[Milsurplus] [MMRCG] Hello R1155 Fans

[Gordon Smith]

Okay, a little more info. Per the Linked page, Mullard classifies the 6K8G and VR99/X66 as the same tube: https://mullard.org/products/6k8g-brimar-arth2-vr99-vr99a-ech35-x65-x66-za5307-cv1193-cv1944-for-marconi-cr100-r1155-r1297-ws19-zc1-r103-r208-r206-dst100-358x-pcr-r1475

This page also cross references the two tubes: http://www.r-type.org/exhib/aaa0680.htm

73, Gordon KJ6IKT


> On December 21, 2022 at 12:47 AM Gordon Smith <gfsmith at cox.net> wrote:
> 
>     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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