[Amps] 8122 and 8072

[Jim W7RY]

Quite a while ago, I was tying to figure out how to get the cooler fins off 
of an 8122 and back onto an 8072. It looks like they are welded onto the 
outer plate structure of the 8122.

They are the same tube with the exact ratings (except for plate 
dissipation).

73
Jim W7RY



-----Original Message----- 
From: Michael Clarson
Sent: Friday, May 09, 2014 12:46 PM
To: Fuqua, Bill L
Cc: amps at contesting.com
Subject: Re: [Amps] Using computer CPU coolers on GI46b triode ?

Bill: Yes -- Familar with the 8072. It was used in a lot of land mobile
radios, conduction cooled. They would run at 100 Watts out. Plate
dissipation was only 100 Watts in the conduction cooled mode. To contrast
conduction vs forced air, the 8122, same tube with forced air heat sink had
a 400 Watt dissipation. The 8072 was a deal in the late 1970s. One could
buy them new via conventional channels for $20. --Mike, WV2ZOW



On Fri, May 9, 2014 at 2:55 PM, Fuqua, Bill L <wlfuqu00 at uky.edu> wrote:

>   I once made a heat sink for 4 6AG7 tubes by drilling out a large block
> of aluminum boring
> holes in it aprox. 1 in dia and using a tungsten tipped saw blade cut
> slots for fins. Worked
> well. Somewhere I have some heat sinks for some 8072's ( 8122 without
> fins) used in
> a 500 watt plasma generators. Some were made of sheet metal, and others
> were machined
> blocks, both were forced air cooled, neither worked very well. The
> manufacturer had to
> can the product. They were not reliable. At that time 8072's were much
> cheaper than 8122s.
>  I would not recommend use of heat pipes like those used in many
> computers. A computer has
> to dissipate much less heat than a power tube.
>
> 73
> Bill wa4lav
>
> _______________________________________
> From: Amps [amps-bounces at contesting.com] on behalf of Joe Subich, W4TV [
> lists at subich.com]
> Sent: Friday, May 09, 2014 2:17 PM
> To: amps at contesting.com
> Subject: Re: [Amps] Using computer CPU coolers on GI46b triode ?
>
> On 5/9/2014 11:12 AM, Carl wrote:
> > Subject: Re: [Amps] Using computer CPU coolers on GI46b triode ?
> >
> > I can easily see boring a CPU sink as a simpler alternative as long as a
> > round silicone rubber chimney isnt required.
>
> That may be possible with an old "block with fins" type heat sink but
> many of the newer ones use a relatively thin plate/heat spreader and
> tubes filled with a heat transfer fluid.  The tubes bend upward to a
> radiator in the normal air flow or with or have a fan mounted to the
> radiator.  Drilling/boring one of those would damage the heat tubes
> and render it useless.
>
> 73,
>
>     ... Joe, W4TV
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