[Lowfer] To Q or not to Q?

Wed, 13 Feb 2002 20:14:36 -0600

Yea, but every little bit helps. Did you read on the RSGB reflector about
not bothering to use Litz wire on a transmit loop antenna??? Interesting. Go
for the higher Q coil.

Mike>WE0H
http://www.geocities.com/we0h/index.html

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Ashlock,William
Sent: Wednesday, February 13, 2002 6:24 PM
To: '[email protected]'
Subject: [Lowfer] To Q or not to Q?

Do you guys know what the effect is on your signal when you go from a plain
old garden pea variety coil with a Q of say...200 to an exotic coil with a Q
of 400? If you have a total system resistance of 25 ohms, excluding coil,
which is pretty good, the signal gain is ~20%. If the system resistance is
50 ohms the gain is ~10%. I think I will sequence my signal between normal
and -20% so you guys can see how small this difference is.

Killjoy Bill

-----Original Message-----
From: Mitch Powell [mailto:[email protected]]
Sent: Wednesday, February 13, 2002 3:10 PM
To: [email protected]
Cc: [email protected]
Subject: Re: [Lowfer] Coil question???
Importance: High

Mike:
I wound that same coil last week - following ideas from Dex's pictures.
With 18 inch diameter, I used #14 plastic covered household wiring. I
Had 11 vertical 3/4" PVC pipes and did a basket weave.
Coil was 70 turns - height was 7 inches. Inductance measured on Boonton
Q meter was 2.4 mH and Q >400. I couldn't come within 2 feet without
changing the resonant frequency.
Then used a plastic pail to wind a variometer - 10 inches diameter, 4 inches
high, close-wound - same #14 plastic covered wire.
Can tune from 2.3 to 4 mH.  or over the entire 160-190 kHz range.

Calculated all these values with Bill Bower's formulas, and was within a
turn in each case - great stuff !

Hope this helps.

73
Mitch VE3OT

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