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Re: [TenTec] Corsair II buzz

To: Gary@doctorgary.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Corsair II buzz
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Thu, 02 Apr 2009 18:13:17 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Gary Smith wrote:
> Thanks 
> I have noticed the "buzz" on several different power supplies 
> including a deep cycle battery. It's definitely not a hum but sounds 
> like something with odd harmonics, a definite buzz.
The most common source of "buzz" consists of "triplen" harmonics of the 
AC power line, coupled  from the  3-phase  power line that is probably 
providing your residential service.  See my recommendations for bonding 
together the gear in your station to kill this noise. Triplen harmonics 
are harmonics whose orders are divisible by three -- 180 Hz, 360 Hz, 540 
Hz, and so on.

http://audiosystemsgroup.com/RFI-Ham.pdf   and

The first one is a tutorial in text form that covers a lot of material, 
including this. The second is a Power Point that covers much of the same 

My solutions are very simple and inexpensive, and don't involve going 
inside the radio.

 These harmonics are produced in power systems by current flowing at the 
peak of the cycle to charge the input filter capacitors in electronic 
power supplies (both linear and switchers).  Most current cancels in the 
neutral (and in the green wires) of 3-phase systems, but triplen 
harmonics add. So-called "high leg Delta" power distribution is widely 
used in neighborhoods where a few small users need 3-phase but most need 
120/240V. It's a 240V Delta, but with one side being center-tapped to 
feed residences. This triplen current is the source of what we call 
"ground buzz." It's there because there's no neutral feed to those 
3-phase users, so all their triplen current goes to ground in the 
neutral for residences! 

This is yet another reason why it's a very good thing to bond all 
grounds together (the most important being lightning). To learn more see 
the tutorials.


Jim Brown K9YC
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