[ARC5] Suppressor connection in ARC-5 receivers.

[Bob Macklin]

There was no incentive for ARC to improve the selectivity of the ARC-5 
receivers.

They were primarily AM receivers where critical tuning was not a desirable 
feature.

For long range communication the liaison sets in the bombers were used. And 
they were used in CW mode for that function.

Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"
----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "ARC-5 Mail List" <arc5 at mailman.qth.net>
Sent: Thursday, January 31, 2013 9:42 AM
Subject: [ARC5] Suppressor connection in ARC-5 receivers.


>I have been very curious as to why the engineers at ARC connected the
> suppressor grids in the IF stages of their receivers to the cathodes 
> externally,
> yet used variable cathode bias for gain control in those stages.
>
> When I broached a question about the effect of doing this, no one could
> provide an adequate answer, and I most certainly had no idea either.
>
> Reading a PDF article on the use of diodes found in an article originally
> printed in 73 Magazine back in the 1960s, I found this statement:
>
> "If the suppressor grid in a high-gain pentode is disconnected from 
> ground,
> the tube will oscillate..."
>
> This was followed by a very simple diagram detailing a diode connected
> between the suppressor grid and ground, supplied with a variable, 
> controlled,
> forward-bias, making the stage regenerative, enhancing selectivity, and
> providing a "BFO" for those receivers without one.
>
> From this I inferred that raising the suppressor grid above ground 
> enhances
> gain. Perhaps ARC engineers used this principle?
>
> Kenneth G. Gordon W7EKB
>
> "Courage is being scared to death but saddling up anyway."--- John   Wayne
>
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