Hi Denton,
Not sure why you are experiencing that, but more important, why are you even
trying to work with a balun? This is an unbalanced antenna.
I suggest you follow the design of the 160m version which Scott, W4PA,
published many years ago - just build it half size.
- Make the vertical section as long as possible, and the overall length
about 75 to 80 ft.
- Cut the radials to a quarter wavelength.
- Insert a small variable capacitor between the antenna and the center
conductor of the coax (at the feed point). 500 pF should suffice. Probably
less.
- Tune the variable C for lowest SWR at resonance (should easily be below
1.5:1 - mine went to 1.1:1)
- Replace the variable C with a fixed C that is capable of handling the high
voltage. For this I used a fixed C slightly lower than the required amount
and then used a piece of RG-213 soldered in parallel to the fixed C to
provide the rest. Cut this piece of coax longer than needed and prune to
the desired length (such that you have best SWR again).
I would recommend inserting an RF choke in the coax at the feed point,
either by coiling some coax to make the choke, or use one of the many
commercially available ones (source: Radio Works, MFJ, etc.).
I ran this last year on 160m during CQWW CW and it out-performed all other
antennas I had previously built (on my property) by a significant amount. I
basically worked everything there was to be worked on that band (following
the cluster) with just 500w, and most was worked on the first or second
call. When calling CQ I even had transatlantic answers. (Call sign was
DJ2T last year).
Good luck in the contest this weekend.
Unfortunately I don't have much time this weekend due to a death in the
family, but I will be on in the evenings.
73
Rick, NJ0IP / DJ0IP
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Denton
Sent: Friday, November 23, 2007 1:19 AM
To: Discussion of Ten-Tec Equipment
Subject: [TenTec] balun noise?
Not really a ten tec question...but this little group seems to be
particularly knowledgable...
I am tinkering with an 80 meter inverted L antenna, and I noticed that when
I hook up any kind of balun at the feedpoint, the signal to noise is much
more prevalent than when feeding the L directly with coax.
The L has a few radials attached and shares a common ground rod with the
radio station ground.
Wonder whythe worse signal to noise. Thanks...
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