[Top] [All Lists]

Re: [RFI] LCD TV wipes out AM BC band

To: "K8RI" <k8ri@rogerhalstead.com>, rfi@contesting.com
Subject: Re: [RFI] LCD TV wipes out AM BC band
From: "Dale Svetanoff" <svetanoff@earthlink.net>
Reply-to: svetanoff@earthlink.net
Date: Tue, 22 Feb 2011 11:34:43 -0600
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>

An excellent question, plus I should have included the Toshiba model info
in my posting.

I can think of at least two systems within the set that could be the
noise-makers: 1) The switching power supply that operates the whole set. 
These days, it is not uncommon to have switching freqs as high as 3 (or
more!) MHz.  I made no analysis of the noise or its pattern, except that it
is broadband in nature and strong across the AM BC band.  2) The other
likely candidate could be the drivers for the CFLs that provide the
backlight.  I did notice an upward "sweep" in frequency (as heard on the
speaker of the radio) each time I switched on the Toshiba set.  That sweep
lasted for perhaps 2 to 3 seconds, then stopped.  My thoughts are that
maybe the CFL drivers are "ramping" up the lamps over that period of time,
or they are adjusting to a pre-set drive level to maintain a given
background intensity.

My set is the Toshiba Model 19AV600U, which seems to be a popular model.  I
suspect that it has been superceded by something "better" by now, but I
have seen these in hospitals, motels/hotels, commercial establishments, and
so forth.  Remember, any set that is going to cause a problem in the region
of 1 MHz or so will do so when in close proximity to the antenna of a
victim radio.  Since most AM BC band radios have integral antennas (usually
ferrite bar or rod types - the one in the Super Radio III is a whopping
200mm long [nearly 8 inches]).  If anyone does note such interference from
a TV set or monitor, please post to the reflector with info about the
offender.  Thanks.

73, Dale

> [Original Message]
> From: K8RI <k8ri@rogerhalstead.com>
> To: <rfi@contesting.com>
> Date: 2/22/2011 12:11:18
> Subject: Re: [RFI] LCD TV wipes out AM BC band
> On 2/22/2011 12:14 AM, Dale Svetanoff wrote:
> > A bit of news I discovered early today:  I have a 19 inch Toshiba LCD
HDTV that serves double duty as a TV and as my computer monitor.  I've had
the set for about a year and a half and like it very much.  I have posted
some prior comments on this reflector about Ethernet radiating from the set
when OFF, and reduced when ON.  Other than that, I've had no RFI issues
with the set until now.
> What in a non CRT set runs on those frequencies?
> 73
> Roger (K8RI)
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi

RFI mailing list

<Prev in Thread] Current Thread [Next in Thread>