Bob,
I'm sure George will eventually read this. The last time I contacted
George there was some now-forgotten thread being dragged out ( as is usual
the case here), and I in passing, asked him about the 4CX1600B amp that he
constructed as per the Tech Bulletin from Svetlana's website. He said that
the amp is trucking along just fine and has not had any problems with it to
date. I was going to homebrew an amp using one of the popular ceramic style
tubes. The economy of the 4CX1600B made it a pretty good candidate. I then
became a recipient of an RF deck for a pair of 813's and a 4-1000 hulk that
was "modified" to the point of having to be stripped and started over.
Having said that, I haven't heard anything bad about the 4CX1600B other
than the delivery by Svetlana USA.
Did I make the issue clear as mud?? (HI,HI)
73,
Mike(y)
W3SLK
----- Original Message -----
From: Bob Marston <k1ta@contesting.com>
To: <amps@contesting.com>
Sent: Monday, November 27, 2000 11:08 AM
Subject: [AMPS] 4CX-800s vs 4CX1600s
>
> Greetings Steve and Group
>
> Here are my observations on the 800 vs 1600 issue.
>
> First the plate dissipation number speaks to one factor, the ability of
the
> anode cooler to dissipate excess heat at a rate fast enough to keep the
the
> tubes plate seals temperature below the destruction point. That is it !
Ian
> White points out that the 4CX-1600B and the 4CX-1600U while having
> designations that are very similar are quite different tubes. The maximum
> available plate current is directly to the available emission of the
> filament. And as a result is directly proportional to the wattage
> dissipated by the filament, keep in mind that we are talking about the
same
> type filament. (oxide coated filaments have a higher emission level than
> thoriated tungsten) A small tube can be pushed for an 1.5 amps but how
long
> will it last? With this being said the emmission available from 2
4CX-800s
> at 84 watts total filament power is 60% higher than a single 4CX-1600B at
> 52 watts.
>
> Now for the other side. Because 2 tubes can never be exactly identical
this
> configuration will have higher intermodulation distortion products. If
done
> right with tubes that are nearly identical the increase can be limited to
> less than a few db.
>
> The 4CX-1600B with the exception of the Austrailian Emtron design has not
> seen it's way into commercial designs because Svetlana can not provide a
> reliable deliver schedule for the tube. George Daughters has built a
> homebrew amp around this tube and his intial reports were good. He hasn't
> said anything about how the amp has held up in ongoing service.
>
>
>
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