Mag loop aerial for the Den

[pwdrive]

Out of interest regarding NIC's, look at the author, Mr Wellbrook Loop?

http://lists.contesting.com/_antennaware...00006.html

Lawrence.

[Radio Fixer]

Built a BIG loop  .

Horizontals are almost 3m and the verticals 1.3m.  Decided to go away from the window frame entirely and on the top its supported by a curtain rail.  The curtains are only dressing for the ends, the good ladies touch.  But they hide the vertical pipe runs.  At the top of these I have included a compression coupler so undo these and the top section can be lifted free, the whole loop can be dismantled  in minutes.The horizontals are now painted matt white and disappear but for the pic I have shown them unpainted else they don't show up.

   

   

   

   

It works excellently   with loads of powerful stations across the MW band and LW clean as a whistle.  Had some sort of gritty noise but turn off the Virgin Media cable modem and that goes

Gary

[pwdrive]

Proper job Gary, sounds impressive.


How do you turn the house round....Only joking

Lawrence.

[AlanBeckett]

Wonderful.
Have you by any chance tried it downstairs ie closer to the Ground?
I suppose I could mount one upstairs and run the cable down.

Alan

[Radio Fixer]

I couldn't do that Alan but if you read all the 'stuff' somewhere it says that height is not an issue with just the magnetic part.  Certainly with the Wellbrook that is not too far off the ground, maybe 4ft and it works just fine.  I have an issue with it that the gain seems down from when it was on a short coax but the signal is clean and a pleasure to listen to.  I like the plays you get in the afternoon on R4 if I can tear myself away to listen.

The mag aerial is a revelation to me and the best improvement we can make to our old radio enjoyment.  Seems odd that it took me so long to get there but aerials and propagation and such things I never got involved in not being a Ham (ham joint curry for dinner tonight Um! ).

Give it ago, even the 20 SWG wire was pretty astounding.  Copper tube is cheap now at Screwfix; about a fiver for a 3m length.  I didn't have any leaks from the plumbing either  .

Gary

[Murphyv310]

Brilliant Gary.
Your experiments prove that the ferrite filling of the Wellbrook could be snake oil!
Once I am all fixed up I want to build another loop with alloy tubing made into a circular loop of between 1.5 & 2 meters, I'd like this mounted on the gable end with a rotator.
The losses though on the coax will be down to the bifilar winding on the output toroid which I reckon could be around 150 ohms, I was going to reduce the secondary turns by 50% on mine to see what effect it has. A job for later in the year though.

One thing that comes to mind, even though you have your "loop" around the window Gary, the performance will be even better just a few metres outside, so it just goes to prove how well these single turn loops actually perform.
How is it on Long wave? Are you getting a good few continental stations?

[Geordie McBoyne]

The compact Philips model 141U employs a loop type aerial. Performance is impressive, as good as a ferrite rod aerial.
Link to a set I serviced last year:   http://www.vintage-radio.net/forum/showthread.php?t=117841&highlight=Philips+151U

Geordie McBoyne.

[Radio Fixer]

Really Trevor its a test feature for radios that I restore, this Den room being part workshop and display area. The options were drill a hole and run another wire down the garden, string a wire around the room or the Mag Loop. Obviously that came out the best. I could have strung a wire around the loft or even built the Loop up there but then there is the problem of getting the wire to here, in a fully boarded loft and limited head height. Overall I'm very happy with the Loop and thanks for your help, links and encouragement.

For the best radio, in the lounge, that is connected to the Wellbrook its very good but maybe not as good as it should be. When the weather warms up I will dismount it and bring it indoors, I know how much gain it had when on a short coax (it folded the eye back on itself on R4, the radio being an HMV 650). This is the radio and setup that I was referring to about the loss possibly being in 50 + ft of coax.

For the Den Loop the coax is only 6 ft long so maybe the matching or lack of it doesn't matter that much. I haven't tried an external transformer with it to the radio but will give that a go.
On LW R4 the station is received crystal clear, a pleasure once again to listen to but it needs some local electronics turned off as said. It picks up 3 or 4 French stations that are all almost noise free but note that the radio is pretty good as well (tuned RF etc) being a Marconi 561.

Most interesting the info on the Philips 141U Geordie, I will look out for a good one. I'm very enthralled by Philips at the moment although I have been a fan for sometime.

Gary

[pwdrive]

It's been mentioned that the Wellbrook loop had a ferrite filling? Could someone expand on that for me?

Lawrence.

[Yorkie]

Just curious - what's the purpose of the link that I've annotated on the attached circuit please?