I second Chris' suggestion to use the portable flag loop with preamp.
Within the past 4 months, I have used one about 5 times to pinpoint noise
sources.
Either build one from WD8DSB's article in March 2021 QST or (like I did)
buy the kit for $120 from DX Engineering. Note, DXE says estimated
delivery late October.
Needs a pre-amp. I also bought the DXE preamp ($135) - and its built-in
attenuator has helped bring the signal strength back to mid-scale as got
closer to the source.
The loop's null seems very sharp. So, locating accuracy is helped when the
loop is mounted on a tripod. This is much better than wandering around with
the loop swinging wildly.
Also, signal strength is affected by having your body near the loop - so
that's another good reason to mount the loop on a tripod, make incremental
azimuth changes, and do what you can to keep your body from affecting
signal strength measurements.
73,
~ Alan K0AV
On Thu, Sep 9, 2021 at 6:51 AM Christopher Wawak <kc2ieb@wawak.org> wrote:
> I have had trouble with an Arrow small magnetic loop. worked great on VHF,
> but even with an external preamp I have major trouble finding HF signal on
> an ic705.
>
> I have had REALLY GOOD results with the DXE flag antenna:
> https://www.dxengineering.com/parts/dxe-noiseloop. that with a preamp
> worked well to find noise in the 7mhz range.
>
> I know this can be frustrating, but you'll figure out the noise. It's too
> weird to ignore.
>
>
>
> On Thu, Sep 9, 2021 at 8:21 AM Joe Galicic <galicic@comcast.net> wrote:
>
> > Hi Chris,
> >
> > I was using my K3 and a small diameter magnetic loop antenna sticking up
> > through the sunroof of my car. I've found noise sources with this setup
> > before.
> >
> > I can hear CW and FT8 signals on the loop but cant hear the RFI "signal"
> > on the loop. I thought this was very odd since the signal is pretty
> strong
> > on my shack radio.
> >
> > One of my neighbors about .5 miles away has a new solar installation. I
> > drove past that house and it was quiet.
> >
> > We don't have powered channel markers in the lake.
> >
> > We do have lots of gulf carts around here so perhaps this is a battery
> > charger ?
> >
> > Thanks,
> >
> > Joe
> > N3HEE
> >
> > On 09/09/2021 8:02 AM Christopher Wawak <kc2ieb@wawak.org> wrote:
> >
> >
> > Have you considered a start at the hams house? drive towards your house.
> > Park car where you begin hearing the wee woos and do your df from there.
> >
> > Can you tell more about what you experienced when looking around for the
> > signal?
> >
> > 73 kc2ieb chris
> >
> > On Thu, Sep 9, 2021 at 7:55 AM Joe Galicic < galicic@comcast.net> wrote:
> >
> > > Greetings All,
> > >
> > > Here is something for all of you RFI sleuths to have some fun with.
> > An interesting "signal" has appeared in the last couple of weeks at my
> QTH.
> > >
> > > Clues:
> > >
> > > I've eliminated my house.
> > >
> > > I've driven around the neighborhood with direction finding gear (K3
> > with small magnetic loop antenna) with no luck so far.
> > >
> > > A local ham 5 miles away can't hear it.
> > >
> > > The "signal" is there 24/7.
> > >
> > > It is also on 40 meters.
> > >
> > > Any ideas what this could be ?
> > > See video here https://youtu.be/sl050wudAm0
> > >
> > > Joe
> > > N3HEE
> > >
> > _______________________________________________
> > RFI mailing list
> > RFI@contesting.com
> > http://lists.contesting.com/mailman/listinfo/rfi
> >
> >
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