[ARC5] Receivers and mixer noise.

[john rose]

1935 was a watershed year in tube development. I remember reading the League Handbooks from that era. The 6L7 mixer came out and you would have thought from the way they gushed about it, this was the ‘second coming’. A year or two later the 6K8 (also introduced in 1935) was the darling of the Handbooks probably because it did not require another tube, the LO. Right on the heels of this, the 6SA7 (also introduced in 1935) became the darling of the Handbook. The converter war raged, with advocates of pentagrid converters siting lower noise without having to worry about someone moving the grid cap wire and the triode/hexode citing more gain. The 6BA6 put an end to that.

I don’t have a Army/Navy Preferred Types list prior to 1945. It may have come down to the 6K8 was the A/N choice.

A sub for the 6SK7 would be the 6SS7 if you are willing to deal with the filament current issue, there never was a 12SS7. It has twice the gain, half the noise and half the heater draw. 






From: arc5
Sent: ‎Monday‎, ‎October‎ ‎27‎, ‎2014 ‎9‎:‎33‎ ‎PM
To: kgordon2006 at frontier.com
Cc: arc5





The **K8 was widely used in that era.  Has high conversion gain if I  
remember correctly which may have been one reason for It's popularity.

Dennis D.  W7QHO
Glendale, CA

************
On Oct 27, 2014, at 4:22 PM, Kenneth G. Gordon wrote:

>
> Then again, knowing what we do about ARC engineers, perhaps they chose
> the noisy 12K8 for a very good reason.

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