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Clyde

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This past weekend I was finally able to field test the Kenwood TM-D710A and the Diamond X-50.
I was in the high desert of California.

Hitting the WIN System was no problem, but I was almost completely in the shadow of Freemont Peak when i tried some other repeaters. Being able to bump the power from 5 to 10 and even 50 watts made making most contacts easy!

The Diamond X-50 is an excellent antenna! It comes pre tuned, and can withstand a 100 + mph wind.

I had the X-50 attached to a painter's pole that extended to 15 feet. the way attached it to the ground was by using a steel fence post with three hose clamps

I didn't get much in the way of simplex either. Mostly due to a lack of people in the area.
20140405_120347_resized.jpg
 
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Well, lets look at your situation from a technical standpoint.

1'st - all vertical antenna's requires some type of ground plane.
A simple ground plane for 146.550 / 440 MHz would be at least 4 wires / 4 feet long, to as many as 120 wires - 4 feet long.

2'nd - Height gain, at UHF frequencies, when you raise the antenna from 24 to 36' above ground level, you achieve the equivalence of about about 10 db of gain.
To relate this to non technical terms - if you had a signal that was S-6 at 24' and you raised your antenna to 36' - you would achieve 2 more S units of signal. Or if your signal was S-6 with 50 watts and you raised your power to 400 watts it would appear just as strong.

http://kf7ekb.com/power-dbs-s-units/

3'rd - we have to look at path loss - how far is it to the repeater and what is between the transmit antenna and the receive antenna.

4'th - we have to look at ground conductivity.. The soil looks very dry, not a good thing for RF.

5'th - we have to calculate how far the repeater will talk.
Repeaters are built to service a general area. For the most part, for coordination purposes - we space repeaters 120 miles or more apart. The reason for this is - we can expect a good repeater, on top of a mountain, with a moist soil content - or sprinklers, built on top of a tower at least 180' above ground level and at least 100' above average terrain - to talk about 65 miles on a good day in all directions - depending upon its antenna radiation pattern.

The one point that most people confuses is HF with VHF and UHF.
HF the signal goes up, down and forward. It is a very long wavelength and by manipulation we can raise or lower the antenna to achieve the pattern we desire.
What I am saying is that as long as we do not have a radio black out - we can expect to find something somewhere on some band.. Usually 40 meters in the daytime and 75 and 160 at night.

VHF and UHF and all radio frequencies is line of sight for reliable communications.
Once you go beyond line of sight, all bets are off.

Repeaters are only designed to service a specific local area - they do not take the place of HF and simplex for both local and distant communications, especially in a SHTF situation.

Thanks for the write up...

It would have helped if you would have taken along a 4 element / 2 meter beam antenna and another antenna such as the Diamond X510.... Then as long as you compare one to another within one hour of each other you can replicate actual radio conditions for both antenna's.
 

Clyde

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1'st - all vertical antenna's requires some type of ground plane.
A simple ground plane for 146.550 / 440 MHz would be at least 4 wires / 4 feet long, to as many as 120 wires - 4 feet long.
The X-50 does have three ground planes built into it at the base.

It would have helped if you would have taken along a 4 element / 2 meter beam antenna and another antenna such as the Diamond X510.... Then as long as you compare one to another within one hour of each other you can replicate actual radio conditions for both antenna's.
If only I could afford more antennas.

These are the repeaters I was hitting;

Frequency.........Tone......Location.....................................CountySt/Pr Call
147.1950+................141.3........Victorville, Quartzite Mountain............San Bernardino,CA...................W6NVY
146.3850+...............146.2........Running Springs, Keller Peak..............San Bernardino,CA...................KE6TZG
147.9750-................100.0........Ridgecrest, Inyokern, El Paso Peak.....Kern,CA.....................................WI6RE (WIN System)
448.8000-...............100.0........Ridgecrest, El Paso Peak......................Kern,CA......................................WI6RE (WIN System)

Thanks for your input!
 
