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Robin,
At this stage, rather than add turns, why not add some extra capacitance
across the trimmer? I would imagine the L/C ratio isn't critical in this
instance. As a start, I'd try something a little less than the range of the
trimmer itself. I don't have the information to hand but if the trimmer is
say 5 to 40pF then something around 30pF can't be too much.
Just tack the cappy on the back of the board at this stage.
Of course you might need more capacitance still, but it's an easy experiment
to make.?
Regards,?
John
G4YTJ


Sent from my mobile phone

-------- Original message --------
From: robin.travis@...
Date:
To: [email protected]
Subject: [QRPLabs] Winding Tip for 80 Mtr QCX transformer (T1)

Hi Des (again) and others
I just searched this topic and your name came up again.
I had to have 3 attempts to wind the T1 transformer.

On the first attempt, I ran out of 28swg wire to complete the winding having
obviously?used generous amounts for the other inductances.
(QRP Labs - please note that a little more wire would not go amiss).
I had some 27swg and 30swg wire and decided to try the 27swg?but trying to
wind 83 turns on a T50-2 toroid is no easy task and I abandoned this in
favour of the 30swg.

I managed to wind the transformer with quite a bit of overlap of 30swg wire
and I presume I have wired it up correctly as I am now hearing stations?
reasonably well from continental Europe. Obviously, 30swg wire?is quite
delicate but it?is certainly workable if one is careful.

The issue I have is with the alignment: it is starting to peak but I am only
achieving a scaling factor of 5 with the plates of C1 completely closed and I
now have to add some more turns.
For optimum performance,?is the target value around 9 as indicated in the
manual and I am wondering whether it is easier to remove turns rather than
add.
In other words, would it be better to add 10 turns rather than 5 turns as
suggested in the manual ?

Again input from you or any other would be most welcome.

73s

Robin
G4DNP