[Amps] 4CX5000A in common grid circuit

Mon May 6 04:00:00 EDT 2013

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 at kolumbus.fi>
 To: "g8on at fsmail.net" <g8on at fsmail.net>, "amps at contesting.com" <amps at 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 at fsmail.net
 > To: markku.a.oksanen at kolumbus.fi; km1h at jeremy.mv.com; villelintervo at hotmail.com; amps at 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 at kolumbus.fi>
 >  To: "Carl" <km1h at jeremy.mv.com>, "g8on at fsmail.net" <g8on at fsmail.net>, "Ville Lintervo" <villelintervo at hotmail.com>, "amps at contesting.com" <amps at 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 at jeremy.mv.com
 >  > To: g8on at fsmail.net; villelintervo at hotmail.com; amps at 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 at hotmail.com>
 >  > > To: "amps at contesting.com" <amps at 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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