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Post by Druid Hills Radio on Mar 20, 2017 13:31:07 GMT
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Post by Deleted on Mar 20, 2017 14:19:59 GMT
More From CarlJim, the Low Power Radio Resources at my Low Power Supercenter is loaded with almost all of the links ever linked on these forums on every subject. Carl's Low Power Supercenter
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Post by Druid Hills Radio on Mar 20, 2017 15:18:46 GMT
More From CarlJim, the Low Power Radio Resources at my Low Power Supercenter is loaded with almost all of the links ever linked on these forums on every subject. Carl's Low Power Supercenter Where is the door greeter?
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Post by Deleted on Mar 20, 2017 17:34:03 GMT
Good Suggestion
Druid Hills good idea: "Where is the door greeter?"
Yes, that would be the right touch.
May we have permission to use your picture?
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Post by Druid Hills Radio on Mar 20, 2017 17:57:14 GMT
Good SuggestionDruid Hills good idea: " Where is the door greeter?" Yes, that would be the right touch. May we have permission to use your picture? Certainly
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Post by Deleted on Mar 20, 2017 20:31:18 GMT
Continuing the Discussion
As indicated yesterday, I'll be back with links, quotes and opinions to give Jim Henry as much information as we can about the questions raised at the open.
This is a quote from PhilB's "Ultimate Part 15 AM Installation" which has an active thread at part15_us:
Ground Radials: antenna modeling software shows a dramatic improvement in field strength for a ground-mounted 3m antenna when you install 32 to 64 ground radials at least 30 ft long.
On another point, the question about the gauge of copper wire used for radials... my thought:
The thicker the wire the better. Insulated cable or bare is as good. Solid or braided, although solid might weather better over time.
Finally for now, laying the radials on the surface of the ground and using garden staples to hold them in place:
Yes indeed! It will work very well, the wire doesn't need to be buried. As roots grow in the dirt the staples and wire will be further "wed" to the surface.
When I return I'll start talking about audio connection to a remote antenna location.
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Post by End80 on Mar 21, 2017 14:18:17 GMT
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Post by Boomer on Mar 22, 2017 0:42:16 GMT
I like how ISS recommends the short ground plane, small plane for the frequency, but lots of wires in the ground plane disc. I can see what they're getting at I think, high wire density in the highest current area close to the antenna, to send out stronger signals than just a few longer wires would.
I've been interested in traveler's info stations for a long time, since I had a portable radio that had dial markings for the stations at 1610. I never heard any of the stations, but later read about them in an electronics magazine, an article about different low power broadcasts that were little heard. I always thought that would be a good model for a community radio system, a mile of good signal and able to fit in an average urban lot.
I knew they used short vertical antennas and must have small ground planes too, and wondered what the efficiency actually was, and calculated it out, based on quarterwave broadcast antennas over a regulation ground plane. My results were that a TIS had an ERP of 125 milliwatts, figuring on ten watts power out from the transmitter. I was surprised at that, you can hear a TIS on a clear frequency for several miles with ease.
I thought that's something that TIS installers don't want you to know, because they always use 10 watts in their literature. It gave me hope, showing how low power can actually get out, and not to laugh at milliwatts.
Boomer
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Post by End80 on Mar 22, 2017 9:15:35 GMT
Boomer said "..I always thought that would be a good model for a community radio system, a mile of good signal and able to fit in an average urban lot.."
That's a extremely interesting thought and one that has occurred to me recently. However, the TIS classification rules is rather limited in content, but if a completely new classification (such as occurred in 76) to be created utilizing the same type of installs would be ideal (and a reasonable request) for localized community radio. However, you can absolutely count on the NAB and other organizations would strongly fight against any such new licensed proposals.. They always have, the fought tooth and nail against TIS stations back in the 70s, and that fought against the lifting of 5khz filters for TIS recently ( some of their arguments was almost laughable, but they genuinely expressed that improving audio of TIS would be a threat to the radio industry)
However, those considerations would obviously require forms of license, but not as unachievable.. such ideas is rather different than possible hopes of amending some of our part15 rules, if part15 amendments ever get considered, it really can't be expected that they would ever be major changes... it's not a reasonable expectation, part15 is a protection device, not a broadcasting venue, but nevertheless a lee-way is available within it to utilize in limited manners. To propose amendments simply because our hobby stations have difficulty achieving community radio presence is simply not a valid argument for the FCC.
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Post by radiodugger on Mar 22, 2017 19:00:53 GMT
Jeff (Station 8) says 8th Wavelength ground radials provide a vast improvement in range as tested. It is said that radial pattern density in one direction can "directionalize" the signal somewhat. I cannot confirm this.
Doug
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Post by Deleted on Mar 22, 2017 19:18:26 GMT
Experience from Here
RadioDugger said: "It is said that radial pattern density in one direction can "directionalize" the signal somewhat."
I'll explain why I think that is true.
My AMT5000 is inside the back window of the building. The antenna is the metal windowframe with enough wire attached outdoors at the top to measure 3-meters.
But the rear yard being all uphill the signal wasn't getting 100' to the top edge, where I often did yardwork with a radio.
I dropped a ground wire through a hole in the floor to a copper radial wire laid on the ground up to the top of the hill (north). Zing! Total 100% reception all the way up.
An equal length of copper wire was put in the opposing direction (south) to balance the (2) radials, but this one entered the basement, ran along the I-beam and was therefore not "on the earth", even though it achieves the loading objective of radial wires.
Result: the reception on car radio going north is over 2,000 feet, other directions under 1,000-feet.
The greater lobe is in the direction the earth-laid radial is pointing.
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Post by mighty1650 on Mar 22, 2017 20:10:05 GMT
I can confirm radials can add directionality to your signal, case in point when the yard crew clipped a few of my radials.
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Post by Druid Hills Radio on Mar 23, 2017 0:58:03 GMT
Experience from HereRadioDugger said: " It is said that radial pattern density in one direction can "directionalize" the signal somewhat." I'll explain why I think that is true. My AMT5000 is inside the back window of the building. The antenna is the metal windowframe with enough wire attached outdoors at the top to measure 3-meters. But the rear yard being all uphill the signal wasn't getting 100' to the top edge, where I often did yardwork with a radio. I dropped a ground wire through a hole in the floor to a copper radial wire laid on the ground up to the top of the hill (north). Zing! Total 100% reception all the way up. An equal length of copper wire was put in the opposing direction (south) to balance the (2) radials, but this one entered the basement, ran along the I-beam and was therefore not "on the earth", even though it achieves the loading objective of radial wires. Result: the reception on car radio going north is over 2,000 feet, other directions under 1,000-feet. The greater lobe is in the direction the earth-laid radial is pointing. DHR: "Carl proves that a single accurate measurement is worth a thousand expert opinions."
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Post by Deleted on Mar 27, 2017 0:20:06 GMT
About how long are these radials?
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Post by Deleted on Mar 27, 2017 2:10:07 GMT
Radial Length
CENTINEL asks: "About how long are these radials?"
You are probably asking about my radials so the answer is...
I've never made a precise measurement but ABOUT 100-feet to the north and 100-feet to the south.
Might only be 60-feet. They are matched length.
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