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Author Topic: 35 mile problem  (Read 24523 times)
K1CJS
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« Reply #30 on: September 14, 2011, 03:07:58 PM »

Quote
A vertical ground plane antenna up 20 feet of more are base. But, when band opens up there will be QRM issues. 2m FM is really best viable solution here and quite doable.

I only wanted to know for my own edification, I am leaning 2m, I am thinking an Arrow 146-4-BP 4 element beam with 100ft LMR400 and mounted roughly at 35ft as I can't go much higher than that.

My 857d puts out 50 watts which should be more than enough power, and we can try it against an HT at the other end, I'm sure he will be able to hear me, but I'm doubtful I will be able to hear the HT with a whip on it, most likely will have to figure out a roof mount antenna for him, or go to a mobile setup in his car.

You seem set on doing it that way, so why are you asking?  The way you propose, the person with the HT may be able to hear you quite well, but you may not hear him that well at all.
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W8JX
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« Reply #31 on: September 14, 2011, 06:08:56 PM »

If I may suggest that if you are going to go through the trouble to put up a beam and the extra expense of LMR400 that you put up a bit for than a light duty low gain portable beam. It would offer no gain advantage over a good collinear vertical and likely have less effective gain because the vertical will be 12 to 15 feet higher than beam. If you stay with beam, use a bigger one.

 Well, I was looking at the gain less than I was looking at focusing direction, and trying to get away with a small beam due to where it has to be mounted. I am assuming a vertical orientation of the beam and really don't have the room to have an 8ft beam, so I was attempting to keep it small. Since it is necessary to mount the antenna about 90ft from the shack, I figured it was best to go with LMR400 to reduce loss on the coax...

 I am wide open to suggestions though!


Directivity and Gain go hand in hand. A beam with say 7dbi is actually inferior to say a Hustler G7 vertical that has 7dbd of gain (or 8.7dbi they sometimes use dbi ratings because they look higher). Just because it is directional, it does not mean it is better than a good vertical. If horizontal space is limited against a longer boom on a beam and more element than 4, I would go vertical with a G7 and get it as high as you can and you will not be disappointed. Many have used them as a repeater antenna.
« Last Edit: September 14, 2011, 07:43:53 PM by W8JX » Logged

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Ham since 1969....  Old School 20wpm REAL Extra Class..
KD8PGB
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Posts: 138




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« Reply #32 on: September 15, 2011, 02:57:05 AM »



You seem set on doing it that way, so why are you asking?  The way you propose, the person with the HT may be able to hear you quite well, but you may not hear him that well at all.

I'm actually not set on anything yet, I am trying to get opinions on the best way to do it. I was  under the apparently false impression that a directional yagi would be more sensitive in the specific direction (than an vertical) and therefore be able to pickup the HT.

I have a Jetstream JTB3 vertical (4.5db gain), its currently only about 12ft off the ground, now I'm wondering if I could get it up high if it would not suffice? I can probably get it up about 35 or 40 feet.  Or should I be focused on something with considerably more gain like a Hustler G7?
« Last Edit: September 15, 2011, 04:10:50 AM by KD8PGB » Logged
AA4PB
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« Reply #33 on: September 15, 2011, 04:25:29 AM »

A good Yagi will have more gain, and therefore receive a stronger signal, in the direction it is pointing than an omni-directional vertical. No one can guarentee that it will be enough difference to receive an HT with a "rubber duck" antenna. It will increase your odds however. There are just too many variables to make any guarentees.

The directional antenna will also lower noise and interferrence received from directions other than where it is pointing. This may or may not make any difference depending on your particular situation.
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Bob  AA4PB
Garrisonville, VA
KD8PGB
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Posts: 138




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« Reply #34 on: September 15, 2011, 04:41:36 AM »


 But is gain simply gain regardless of vertical or yagi? I'm getting confused!

 Would a Hustler G7 at 8db gain be better than an Arrow yagi at 4db gain? I would think so, but is the directional isolation more important?

Would my "inexpensive" JTB3 vertical at 4.5db gain @ 40ft be worse than a 4db yagi at the same height?
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AA4PB
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« Reply #35 on: September 15, 2011, 08:13:56 AM »

Well, basically gain is gain whether vertical or a Yagi BUT you have to be careful about the reference and measurement conditions. Gain can be measure against a dipole (dBd) or against isotropic (dBi). The dBi reference results in about a 2dB increase in the number. A vertical may be referenced against a 1/4 wave whip as well. If the references are not the same then the absolute amount of signal received by the two antennas will not be the same.

An omnidirectional vertical gets its gain by narrowing the focus vertically and (hopefully) placing it down near the horizon. A yagi gets its gain by narrowing the focus horizontally to concentrate the signal in one direction.

