Steve - when I see an increase in Intermod, my mind goes away from poor
grounds, and towards oxidized connectors and flaky relay contacts.
Reseat all connectors, tighten all screws, and hot-switch relay contacts till
you find the offender.
Tim N3QE
Sent from my iPhone
> On Dec 7, 2016, at 4:35 PM, VE6WZ Steve <ve6wz@shaw.ca> wrote:
>
> I’m wondering what experiences are out there regarding small vertical array,
> or beverage performance in the winter over frozen ground.
>
> The reason for this question is that over the last 2 weeks or so, my HI-z
> (24’ vertical) SDR skimmer antenna at my remote QTH has shown somewhat
> diminished performance and a dramatic increase in AM inter-mod byproducts on
> 160.
> During the somewhat hasty install of this antenna (the SDR “RBN skimmer”
> antenna was not considered an important part of the station) I had some
> trouble driving the ground rod for the HI-z amplifier and only ended up with
> about 3’ of copper pipe driven into the ground. During this past summer and
> fall the performance was good.
> Winter has been here for a while. Last night it was -28 deg C. Today, that
> rod is now probably sitting in a block of solid ice. (ok, not solid ice, but
> the conductive dissociated ions from the native salts distributed within the
> soil are now locked in ice)
>
> In truth I am not really concerned about this particular antenna, but I do
> plan to install an 8 circle array as well as some beverages this summer and
> this problem got me thinking about making sure I have a “seasonally stable”
> ground system up here in the frozen north.
> Some quick research points to potential frost depths ranging from 6’-8’
> depending on snow cover and soil type. Perhaps driving deeper rods could
> help, but it seems to me that there will still be a seasonal change of
> consequence. Literature associated with various short vertical array products
> indicate that 3’-4’ rods should be adequate, but is this true in a northern
> climate?
> For the most part, I could care less whether the array works in the
> summer…..it’s during our winter DX season that I want performance.
>
> Perhaps a very carefully designed and symmetrical short ground radial system
> could stabilize things, but I know with phased rx vertical arrays this can be
> a big problem and cause phase imbalances. Perhaps on my beverages a small
> radial system at the termination would be helpful.
>
> I am not new to rx antennas, having built and used numerous single wire
> beverages, reversible beverages and end-fire phased beverages as well as
> passive and active (Hi-z) phased vertical arrays at my home QTH, but have
> never “noticed” a problem.
> BTW, it is possible that there is something else going on with my SDR antenna
> other than a ground problem, and I will be checking that out next time I’m at
> the station. However, I think I’ll still want to consider the frozen ground
> impact even if there is something else going on.
>
> Any experiences, measurements or ideas from those living in places where it
> snows a lot, you have something called a “block heater” for your car, and
> when you work outside you last about 5 minutes before your hands and toes are
> numb??
>
> de steve ve6wz.
>
>
> Steve Babcock
> Lead Geologist, Mature
> TAQA North Ltd.
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> M +1.403.870.0082
> 2100, 308 – 4 Avenue SW, Calgary Alberta
> Canada T2P 0H7
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