Hello Jacques,

I believe that the 6K8 and CV1099 are interchangeable.  But, can't swear to it.  However, here are the drawings I just dug up:



Pin-outs look the same to me.

Al

Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/

On 12/20/2022 9:31 PM, Jacques_VE2JFE wrote:

Hi Al,

 

In the R1155, V4 is not a 6K8, it is a Osram X66 (CV1099 / VR99) and this tube cannot behave as a 6K8 because the grid 1 and 3 are interchanged between the two types.

 

73, Jacques, VE2JFE in Montreal

 

De : MMRCG@groups.io <MMRCG@groups.io> De la part de Al Klase
Envoyé : 18 décembre 2022 16:28
À : MMRCG@groups.io; ARC-5 <arc5@mailman.qth.net>; milsurplus@mailman <milsurplus@mailman.qth.net>
Objet : Re: [MMRCG] Hello R1155 Fans

 

Hi Dave,

Thanks for the video.  I don't know much about the LO pulling except from, just now, looking at the schematic.  The cathode and grid-return of the triode section of V4 go directly to ground.  So it's hard to see when the interaction comes in.

The first thing I'd do is swap out V4, a 6K8, in case there is some internal leakage from the AVC'ed signal grid..

A stitched together copy of the N-schematic is attached.

This was another case of the original .pdf's I was working with being locked up so I couldn't extract the images.  However, today there is an easy fix for that:  Printing the file using Microsoft "Print to PDF" gets you an unlocked copy.  Extract the schematic images a .png's and stitch them together using "Image Composite Editor" another free marvel from Microsoft .

Merry Christmas,
Al

Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/

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