Hi all
I've had several printers in my shack that had switching power supplies 'in
the cord' and thus the units were powered on all the time even if the front
switch was turned off. This let the computer command the unit ON when it
needed to print. Every one of them would make radio noise and it seemed to
get worse if the printer was off and thus a very light load was on the power
supply. I would put ferrite chokes on the power lines and that seemed to
keep the problem to a manageable level.
These were all HP units so add them to your list of 'bewares'!!
73's all
Jim K5QQ
-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of Henry Pfizenmayer
Sent: Saturday, August 13, 2005 11:38 PM
To: RFI List
Subject: [RFI] New source of noise
A couple days ago a very rough , frequency unstable , bunch of birdies
about every 39 khz appeared in the low end of 40 meters - further checking -
the birdies exist from 500 khz up thru at least 8 mhz - and higher with an
ICOM R10 and its (very insensitive ) whip held anywhere near the printer or
its cord.
I traced the birdies to a label printer by Brother Model QL500 The label
says its tested to comply with FCC standards for Home or Office use and
Class B digital apparatus Canadian ICES-003.
The birdies are there whenever the thing is plugged in - whether it is
turned on or not with the front panel switch. I have had the thing plugged
in for several months with no problems but apparently something has changed.
So FWIW - if you have a Brother QL500 beware !
Regards _Hank K7HP
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