Neil, I looked at your photographs
again. What a great "on the ground"
installation!
I had asked a few weeks ago about
radials and if they would work just
sitting on the ground. Well, there's
the answer. They sure do!
I have seen ham radio portable vertical
antenna installations... What about
this set-up?
It would be really cool if you made this
permanent. But if you are unable to,
maybe you can make some kind of portable
package that you can deploy when you want.
If it was me, I'd put the whole thing in
a big plastic tool box. (Except for the antenna.)
Either way, it looks really really good.
Bruce, DRS2
P.S. I have now found all of the lost pieces to
my original outside Part 15.219 installation.
The one thing that is still hanging me up is: the
area of the yard where the transmitter was
sitting on the ground is grown over. (It was
in the corner of the back yard.) Underneath
that spot is a 16 radial ground system.
I have found the original "high Q" coil
that actually connects to the inside of
my SS-Tran AMT-3000. And two days ago,
I found the "ferrite rod" I used to fine
tune the coil.
This spot was really far from the house. I am
thinking of abandoning that ground radial system
and putting the transmitter in another spot.
I have several other projects before this one.
But finding the coil and the "ferrite rod" made
all the difference. -Bruce
"I had asked a few weeks ago about radials and if they would work just sitting on the ground. Well, there's the answer. They sure do!"
Yeah I had answered that question the day of your inquery but I guess validation was needed. Now you are assured what I said is correct. It even works good over a non-dirt surface like a parking lot or on a tennis court. Of course anyone is welcome to actually do it and find out I am correct there as well, though not necessary.
At least now there is a drawing/picture/illustration to actually visualize it, though as simple as laying down a table cloth on the dirt under a tree impressing the date on a picnic.
RFB
Would a ground area like that pass the muster? Just curious..
My first ground area was made with chicken fencing. 2 peices (48"X25') laid in an "X" configuration below the base. I soldered a few spots together where the fencing crossed to assure a good connection. I mounted things on a 3' tripod roof mount right in the center of the "X". I tested a Rangemaster and an SSTran at the same location with many hours of tweeking and peaking to assure the best of both. The SSTran won hands down. You can see the loading coil for the SSTran antenna in my avatar.
I operated both units remotely through some Cat-5 ~ 60' away from the house. I converted my 12 v.d.c. house supply to 24 volts using a voltage converter. (I'm totally off grid) Both units will handle 24 v.d.c. I used a pair for power and another pair for audio. Worked well..
From viewing the picture I admire the way the radials merge into a soldered twist that is formed into an upward mounting post for attaching the transmitter.
I went back to the photo to count the radials, and noticed your text gives the total as "11".
11 is an odd number. I would have thought that each branch of the radial needs its equal-opposite to avoid radiating radials.
There is a reason for the 11 radials and it dates back to when I made them a few years ago. I was planning on a permanent installation at the time but put it on indefinite hold. Ten radials were made and the eleventh wire was added to connect to the electrical service ground stake or a grounding rod of its own. This probably would have upset the current balance and the ground stake should have been placed in the center of the starburst rather than at its end. It may have been better if I cut this extra one off but I doubt the vertical component of the radiation was affected much.
Neil
"Would a ground area like that pass the muster? Just curious."
Why wouldn't it pass? Ground is from the surface of the Earth and on down. Anything above that surface is not ground unless it is a wire or other conductive object sticking up or over the surface directly connected to that ground radial system. In the sense of 219, keeping the ground connection from the TX to the laid down ground radial wires as short as possible is what matters, and is where that field agent is going to look.
Until the rules clearly say you cannot lay down ground radial wires on the surface of the Earth, can't see any reason why it would not be allowed.
RFB
Yup! I remember that you answered
that ground radials would work on
the ground without being buried.
Believe me when I tell you that I
completely trust your info. As far
as I'm concerned, if you say it -
it's true. I didn't need any further
validation.
I was just really excited for Neil and
was excited in general, so that's what
came out with my words on the keyboard.
If I wasn't for you and so many of the
other guys here, I would never have
learned as much as I have.
Best Wishes, and Thanks Always,
Bruce, DRS2
how about 1/4 or 1/2 wave piece of conductor laid out on ground spiraling out from tx mast to out perimeter in a circular fashion in place of tradition radials laid out symmetrically
Ya, I've wondered about a spiral ground.
I either asked about it once, or thought about asking it.
If I asked about it, it may already have been answered back then, but if I never asked, it has yet to be answered.