One of the benefits of a directional antenna of course is that it minimizes noise and interferrence from other directions while an omnidirectional vertical receives equally from every direction.

« Last Edit: September 15, 2011, 08:16:40 AM by AA4PB » Logged

Bob  AA4PB
Garrisonville, VA
KD8PGB
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Posts: 138




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« Reply #36 on: September 15, 2011, 08:29:58 AM »

Well, basically gain is gain whether vertical or a Yagi BUT you have to be careful about the reference and measurement conditions. Gain can be measure against a dipole (dBd) or against isotropic (dBi). The dBi reference results in about a 2dB increase in the number. A vertical may be referenced against a 1/4 wave whip as well. If the references are not the same then the absolute amount of signal received by the two antennas will not be the same.

An omnidirectional vertical gets its gain by narrowing the focus vertically and (hopefully) placing it down near the horizon. A yagi gets its gain by narrowing the focus horizontally to concentrate the signal in one direction.

One of the benefits of a directional antenna of course is that it minimizes noise and interferrence from other directions while an omnidirectional vertical receives equally from every direction.



So for the noise reduction alone that would lead me to believe the yagi is a better choice for receiving a weak station at known location. Would that be true?

So on a yagi, essentially the higher the gain, the more focused the antenna is? In effect the lobe should be more narrow? Would this also lead to further noise reduction? Higher gain = narrow lobe and less noise? 



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W8JX
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« Reply #37 on: September 15, 2011, 03:04:03 PM »

Well, basically gain is gain whether vertical or a Yagi BUT you have to be careful about the reference and measurement conditions. Gain can be measure against a dipole (dBd) or against isotropic (dBi). The dBi reference results in about a 2dB increase in the number. A vertical may be referenced against a 1/4 wave whip as well. If the references are not the same then the absolute amount of signal received by the two antennas will not be the same.

An omnidirectional vertical gets its gain by narrowing the focus vertically and (hopefully) placing it down near the horizon. A yagi gets its gain by narrowing the focus horizontally to concentrate the signal in one direction.

One of the benefits of a directional antenna of course is that it minimizes noise and interferrence from other directions while an omnidirectional vertical receives equally from every direction.



So for the noise reduction alone that would lead me to believe the yagi is a better choice for receiving a weak station at known location. Would that be true?

So on a yagi, essentially the higher the gain, the more focused the antenna is? In effect the lobe should be more narrow? Would this also lead to further noise reduction? Higher gain = narrow lobe and less noise? 


Noise/static is not a issue on 2m FM.  Gain is gain and a 7dbd gain G7 will easily out perform a 4 element yagi on 2 meters for several reasons. One is larger capture area. Two, it will have a very low and focused angle of radiation. Three, if you put up a yagi at say 30 feet it is at 30 feet but a G7 at 30 ft at base will exceed 45 feet at tip.  Also hustler is rated 7 dbd not dbi like a lot a lot of fiberglass verticals. I have had on up for close to 20 years and have had no issues with it at all and still same feed line too.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
K1CJS
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« Reply #38 on: September 16, 2011, 12:33:14 PM »

I'm actually not set on anything yet, I am trying to get opinions on the best way to do it. I was  under the apparently false impression that a directional yagi would be more sensitive in the specific direction (than an vertical) and therefore be able to pickup the HT.

I have a Jetstream JTB3 vertical (4.5db gain), its currently only about 12ft off the ground, now I'm wondering if I could get it up high if it would not suffice? I can probably get it up about 35 or 40 feet.  Or should I be focused on something with considerably more gain like a Hustler G7?

Jetstream antennas aren't as good as some of the other antennas that are available.  They're what a lot of people refer to as 'Pacific Rim knockoffs.'  In other words, a copy of a proven design antenna that was made somewhere else--and may not be made as good as the original was made.  It may work fine for you, then again, another comparable antenna may work better.

Generally speaking, the higher you can get the antenna, the more range you may have while using it, but as others have said, there are a lot of factors that figure into it.  Now, if you were to put antennas on higher supports at BOTH ends, you improve chances that you will get a signal through.  A yagi will tend to ignore--that is, reject signals from the sides and will tend to maximize signal transmission/reception in one direction.  It's similar to how putting a passive megaphone to your mouth--or your ear--may help you to hear or talk to someone a little farther away.  It doesn't improve the signal, it just concentrates it--that is where the gain factor comes in.

An omnidirectional antenna with more gain would tend to concentrate the signals from all direction, but to a greater factor.  Now, if all you want to use the two meter stations at either end is to communicate with each other and with nobody else, you may well be better off with the yagi.  BUT--if you want to have general use stations to talk to anyone, anywhere, you would be better off with good, high gain omnidirectional antennas such as your Jetstream--or a Hustler G6/G7.  Such an antenna setup at both ends would let either of you talk to the other station--and with anyone else you may want to.

