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Old March 10th 06, 10:33 PM posted to rec.radio.amateur.antenna
John Ferrell
 
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Default Dipole Extension

I agree on the part about the wx.
I doubt the antenna is really centered on 7.2 if it is up to 2:1 at
7.050. IF I were going to try to change anything, I would go to the
hardware store electrical department and get a couple of screw type
wire splices that are intended to splice about 12 ga. wire. Get the
type that come apart so that you don't have to cut the antenna to
string them on the wire. Alligator clips don't weather well here. You
can add a foot on each end of the 40M section and trim from there. I
hope the antenna goes up & down easy!

I would keep tabs on what is happening to the 80M operation as I went.
The environment around the antenna (height above ground, quality of
ground) may lead to erratic measurements. 2:1 is not a bad SWR. Your
ability to tune it out fixes everything except the losses in the tuner
and I doubt if they are high enough to consider!

Before you take any advice from me remember I consider myself an
antenna student, not an expert!

On Fri, 10 Mar 2006 20:24:41 GMT, "Dick, AA5VU"
wrote:

In article ,
John Ferrell wrote:

The 1/2 wave difference on 40M of 7.2 and 7.1mhz is only about a foot.
The change in a DIPOLE at 40M would be difficult to measure.

I would not change it.
Do you have an indication that it needs adjustment?


John,

When i trimmed it the first time (years ago) I was working mostly SSB so
it is great in phone band and okay in the old Novice portion. I am now
working mostly 40 meter RTTY and PSK and these are at 7.070 and 7.035.

The current antenna shows SWR of about 1:8 at 7.100 and goes up to
2:0 at 7.050. My TS-570S tuner makes the rig smile but I feel it would
be better if I could extend it a bit.

The problem is there is no wrapped back wire that I could let out and
hate to use a jumper extender at the loading coil.

I may have to just bit the bullet and cut some wire per the formulas by
Steve, K9DCI, and solder it in the middle some place.

Still thinking about it. The WX in South Texas is too nice for antenna
work. I will probably put it off until the WX is bad.

73, Dick AA5VU

John Ferrell W8CCW