[Amps] IM distortion and such

[Will Matney]

Joe,

Yes, I fully understand this. The Ameritron amp is not a class B amp either. I didn't see a listing included in the PDF for a class AB if I recall. It should be better operating in class AB. The other curves though are for higher plate voltage and currents than listed under maximums. These are for pulse rated, etc. The class B maximums do show though that a drop in plate voltage, and a small drop in plate current (10 mA) betters the IMD performance by 5 dB. It's sure to better it in class AB and A too.

Best,

Will

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

On 6/27/06 at 12:29 PM Joe Subich, W4TV wrote:

>Will, 
>
>The numbers you quote are based on Eimac's suggested operating 
>conditions for a particular class of operation, input power 
>and plate voltage.  The do not necessarily represent the best 
>IMD performance available from the tube.  
>
>The Eimac datasheet is based on the old 1 KW DC input rules. If 
>you look, it is for class B at 1000 W PEP input and 2500 V on 
>the plate. 
>
>The AL-80/SB-1000 is AB2, 2700 - 3000 Volts on the plate and 
>about 1500 watts PEP input.   
>
>73, 
>
>   ... Joe, W4TV 
> 
>
>
>> -----Original Message-----
>> From: amps-bounces at contesting.com 
>> [mailto:amps-bounces at contesting.com] On Behalf Of Will Matney
>> Sent: Tuesday, June 27, 2006 9:07 AM
>> To: amps at contesting.com
>> Subject: Re: [Amps] IM distortion and such
>> 
>> 
>> Tom,
>> 
>> It says it on page two of the Eimac 3-500Z spec sheet. See 
>> the one the link was provided for earlier.
>> 
>> 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.
>> 
>> Best,
>> 
>> Will
>> 
>> 
>> 
>> *********** REPLY SEPARATOR  ***********
>> 
>> On 6/27/06 at 5:46 AM Tom W8JI wrote:
>> 
>> >> They can be used on up in current, say for pulse circuits 
>> >> and RF heating. The 400 mA is the maximum plate current at 
>> >> single tone for minimum distortion. That's for 600 watts 
>> >> PEP useful power each. That's listed in the tables on page 
>> >> 2 or 3 under a class B RF amp.
>> >
>> >Will,
>> >
>> >Where did you get the idea 400mA is a "minimum distortion" 
>> >condition?
>> >
>> >73 Tom
>> >
>> >
>> >
>> >
>> >
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