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In electrical engineering, a ground plane is an electrically conductive surface, usually connected to electrical ground. The term has two different meanings in separate areas of electrical engineering. In antenna theory, a ground plane is a conducting surface large in comparison to the wavelength, such as the Earth, which is connected to the transmitter's ground wire and serves as a reflecting surface for radio waves.


In telecommunication, a ground plane is a flat or nearly flat horizontal conducting surface that serves as part of an antenna, to reflect the radio waves from the other antenna elements. The plane does not necessarily have to be connected to ground. Ground planes are particularly used with monopole antennas.



For a monopole antenna, the Earth acts as a ground plane to reflect radio waves directed downwards, making them seem to come from an image antenna. To function as a ground plane, the conducting surface must be at least a quarter of the wavelength (λ/4) of the radio waves in size.

The ground plane doesn't have to be a continuous surface. In the ground plane antenna, the "plane" consists of several wires λ/4 long radiating from the base of a quarter-wave whip antenna.

The radio waves from an antenna element that reflect off a ground plane appear to come from a mirror image of the antenna located on the other side of the ground plane. In a monopole antenna, the radiation pattern of the monopole plus the virtual "image antenna" make it appear as a two element center-fed dipole antenna. So a monopole mounted over an ideal ground plane has a radiation pattern identical to a dipole antenna. The feed-line from the transmitter or receiver is connected between the bottom end of the monopole element and the ground plane. The ground plane must have good conductivity; any resistance in the ground plane is in series with the antenna, and serves to dissipate power from the transmitter.

http://www.csgnetwork.com/antennagpcalc.html

upload_2014-4-9_7-45-11.png
 
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Radials works one of two ways.

Either you place the radials directly below the antenna, at a 45* angle, or you place the radials at or near the surface of the earth in a radial pattern - hence the term radial.

4 radials in the air can take the place of 36 radials on the ground.

Without getting into the physic's - all I can say is that the improvement by putting ground radials on the ground doesn't always show a person what is happening when dealing with fractions of micromicrovolts µµV..

The ploy made by Diamond and other companies is to sell you an antenna that requires no knowledge to install.. Simply put it up in the air and attach some coax and transmit.

All vertical antenna's requires some type of ground plane.
Yes you are right, there is radials beneath the antenna already incorporated by Diamond.
 

Clyde

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Radials works one of two ways.

Either you place the radials directly below the antenna, at a 45* angle, or you place the radials at or near the surface of the earth in a radial pattern - hence the term radial.

4 radials in the air can take the place of 36 radials on the ground.

Without getting into the physic's - all I can say is that the improvement by putting ground radials on the ground doesn't always show a person what is happening when dealing with fractions of micromicrovolts µµV..

The ploy made by Diamond and other companies is to sell you an antenna that requires no knowledge to install.. Simply put it up in the air and attach some coax and transmit.

All vertical antenna's requires some type of ground plane.
Yes you are right, there is radials beneath the antenna already incorporated by Diamond.
Thank you for sharing all of this information, It is much appreciated.
Would you suggest adding some ground plane to the base of the antenna?
Also, If I may inquire, is the antenna affected by the fact that it is mounted directly to the aluminum painters pole? If it does should I make a connector so it is only connected to the non metallic portions?
 
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You want the antenna to be grounded to a DC ground.
The ground is half of the antenna for most antenna's.
Getting the antenna as high as you can possibly get it and getting some ground radials underneath it is a real cheap way to get better performance.
Using coax with the lowest possible loss is also another way to improve performance.
At UHF frequencies - better coax pays dividends in performance.

http://en.wikipedia.org/wiki/Coaxial_cable
@ 750 MHz - LMR 400 only has about 3.544 DB of loss, compared to twice that amount for RG 8U and twice again if you were using RG 8X in 100 feet of coax....

