[ARC5] [MMRCG] Hello R1155 Fans

[Phillip Carpenter]

A much better equivalent is the 6TE8-GT. These are available in Europe (Italy). The 6TE8 has a much higher transconductance than the 6K8.

Phillip WB4PAC 

Sent from my iPhone

> On Dec 21, 2022, at 12:27 AM, Dave Rossetti <drossetti at comcast.net> wrote:
> 
> 
> According to the Radio museum website, the 6K8 is equivalent to the CV1945, not the CV1099. Here is the link:
> 
> https://www.radiomuseum.org/tubes/tube_6k8.html
> 
> Dave Rossetti
> 410-279-0226 mobile
> 
> On Dec 20, 2022 11:45 PM, Al Klase <ark at ar88.net> wrote:
> 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 at groups.io <MMRCG at groups.io> De la part de Al Klase
> Envoyé : 18 décembre 2022 16:28
> À : MMRCG at groups.io; ARC-5 <arc5 at mailman.qth.net>; milsurplus at mailman <milsurplus at 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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