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Message-ID: <9D7C2F9B306347BEA848AC1560D1162B@JimPC>
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
References: <000a01cac139$b9d5e5a0$0401a8c0@xphd97xgq27nyf>
In-Reply-To: <000a01cac139$b9d5e5a0$0401a8c0@xphd97xgq27nyf>
Date: Thu, 11 Mar 2010 20:34:26 -0000
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Subject: LF: Re: DREAM 9 ANTENNA
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Dear Mal, LF Group,

G3KEV wrote:
... Base load the antenna with the necessary inductance for resonance and if 
necessary add another small inductor in series to ground and adjust with 
taps up from ground to get a 1 : 1 match with the coax feed from the TX, 
readjust the main inductor to maintain resonance if necessary.
This system has never failed me on 73, 137 and 500 kcs and this would be my 
approach on 9 kcs.
...

- However it would fail at 9kHz, or on any other band, if the total loss 
resistance of the antenna and main loading coil is >50ohms. This is often 
the case with smaller antennas than those at G3KEV, especially at lower 
frequencies. At 9kHz, it seems to be quite hard to make the loading coil 
resistance by itself as low as 50 ohms. If the total loss resistance IS 
greater than 50ohms, then a different configuration of matching network is 
required.

BTW, Mal, I don't ever remember hearing you on 73kHz...

Cheers, Jim Moritz
73 de M0BMU