[RFI] 30 M Shuts Down Internet Cable Modem

[Dan Butler]

Thanks Wes.  I have ordered both the 1:1 balun and several type 43 rings 
from Palomar in the US and hopefully they will arrive in the next couple of 
weeks.

Unfortunately, out of all the connections and wall warts I have in my junk 
box, I do not have anything that will fit the jack on this modem.  I can 
check with some of the local suppliers here in Singapore but it is a bit 
like looking for a needle in a haystack.  However, if the ferrite rings are 
not successful, that will be my next move.  The internet provider supplies 
the modem and I really do not want to approach them on the issue as I am one 
of only 10 active hams in Singapore and once they know about me, I will 
probably be the "cause" of any issues in my area.

73, Dan

-----Original Message----- 
From: Wes Attaway (N5WA)
Sent: Tuesday, March 26, 2013 11:21 AM
To: 'Dan Butler' ; rfi at contesting.com
Subject: RE: [RFI] 30 M Shuts Down Internet Cable Modem

One thing to look at would be the power cube that feeds the modem.  There
are a couple of things to try.  One would be to wrap as many turns of the IN
and OUT wires around toroid cores.  Jim Brown would probably give good
advice on this.  Try whatever cores you have, although Type 31 might be the
best if you have it.

Alternatively, you could try a different power supply to feed the proper
voltage to the modem.

I helped a local ham recently who had bad TVI on several TV sets (DirecTV)
and we narrowed the problems down to the power units feeding the DirecTV
boxes.  He replaced the power supplies with units from Radio Shack and the
TVI went away.

----------------- Wes Attaway (N5WA) ------------------- 
1138 Waters Edge Circle, Shreveport, LA 71106
    318-797-4972 (Office) - 318-393-3289 (Cell)
        Computer Consulting and Forensics
-------------- EnCase Certified Examiner --------------- 

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Dan Butler
Sent: Monday, March 25, 2013 9:44 PM
To: rfi at contesting.com
Subject: [RFI] 30 M Shuts Down Internet Cable Modem

I live on the 15th floor of a 17 story apartment so "proper" grounding is
not possible. I use an end fed multiband dipole which theoretically does not
require RF grounding. However, I do have a multiple wire counterpoise hooked
to the tuner. I recently converted from a 20/40 end fed dipole to the 6-80
end fed dipole, so have just started using the other bands. Now when I TX on
30 M (and occasionally 17 M) the internet cable modem which is in an
adjacent room about 20 feet away, cuts off - all the lights go out, then it
starts once the TX is finished. I placed a steel bowl over it and wrapped it
in foil but it still cuts off. I disconnected the router cable and the cable
input and it still cuts off. I presume I have some sort of power supply
issue but not sure how to address that.

Thanks in advance for any useful suggestions.

73, Dan 9V1DB
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