From: "Hans-Joachim Brandt" <hajo.brandt.dj1zb@t-online.de>
To: rsgb_lf_group@blacksheep.org
References: <3A7E870B.22556.5402A0@localhost>
Subject: Re: LF: Earthing the mast
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Date: Mon, 5 Feb 2001 13:54:58 +0100
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Thank You for this description!
I would recommend: Keep both masts grounded.

73 Ha-Jo, DJ1ZB


Mike Dennison schrieb:
> A few weeks ago there was a discussion about whether to earth 
> masts, or leave them 'floating'.
>
> In the continuous search for more dBs I tried earthing my mast on 
> Saturday.
>
> I have a 14m (45ft) mast attached to the brick wall of the house by 
> 'T' and 'K' brackets, standing off about 300mm (1ft). Its base is 
> 600mm (2ft) above ground level. The vertical part of the antenna is 
> about 1m (3ft) away from the mast. 
>
> I connected the mast to the wire which runs from the Tx to the earth 
> stakes. I expected the capacitance between the mast and the 
> vertical to change the tuning. The change was in fact very small, but 
> the first thing I noticed was the variometer tuning became much 
> more critical. The second thing was a 10 per cent increase in 
> antenna current. Conclusion: the Q of the antenna had increased. 
>
> I was still prepared to believe that I had simply added a capacitor 
> from the antenna to earth, but when I checked the receive 
> performance the signals improved by 1-2dB (tested by monitoring 
> DCF and detuning until one of the 'S-meter' LCD blobs flickered, 
> then noting  that the blob stayed on with the earth connected), and 
> the local noise level reduced at the same time.
>
> Another effect, in the short time since I made this change, has been 
> the antenna current has been stable. Before, it would vary by 
> between 10 and 20 percent from one day to the next, depending on 
> the weather, and I assumed this was absorption by trees.
>
> It seems that the mast/wall was acting as a resistor to earth, 
> absorbing a different amount of RF from day to day.
>
> I also earthed the mast at the far end of my inverted-L and 
> connected the two with a wire, but this had much less effect. This 
> mast is already stuck in the mud at its base so was probably already 
> earthy.
>
> What to do next? 
>
> Mike, G3XDV (IO91VT)
> http://www.lf.thersgb.net
>
>