[Milsurplus] [MMRCG] Hello R1155 Fans

[Gordon Smith]

Here is a link to a restoration of a R1155 where the previous owner had replaced the VR99 tube with a 6K8G. Per the article, this is described as a "Sensible" replacement for the VR99: http://www.chavfreezone.me.uk/t1154r1155/2012/r1155a.html

Just relaying what was said, YMMV. 73, Gordon KJ6IKT

> On December 20, 2022 at 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
> 
>     ARK Sig Block Al Klase - N3FRQ
>     Jersey City, NJ
>     http://www.skywaves.ar88.net/
>     On 12/20/2022 9:31 PM, Jacques_VE2JFE wrote:
> 
>         > > ARK Sig Block
> > 
> >         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 mailto:MMRCG at groups.io <MMRCG at groups.io> mailto:MMRCG at groups.io De la part de Al Klase
> >         Envoyé : 18 décembre 2022 16:28
> >         À : MMRCG at groups.io mailto:MMRCG at groups.io ; ARC-5 <arc5 at mailman.qth.net> mailto:arc5 at mailman.qth.net ; milsurplus at mailman <milsurplus at mailman.qth.net> mailto: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/ http://www.skywaves.ar88.net/
> > 
> >         _._,_._,_
> > 
> >         ---------------------------------------------
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> >     > 




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