[Amps] Tuned Input - IMD and efficiency

[R L Measures]

On Aug 8, 2006, at 5:08 PM, k7rdx wrote:

> Phil&Group...That`s a very effective solution for the big tubes  
> when running
> 5+kv, adding a supressor to the cathode side tamed my pair of 4x1`s  
> running
> 6700v. I seem to remember posting this some time ago..Some of the  
> older ARRL
> Handbooks recommended this method to help tame the larger glass
> tubes.And,BTW,I didn`t use nichrome,just good old silver plated  
> copper..Jim,
> K7RDX..

Nickel-chromium (resistance) wire is like copper wire with the  
resistor built in.

“The combination of both resistance and inductance is very effective  
in limiting parasitic oscillations to a negligible value of current.”

- -  F. E. Handy   1926 Radio Amateur's Handbook



> ----- Original Message -----
> From: "Phil Clements" <philc at texascellnet.com>
> To: "'Steve Thompson'" <g8gsq at eltac.co.uk>; <amps at contesting.com>
> Sent: Tuesday, August 08, 2006 3:46 PM
> Subject: Re: [Amps] Tuned Input - IMD and efficiency
>
>
>>
>>> As an aside, adding some capacitance with low inductance leads from
>>> cathode to grid won't only help linearity/efficiency, it might  
>>> improve
>>> vhf stability too.
>>>
>>> Steve
>>
>> A trick my Elmer showed me many years ago on a 4-1000A was to put  
>> a 25pf
> cap
>> in series with a 10 ohm resistor from each filament pin to chassis  
>> ground
>> using short leads. This really tames this savage beast, and is really
>> effective when running >5 kv on the anode. We are talking grounded  
>> grid
>> here, with the grid and screen strapped to chassis ground. This  
>> really
>> settles things down on a 4X1.
>>
>> (((73)))
>> Phil Clements, K5PC
>>
>>
>>
>>
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R L MEASURES, AG6K. 805-386-3734
r at somis.org