RE:Hamstick 40

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From: MSgt Cameron C.R. Bailey (CBAILEY@PAMDT.ANG.AF.MIL)
Date: Tue Aug 01 1995 - 07:48:16 EDT


Jim Ehrmin wrote on: Tuesday, August 1, 1995 2:51:49 EDT

>I may be missing something here. Obviously I am not an antenna wizzard. I am
>not sure how the inductive coil works electrically in this case. It sounds
>like
>a number of us are spending more time then we planned tuning hamsticks. Of
>course, the price of the hamsticks makes them very attractive. I like having
>the Norcal 40A in the car. I spend a lot of time driving my kids around and
>sometimes I wait in the car for them and work CW for an hour or so while
>they
>are doing their activity. I like the challenge of mobile CW qrp as well.

>If someone has won the tuning battle with the coil I would appreciate hearing
>about it.

>Thanks and 72/73,

>Jim Ehrmin KB7SOK
>tenspeed@tc.fluke.com

----------------------------------------------------

Jim,

I have fought the coil battle as well on my 80 meter stick. I had over
1000 square feet of metal for a ground plane (mobile home roof). I
saw the same thing you have. I did not have the antenna analyzer at the
time, so I do not know what was going on. All I saw was reflected power.
I surrendered and the coil is still in my desk somewhere.

My victory came on the mobile 40 meter stick. But not after several defeats
such as blowing the final (Q7) on my NorCal 40. That happened when trying
to tune a mag mount stick with a MFJ 941C tuner. Don't recommend doing that.

Not giving up, I used the capacitive loading method shown in the instruction
sheet. First I went with the trunk mount. Then I tuned the antenna with a
430 pf cap on the base. Then I played with different capacitors and stuck
with the 430 pf. I have about 1.2:1 SWR on 7.040 Mhz. The impedance came to
48 ohms. You will find that the SWR will dip at antenna resonance and
decrease as you insert the proper capacitance. My required antenna length is
about 50 inches. Lakeview gave me a 49 inch whip. (Story of my life).

I am not an antenna expert, but enjoy learning and experimenting. I enjoy it
much more now that I have an analyzer. The hamsticks have inductive
reactance with the windings on the antenna. I would think that the coil you
have only adds to the reactance and permits you to adjust it. Keep up,
don't give up. You'll win sooner or later.

72 de kt3a

---------------------------------------------
Cam Bailey
SOGNET LAN Administrator (Banyan)
211 Engineering Installation Squadron
Fort Indiantown Gap (Annville) PA
DSN: 491-8737 Comm: 717-861-8737 FAX: 8268


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