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Re: [RFI] Keyboard RFI

To: rfi@contesting.com
Subject: Re: [RFI] Keyboard RFI
From: Gary Smith <wa6fgi@yahoo.com>
Date: Fri, 23 Aug 2013 07:11:25 -0700
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
I would call the cable guy and let him know. And, I'll bet, when you tell them you have 50v at the connector they WILL get excited. Tell them you cat (or dog) walked by it and then unexpectedly barked (or hissed) at it what ever the case was, inferring they were zapped.

Wouldn't be surprised you get a quick response after that.

Gary...wa6fgi


On 8/22/2013 12:12 PM, Dale wrote:
Charlie,

While the hash noise must truly be bad news, that 50V on the CATV line could be 
even worse.  Is that 50VDC or 50VAC?  If it is AC, it sounds as if there is 
significant leakage current (or coupling) within a power supply that is 
operating  some part of your CATV systems.  If that potential is on the cable 
coming from the outside world into your house. you need to advise the system 
operator ASAP.  The fcat that you can draw an arc means you have a very 
definite safety hazard present.  If there is 50VDC on the cable, then you still 
have  safety issue, but that would indicate that some power supply voltage has 
been coupled onto the shield of the cable.  That is probably not by design.

73, Dale
WA9ENA


-----Original Message-----
From: Charlie Gallo <Charlie@TheGallos.com>
Sent: Aug 22, 2013 12:03 PM
To: rfi@contesting.com
Subject: [RFI] Keyboard RFI

Hi Gang,
So, got the SW Radio, and have found some interesting RFI sources around the 
house, have suppressed some, have a tech call in on another (the cable TV line 
has HORRID noise on it low, and if you lift it off the ground, has about 
50volts potential to ground (yes, it'll draw an arc!!!))

One odd thing I found - every keyboard around the house (and I have different 
brands from cheap to Unicomp Model M keyboards) has horrid RFI _IF_ you are 
close to it (like the hand held within say 6-9 inches)

Any clues to a GOOD keyboard that doesn't broadcast like mad (they are all 
wired USB keyboards)

--
73 de KG2V - Charles Gallo
Quality Custom Machine-shop work for the radio amateur (sm)

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