[ARC5] Plate impedance...

[WA5CAB at cs.com]

OK.  With reference to the original question (what is the output impedance or 
resistance [and at 7 MC we can ignore the effects of a few uuf and a few nHy] 
of a pair or 1625's [pair assumed, Clarke, since that's what's in a standard 
Command Set transmitter and the maximum CCS and ICAS plate current rating of a 
single 1625 is only 100 mA] operating at 550 VDC and 150 mA), the answer is 
3666.67 ohms (Vp/Ip), as I originally said.  Had the question been "what is the 
optimum (maximum efficiency) load impedance/resistance to hang onto a Class x 
AC Power Amplifier operating at V VDC and I A, then the answer would be 
given, to a first approximation, as below.

Further reading between the lines of the fine print in the quoted article 
leads me to believe that the optimum figure for the Command Set transmitters is 
closer to K = 1.9, because of the low grid drive.

But in any case, the answer to the original question as actually stated has 
nothing to do with AC or DC.  The answer to the intended question (not actually 
asked) does.

In a message dated 12/15/2008 12:00:43 AM Central Standard Time, 
kgordon2006 at verizon.net writes: 
> >On Dec 14, 2008, at 8:59:32 PM, "Kenneth G. Gordon" 
> ><kgordon2006 at verizon.net> wrote:
> >     That is for DC. For AC, one formula used is plate voltage divided
> >     by twice the plate current.
> >
> >I stand corrected.  From he 1989 RAHB, the approximations are:
> > Rl = Vp/KIp where 
> >K= 1.3 for Class A
> >K= 1.5 for Class AB
> >K= 1.57 for Class B
> >K= 2 for Class C
> 
> Thanks, Dennis. I needed those values. I'll put them in my 
> files. Much appreciated.
> 
> 

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480
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