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RE: LF: Re: 500KHz NoV

To: <[email protected]>
Subject: RE: LF: Re: 500KHz NoV
From: "Chris Trayner" <[email protected]>
Date: Tue, 5 Aug 2008 22:08:23 +0100
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]>
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Thread-index: Acj3JbWZcqzABK/nTDi2Mb5D8rN1iQAFFa60
Thread-topic: LF: Re: 500KHz NoV
Dear Mel.


Thanks for your thoughts.
 

> Considering today's pass marks at University is 30% 

Not at any of the ones I know of. The pass mark is 40% for undergraduate, 50% 
for postgraduate.

> Since the radio amateur examination has been reduced to a tick test(multiple 
> choice) everyone is in with a chance, guess work,

Again, I'm afraid that's not actually true. People have understood this random 
chance since multiple-choice was invented, and work round it. For every answer 
you get wrong, you score a certain minus mark, calculated so that someone who 
guesses at random will get roughly zero.

> This is not only my opinion but lots of others, to whom I have spoken. 

Well, you can find people with many opinions. Did they have hard facts such as 
the above?



> An  earth spike is better than an ANTENNA !!!!!!!!!!!!!

I think the original comment to which you were replying was:
"Oddly , a good earth looks to  do more for the signal than the Ae , any pipes 
rods  ect in the ground , use individual wires and bring them all back  to the 
same earth point , its not conductance that makes the difference is ground 
capacity , the more the better , wires under the top of the ae will add  to  
the return path for the current...  "

I don't think the correspondent was saying that an earth was better than an 
aerial. He was saying that improving the earth did more than improving the 
aerial. 
This is not surprising if the earth was originally poor. Remember that the 
current from the Tx has to flow (to put it crudely) out through the aerial and 
back in through the earth. If either has a high resistance it will restrict the 
current. Suppose (to invent some fictitious figures) that the aerial has a 
resistance of 100 Ohms and the earth 1000 Ohms, thus a total of 1100. If you 
halve the aerial resistance you will bring the total down to 1050, but if you 
halve the earth resistance you will bring it down to 600. 
So to speak, a poor earth throttles a good aerial.
This is just the old common sense that if you have a good thing and a poor 
thing, you're often better off improving the poor thing.


> If possible get a 1/4 wave antenna installed at a good height otherwise 
> expect poor results on MF. A match stick is a poor performer.
G3KEV

You're absolutely right, of course. Part of the name of the game for amateurs 
on MF, who can't afford the towers for 1/4 waves, is what we can do with 
shorter aerials.


> I have not heard any signals from from the EARTH man.

I'm not sure whether that was intended to be rude to him, but if so I'm not 
sure it's the best way to encourage a fellow amateur who is trying to get 
something going.



Best regards,
Chris G4OKW


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