[Amps] Negative feedback passive input tetrode

[Fuqua, Bill L]

   The 30S1 is biased cathode driven 4cx1000a.  The negative feedback is to the control grid and is a voltage divider between plate and control grid. The 30L1 was neutralized so that it would work properly on 10 meters.

It used an air core transformer and variable capacitor between input an and plate. Have to look at the schematic, but the parallel 811A tubes did not work well at higher frequencies.

   Being that I a looking at grid driven it is a bit of a different story. Neutralization of a grid driven amplifier prevents tuned-grid tuned-plate oscillation.

    Yes, the cathode resistor is the easiest method indeed.


73

Bill wa4lav



________________________________
From: RCM <robrk at nidhog.net>
Sent: Thursday, December 14, 2017 2:28 PM
To: Fuqua, Bill L
Cc: AMPS submit
Subject: Re: [Amps] Negative feedback passive input tetrode


> On Dec 14, 2017, at 13:04, Fuqua, Bill L <wlfuqu00 at uky.edu> wrote:
>
>  I just had a thought.
>
> Has anyone see or used negative feedback to better obtain lower IMD in a passive (resistor terminated) input tetrode amplifier?
>
>  Any thoughts or references or experience?
>
> TNX es 73
>
> Bill Fuqua
>
>
> Merry Christmas
> _______________________________________________

What was Collins doing in the 30S1?

I thought they did the same thing in the 30L1, but don’t see any circuit.

I looked at the ‘S1 manual, and see some transformer on the schematic, but have yet to find a description.