Especially Motorola used the 8072 extensively in their 450 MHz base stations
and in a few mobile units. I still have a number of the tubes, brand new, that
I acquired when I got the tube stock and several pieces of test equipment from
a very large private two-way radio system that was "self maintained". That
system went to a 896 MHz trunked system that was maintained by the manufacturer.
Glen, K9STH
Website: http://k9sth.com
On Saturday, May 10, 2014 9:33 AM, Carl <km1h@jeremy.mv.com> wrote:
Yep, it requires some machine tools to do it neatly. The 8072, 8121, and
8122, and a few variants, are the same basic tube.
The 8121 with vertical grooves machined in also do a good job in the
NCL-2000 and are becoming more available as equipment and spares are being
retired.
They are also a same socket swap and air flow compatible into a MLA-1250 and
2500 if you want to make the PS changes and swamped grid input as in the
NCL-2000.
Carl
KM1H
----- Original Message -----
From: "Jim W7RY" <w7ry@centurytel.net>
To: "Michael Clarson" <wv2zow@gmail.com>; "Fuqua, Bill L" <wlfuqu00@uky.edu>
Cc: <amps@contesting.com>
Sent: Friday, May 09, 2014 10:48 PM
Subject: [Amps] 8122 and 8072
> 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@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@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@contesting.com] on behalf of Joe Subich, W4TV [
>> lists@subich.com]
>> Sent: Friday, May 09, 2014 2:17 PM
>> To: amps@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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>>
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