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Thread: Simplex Base Station to Mobile Setup

  1. #1

    Default Simplex Base Station to Mobile Setup

    My wife and I have recently moved to a rural area of Montana, that is both mountainous and wooded. I work from home, but my wife does volunteer work that has her driving in all directions, often in the backwoods (with hills\mountains between us), but no more than a 20 mile radius away from home. Needless to say, she has no cell coverage most of the time, but we often have need to communicate, and I especially worry about her in the winter time, where icy conditions can easily leave her stranded.

    I'm very glad that we have this need, because it has given my wife incentive to get her license, and I'm excited to share this hobby with her. Now as for myself, I used to have a tech plus license, and passed the old General exam but failed on the 20 wpm code (I hadn't even planned to go for the General license at the time but figured I'd give it a shot!). Unfortunately, it's been 20 years since then, so I have a lot of studying to do, myself, since it has been so long, and I know I need to retake the test.

    I know I am sort of jumping the gun here, by asking for advice at this point, but winter is coming and I'm hoping to get something set up before the weather gets worse, and I also will need to be able to give her a rough cost estimate to get her on board with this, or I might get myself in a whole load of trouble.

    So on to my question:

    What band do you think would be best for this situation? And what type of antenna to use (On both ends)?

    A couple things to keep in mind - I would prefer to build my own antennas. Also, I have a two story house I can mount an antenna on, and I also have a couple of very tall fir trees if that would help with mounting an antenna.

    My initial plan was to use 2 meter band with DMR, and this is kind of where I am leaning at the moment. With 2 meters, I could get a nice waterproof HT for when I'm out fishing, which would be nice. But I figured I'd ask for some advice, since I'm not sure what kind of distance I could get simplex with 2 meters in these conditions, and communicating with my wife's vehicle out in the backwoods is a greater concern.

  2. #2

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    ok, just a jab for fun, but the General class never had a 20 WPM requirement, that was the extra class...your memory (like mine is slipping on the numbers) General was 12 or 13 WPM, can't remember that was a long time ago.
    20 miles simplex is doable, but the mountainous terrain may be an issue. The two story house is not an issue and neither is making your own antenna.
    Cost will depend on you, but at least go with two good mobile radios, I would not try an HT on either end for your use. Antennas, well on both ends it will pretty much be a vertical in the VHF/UHF area that you would most likely use. Lots of mfg's in the mobile arena, you can make your own vertical for the house.

  3. #3

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    You're right, I had gotten things mixed up! I had taken the 20 WPM exam just to try it, but failed miserably. Then I failed the General class after that (By 1 question!). I was happy to come away with my tech plus though, because that's what I had been after anyways!

    As for an antenna for the house, I had made a J-pole antenna out of copper pipe in the past, so I could always do that again. But I've also wondered about making a dipole antenna. Does anyone have a link to good information on antennas (specifically for 2 meters)?

    As for VHF versus UHF, I had assumed that VHF would be the better option, but could it be possible that UHF would perform better in forests/mountains?

    In regards to HT's, I wouldn't be using that for long range. I tend to wander off for the day when I'm out fishing, and my wife is a worrier. I'd usually be using it for <1 mile - 4 miles or so, which should be easy enough if I get an AiLunce HD1 like I was planning.

    For radios, I was eyeing a Retevis for that as well, to stay consistent. The RT-90, specifically (RT-90). I never would have thought I'd be buying Chinese stuff, but I guess everything is made there anyways, these days! And there's not a ton of DMR options for mobile radios, but I'm really interested in trying it out.

    Thanks for the advice.
    Last edited by Mobius1; Wed 17th Oct 2018 at 23:39.

  4. #4

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    Topography is the key here. There are quite a few predictors on the net, where you enter your houses coordinates and the height of the antenna and it predicts the coverage either as a graphic display or as location to location - you'd enter your home and the place you fish, and it tells you if there is a path or not. Once you check how the RF will fly, you can move onto the kit. Where I am it's quite flat, but the nearby town 10 miles away is below the RF horizon, as there's a slight hum between here and there. In the other direction 30 miles is possible, but only 6 miles North.

  5. #5

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    Quote Originally Posted by paulears View Post
    Topography is the key here. There are quite a few predictors on the net, where you enter your houses coordinates and the height of the antenna and it predicts the coverage either as a graphic display or as location to location - you'd enter your home and the place you fish, and it tells you if there is a path or not. Once you check how the RF will fly, you can move onto the kit. Where I am it's quite flat, but the nearby town 10 miles away is below the RF horizon, as there's a slight hum between here and there. In the other direction 30 miles is possible, but only 6 miles North.
    That sounds great! I tried to find something like that, but maybe I'm searching using the wrong keywords. Could you recommend a site?

