Message-ID: <2000013117505668199@zetnet.co.uk>
Date: Mon, 31 Jan 2000 17:50:56 GMT
To: rsgb_lf_group@blacksheep.org
From: "Peter Dodd" <g3ldo@zetnet.co.uk>
Subject: Re: LF: 8 kHz loading coil and 73kHz
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> > I have an idea of resonating my existing vertical on 8 kHz.
> > Is there a practical way to construct a 600 mH loading coil, withstanding
> > 3-4 A and high voltage? Any *large* toroids on the market?'
> > /Christer
> > sm6pxj

> Are we locked into HF thinking here? Why not use an iron cored 
> inductor such as the output transformer from a QRO valve audio 
> amplifier? 
> Mike, G3XDV 

Although an output transformer might be fine for a matching 
transformer it would not be suitable for a loading coil because of 
the high voltage across it. It might be more practical to use several 
coils in series with the lowest one being a variometer.

On 136kHz I now use a variometer and coil designed for 500kHz with 
the additional inductance mounted in a weather proof enclosure 
outside the shack.
On 73kHz I use the variometer and 136kHz loading inductance inside 
the shack with an additional inductance outside the shack, thereby 
spreading the voltage gradiant over this three-stage booster.
On 8 kHz this could be taken the necessary stages further.

Whichever way you play it you will need a lot of wire!

While on the subject of 73kHz I hope to be on tomorrow at the bottom 
of the band before 1000UTC


Regards, Peter, G3LDO

<g3ldo@zetnet.co.uk>