Ami,
RFI problems like yours have plagued many of us, me included.
As Jim, K9YC mentioned, his information is very good reading to understand the
cause and
help with diagnosing and solving the RFI.
I have had repeated fun chasing RFI here at my QTH and heres what I do to track
down the source:
First thing is to determine if the noise source is in your own dwelling or
external to your dwelling.
If you can power your radio from a battery temporarily, have it listening to
the noise and shut off
AC power to the house with the main breaker. If the noise goes away it is in
your house somewhere.
If it doesnt then it is external to the house. If it is in the house, then
one by one, turn on the circuit breakers until
the noise reappears, that will be the circuit the noise maker is on. Then you
can go around and disconnect one by one
everything that is plugged in to this circuit. You will be able to determine
where the culprit is this way.
If it is external to the house then you will need to do some checking with a
portable AM radio to start with
and see if you can zero in on the location. Hopefully it is inside your
house. I have found a number of RFI offenders
this way. The last culprit was a battery charger for a portable drill in the
garage. Another one was our satellite TV receiver,
I had to unplug it from the outlet to find it was an offender, even though it
was turned off the power supply is always on
and generating noise.
I hope this helps a little, good luck on finding the noise source and keep us
posted !
73,
Bob
K6UJ
On Jan 20, 2013, at 11:05 AM, AMI SHAMI wrote:
> *Hi all*
>
> * *
>
> *For several years I am suffering from internodes carriers spaced 9 KHz
> apart on 160m and 80m.*
>
> *On 80m it starts 0n 3501, 3510, 3519 etc, on 160m 1809, 1818, 1827, 1836,
> 1845, etc. the one on 1845 is very much stronger that the others, *
>
> *Some are S7 and the stronger can be on some RX ANT S9++.*
>
> *The strength of those carriers is affected by changing the RX ANT and TX
> ANT.*
>
> *MY TX ANT is 27m tall vertical as Ground plain with 5 elevated radials 27m
> long all standing at 16m high roof and the vertical is self support at a
> corner of the roof, *
>
> *The ANT tuner is at the base of the ANT switched from the shack 160/80m.*
>
> *My RX Ant's are flag, diamond, slopper, and small magnetic loop, all
> mounted on the same 14x14m flat roof.*
>
> *I found that the strength of those IM carriers is lower when my TX ANT is
> set on 160m.*
>
> *In the area are two strong broadcast transmitters, one about 3km away with
> about 500kw and another in the opposite direction 7km away of 50kw both AM.*
>
> *I HAVE MANY BCB FILTERS inserted on each RX ANT and at the RX input of my
> K3.*
>
> *I ALSO HAVE MANY FERRITES-#31- ON ALL FEEDERS AND LINE CABLES.*
>
> *It looks like my TX ANT re-transmit those BC stations.*
>
> *Any idea why this 9Khz spacing, and any suggestions what else can help.*
>
> *I am using also MFJ- 1026 noise canceller which helps a little.*
>
> *Another unknown noise source is only on 160m is spaced 1Khz apart much
> lower about 2 S units above the basic white noise of the band, *
>
> *These noise peaks are on every half Khz all over the band say 1820.5,
> 1821.5, 1822.5 etc.*
>
> *This noise is canceled out quite well with the MFJ. *
>
> *Any idea what can be the source of this noise.*
>
> *I know that most of my problems could be easily solved by moving from this
> QTH, but any suggestions for this situation.*
>
> * *
>
> *Thanks*
>
> * *
>
> *73 Ami 4X4DK*
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