Envelope-to: dave@picks.force9.co.uk
Delivery-date: Sun, 05 Feb 2006 16:44:19 +0000
Message-ID: <002601c62a73$2f204f10$2201a8c0@pcroelof>
From: "Roelof Bakker" <roelof@ndb.demon.nl>
To: rsgb_lf_group@blacksheep.org
References: <007001c62a34$97e808b0$2101a8c0@AUG2004> <007701c62a41$1414dbf0$8b1c0d54@traceydlqceh0p>
Date: Sun, 5 Feb 2006 17:42:42 +0100
MIME-Version: 1.0
Subject: LF: Re: Active_antennas
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Reply-To: rsgb_lf_group@blacksheep.org

Hello Walter, Tracey, Alan,

It happens to be that I own a battery powered SPM-3 and I have often used a 
(mini) whip without any connection to ground. As a whip is a monopole some 
counterpoise is necessary. I gathered that this happened by capacitive 
coupling between the case of the SPM-3 and earth (the real thing). As the 
(mini) whips capacitance is small, the value of the capacitor to earth need 
not be very large.

This was confirmed when I lifted the SPM-3 from the plastic garden table and 
put it on the ground: the signal level increased. If I remember correct it 
was in the order of 1 dB or so.

Regarding Tracey's suggestion, when the weather is a bit more like it, I 
will hoist the contraption up a fiberglass pole. The only problem is that 
the capacitance of the SPM-3 to ground will be substantial larger than from 
the (mini) whip.

Best regards,

Roelof Bakker, pa0rdt