[Milsurplus] AN/SRT-4A Marine Transmitter

[AKLDGUY]

OK, thanks. I asked because I've used a triode-connected 6AQ5 as the
oscillator in my SCR-183 transmitter (BC-AO-230) model, as recommended by
David Stinson. Stability has not been great; it warbles around the intended
frequency. I considered changing to the 6C4, which I thought would be a
fine oscillator, but David recommended against it.

Neil ZL1ANM

On Fri, 17 Aug 2018, 11:14 AM Kenneth G. Gordon <kgordon2006 at frontier.com>
wrote:

> On 17 Aug 2018 at 7:47, AKLDGUY wrote:
>
> > Interesting observations on beam tubes as oscillators.
>
> Both the Orr and RSGB handbooks make this point also
>
> > What about when the screen is strapped
> > to the plate, effectively turning it into a triode? Or did you mean that
> too?
>
> No. I haven't thought about that part of it.
>
> I was referring specifically to the ECO. The Electron Coupled Oscillator,
> in which the screen
> is supposed to be acting as the "plate" of the the triode formed by it,
> the grid, and the
> cathode.
>
> In the ECO, as you know, the electron stream from that "triode" oscillator
> then couples itself
> to the plate circuit, the screen also acting, more or less, as a shield
> between the grid and
> the plate.
>
> This results in greater stability of the oscillator, and the parts of the
> tube after the screen
> grid essentially act as a buffer amp.
>
> Beam tubes, by their very design, completely negate this characteristic,
> since the
> beam-forming plates couple any signal at the grid (or cathode) of the
> oscillator-proper
> directly to the plate, bypassing any "shielding" effect the screen might
> be able to offer.
>
> Thinking about it now for a bit, triode oscillators are a different
> matter. If a beam-tube was
> triode-connected (depending on the connection: screen to plate or screen
> to grid) there
> would be no ECO action and therefore it shouldn't matter. "Shouldn't", I
> would guess.
>
> Ken W7EKB
>
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