  6. #6

    Join Date
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    Default

    Investigate this predictor. Helpful info. Input your location and you're off.
    https://www.heywhatsthat.com/

    Plus, look over this extensive site about mobile radio. You'll be glad you did.
    https://k0bg.com/

  7. #7

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    Thanks for the links! I can't wait to get a radio and compare the predicted results with real world results.

    I've been doing a lot of reading on 2 meter antennas, and if there's one thing I've learned, height is king, and what is "best" is highly subjective. At the moment I am focusing more on my base antenna, since that's what I need to get built before winter (Or at least I hope to.). At this point, I've decided that mounting from my second story is probably the better choice, based on what I feel comfortable doing at this time. With a mast, I could get some pretty significant height.

    From what I understand (and please correct me if I am wrong!), for my simplex situation, gain is really going to make a difference. If I understand correctly, J Pole antennas have 0 gain, and dipoles just a little bit of gain? I see a lot of recommendations on the web for Collinear antennas (The Ringo Ranger seems to come up a lot.), which seem to have great gain. But I also was wondering if an IsoPole antenna could be the option for me, like this. I haven't done any digging for homebrew plans for one, but it looks doable enough. But I don't see IsoPoles come up often, why is that?

    One other question I have, is about power. I know it's possible to go over 50w with a mobile transceiver, but is there a point of diminishing returns? Would there be much, if any, benefit to going higher than 50w? And generally, about when (wattage wise) do you need to invest in extra equipment, to meet the power demands in your car?

  8. #8

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    No - there's a small difference in the horizontal radiation pattern between the J Pole variations and a dipole - but they have no practical gain. 5/8th antennas are either assumed to have gain (typically a 3dB figure) but others claim they don't. Probably the best solution if you want gain is a phased stack of two or 4 dipoles - in fact, assuming you need more gain in one direction rather than a perfect omnidirectional pattern, you can stack 4 dipoles on one side of a mast and get a squished omnidirectional pattern, favouring a certain direction - 6dB gain over the single dipole is possible. Colinear antennas, containing multiple elements that are only modestly long might get you 4.5dB or so gain over a dipole - which is the standard all antennas are judged against. I can't see much point going much of around 10-20W because it's two way. No point in them being able to hear you with your loud voice when you can't hear their weak one. 10W seems to be to me balanced - , and perhaps even a bit much compared with the poor antenna and lower power the other end. It's usually the receiver that sets the range.

  9. #9

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    Well, if 10w got the job done, I could just connect the antennas to the HT's I planned on getting. The AiLunce HD1 is 10w, and from what I've seen from tests, it is true to that wattage at high power. If that could get me by for now, that would be nice. I'd still want to get tranceivers eventually, but at least getting the wife on board initially would be easier!

    If I understanding this correctly, the horizontal beam pattern matters, since that is where the gain is focused, and that's where I'll be transmitting to and receiving from, so my signal vertically isn't so important?

    Does anyone know of a good site that compares radiation patterns of antenna types?

    And as far as the phased dipoles go - What would be the advantage of that over say, an omni-directional array of yagi antennas? Is it just a matter of size?

    I'm still interested in the IsoPole antenna, but I can find very little info about them, other than a few people claiming they are amazing. I even did a search on these forums and not one post came up!

  10. #10

    Join Date
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    Mount a beam at home in the vertical plane so the energy will be more in phase with the energy from the vehicle, since most car antennas are vertical. Horizontal polarization is good for SSB or CW signals, home to home/field. You will need a way to turn the home antenna for maximum gain towards your spouse, lots to consider here. 50 watts is a good power level, better than 10 for use in hilly terrain.

    Look here for mobile ideas - https://k0bg.com/

  11. #11

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    Ha! We have a laugh about the US loud voice technique - no offence intended - but we're quite used to folk on the HF bands who run full tilt maximum power, but can never hear the replies!

