signals.
 >  >  > 
 >  >  > Carl
 >  >  > 
 >  >  > 
 >  >  > 
 >  >  > 
 >  >  > >
 >  >  > > The G2DAF configuration has had, over many years, a very poor 
 > reputation 
 >  >  > > for producing broad signals.
 >  >  > >
 >  >  > > 73
 >  >  > >
 >  >  > > Peter G3RZP
 >  >  > >
 >  >  > > ========================================
 >  >  > > Message Received: May 05 2013, 11:07 AM
 >  >  > > From: "Ville Lintervo" <villelintervo@hotmail.com>
 >  >  > > To: "amps@contesting.com" <amps@contesting.com>
 >  >  > > Cc:
 >  >  > > Subject: Re: [Amps] FW: 4CX5000A in common grid circuit
 >  >  > >
 >  >  > > Markku,  Have you given a thought for g2daf -configuration tog serve 
 > your 
 >  >  > > purposes ? http://www.g4dmp.co.uk/g2daf-lin.pdfSM2CEW describes his 
 >  >  > > implementation with QBL5/3500 http://www.sm2cew.com/ampli.html  
 > Ville 
 >  >  > > oh1jd
 >  >  > >
 >  >  > >
 >  >  > > _______________________________________________
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 >  >  > >
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