Amps
[Top] [All Lists]

Re: [Amps] Anode Impedance of 4-400A

To: "'Phil Clements'" <philc@texascellnet.com>, <Amps@contesting.com>
Subject: Re: [Amps] Anode Impedance of 4-400A
From: "Joe Subich, W4TV" <k4ik@subich.com>
Date: Tue, 15 Nov 2005 19:22:02 -0500
List-post: <mailto:amps@contesting.com>
Phil, 

What class of operation, A, AB1, AB2, B or C and what conduction 
angle if class C?  The 1.8 factor is an averaging factor based 
on conduction angle.  For example, class A will be Ep/Ip while a 
single tube in class B will be Ep/(2*Ip) because the peak currents 
are twice the DC average due to the 180 degree conduction angle.

A typical tetrode amplifier will have a lower multiplication 
factor since it will generally be operated in class AB1 (no 
grid current, longer conduction angle), while most triodes in 
grounded grid will have a higher multiplication factor due to 
the lower conduction angle (closer to class B). 

To simply use 1.8 is close but if the 4-400A is being used as 
a tetrode and grid driven, 1.8 will probably give too low a 
plate impedance ... the multiplier for AB1 is closer to 1.55 
or 1.6. 

73, 

    ... Joe, W4TV 
  
 

> -----Original Message-----
> From: amps-bounces@contesting.com 
> [mailto:amps-bounces@contesting.com] On Behalf Of Phil Clements
> Sent: Tuesday, November 15, 2005 6:40 PM
> To: 'Patti'; amps@contesting.com
> Subject: Re: [Amps] Anode Impedance of 4-400A
> 
> 
> The load impedance of any tube or group of tubes is anode 
> voltage under load divided by total anode current times 1.8. 
> It matters not what the type or brand of the tube(s) are. A 
> single 8877 amp that has 4000 volts on the anode and an anode 
> current of 1 amp will have a plate load impedance of 2222 ohms.
> 
> (((73)))
> Phil, K5PC
> 
> 
>  Subject: [Amps] Anode Impedance of 4-400A
> > 
> > Does anyone know the 'rough' load impedance of a pair of 
> 4-400A's with
> > 3500V on the anode?
> > 
> > In some of EIMAC literature (W6SAI AS-1 Publication), there 
> are tables,
> > which list it as 5000 Ohms.  Is this for one tube, or two?
> > 
> > The 1982 ARRL Handbook contains a design with a pair.  The 
> PI network
> > values listed there, equate to a load of 5000 Ohms, with a 
> Q of about 12.
> > 
> > 
> > I am just trying to cross a few items off of my list.
> > If someone can contact me off list, I would appreciate it.
> > 
> > Thanks
> > Eric Thielking
> 
> 
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
> 
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps

<Prev in Thread] Current Thread [Next in Thread>