    As to the arrays - forget the phasing thing - the phasing harness is just the way to connect multiple antennas together so the antennas match each other and present a 50Ohm load to the transmitter. Look up things like 4 stack - or look in the amphenol-JBeam documents. For commercial VHF and UHF, you stack 4 dipoles above each other. You can choose to mount them at 90 degrees to each other which produces a pretty even omnidirectional pattern in the horizontal plane - that is what you see viewed from above, but is a Vertically Polarised signal, for mobile antennas and hand-helds. WZ7U's idea of a vertical beam could be attractive, if you know where the distant station will be. Mount a yagi (a dipole, with added directors in front and a reflector behind) on a rotator, and you can quite easily get 10dB gain over a dipole - which is pretty much like transmitting with 100W rather than the ten Watt one you have - and IS reciprocal boosting receive and transmit gain, and therefore distance. The more elements the beam has the more gain, but the narrower the beamwidth. So much depends on what you are planning on doing. Wander outside the beam width angle and the gain drops like a stone, so route planning, beam swinging and so forth get more complex. You could put an omni antenna on top, and have a switch between them. When the signal starts to get weak, you switch to the beam and swing it, and at some point the signal goes up. It does rely on the skill of the person at that end of course.

    I realise I'm a lone voice in the power stakes, but working somebody with more power can be VERY frustrating. You can hear them loud and clear, but they cannot hear you! Over the years receiver sensitivity has not changed much, but now everyone seems to wish to shout loudly with as much power as they can get together. Then they complain they can't hear anything. This is much less common in Europe. It's gone up a bit, but not that much.

  12. #12

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    I've looked over the mobile radio site, but I haven't found anything on the site that pertains to anything outside the vehicle side itself. But in my case that's only half the setup.

    A Yagi would only work if I knew where she was going exactly, but that's rarely the case.

    I like the phased dipole idea, because I could focus gain on certain areas, yet still obtain omni-directional capability (If I'm understanding it correctly.). I'm trying to find more information on it, so that I could hopefully make my own. Do I connect them in parrarel? In series? I don't even know where to start! I guess I really need to hit the books...

    As far as power is concerned, I was wondering if the extra power would help get through some of the woods and mountainous areas. Both ends would be transmitting at 50w if I went with the tranceiver I was thinking of (The Retevis DMR mobile unit.).
    Last edited by Mobius1; Sun 21st Oct 2018 at 02:04.

  13. #13

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    If both have high power then the extra power makes sense. Putting all 4 on one side produces something a little cardioid shaped, with a small null at the rear, which you'd use as your area of least interest. Not really cardioid, but no longer a perfect circle.

  14. #14

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    What do you guys think about a vertical bazooka antenna like this:

    http://www.hamuniverse.com/vertbazooka.html

    A bazooka antenna seems like it would be easy to get into my tree.

    Another homebrew antenna I'm looking at, is this one (It's for 440 but I could convert the measurements to 2 meters easy enough.):

    http://www.rason.org/Projects/collant/collant.htm

    This one is 8 elements stacked, which is one thing I am having a difficult time finding information on - radiation patterns.

    Because of the potential variances in elevation where the car might be, I assume stacking too many elements would work against me under certain circumstances. At most, a 2000 foot elevation difference is what we'd have (the mobile side being higher.). Would focusing my gain horizontally with 8 elements limit my radiation pattern to too low of elevation? I'm having a hard time finding data on radiation patterns, honestly. Increasing gain sounds well and good, but how can I find out what would be TOO horizontally focused for my situation?

    And then there's the mobile side. I am assuming that for my needs, a 1/4 wavelength antenna would be the better choice over a 5/8? I know it really depends on the situation, but since I'd be dealing with mountains/trees being in the way, and differences in elevation, I am assuming 1/4 would be better overall. Has anyone compared the two in mountainous terrain?

    EDIT: One other question. I was looking into using an amplifier with a HT, instead of using a mobile transceiver. Are there disadvantages to this? My thoughts are that I could attain 100w of power with DMR, and could get two amps and 2 HT's, rather than having to buy the two mobile transceivers.
    Last edited by Mobius1; Mon 22nd Oct 2018 at 19:17.

  15. #15

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    One thing I've been wondering, which hasn't really been discussed, is if I'd be better off using the 6 meter band. Wouldn't that function much better through forests and mountains?

    One problem I'm noticing, is 6m amplifiers seem pretty few and far between. But maybe I could Homebrew something...
    Last edited by Mobius1; Thu 25th Oct 2018 at 00:18.

  16. #16

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    I've tried making those antennas - results were to be frank, terrible. Not, I think with the actual antenna, but the construction. The multiple lengths all soldered together was a good example. I cut them as accurately as I could, I soldered as carefully as I could, I used all the correct techniques and the performance sucked. I found on disassembly a couple of strands that might have been shorting, but on desoldering I melted the next section and so on - it performed terribly on the VSWR meter, the antenna analyser and in practical tests. A lesson in theory not really translating to practical useful antennas. Almost certainly my construction skills. I wonder if a tress is going to work for you?

