All,
Just a slight correction on the Cable from the Main Electrical Panel into
the Bedroom. It is a 6/3, 6AWG with L1, L2, N & a Ground wire.
Thank you,
Mike
W5CUL
-----Original Message-----
From: Amps <amps-bounces@contesting.com> On Behalf Of w5cul@sbcglobal.net
Sent: Monday, May 3, 2021 8:26 PM
To: Amps@contesting.com
Subject: Re: [Amps] Alpha 87A Power Supply Question
All,
First Thank You to all who replied!!! I received a lot of replies off list,
too many to answer individually. So I will attempt to answer all the
questions in this one response as best as I can. It does appear that I need
to add a little more detail surrounding my setup as a lot of the questions
were centered around that, and then some about how the Amp was wired
itself...etc. So here goes.
It is a 3/6 cable with a ground wire that runs from the Main Electrical
House Panel to a 4 Pole 50amp Dryer Receptacle in the bedroom. From there
the sub-panel is plugged into the dryer receptable using a 4 Pole Dryer Plug
(L1,L2,N,G) . 2ea 120Vac and 2ea 220Vac Circuits come out of the sub-panel,
each with their own CB. One set of 120Vac receptacles are wired into L1,
Neutral and Ground. The other is wired into L2, Neutral and Ground. The 3
Pole 220Vac Receptacles are wired to L1, L2 and Neutral, more on that later.
One gentleman asked me why 2 independent 120Vac Circuits, why not use just
one 15amp Circuit for all the 120Vac needs? I split out 2ea so that I could
balance the load across L1 and L2.
Another Gentleman discussed a 4 Pole Dryer Receptacle versus the older 3
Pole Receptacle, and that was much appreciated as it jogged my memory of how
I had this setup at my father's house when I was having to take care of him
in Mississippi. I did not run a dedicated 220Vac to the bedroom where I had
a temporary station setup, yet just borowed from his Dryer Receptacle that
was in the laundry room across the hallway when the dryer was not in use,
which was not too often. And his Dryer Receptable was the older 3 Pole
type, L1, L2 and N. And that answers why I wired the 220Vac Receptacle off
the Sub-Panel that was feeding the Alpha at that time the way I did.
The 220Vac line coming out of the Alpha is wired into a 3 prong plug, L1, L2
and a "Green Wire". After re-reading the 87A manual this morning, it does
say that the Green Wire can either be wired to Neutral or Ground, stated in
that order. So, when I wired up the 220Vac Receptable all those years ago
for use in my Dad's house, I wired the 3rd prong to Neutral such that the
Alpha's Green Wire will be connected to such. The manual indicates it can
be wired either way, to N or G. While under use at my fathers house, there
was no low level 60Hz hum in the speakers, but then it was not a true 4 pole
service like it is here now.
After coming back from Mississippi permanently, I just recently started
getting this station back together. Keeping in mind that the Dryer Plug for
the Sub-Panel was setup for 3 Pole and that it can plug into a 4 Pole
Receptacle, I did use that arrangement to temporarily get power to test out
the Alpha after the big move. During that recent testing, prior to having a
dedicated 4 pole 220Vac Line installed into this bedroom, I did not
experience any low level 60Hz hum with the Alpha plugged into the Sub-Panel.
Keep in mind that all of the 120Vac equipment was being powered by the
"Bedroom" Circuit at that time, not this new 4 Pole 220Vac Circuit. So this
is prompting me to rewire the 220Vac Plug and taking the Alpha's "Green
Wire" to Ground as opposed to the Neutral and see what happens.
And lastly, a Gentleman asked me about Station Grounding, is all the
equipment bonded together and is there a Station Ground. There is no
Station Ground at this time, it is floating, or using the Ground that comes
in from the 4 Pole 220Vac Circuit. I plan on installing such this weekend.
Not just a "Ground", but an RF Ground that extends from ground rod to ground
rod that are appropriately spaced from each other and that are bonded by
copper shielding. As for the bonding of the equipment to each other, that
is actually being accomplished by the Coax cabling that interconnects the
equipment. The SO239 connecters are bonded to the equipment chassis, so
when you connect up a Coax from one piece of equipment to another, you are
affectively bonding those chassis together using the ground shielding of the
Coax.
So I think my first step is to re-wire the 220Vac Receptacle that is feeding
the Alpha and see if that helps. If that does not eliminate the hum, the
next is to replace the Caps in the Transformer Line in the Alpha, one may be
leaky as one Gentleman said.
Again, Thank You all for your replies, advice and guidance. I certainly
have some more ideas now and a path to move forward with.
Thank you,
Mike
W5CUL
-----Original Message-----
From: Amps <amps-bounces@contesting.com> On Behalf Of w5cul@sbcglobal.net
Sent: Monday, May 3, 2021 12:26 PM
To: Amps@contesting.com
Subject: [Amps] Alpha 87A Power Supply Question
Good Afternoon Gentlemen,
I have a rather quirky situation and a question about it. I have been
chasing down a low level 60Hz hum I get across my speakers when I plug my
Alpha 87A into a shared A/C Service for the shack. I say shared because I
am referring to a dedicated 6AWG 220Vac line that runs from the Main
Electrical Panel for the house to the shack (bedroom). From there it is
connected to a Sub-Panel that splits out 2ea 220Vac Lines and 2ea 120Vac
Lines all with appropriate CBs. All the 120Vac equipment to include
Transceivers, computers, speakers etc...are powered by the two 120Vac lines.
The Alpha is powered by one of the 220Vac Lines. So as the issue goes, with
all the 120Vac plugged in and powered up, transceiver turned on, white noise
emanating from the speakers, the moment I plug the Alpha 87A into one of the
220Vac sockets, CB turned off, I immediately get a low level 60Hz hum coming
out of the speakers. Since this sounds like a neutral or ground feedback
loop, it prompted me to check the wiring on the Alpha. So I unplug the
Alpha and perform a continuity check from Leg 1 of the plug to the chassis
of the Alpha, Leg 2 to the Chassis and Neutral to the Chassis. As for the
120Vac Legs, there is no continuity to the Alpha Chassis. But there is
direct continuity from the Neutral of the 220Vac Alpha plug to the Chassis
of the Alpha. So the question I have is should the Neutral on the Alpha
plug have such continuity to Chassis Ground, or do I have a bad Capacitor
somewhere in the Alpha? I will say that the Alpha 87A does operate as it
should and does put out full power.
Thank you in advance,
Mike
W5CUL
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