 
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KD8PGB
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« Reply #39 on: September 16, 2011, 01:36:02 PM »

Ok,
Today I did a test, I have a nice repeater near my house with an antenna at 180ft,  I went to my son's house with both my mobile and my HT, set them both on the repeater.  I keyed my mobile and made a call to the repeater. The repeater tripped open, and my handheld heard it, no problem, however my audio did not come through, only the repeater opening with no audio. So this leads me to believe that the mobile is sending a strong enough signal (CTCSS) to open the repeater, but the audio is not strong enough to be heard at the repeater.

So my next test was to key the HT against the repeater, and to my surprise the repeater opened! My little 5w HT with a 19" rubber duck opened the repeater from 40 miles away! But again the audio did not come through, which I really didn't expect the HT to have audio go through but it really surprised me that it opened the repeater at all.

So what this is telling me, is that FM 2m across this distance / terrain is not going to be effective unless I put a very high antenna up on both ends, apparently higher than what is possible at my house or my sons house.

I know, why not use the repeater and a higher antenna at my sons house? Because we don't want to tie up the repeater with our jabber and we don't want to rely on the repeater in the event of a power failure.

So now I am wondering if 10m is not a better option?
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W8JX
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« Reply #40 on: September 16, 2011, 03:15:23 PM »

Test was not very effective or relevant. I cannot say for sure why audio did not come thru but it was repeater doing it not you. If it was CTCSS it would not even key without it. I you put up a G7 at least 30 feet at base and son use a external antenna you will be able to talk. 35 miles is not hard to do at all on 2m.
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K1CJS
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« Reply #41 on: September 17, 2011, 11:34:06 AM »

OK Dan.  Now, you have to know a few things about that repeater to see how meaningful that teat was.  First, what kind of antenna is it using?  There is a difference between a Stationmaster (a very good, high gain antenna) and a Ringo Ranger (a plain antenna with no gain).  How high is that antenna mounted?  Does that repeater use a preamplifier before the receiver?  Is the repeater a quality commercial model, or is it a cobbled together home made version?  (I'm not saying there is anything wrong with that, some homemade repeaters are good.)  And there is more to consider too, such as weather and atmospheric conditions.

It isn't as simple as "I can key the repeater with my 5 watt HT."  There are a lot of other factors involved, and most of them have to do with details--just as your setting up the antennas and the rigs at your house and your sons house does.
« Last Edit: September 17, 2011, 11:35:42 AM by K1CJS » Logged
KD8PGB
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Posts: 138




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« Reply #42 on: September 18, 2011, 02:29:21 AM »

Test was not very effective or relevant. I cannot say for sure why audio did not come thru but it was repeater doing it not you. If it was CTCSS it would not even key without it. I you put up a G7 at least 30 feet at base and son use a external antenna you will be able to talk. 35 miles is not hard to do at all on 2m.

 On the contrary, there is some relevance to the test in that I was able to open the repeater with CTCSS,  but could not hear my audio returning from the repeater, I tried this several times with both the mobile and the HT and the repeater opened every time. What this showed me is that I can hit 180ft omni-directional antenna, next I need to test to a somewhat lower antenna as I cannot put mine up 180ft regardless.

I am getting two conflicting opinions here on the forum, both make sense, and I want the best possible solution before I spend my cash. I understand you have had great results with the G7, I'm just trying to quantify if it is the best solution for my application.
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KD8PGB
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« Reply #43 on: September 18, 2011, 02:32:43 AM »

OK Dan.  Now, you have to know a few things about that repeater to see how meaningful that teat was.  First, what kind of antenna is it using?  There is a difference between a Stationmaster (a very good, high gain antenna) and a Ringo Ranger (a plain antenna with no gain).  How high is that antenna mounted?  Does that repeater use a preamplifier before the receiver?  Is the repeater a quality commercial model, or is it a cobbled together home made version?  (I'm not saying there is anything wrong with that, some homemade repeaters are good.)  And there is more to consider too, such as weather and atmospheric conditions.

It isn't as simple as "I can key the repeater with my 5 watt HT."  There are a lot of other factors involved, and most of them have to do with details--just as your setting up the antennas and the rigs at your house and your sons house does.

I am not sure what the club is running for a repeater or antenna, I will have to get on and ask one of the members about it ,  I'm sure its a good unit, not some cobbled together system, they are one of the biggest clubs in the state. But the antenna is at 180ft up, which is a massive help, at that height I am sure line of sight is nearly unobstructed from my sons house.

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AA4PB
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« Reply #44 on: September 18, 2011, 05:16:41 AM »

There is something wrong somewhere if you can reliably key the repeater but can't get your audio through it.
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Bob  AA4PB
Garrisonville, VA
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