    Their radiation pattern is omnidirectional - the gain comes from lowering the horizontal beam angle, reducing what gets wasted going upwards. Think of the usual torrid shaped pattern from a vertical antenna. so much goes up at 45 degrees. The stacked antenna designs reinforce the horizontal plane emissions giving them more reach. Always omnidirectional as they are symmetrical viewed from above, like the 4 stacks 90 degrees apart nearly are.

    I'm thinking about the practicalities of an antenna on a thing like a tree? Maybe it's going to have to be a proper tower? My own experience with trees is that the damn things grow, and bend, and rarely have trunks that can support an antenna vertically and keep them there. Maybe a tall pine or something could be OK, but how do you actually get up there, to the very top!

    Can you use an amp with DMR? I was under the impression that the switching time on a pulsed DMR signal prevented conventional amps being used as they are normally relay switched - impossible on DMR? Nothing wrong with an HT and an amp in FM, but digital I don't think will work.
    Last edited by paulears; Thu 25th Oct 2018 at 08:42.

  17. #17

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    I have not used 6 meters in a long time, but back in the 1960's, 6 meters was commonly used by hams in southern arizona (where I lived for a while as a teenager) for mobile radios (heath kit lunch box comes to mind). I think it would be a bit more expensive to start out with than 2 meters and would require a larger antenna at your home. I have used a handheld LGPD (2 meters and 70cm) beam with my HT (from my back yard)and get repeaters about 30 miles from my home just north of Houston, of course the terrain here is flat.
    That little antenna is used for fox hunts as well. Normally I have a dipole up 40' on my tower and a 50 watt base rig from home.

  18. #18

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    I'll have to look into the DMR amplifier thing.

    As far as 6m goes, I managed to find a decent priced radio, the TYT-9800, which goes for around $180-200 new. It's FM only, quad band (Including 10m.).

    It's hard to find much 6m FM info, because so many people seem to discourage it and recommend SSB instead. 6 meter FM is "dead" or so they say (It's no wonder, if hams are steering people away from it!). But a dead FM band with hardly anyone on it? That sounds perfect for simplex! I'm not becoming a ham to DX, so I'd happily use the less "magic" side of the band . Assuming I decide to go that route over 2m...

    One thing I didn't really think about, is that typically when my wife is in the area where there would be mountains between us, one bounce off of the mountain range to the east of her (which I have line of site on) would reach pretty much anywhere she would be. When it comes to reflecting radio waves, I'm under the assumption that 6m would be better?

    I am hoping I can find a reasonable design for a 100-160w amplifier for 6m, and that might really steer me in that direction. They make 100w mobile radios, but the cheapest I could find was about $600.

  19. #19

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    I've been doing a lot of digging, and am sort of leaning toward getting these:

    https://www.gigaparts.com/yaesu-ft-8...SABEgJfu_D_BwE

    It's a LOT pricier than I was expecting, but it's the only nice 100w 6m unit that I can find, and the DNR capabilities sound pretty awesome. I'd have to get my wife on board, as I mentioned earlier, but I already took preemptive steps and told her I decided not to buy a molten salt bath I was planning on getting (Knifemaking....my other expensive hobby!).

    If I decide to go the 6m route (And possibly even 10m and beyond, with those radios!), here's my plan, equipment wise, besides the radios I linked earlier:

    Base Antenna - Dominatgor 6m. According to reviews, this antenna is one of the best 6m verticals. I may homebrew something instead, if I can find some good plans.
    Mobile Antenna - Larsen NMO-50c
    Coax - Heliax LDF1. I'll probably want 100' of it to be on the safe side. (EDIT: Just realized that link is for 1/4". I'd probably get 1/2".)

    I still have to decide on how to mount the antenna on my roof, and how high I want to go. I bet I could get a mast pretty darn high with 3 levels of 4 guys lines (30 feet?).
    Last edited by Mobius1; Mon 29th Oct 2018 at 18:39.

  20. #20

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    ok, just a jab for fun, but the General class never had a 20 WPM requirement, that was the extra class...your memory (like mine is slipping on the numbers) General was 12 or 13 WPM, can't remember that was a long time ago.
    20 miles simplex is doable, but the mountainous terrain may be an issue. The two story house is not an issue and neither is making your own antenna.
    Cost will depend on you, but at least go with two good mobile radios,[QUOTE=Obed;38104]I would not try an HT on either end for your use.[/QUOTE Antennas, well on both ends it will pretty much be a vertical in the VHF/UHF area that you would most likely use. Lots of mfg's in the mobile arena, you can make your own vertical for the house.]

    Why do you recommend mobiles over HTs for this?

    Sent from my Moto Z (2) using Tapatalk

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