This has got me doodling now.

Thinking of a noise-killing setup for the LFs in urban areas.

As we know, an inverted 'L' or similar can usually be pursuaded to put out a fairly mighty LF signal, given a good dose of copper below ground, but - as monopoles - they are very noisy on receive.

What if you were to re-wire a phaser, so that on transmit the signal goes to the inverted 'L' and the Wellbroke is isolated, but on recieve the Wellbroke is the 'main' antenna and the monopole becomes the 'noise' antenna?

If you add together the noise-cancelling effect of the loop, put it on a cheap rotator in the loft and add the phaser, I bet you could get rid of almost any QRM and really dig 'em out.

I did suggest a vertical and loop in a previous thread where someone was having problems with high noise and limited space. As for the phaser this one look good http://webzoom.freewebs.com/g8jnj/Anten ... e%2002.pdf
and combined with the simple coax relay sequencer circuit from this link viewtopic.php?f=59&t=38849 and the loop in this thread you will be set up, you can miss out the relay sequencer circuit you have a transceiver that can separate RX antenna and from the TX.

Peter GM1CMF

Looks good.
The only 'niggle' would be that if you 'set' the phaser and then rotate the loop, the relative amplitudes will need re-adjusting. Hopefully as the antennas have not moved closer together or further apart the phase should still be OK as long as you don't rotate 'other side' with the loop. Maybe a way of shifting one antenna 180 degrees would fix that?

Think we need a sticky on Steve's creation.

It would be good if someone did a kit of parts, a few will be put off by having to find the bits, I am still looking for the 2n2222's I have squirreled away to get a start on it.

Peter GM1CMF

That's almost exactly what I've got, but I don't use the TX antenna as a noise picker-upper, I use a selection of random wires. The Wellbrook is outside on a cheap rotator and is the main station RX antenna. It feeds the noise-canceller along with the noise antenna. Combining the nulling properties of the loop and the abilities of the noise canceller can be amazing.
Sometimes though, the noise picked up by the noise antenna just doesn't match the noise coming from the loop, so I've been thinking of making a second loop and mounting it on the same rotator as the Wellbrook, but at right-angles. This would be the noise antenna.
Being at right angles, it would pick up max noise when the Wellbrook picks up least, and this *should* be very effective when the right knobs are twiddled.

(goes for a lie down)

I've dabbled in noise cancelling, on 50MHz, and a little on 70MHz.
I've been using ANC-4 units.
I used a combination of 5ele Yagi, 5ele dual band Yagi, (on different masts, vertical and random wires.

There didn't seem to be any "magic" combination, it depended on the direction of the received signal, apparently whether it was ES or tropo (possibly an angle of incidence thing but I'm not sure), and the time of day.

Vertical noise source antenna seems to be the best, hardly surprising as vertical polarisation seems to be much more prone to noise problems.

Still a lot of tests to do, after I've rearranged the antennas.
I need to put a vertical near to the boundary of the property, as close to the main sources as possible.
I foresee many hours of "fiddling".

Cheers

Tony

Found that my old MFJ noise phaser still works after all those years in a binbag in the loft.

Just realised that I already have the answer for LF.

Use any old monopole wire as the transmit antenna, but turn its Rx gain down to zero, then plug a random loft balanced dipole / Wellbroke into the 'aux/noise antenna' socket and whack the gain up.

If necessary, then use the monopole as the noise antenna by mixing-in a bit of the clag it picks up.

Glad I bought it now, cos a new one costs the same as a Wellbrook

No!

This is the only source I know:
http://active-antenna.eu/

That amplifier is much more complex - and capable - than the simple design I was using.

73,
Steve G3TXQ

I've got around to erecting the noise loop and time will tell if it is better than the wire noise aerials. It's basically a mini-Wellbrook, but it has six turns feeding the amplifier instead of just one.
Just on a tangent, has anyone here had a gander at this site?

http://www.zen22142.zen.co.uk/Media/fsi.htm

He has some odd ideas and he certainly likes to go on a bit, but his Ferrite Sleeve antenna is very interesting. You'll need to scroll down through about half a mile od waffle before you get to the aerial itself.
Anyhow, I made one with 37 4-inch rods on a cardboard former and it is quite impressive. It outputs signals about 20dB stronger than a standard ferrite rod antenna and it is only 4 dB short of my Wellbrook. Mine covers about 500 KHz to just over 2 MHz.
I'll put up a photo or two soon.

.
Here's the noise loop nestling inside the Mighty Wellbrook. I couldn't find a brighter colour.

Here's my 'Gattling gun' MF antenna under construction. It was quite a laugh getting all those ferrite rods to behave...

Oops, just one more before I go and grill the horse-sausages for tea. This is a plot of our local Gold 1458 transmitter. The lower one is from a standard ferrite rod adjusted for max output into the 50 ohms of the analyser. The big one is from the Ferrite Sleeve antenna, similarly adjusted.
It's pretty potent for its diameter, although it's quite heavy. More convenient than a loop for sticking in the car though.

That screen shot looks excellent so I rushed to the link you've posted and then... ground to a rapid halt as my eyes started to bleed, not being particularly mad or a genius I couldn't get traction even by skipping halfway down the page... is he bonkers?

In summing looks great but no clue how it works.

Cheers, Dave.

Dave,
I don't understand the detail of the theory, but what it seems to point to is that the ferrite rod doesn't concentrate the magnetic flux which is converted to emf by the coil - he reckons it's the coil that directly picks up the field and induces some sort of 'spin field' into the ferrite.
But he asks why doesn't a big fat rod provide better signals? This is something I've found as well, a big fat tempting ferrite rod always disappoints!
He says this is because fat rods develop a sort of anti field deep inside which fights the stuff going on on the surface.
So what we need is a fat ferrite rod with no middle so that there is no destructive field.

Well I don't know, but it seems to work. An earlier version I made with just six rods had 10dB gain over a conventional rod, but the 37 rod version adds just another 10dB, so there seems to be some law of 'diminishing returns' in operation.

Well UFO s apart, he seems to be a character! Would you use that ferrite sleeve antenna with an amp in place of a wellbro(o)k (e) loop?

David