Re: LF: VLF Loading Coil Problems - G3XIZ

[Chris Osborn <g3xiz@yahoo.co.uk>]

Maybe you're right Andy.
The coil was intermittent and gently moving the turns with a paint brush cured the problem temporarily.
That's why I 'assumed' it was a s/cct turn and subsequently rewound the bottom section.

I'm now wondering whether the quick-dry varnish I used to cement the fine wire in place has lowered the Q

All suggestions welcome

73
Chris
G3XIZ

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From: Andy Talbot <andy.g4jnt@gmail.com>
To: rsgb_lf_group@blacksheep.org
Sent: Wed, 29 December, 2010 9:44:33
Subject: Re: LF: VLF Loading Coil Problems - G3XIZ

On a large air cored coil I would have thought a shorted turn would just shift the inductance very slilghtly -  rather than lowering the Q significantly.

Andy

www.g4jnt.com

 

 

On 29 December 2010 08:26, Chris Osborn <g3xiz@yahoo.co.uk> wrote:

LF,

Many thanks for all efforts, advice and suggestions from members of the group.
I shall E-mail them personally within the next few days.

I spent several hours yesterday re-winding a section of my VLF loading coil.
There are abour 1200 turns of  0.2 mm wire which had to be hand wound at a rate of 4 turns per minute (max).

I was disappointed (to say the least) when the coil resonated at the correct frequency but had a very low Q.
Either there's a short-circuit in the other section of the coil or I've introduced a short into the newly re-wound part.
In any event I am QRT until I can sort the problem.

I have social engagements today and will take another look at it tomorrow.

73
Chris G3XIZ