[Boatanchors] 8122 Suitability/Selection (was: 6146 discussion on )

[Glen Zook]

Hoping not to be attacked!  The 8072 is basically the same tube as the 8122 EXCEPT that the 8072 was designed to be used in cavity type 450 MHz amplifier designs.  As such, there is no heat sink on the tube.  It is possible to fabricate a suitable heat sink which allows air cooling of the tube so that I can be used in place of the 8122.  Also, in some cases, a heat sink from a defunct 8122 can be used.

Whereas the 8122 tubes are both expensive and hard to find, the 8072 tubes are plentiful and relatively inexpensive.  This is because Motorola, as well as other commercial two-way manufacturers, extensively used the 8072 in their 450 MHz base station units and in a relatively few mobile units.

Although I do not have any equipment that uses either the 8122 or the 8072, I do have a number of the 8072 (mostly brand new, a few used) that I acquired the tube stock from a large, self maintained (over 300 base stations and 3000 mobile units), that went to an 896 MHz trunked system a number of years back.  Most of the tubes were made by RCA.

If someone wants to adapt the 8072 tubes I can probably be traded out of some of the 8072 tubes.

Glen, K9STH

Website:  http://k9sth.com


--- On Wed, 7/6/11, D C *Mac* Macdonald <k2gkk at hotmail.com> wrote:

Might I ask how Burle 8122s can be correctly chosen for use in the National NCL-2000 amp?
 
I have previously been advised that original NOS RCAs are no longer available at decent cost.