[Boatanchors] Is 4657 same animal as the 8072?

[Carl]

I never saw a GE manufactured 8072, maybe they private labeled ones from 
RCA.

The tube had some internal changes in the late 60's to mechanically 
stabilize the screen so that may have caused some change in the parasitic 
frequency.

With 6-8 UHF Master Pro's running in the trailer out back for almost 15 
years they were extremely reliable for tube technology. All the repeaters 
here now are Kenwood and Icom.

Carl
KM1H


----- Original Message ----- 
From: "Rod Hogg" <revcom at wbsnet.org>
To: "'Drew P.'" <drewrailleur807 at yahoo.com>; <boatanchors at mailman.qth.net>
Sent: Tuesday, October 20, 2009 11:39 AM
Subject: Re: [Boatanchors] Is 4657 same animal as the 8072?


Didn't Motorola spin off the semi division, in 2004, formed Freescale
Semiconductor LLC? They then sold themselves to the Blackstone Group in
2006, is privately held now.

On the 8072, GE used them in their MASTR pro series UHF transmitters. We
used a lot of them in control stations and some mobiles. They had a massive
heat sink that was also the PA coil. The tubes were also used in EF Johnson
949 UHF repeaters, I think were designed and maybe built by COMCO. Johnson
was having a hard time getting FM to work for them.

The 8072's originally used in the GE equipment I think were built by GE but
later we got RCA tubes.  They did NOT work right.  Had a mod that came out
where you removed a tab or two on the screen bypass capacitor ring to "tame"
them down, had a parasitic oscillation if I remember right.

Rod
KØEQH



-----Original Message-----
From: boatanchors-bounces at mailman.qth.net
[mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Drew P.
Sent: Monday, October 19, 2009 10:02 PM
To: boatanchors at mailman.qth.net
Subject: Re: [Boatanchors] Is 4657 same animal as the 8072?

David Hollander wrote:
Message: 1

"Their are an awful lot of ex-Motorola people around. I spent 27 years in
Discrete Semiconductors (Power transistors, Power MOSFETs, Rectifiers
and RF power transistors) here in Phoenix. Sadly the company is in a
death spiral and has been for the past 10 years. Motorola was the
largest employer in the state of Arizona for many years with a peak of
close to 30k employees. Their might be 100 people left working for the
company here."

>From your perspective, how does Moto's spinoff of their semiconductor
division to ON Semi figure in?

Drew







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