[BC] Re: Saving Your Own Life

[Mike McCarthy]

There are TX's with up to three sources of AC.

Harris SX series has two (Control and RF), plus whatever was wired into the 
rack bay section in front.  Some stations with SX1 and 2.5 wired two 
circuits for the box, others 1.  On the 5, you had to use two as the 
control side was single phase the RF was three phase.

MM

At 09:19 AM 10/21/2005 -0400, cldube wrote
>Our FM-20B has no such thing. Was this common of earlier versions?
>Exciter, IPA & control board are all 220. Anything lower comes from a PS 
>(i.e. fans).
>Once you kill the three phases, it's cold.
>
>Chuck Dube
>WFCR
>Amherst
>
>
>----- Original Message ----- From: "Milton R. Holladay Jr." 
><miltron at mindspring.com>
>To: "Broadcast Radio Mailing List" <broadcast at radiolists.net>
>Sent: Thursday, October 20, 2005 9:56 PM
>Subject: Re: [BC] Re: Saving Your Own Life
>
>
>>One of the most hazardous, stupid xmtrs that most of us have encountered is
>>the FM-20 and its smaller brothers which have not only the 3 phase circuit,
>>but a separate 120 volt circuit, waiting to bite you. Any that I have had my
>>hands in now have the 120V tied to one of the 120V legs of the 3 phase, so
>>that when it's off, it's ALL OFF !
>>M
>>----- Original Message ----- From: "Phil Alexander" <dynotherm at earthlink.net>
>>To: "Broadcast Radio Mailing List" <broadcast at radiolists.net>
>>Sent: Wednesday, October 19, 2005 10:20 AM
>>Subject: Re: [BC] Re: Saving Your Own Life
>>
>>
>>>On 18 Oct 2005 at 18:02, Kevin/Tieline Technology wrote:
>>>
>>> > Imagine my surprise after about 3 years of working on this TX that I
>>> > find a THIRD breaker box hidden deep inside and down toward the ground
>>> > inside a RACK of all things!!!
>>> >
>>> > I discovered this after I bought an inductor pen that lights up > 
>>> whenever
>>> > it's near AC without having to come into contact with AC.  I had been
>>> > waving it around the TX and down in front at the base of the TX it
>>> > lights up bright red even though I had the front open, breakers 
>>> were > off
>>> > and ground stick was used to check that nothing was live.  The pen had
>>> > found the live AC still going to the low voltage power supply!  Well
>>> > duh!  And I thought I had thought of everything.
>>> >
>>> > I *trusted* the previous engineer who showed me around the TX plant.  I
>>> > wonder if HE knew about the 3rd breaker.
>>> >
>>> > As Cowboy said "Trust, but verify."
>>
>>
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>
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