Don,
I am trying to figure out WHY your microwave produces RFI. Unless there
have been some major changes in microwave design very recently, the
commodity status of this device has relegated it to a very cost-conscious
design using mature technology. For the most part, microwaves have used
conventional iron core transformers (with minimal amounts of iron and
copper, to be sure) for the HV supply. The other prime components are
usually the HV rectifier, perhaps a low value HV filter cap, and the
magnetron tube itself. (In some brands of oven, the recitifer and
magnetron are integrated into one assembly.)
Now, when you mention the rather strong RFI, two possible ideas come to
mind: either your microwave is using a high power, high voltage switching
power supply (which tends to be a costly device for several reasons) or
you have a malfunction in the HV circuit (arcing) or controller. A high
power switching power supply that has little or no RFI suppression could
and would be a terrible nosie maker. (From previous postings about
variable speed laundry machines, we know that appliances seem to be exempt
from FCC emissions requirements.) Can you supply the make and model of
your microwave? It would be very interesting to know the nature of its HV
power supply. Of course, the low voltage control electronics could have a
small switcher powering them, and perhaps that's the problem.
Finally, there could be arcing in the HV unit or the magnetron itself. You
may wish to do a little RFI sniffing as a precautionary measure. I've
seldom heard of microwave ovens causing interference except in the region
of 2.45 GHz, which is their operating RF frequency range.
73, Dale
WA9ENA
"Donald Kerns" <dkerns@cruzio.com>
Sent by: rfi-bounces@contesting.com
05/07/2008 04:11 PM
To
rfi@contesting.com
cc
Subject
[RFI] Microwave RFI - radiated (?)
Hello all,
The band scope on my IC-756ProII lights up with about 15-20 dB of noise
(not
to mention killing any QSO) anytime the microwave oven in my kitchen runs.
This is most evident on 40m, haven't really checked on the other bands
yet.
They are at two opposite sides of the house with at least 50' separating
them.
I've tried 4 turns of the appliance cord around one of "Doctor Brown's
Magic
Toroids" to no avail (That's all that easily fit).
Time to earn some XYL points with a new microwave?
73 de Donald
AE6RF
--
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|