While I was president of Alpha/Power and involved in repair of
Alpha 77 amps I asked Dick Ehrhorn why he had designed the
amps with only a 3-wire AC connection and with a 120 VAC blower
since this design made the amp much more difficult to use
in foreign countries that have 220-only service. (If you insist on
using a 120 VAC blower at least design the transformer so that
the primary can be used as an autotransformer to power the
blower.)
Dick was quite candid about his answer saying that he just didn't
know any better at the time. Pointing out the difference between
an electronics engineer and an electrician/electrical (power) engineer.
I truly appreciate candor. In the early days of microprocessors
(S-100 bus and CP/M and 8080s) Dr. Godbout brought out an
8K Basic on ROM (a bank of 1702s on its own board, if I recall)
This seemed like a major breakthrough since it obsoleted the
requirement of loading 8K Basic from the paper tape reader which
took about 30 minutes each time you turned on your computer.
But running Basic from ROM rather than RAM seemed like it
might be a bit slower--so I called him and asked him just how
fast his Basic ran from ROM. His answer was, "Its slower than
hell!" That sort of candor and honesty with no marketing hype
impressed me and it still does. Tell me what your product will
do AND WHAT IT WON'T DO and I will make the decision based on
proper information and I will be a good customer. Hide shortcomings
from me, only to be discovered after I buy your product then I won't
be back--unless you have me by the short hairs--like Microsoft!
73--John W0UN
At 08:10 AM 12/3/2003, Paul Christensen, Esq. wrote:
"NEVER 'consider' or tie neutral to ground. They are NOT the same....
Neutral carries current by design, the ground should never carry current
unless there is a fault."
An excellent point Bill. All too often, folks use a neutral as a ground. I
suspect it stems from the fact that neutral is tied to the Xo terminal
ground point within the distribution panel.
I have recently been engaged in several debates with engineers over Alpha's
use of a common ground & neutral in their 77-series amplifiers. Alpha uses
a single terminal for ground and for a current carrying 120VAC neutral for
its blower. A simple jumper cut on the Cinch-Jones power plug corrects the
problem, but it requires the poroper electrical distribution with the use of
four-wire service (Line-N-Line-Ground). So, I decided to run new four-wire
#8AWG service when I moved into the new house a couple years ago. Now, if a
neutral fault occurs at the distribution panel, I do not have to worry that
the amplifier case, coax connections, etc. will cary the current for the
blower. In retrospect, Alpha should have used a 220/240VAC blower in the
first place. This would have allowed the use of the traditional 3-wire
(Line-Line-Ground) service.
An Alpha 77-series amp configured for 220/240VAC service and fed with
anything but four-wire service with the appropriate detachment of neutral
and ground at the power plug is an electrical no-no.
-Paul, W9AC
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