Topband: Beverage feed line...too long?
iz4efn at gmail.com
Sun Sep 23 13:57:02 EDT 2007
We took some days to think about our setup and reading your suggestions and
I will start with some considerations, trying to answer your questions and
better explain aour environment.
The transformer we used is a homebrewed 9:1 transformer, coming from a
someone else previous beverage installation.
In these days we went back to the beverage area, and decided to never trust
our friends again: unfortunately (let me say, fortunately) the transformer
has coax and beverage grounds wired together. I don't know how it could work
fine for him, but we will surely catch a lot of snakes fixing it.
Beverage ground: it's provided by a 6 feet grounding rod in a
medium-conductive soil. For now, we have no radials on it, but will add some
The beverage doesn't pass near metal structure.
The beverage terminates sloping at both ends. I think this fact comes from
some readings, but I actually don't know anything more. Comments welcome.
RG58: We used this cable because we had a lot of it. Some other italian
stations are using SAT TV cable. It's even cheaper than RG-58, and it's 75
ohms. We just decided to stay on the 50 ohms and use what we had.
We are already rolling a new transformer, right as it should be (coax not
Mixing ON4UN book, your links and suggestions, we will follow the following
- transformer replacing
- eventual un-sloping of both ends
- preparing a choke between 5m and 1/8 waveleght from the beverage as
suggested and described
- grounding the coax on the baverage end of the choke
- grounding the coax toward the shack every 100m (maybe less?) to reduce
coax shield resistance and kill some snakes
- choking and connecting the coax shield to a good ground in the shack.
Talking about our K9AY, since the similar noise level is really showing
common mode issues on both of the antennas as Gary says, I think we will
first fix the beverage, and compare the two guys leaving the K9AY as we
always had it. Will be fun to compare the noise levels after having been QRV
some nights in this actual wrong conditions.
BTW, we may choke and properly ground also the K9AY feedline.
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