[Amps] Aplha 91b

[R.Measures]

On Jan 10, 2005, at 9:29 AM, Will Matney wrote:

> I'm with Rich. I'd like to see the 4CX800 autopsied to see it's faults 
> or good points. Since this tube is becoming one of the most popular 
> amateur tubes out, this would be a good thing for all I would think. 
> Since Rich has done it before, and knows what to watch out for, he 
> would be the one to do it.

Also, my cousin Virginia Ann is a county coroner.
>
> Will
>
>
> On Jan 10, 2005, at 1:46 AM, Fortra wrote:
>
> > Hi Rich,
> >
> > the Alpha 91b being produced in Bulgaria used GU74B or 4cx800.
>
>
> Good point, Nermin.  The last I heard, the 91B used 2, 4cx800As.  If
> the 4cx800 uses a gold-plated grid, the problem could be gold migration
> to the oxide cathode.  If the grid is not gold-plated, perhaps the
> cathode is getting tired,
> -  If anyone has a kaput 4cx800 that they would like to donate, I would
> like to autopsy it to find out out what happened and post JPGs of the
> guts on my Web site.
>   cheerz
>
> > What are the contents and materials used in Russian tubes, i do not
> > know!
> >
> > Regards,
> >
> > Nermin S58DX
> > ----- Original Message ----- From: "R.Measures" <r at somis.org>
> > To: "Helmut (DF7ZS)" <hm at df7zs.de>
> > Cc: <amps at contesting.com>
> > Sent: Monday, January 10, 2005 10:38 AM
> > Subject: Re: [Amps] Aplha 91b
> >
> >
> >> On Jan 10, 2005, at 1:25 AM, Helmut (DF7ZS) wrote:
> >>> Hi there.
> >>>
> >>> I had some problems with my Alpha 91b yesterday.
> >>> Maybe somone can have a good guess based on the symtoms I had:
> >>>
> >>> 10m band. Tuning with 10w resulted in about 800w out - as usual.
> >>>
> >>> 30-60w input resulted in solid 1k out - I remember it was more 
> before
> >>> ???
> >> Your 8874s may have gold contamination on the cathodes.  The gold
> >> comes from the grid-plating and gold poisons emission, so P-out
> >> drops.  However, the problem can usually be corrected.  Do you have
> >> access to a high-pot tester?
> >>>
> >>> I tried to make the fine tuning with 70w carrier - did that before 
> -
> >>> but
> >>> the amp imidiatly went on "FAULT" !
> >>>
> >>> The SWR was perfect on 10m - same results on 15m as well.
> >>>
> >>> On 20m it produced some more output, but also here I was not abel 
> to
> >>> get
> >>> the red 1.5k LED to lit - as it usually does on all bands. :-( Also
> >>> 75w
> >>> carrier results imidiatly in "FAULT" ....
> >>>
> >>> I did not have a dummy load for high power available for any 
> further
> >>> testing.
> >>>
> >>> The IP did not WENT over 1A before the fault came.
> >>>
> >>> Could it be that one tube is down ?
> >>>
> >>> 73sss
> >>>
> >>> Helmut
> >>>
> >>> www.df7zs.de
> >>> www.skydive-video.de
> >>>
> >>>
> >>> _______________________________________________
> >>> Amps mailing list
> >>> Amps at contesting.com
> >>> http://lists.contesting.com/mailman/listinfo/amps
> >>>
> >>>
> >> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
> >> _______________________________________________
> >> Amps mailing list
> >> Amps at contesting.com
> >> http://lists.contesting.com/mailman/listinfo/amps
> >>
> >
> >
> >
>
> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>
>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org