Posted by
Steve Ellington on
Jun 03, 2011; 8:30pm
URL: http://elecraft.85.s1.nabble.com/KX1-Tuner-Norcal-Doublet-tp6436432p6436776.html
That's a bad design for 40m because the input resistance is only about 3
ohms. The designer was concerned about the radiation pattern resembling a
dipole on higher frequencies with little regard to matching.
Using a 4:1 balun would do the opposite of what you want to accomplish. 5
ohms is difficult for any tuner to match and can cause a lot of power loss
in the circuit and with higher power, burn up a torroid coil! That balun
would drop the impedance to an insane value.
Generally a multiband doublet should be 1/2 wavelength on the lowest band.
That's about 65 feet for 40m cw. Also that feedline that the author used no
doubt has a rather low impedance which further complicates things. I'de
guess it is about 100 ohms. Using 300 tv twin lead would help raise the Z
for your tuner to about 15 ohms on 40m even with the 44' flat top. Try that
first.
If all else fails, tie the feeders together and feed it like a long wire
against a counterpoise.
Steve
N4LQ
----- Original Message -----
From: "Burke Jones" <
[hidden email]>
To: <
[hidden email]>
Sent: Friday, June 03, 2011 2:44 PM
Subject: [Elecraft] KX1 + Tuner + Norcal Doublet
______________________________________________________________
Elecraft mailing list
Home:
http://mailman.qth.net/mailman/listinfo/elecraftHelp:
http://mailman.qth.net/mmfaq.htmPost: mailto:
[hidden email]
This list hosted by:
http://www.qsl.netPlease help support this email list:
http://www.qsl.net/donate.html