Dear J, LF Group,
I have been following your antenna problems with interest, and am glad to
hear you are finally QRV!
As far as the transformer design goes - don't change anything yet... With
the windings you describe, the transformer will certainly be having a
significant effect on the impedance transformation of the overall network,
and so if you start making substantial changes to the transformer, you will
quite probably lose the impedance match. So although the transformer may be
less than ideal, best to leave well alone for now!
It is difficult to make any useful comment about possible improvements to
the tuning system without knowing what the current tuning system is exactly.
Re-reading your previous e-mails, the variometer is connected between
antenna and ground, with a link winding to couple it to the coax; I imagine
the link is connected between the coax inner and ground. Presumably the link
winding is wound around the variometer somehow - could you describe
something about it's dimensions, number of turns, position relative to
variometer windings? I can't really visualise where the isolating
transformer would be connected in the system (or what it would isolate, as
far as impedance matching is concerned), so perhaps you could describe how
that is connected.
Will be looking out for your signals next time you are QRV,
Cheers, Jim Moritz
73 de M0BMU
----- Original Message -----
From: J. Allen <[email protected]>
To: LF (RSGB) <[email protected]>; <[email protected]>
Sent: Sunday, July 09, 2006 5:00 AM
Subject: LF: transformer question
> Alan and All,
>
> Alan, you were concerned about the transformer that was added between the
> coax and the loading coil at the base of the 137 kHz. antenna. Here
> follow-up to your question.
>
> If you remember it is a bifilar winding of ten turns which takes up on
inch
> length on a 10-3/4 inch form.
>
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