Heat waves cause spirals before the eyes, just prior to collapsing.
Had some more time to play outdoors and did another antenna test. This time 12 10 foot radials were laid out better and the antenna was set to exactly 3 meters from tip to soil. The turns on the coil were adjusted to give resonance and the tx. input power was 98 mW with 80 mW delivered to the antenna feed point.
Using the truck radio as a receiver I drove one direction and the signal was clear and listenable out to 1.3 air miles. The noise became noticeable beyond 1.3 miles and annoying at 1.5 miles. This is encouraging.
A short walk to about 300 feet from the antenna gave a good listenable signal on a portable radio.
The transmit antenna was located 40 feet behind my house and the signal became noisy on the portable upon entering the house. The noise was electrical buzz most likely from the light dimmers. Though the audio was readable, the noise was annoying enough that I would not listen for long.
A check with my Yeasu FRG-100 receiver using an indoor short whip antenna gave about the same noisy reception as the portable. The receiver indicated S7 for the signal strength and I tuned to a broadcast station running 5 kW omni 13 miles away and it too was noisy with a signal of S7.
Given that a good transmit antenna and efficient transmitter can be used without much improvement in field strength possible the biggest obstacle to in home listening is the man made noise in the modern home environment. Absent electrical noise and with a decent outdoor receive aerial I estimate that a listenable signal can be delivered out to 1 mile. It was not unusual for at home listeners in the '50s to have such a receive system, especially in rural areas and many radios had external antenna connections. With today's radios and lacking a good aerial in home reception of part 15 AM signals seems unlikely.
Neil
Neil, your testing is informative as the many combinations and unexpected variable results are all added together.
Until now I have innocently believed that an outdoor antenna would simply seem "far away" when received indoors. But the noise environment will most likely enter the picture.
I just noticed today that the LED ceiling bulbs I installed are creating a buzz field within several feet.
In some rooms when the compact fluorescents are turned on, there is hum on some radios but not others.
As regards the distance, I have been using "blocks" for measuring, but of course blocks are wildly different here and there.
I will chart out a mile in all directions to find out where that is.
Yes, they can. I hated to sound so negative in my last post but that is the situation here. My wife likes light dimmers and they are installed in every room and some of them create RF buzz even when turned off. Recognizing that my home may not be typical in terms of interference there may be hope depending on the circumstances. I reside in a suburban area yet am unable to receive any AM broadcasts interference free indoors. Part of my problem can be due to the stucco siding which is backed by hardware cloth and metal foil covered sheathing. This could explain the low S7 readings from both my station and the broadcast station.
When I used to listen to AM I relied on my "Big Ear" outdoor dipole antenna which is located away from noise sources. This is the setup on which I received the Talking House from over two miles away.
Neil
I repeated my tests with the outdoor antenna as described earlier and something has certainly changed. This time the signal inside my house was loud and clear on the portable radio. Two possibilities are that today the light dimmers were off and I tuned the portable to the transmit frequency (yes, you read that right). The situation is that for the outdoor test I am using a frequency 10 kHz lower than my usual frequency and I can't say for certain that I retuned the portable the other day. Nonetheless, today the reception was great.
There is another factor which is important, and that is the antenna system load resistance. The measured load resistance of my antenna system is 57 ohms at the feedpoint which indicates substantial ground R losses. Further investigation is underway concerning this.
Neil
The results this time sound like an improvement over the other time, with of course, those uncertainties which make it all questionable.
Mentioning the dimmers reminds me of something I cannot recall. In the fog of memory it seems that, while I was once studying the various causes and cures of RFI (radio frequency interference), I think I read about some way of adding some parts to noisy dimmers to make them shut up.
Here is my pledge as we approach election time. I shall dig back in my RFI file and attempt to find secrets and methods for noise suppression, that we might apply in the constant attempt to clean up the AM dial.
This will be brief. I'm on
a computer that I can't really
see well.
Going up or down one channel can
make a huge difference with noise
in your house. Maybe that's part of the
puzzle of how things changed.
I do a lot of listening between
the AM BCB and the top end of
80 meters. Some frequencies can
be obliterated by house noise.
Also, it seems to me the signal
of your transmitter should be
very strong in your house. I wonder
why it wasn't before? In my last
AM installation, the transmitter was
50 feet (at least) out in the back
yard. It wasn't strong in the house
when I first started getting it running,
but by the time it was all tuned up
it was very strong indoors.
Thank you for doing these tests. In
the long run, this will be a big
help to all of us.
Bruce,
DRS2