A cool day offered the opportunity to go back there and size up the future site of a 3-meter tower/bird-house pole with radials. It is on a rather steep hill, but there is no choice because the yard is a hill. The downhill looks north, the sides are east and west, but the uphill, looking south, is met by a 4-foot retaining wall above which sits even higher ground, on which stands a gigantic McMansion that must ascend 100′ above the proposed site, like a castle or cliff wall. Therefore southern penetration, which does not happen now, will probably not happen with the new tower.
But luckily it doesn’t matter, because the objective is to make the transmitter as remote as possible so that when its tuned from indoors it will be coming from “far away.”
The number of ground radials will be limited by various trees and bushes on the southern side which are to be protected, but we already believe the southern side is a lost cause, so radials probably wouldn’t do much on that side.
To make the project even more fun there will be a back-up system at another location in the event the main tower goes off.
Hug the Ground
Very interesting setup proposal. Strange that signal wont travel up the south side and over the hill and down in the vally below…given MW frequencies love to hug the ground.
You mentioned remote tuning of the antenna system. What is the proposed system for that? Home made or something like a servo-MJF combo type setup?
Hobby Engineering, a website dedicated to home built projects, has a ton of items very useful for building a remote tuning/metering system for your proposed antenna. I built just such a system for my 3m stick and tune it from the comfort of the studio. Comes in quite handy during the winter when snow and well below freezing temperatures makes going outside a last resort. There is even a heating element in the box to keep things nice and cozy warm when the temps drop below 30*. All automatic. Next proposed project for that 3m stick is improving the auto-tuning circuit and sensing system.
RFB
What I Meant
Your response, RFB, had me checking the note I sent because I didn’t recall planning to tune the antenna from indoors. Ah, here’s what I meant…
I meant that I would be inside “tuning the station in on the radio.”
By “remote” I meant that the transmitter would be way out there in a remote part of the yard. The only connection to the house will be low-power, probably 12 but maybe 24-Volts, and a balanced audio line.
But tuning the transmitter and tower brings up some questions…
Once it is tuned the first time, will the weather and moisture and elements make the tuning need re-tweaking every once in awhile?
Environment changes changes a lot
Yes. Ever notice when you tune a 3m stick for a peak, that the antenna’s resonance will change a bit when you move away from it or if a tree limb gets a little to close due to wind and swings the peak out of whack?
Even changes will take place when it rains, snows, dry conditions, fog, sleet. It is quite dynamic. Depending on the environment changes and durations, you can develop a schedule for checking peak resonance at the best intervals for maximum system performance.
It wont change a drastic amount…but for the tiny power put into the system, peaking becomes top priority a majority of the time for maximum energy transfer from the TX to the stick.
When I was using my antenna system prior to the re-construction of the CC station, I determined that a check of the tuning on the antenna was needed about once every 4 days. This was especially true during the winter months when it would snow..then the snow settles on the ground and overnight becomes just a frozen layer of white, then melt and saturate the ground and so on. Then when spring and summer come along, time to re peak the antenna again for the warmer seasons, and the tuning cycles reduced from once every 4 days to about once every two weeks, unless it rained a lot in between each tuning cycle.
In fact you should notice a change a few days or so after it is constructed and initially tuned. This will be due to your new ground system making better and better conductivity contact with the dirt as the ground system sits in the settling dirt. A re tune will be necessary. Then wait a few more days and check the peak again. After a few weeks, it should settle in and not require too much frequent peaking.
Schedule a ground system watering routine too. This is to keep the dirt moist and continue to develop a better conductivity to the earth as time goes by. Try to do the watering in the mornings and evenings as during the day in hot summer season and sun, the water will evaporate quickly and not as much penetrate the ground onto the ground system and surrounding soil.
RFB
Interesting points about
Interesting points about returning the antenna, and the effectiveness of the ground, depending on moisture/humidity. It coincides with my observations on the range of my transmitter.
The range is the greatest on cool, crisp days (presumably when the soil providing the ground has not dried out from the sun). And the absolute greatest early mornings. Nights it drops dramatically due to interference from stations that roll in from who knows where (but are non-existant during the day).
During a rainfall, it drops, but after that rain, it goes up dramatically, again presumably because of the greater effectiveness of the ground.
I’ve decided to live with peaks and valleys of tuning; why bother retuning when you’ll just have to do it all over again (and there’s just little old me being station engineer/director of programming, chief bottlewasher). If it drops on a consistent basis, then yes, I’ll look at it. Plus, here on the northwest Coast, aside from summer, the radio’s ground system pretty much gets watered on every day.
Peaks and Tweaks
“why bother retuning when you’ll just have to do it all over again”
Usually you wont have to re-tune but its just good practice to me to make sure that thing is operating at its peak. Also when seasonal changes takes place, a slight re-tuning should be performed.
I tracked the “highs” and “lows” over a 1 year period and created a graph chart with the dates of the checks and amount of tuning of the air variable for each change that takes place.
I incorporated a home built/designed remote tuning unit using parts from Hobby Engineering. That way I can tune the antenna from indoors and avoid stepping out into the rain or snow.
This remote tuning unit uses a geared down motor assembly, a 2 inch “flywheel” that has a grove for a belt, a DC motor controller and a signal sensing circuit built from junk parts that feeds a meter in the indoor control box to indicate the maximum resonance point.
RFB