[TowerTalk] Broadcast Band AM Transmiiter Intererence on 160M

[Robie Elms]

Jim,

The following is a summary of my recent experience eliminating BC
interference on 160 m!   I am using a K9AY loop for receiving on 80 & 160
m.  I have a preamp in the RX line between the loop and my transceiver, a
Elecraft K3.

Robie - AJ4F

 I was experiencing interference on 160 m with KYST in Texas City, TX.

1. KYST freq 920 KHz. I can hear them very clearly on 1840 KHz

2. On 920 KHz they are 20 db over S9 here.  With my rx preamp on - solid 60
db over S9

3. Listening on 1840 Khz with my RX preamp out of the circuit the
interference was greatly reduced.

4. "pointed" my K9AY loop at KYST and installed a high pass filter in front
of the RX preamp.  This made a huge difference.  I can still hear them on
1840 KHz, but interference is greatly reduced. There is still a significant
artifact exactly on 1840 KHz, but it is very narrow. This "direction" is
not often used as it is toward the Indian Ocean from here.  Artifacts are
even lower with the antenna "pointed" in other directions.

5. Good decoding this AM from JA on 160 m, even stations low in the pass
band.

Filter used Morgan System M-402X.  This filter can be used in the TX line
as well as the RX line.  Rated for 200 W.

Robie AJ4F

On Sun, Jan 30, 2022 at 4:09 PM Lux, Jim <jim at luxfamily.com> wrote:

> On 1/30/22 1:57 PM, Mike Ryan wrote:
> >   There have to be dozens of readers here who have or HAVE HAD AM
> broadcast
> > AM radio interference on 160m and even on 80m. I found some old
> > contributions to the subject where the DLW filter was suggested. I have a
> > friend who uses one by K7FP.  I wonder if anyone would care to share
> their
> > experience here. I need to pick up something asap but before buying I
> just
> > thought I would ask for feedback on actual experience with any brand or
> kind
> > of filter.  By FAR my greatest offender is at 1420AM which is less than
> one
> > mile from my qth.   Thanks.   - Mike, K4CVL
>
>
> What about a tuned trap for 1420?  A 365 pF tuning capacitor and a
> ferrite loopstick for L. (in a box, so the loopstick isn't a tuned
> antenna))
>
>
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