[TenTec] Corsair II buzz

[Gary Hoffman]

yep....you are further up the ladder than we are way out here in the 
country.  I sometimes think we get the last electron left on the vine, so to 
speak  :)   Certainly its true that many areas use higher voltages by far 
than those I described.  Certainly not 240 V 3 phase delta though !!


----- Original Message ----- 
From: <waltk8cv4612amos at att.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Thursday, April 02, 2009 10:21 PM
Subject: Re: [TenTec] Corsair II buzz


> ALL the stuff here is 13,200 V .............. Primary !
>
> Walt K8CV Royal Oak, MI.
>
> ----- Original Message ----- 
> From: "Gary Hoffman" <ghoffman at spacetech.com>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Sent: Thursday, April 02, 2009 9:50 PM
> Subject: Re: [TenTec] Corsair II buzz
>
>
>> Hmmm....in our neighborhood we certainly have nothing remotely like a 240
>> v
>> delta system serving residences, being center tapped and all as mentioned
>> below.
>>
>> What we have are moderately high voltage lines - on my street they are at
>> like 3400 volts, phase to phase.  While three phases are available, only
>> two
>> are run down my street, because that is all they need for our low power
>> use.
>>
>> Local transformers, that service a couple of houses each, pick off power
>> from these two primary phases, and produce a center tapped 240 V AC
>> secondary.
>>
>> If there were a buzz around here, it sure would not be due to the source
>> described.
>>
>>
>> ----- Original Message ----- 
>> From: "Jim Brown" <k9yc at audiosystemsgroup.com>
>> To: <Gary at doctorgary.net>; "Discussion of Ten-Tec Equipment"
>> <tentec at contesting.com>
>> Sent: Thursday, April 02, 2009 9:13 PM
>> Subject: Re: [TenTec] Corsair II buzz
>>
>>
>>> 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
>>> http://audiosystemsgroup.com/HamInterfacing.pdf
>>>
>>> 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
>>> material.
>>>
>>> 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.
>>>
>>> 73,
>>>
>>> Jim Brown K9YC
>>> _______________________________________________
>>> TenTec mailing list
>>> TenTec at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/tentec
>>>
>>
>>
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