SV: SV: [AMPS] Final..

[measures]

>Rich I understand you should take another glance into your old ARRL SINGLE
>SIDEBAND handbooks and learn a little more on the 3/2 law by Child and
>Langmuir . One good article is W6SAIs "Intermodulation distorsion in Vacuum
>Tubes".
>
>You say: "The good news is now you probably know that grid-current in
>grid-driven 
>config. produces distortion". My good news are: it is  true unless you swamp
>your input with a low impedance load. Up to the point the grid starts to
>draw grid current in an AB1 stage 

€  grid current is not allowed in AB1. 

> very little power is drawn from your
>driver. But as soon as there is grid current your driver has to deliver
>power, of course. 

The tube consumes  virtually no driving power in Class AB1 because 
grid-current does not flow at any time during the cycle.  .  

>If your drivers regulation is poor to this varying load,

>  There is no varying load.  The load is the grid-terminating R, which is 
fixed.  .  
>you get flat topping unless you use a swamping resistor across the varying
>grid load. According to Warren Bruene W0TTK, in  another article in this
>ARRL SSB handbook, your swamping resistor should absorb 10 times the power
>the grid consumes. 

I do not agree.  In AB1, the grid looks like a capacitor.  

>He talks about some other ways to solve the problem but
>personally I consider the ACOM solution to use a 50 ohm dummy load at the
>input a better one. This old EIMAC idea from 1957 and another one from an
>old application note on the 4CX600, is an excellent way to get good
>linearity and stability. The 4CX600 used undecoupled cathode resistors to
>develope negative feedback and better linearity. As a side effect ACOM got a
>much simpler input circuitry as well.

There is no way to have a good input match on 20m - 10m without tuning 
out the grid reactance with a roller inductor and Bruene neutralization 
bridge.  
>
>So, Rich show your teeth and take another dive into the physics of the
>electron flow of in vacuum tubes and return for a moment to the childhood of
>Ham SSB in these old ARRL SSB handbooks.
>
cheers, Hans
>
>
>
>
>
>----------
>>FrÂn: measures <measures@vcnet.com>
>>Till: "sm5ki" <sm5ki@algonet.se>, "Lamb" <k7fm@teleport.com>, "Lars Harlin"
><harlins@swipnet.se>, "AMPS" <amps@contesting.com>
>>Ÿmne: Re: SV: [AMPS] Final..
>>Datum: s–n 2 jan 2000 23.49
>>
>
>>>
>>>Thanks Colin! I am really sorry that I started this crazy discussion on the
>>>DAF. If I only had known........
>>>
>>The good news is now you probably know that grid-current in grid-driven 
>>config. produces distortion.
>>Presumably, you are now aware of the 3/2 power law. 
>>In my opinion, this has been a useful discussion.  
>>
>>cheers
>>
>>-  Rich..., 805.386.3734, www.vcnet.com/measures.  
>>
>>
>


-  Rich..., 805.386.3734, www.vcnet.com/measures.  


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