[TenTec] Tuner

[Rick - DJ0IP / NJ0IP]

Walt,

I agree with Jim.  The 238 will definitely match it, but the match point is
probably very sharp and so far you have been tuning past it without noticing
it.

Here's what I suggest.  Use an analyzer such as a MFJ-259B to find the match
point, don't transmit into the antenna.
If you don't have an analyzer and can't borrow one, then connect the 238 to
a 50 Ohm dummy load, and using low power, search for the match point into
the dummy load.  This will pre-set your controls (Capacitor, Inductor, and
Hi/Lo-Cap Switch) in the ball park of where they will be when you try to
match the antenna.

After you find the point where the dummy load has a good match when fed
through the tuner, connect the antenna again and look for the match point
which should be near the settings used for matching the dummy.  Start with
the rig set at 3800 (where you have a good match even without the tuner),
but find the good match when going through the tuner.  Once you find it, QSY
down about 50 kHz, key the rig and while monitoring the SWR rock the
Inductor back and forth to see which way improves it.  That is the way you
will need to move the inductor as you proceed down the band in 50 kHz
increments.  Each time you re-adjust the Inductor, also re-adjust the
Capacitor for best SWR.  You should be able to easily find the settings
using this procedure.

By using the dummy, you won't be placing a carrier on the air for a long
period of time while you are initially searching for the 80m matchpoint.

Also, as James was hinting at, unless you are running openwire to your
antenna, there's not much point in using it on 40m, even though you can load
it.  If you want it to work both bands, then you should either add a second
radiator for 40m, connected in parallel to the 80m radiator (i.e. "fan
dipole"), or replace the balun with a dual-core 4:1 Guanella (current) balun
and move the feedpoint such that it is 1/3 of the distance from one end.
Either solution will enable the antenna will work efficiently on both bands.

If you are using openwire, ignore the paragraph immediately above this one.
You're good to go.

73
Rick, DJ0IP


-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Walt
Stewart
Sent: Monday, July 08, 2013 6:47 PM
To: tentec at contesting.com
Subject: [TenTec] Tuner

I recently purchased a used 238 tuner. It will give me a perfect match on 40
meters with my 80 meter dipole, but I cannot get it to match the 80 meter
dipole cut for 3800 down to the CW area. What am I doing wrong?  

Sent from my iPhone
_______________________________________________
TenTec mailing list
TenTec at contesting.com
http://lists.contesting.com/mailman/listinfo/tentec