Interesting. The 70V shown in the link is my S/N 156, sitting on the
carpeted floor of my shack after I purged the water system. Still have it,
and it sits in a pod on the operating desk. It can be seen toward the bottom
of my QRZ page.
As I recall from an e-mail exchange with Dick Ehrhorn about 20 years ago,
the 70V was discontinued as an evolutionary change. He indicated that in
today's "run it 'till it breaks" society, folks were more comfortable with
near maintenance-free air cooling. Most appliance operators didn't have
the skills, nor the ambition to learn about the 70V maintenance schedule --
just as I have no longer have the ambition, nor motivation to change my
car's oil in my home garage.
Production of the 70V and 70A lasted two years until ETO introduced the
model 77. The 77 uses an Eimac 8877 which has superior IMD performance over
the air-cooled 3CX1000A7 and the vapor-cooled 3CV1500A7. Although the
air-cooled Alphas are noisier than the 70V, they were deemed quiet enough
that a vapor-cooled version of the 8877 was unnecessary and only a small
market would use it. By 1973, I suspect a vapor-cooled version would have
been much more expensive for Eimac to produce.
The 70V concept did not die because of 3CV1500A7 scarcity. Tube scarcity
occurred after ETO decided not to pursue vapor cooling after the 70V -- and
no other market came in to save it.
Paul, W9AC
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Jim Dawson
Sent: Sunday, February 26, 2017 11:54 AM
To: amps@contesting.com
Subject: Re: [Amps] SS amps watercooling - was PowerGenius XL
I don't know what the "good reason" they stopped the 70V was except maybe
for a shortage of tubes, but I owned and used a 70V for years and loved it.
Never had a problem with it.
Jim - K9DD
----- Original Message -----
From: "Thomas Walsh" <w2co@comcast.net>
To: "Jim Thomson" <jim.thom@telus.net>
Cc: <amps@contesting.com>
Sent: Sunday, February 26, 2017 9:38 AM
Subject: Re: [Amps] SS amps watercooling - was PowerGenius XL
> FYI Alpha did produce a water cooled tube amp back in 70'
> See https://www.alpharfsystems.com/?p=1387
> There is probably a good reason they stopped..
> W2CO
>
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