Horizontal long wire MW aerial.

[Murphyv310]

It worked but was totally impractical and drew a couple of amps residual current, so as constant supply some what costly.
I'd like to hear how you get on and what works best in your location, sometimes the oddest things help noise and trial and error often is the best way.
Good luck.

Would that 2 amps be actual watts though, or would it be inductive, could it have been corrected with a PF correction capacitor?
Was the transformer getting hot with no load?


Mike

The transformer was huge Mike.
 It already had PF caps, it did say unloaded current 2amps on the plate. It did run fairly warm. 
Don't forget smart meters charge for reactive loads, I was told this by OVO.

[pwdrive]

""Is the thickness of the conductor used for the aerial important from a reception point of view.
I have 1mm² tinned multistrand PVC wire and I have 5mm² solid copper PVC insulated cable""

1mm CSA tinned copper wire versus 5mm CSA copper wire, no contest, the 5mm copper is the best to use, think of the skin effect and then the skin depth then the resistivity of copper compared to the resistivity of tin which is approx. 7 times that of copper, skin depth for copper at 1Mz is approx. 65um, skin depth for tin is approx. 1.7um, that means the bulk of the current sloshing around in the tinned copper antenna at 1Mz will be sloshing around in the tin layer which has 7 times the resistivity of copper and if the wire is only 1mm CSA then the CSA of the skin depth is small just to compound matters.

Using a larger diameter conductor for the antenna will increase the antennas capacitance which will increase the effective height of the vertical portion of the antenna and therefore reduce the value of the inductive reactance needed to tune the antenna if you happen to be going down that route, reduced inductance means reduced losses, with antenna systems you need to reduce losses at every point if possible otherwise you can end up with one big loss, current is current voltage is voltage, power is power, losses are losses, whether transmitting or receiving.

Lawrence.

[ppppenguin]

Due to skin effect the thickness of the earth wire will make little difference. All the current travels near the surface of the cable.

[pwdrive]

I don't quite follow that?

Lawrence.

[Murphyv310]

Certainly in a practical way any difference is marginal, the lighter cable of course puts less strain on the supports.

[Crackle]

What about bare copper verses pvc insulated copper?

[Crackle]

The new earth is installed to my room now, but I am still working on my old aerial. (Which is about 10 m of RG58 coax with centre and braid connected together.)
Tests are confusing, on one radio the new earth works best, on another the mains earth, (CH pipe) works best.
I had the idea of trying the ATU with a signal tracer amp, no detector needed, just connect the little amp to the output of the ATU.
About 5 stations were tuned individually, the CH pipe gave the loudest reception.

The resistance from the CH pipe to the new earth is 160 ohms.
There is 83mV dc and 43mV ac between the 2 earths.

I will carry out more detailed tests later, and note the conditions and responses, but the radio which worked best with the CH pipe earth was a KB LR10, AC radio with only 2 core mains cable, there tended to be more interference with the new earth. Odd or what.

The ATU seems to have very little effect when used with a transistor radio.
Mike

[Crackle]

Due to skin effect the thickness of the earth wire will make little difference. All the current travels near the surface of the cable.

There should be more surface on a thicker cable, wont that help.
Is this "skin effect" only because we are talking about frequencies of about 1MHz and above.
Mike

[ppppenguin]

Skin effect happens at all frequncies. Including 50hz power lines. The effect is greater at higher frequncies. A thick cable isn't an efficient way tget low resistance at rf. Several thinner cables insulated from each other should work better. Think of litz wire on a bigger scale.

[pwdrive]

There will always be some sort of potential gradient in the earth, measuring ohms between PME earth (house earth) and a TT earth rod I found impossible because of that potential gradient when I was converting the chalet to TT, a loop impedance test was the only way.

Also with a separate RF earth there will be in effect an earth loop that includes all the house mains wiring etc.

Lawrence.