LMR 400 - with a loss rate of 3.544dbm - you are throwing away half of the signal in the coax.
RG 8U you are throwing away - 5.96 dbm at a loss rate of about

RG 8X would make a pretty good dummy load with 10.946 dbm - 90% of the received and transmitted signal lost in the coax...

http://en.wikipedia.org/wiki/Decibel
 

Silent Bob

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Clyde, well both of you. Thanks very much for posting this thread. One area I really suck at is communications, I've read, read, bought stuff, but I have what you call the hex...every time I gear near comm gear, it goes out. Satellite phone's, the old PRC's, the new secure ones...you name it, I am a "Debbie Downer", when it comes to communications. Lol, the wife had to buy me the most expensive cellphone so I couldn't screw that one up. Must be the titanium rod and plates in my body or the cynical view I have for radios. Never had a problem with them, when I was a kid, I enjoyed getting on my dad's old C.B., but in the military and ever since, no luck. So it was just very enjoyable reading what you posted...hope to one day, not be a novice in it.
 
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Clyde, well both of you. Thanks very much for posting this thread. One area I really suck at is communications, I've read, read, bought stuff, but I have what you call the hex...every time I gear near comm gear, it goes out. Satellite phone's, the old PRC's, the new secure ones...you name it, I am a "Debbie Downer", when it comes to communications. Lol, the wife had to buy me the most expensive cellphone so I couldn't screw that one up. Must be the titanium rod and plates in my body or the cynical view I have for radios. Never had a problem with them, when I was a kid, I enjoyed getting on my dad's old C.B., but in the military and ever since, no luck. So it was just very enjoyable reading what you posted...hope to one day, not be a novice in it.
Dad's old CB - 23 channels, the whole shooting match took place on less than one half of one Megacycle . 26.965 - 27.255 - MHz..
http://en.wikipedia.org/wiki/Citizens_band_radio
It was possible to put up one large antenna above the roof of the house, connect a piece of RG 8U coax and hook it up to a radio and talk.
The educated people either invested money into a SWR meter, a dip meter, or an antenna analyzer.
If you tuned the antenna at resonance for channel 11 0r 12 - the one antenna would work over the entire range with a less than 1.5/1 VSWR..
http://www.microwaves101.com/encyclopedia/vswr.cfm
VSWR - voltage standing wave ratio - is important because we are more concerned with the voltage present on the line then we are just the ratio of forward and reflected power.
A 3 watt radio - when everyone else was only using a 3 watt radio, was enough power to talk half way around the world when the band was open.
By incorporating a more sophisticated beam antenna, it was possible to make that simple 3 watt AM signal / 12 watt Peak Envelope Power - Single side band signal appear like a 120 watt signal coming out of a dipole antenna.
A dipole antenna is a simple antenna that is one half of one wave length in size and is center fed. Because we know what to expect from a dipole antenna, and because a 11 meter (27 Mc) antenna is only 18' long, we use this antenna as a reference.
Any improvement over a dipole antenna is called GAIN!
http://en.wikipedia.org/wiki/Dipole_antenna
Gain is measured in Decibels - a decibel is a measurement of gain that was determined by Bell Labs - the people that brought us the landline telephones more then one hundred years ago. The phone company is the only people that concerns themselves with gain - since they have to amplify the landline telephone calls so it will travel through the twisted pairs from your house back to the phone companies hub station.
http://www.engineeringtoolbox.com/decibel-d_341.html

I was just having a conversation with two guys on the UHF radio - 442.200 Mhz, the one operator was 50 miles away and the other one was 40 miles away.
We got to talking about how we needed to get more new hams on the air and that we needed to explain to them the importance of buying a ham radio transceiver and putting up a efficient antenna and using a low loss coax.

The part of being able to tune the antenna to resonance and using a good feed line is the breaking point for most people. This is what makes or breaks a good radio system.
RaDio is a lot of fun when it works and is a PITA when it does not.
 

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