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Re: [Amps] IM distortion and such

Subject: Re: [Amps] IM distortion and such
From: "Will Matney" <>
Date: Tue, 27 Jun 2006 14:44:18 -0400
List-post: <>

No, your not showing everything I said. It does in fact mention "Two-Tone DC 
Plate Current 280 mA" It lists it in the same place with two different currents 
that would cause the same result (with single tone). That would be the only 
reason to place both under the same title. Though this is for class B, I said 
in a later e-mail that I know IMD would be better under class AB or B. Actually 
the IMD shown drops 5 dB by dropping the plate voltage and the plate current a 
small amount under another reference in the spec sheet before this.

For some odd reason, during the last 3-4 days, my mails to this list are not 
posting as soon as I send them. It is like they are being delayed by a few 
hours sometimes before they are posted. Some of these reference mail I have 
sent but hasn't been posted yet.

Again Quote;

RF Linear Amplifier 
Grounded-Grid, Class B

Maximum Ratings

Typical operation (Minimum distortion products at 1 KW PEP input)**
DC Plate Voltage 2500V
Zero Signal DC Plate Current* 130 mA
Single-Tone DC Plate Current 400 mA
Single-Tone DC Grid Current 120 mA
Two-Tone DC Plate Current 280 mA
Two-Tone DC Grid Current 70 mA
Peak Envelope Useful Output Power 600W
Resonant Load Impedance 3450 Ohms
Intermodulation Distortion Products -33 dB

*Approximate Value
** Measured Data From A Single Tube

End Quote

Better IMD was obtained by lowering the plate voltage under "(Minimum 
Distortion Products)" at -38 dB, 500W, and at 2000 Vdc.



*********** REPLY SEPARATOR  ***********

On 6/27/06 at 2:22 PM Tom W8JI wrote:

>> Tom,
>> It says it on page two of the Eimac 3-500Z spec sheet. See 
>> the one the link was provided for earlier.
>Single tone carrier level has absolutely nothing to do with 
>operation in a different set of conditions such as two-tone 
>modulation at a different anode voltage, bias, and power 
>level. You are reading more into the data sheet than it is 
>For a given set of tuning conditions (load line) a person 
>can make the single tone level any level he wants by varying 
>drive and the two-tone test will remain the same as long as 
>the two-tone power level isn't changed. Single tone and 
>two-tone are two totally different conditions, and as the 
>data sheets say other operation is permissible.
>Two other random people besides myself have now posted that 
>the did the equivalent of a transfer function (which is what 
>really measures linearity) and both posted the best 
>linearity when the steady-state loadline was established at 
>about 550mA. Actual performance under one set of conditions 
>cannot be determined by extracting data from a test under 
>totally different conditions.
>73 Tom 
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