Help an ignorant soul out here, please.

Discussion in 'Survival Communications' started by Jay Tx, May 19, 2013.


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  1. Jay Tx

    Jay Tx Monkey+

    I am looking to set up some simple comm's here at the house for fun, and just in case.

    I used to mess around with CB stuff when I was younger, had a few decent set-ups in trucks. But my knowledge ends there.

    Here's what I have left from back in the day.

    Galaxy 44 radio with CB channels, supposedly tuned and peaked.
    Uniden radio with weather channels.
    Astatic mobile noise cancelling mic.
    Another noise cancelling mic, I forget what brand/model, that was suppose to be the stink back then (round oval shape with key angled out from the top).
    Palomar 250 linear, worked on and was swinging about 400watts, receive not working.
    Eagle 100watt linear.

    I know the linears will have to be shelved until the SHTF, so we'll forget about them since I'm not looking to draw any attention to myself.

    I also have a 45amp dc converter from an old slot car track project. I assume it's more than plenty to run what I want.

    I am looking to get a simple start on a base system, and a decent mobile system for the '85 K20 Burb. I have done some window shopping online and have come up with a few ideas, to follow;

    Mobile- Use the Uniden radio with 18' of coax and a 102" whip mounted to the custom roof rack on top of the burb. I tried various wilson antennas on my trucks back in the day, and always found the 102" more to my liking. Had one mounted on the upper rear door hinge on a burb, and another mounted atop the ladder rack on my work truck. Both would skip very well when conditions allowed, and talk impressively (but power will let you do that i guess) in a straight line.

    Base- Use the Galaxy 44 and an A99 or Imax2000 antenna mounted on my shop rooftop The shop sits about 30' from the house, but is, at its closest point, nearest the room where the radio would be. Too many trees close to the house to mount the antenna on it and keep it close to the radio room.
    The A99 was the standard for a simple omnidirectional antenna back in the day, but the Imax2k has come out since then, and I see it's 7' taller than the A99. At some point I would want to get a set of beams and a good base radio, but let's keep it simple for now.

    Here's an issue I will have to overcome. I live out in the country. We are in a low spot geographically, in the area. Our house sits about 20' below the surrounding area, with a very gradual slope taking about a 1/4-3/8 mile before we are back on top of the world. I'm not ready to invest big bucks into a huge tower at this time, so here's my idea for mounting the antenna; My shop's roof peaks at about 14' from the ground. I plan on using a 5' tripod base, with a 20' or so mast. That's roughly 34' to the base of my antenna, and 58' to the tip of the Imax 2k, and 51' to the tip of an A99. We are also moderately wooded around here, with Oaks reaching 40' tall +/-.

    I know, the higher, the better on the antenna. What do ya think about what I have to work with?

    I live roughly 8 miles from one major interstate, and about 15miles from another heavily traveled state hwy. I'd like it if my base would reach each one, or both, but would be satisfied with just talking with a few locals (I see several antennas up within 5 miles of the house). Again, if the SHTF, and I throw on an extra 400watts, I shouldn't have any issue sending a stronger signal that I would want to.

    A few questions, if you will indulge me? And please pardon my ignorance. I have done some research, and read a few threads here, and the technical jargon makes my head hurt. Please, keep it simple for a redneck?

    * What does a power mic do, what purpose does the external power source serve?
    * Would it be beneficial to run a base power mic on my set-up, or would the mobile mic work OK?
    * I have two options for routing the coax to the antenna. I can span from the eve of my house to the eve of the shop, overhead, and keep the coax length shorter. Or I can run it underground between the two structures to keep it hidden. I'm inclined to start out with it overhead for now and bury it later. But if underground is better for any reason, I game?
    * For either application, which brand/type of coax is recommended?

    Sorry about such a long post here. I just wanted to lay out my situation for ya. I am open to any and all suggestions for installation, equipment, etc.. Like I said, I know a little bit, but let's assume I know nothing for the sake of keeping it simple.

    As for budget, like always, it is a concern going in. I do not mind paying for quality equipment and components, not at all. But I want to keep the costs down going in, and build the system up as I go. I think my largest hurdle is the geography, but I won't jump to any conclusions until the guru's weigh in here.

    Thanks,
    Jay
     
  2. chelloveck

    chelloveck Diabolus Causidicus

    There are a few good hams here Jay (I mean that in the nicest possible way), who will gladly help out. BT Post is a mine of information and advice concerning radio transmitting and receiving. Have a look at some of the older posts in this forum, you may find some answers there.
     
    Idahoser likes this.
  3. BTPost

    BTPost Old Fart Snow Monkey Moderator

    Jay Tx.... Lets look at your Comms Requirements first, before we look at hardware.... You have CB Hardware in house already, fine.... so lets define where you needs Comms.
    1. AoO (Area of Operation) Sound like you would like to have local Comms. Basically from your Home, and on out to say 25 miles. Right?
    2. You are not planning to use this Comms for any Text Messaging, or Digital Data Transmissions, and have no need of SECURE Comms. Right?
    3. Your not Rolling in Money, and your not planning on a Lottery Win to fund your system. Right?
    4. You are willing to put some effort, and money, into a working system. Right?

    Assuming that the answers to the above questions are in the most part, Yes.... Then let us assume that the CB Radio Service is a Minimum starting point.
    So Let us look at the Home Base Station first.
    1. ALL CB Radios have a Maximum Tx Power of 5 Watts, unmodified... Period so it doesn't matter which Radio, you decide to install as they ALL will have the same basic RF Output.
    2. A "Power Mic" does one thing, and one thing ONLY. It is designed to push the Tx Audio, into the Modulation System of the Radio, to a 100% Modulation Ratio. This means that the Radio has an equal amount of Carrier Power, and AM Modulation Power mixing in the Final Transistor. (assuming a solid State Radio,
    No tubes) Most CD Radios are designed to limit the Modulation to about 80% so as to NOT exceed 100% on Voice Peaks, which causes Distortion, and Frequency Splatter. They do NOT increase the Range of the Radio in any Significant Amount.
    3. The amount of Coax Cable, needed between the Radio and the Connection Point of the Antenna, is only one of the things that goes into the design of an efficient Radio installation. If you use a Quality RG-8 type Coax Cable, (I would use Beldon 9913, myself) then any distance less than 100 Ft, is NOT going to make any significant difference in the Range of the system.
    4. Powering the Base Radio, is another of those things that a Good Prep'er needs to think about, so that if the Grid fails, you still have Comms. So think about a Battery Backed Up Power System. Something like a Group 27 Car Battery, that is charged by a Constant Voltage Regulated PowerSupply. Which is rated at least 2 times the Maximum Rating, in Amps, of the Station.
    5. Antennas are rated in Gain (db) over some Reference Antenna. (Dipole, or Isotropic)
    I would assume that the smaller of the two, you talked about, would have maybe 1-2 db Gain over an Isotropic Radiator, and the larger one maybe 3-4 db over Isotropic, since they are BOTH Omni-Directional. Just about ANY Omni CB antenna will be very near the same, in Antenna Gain, and therefor whatever you decide will have minimal effect on the Range of the Station.
    6. Most CB Antennas will work better, the higher in elevation they are, AGL. (Above Ground Level) This means Higher is Better. HOWEVER you run into Diminishing Returns, once the Coax Length exceeds 100Ft. This means going higher, makes little sense, if it means the coax length exceeds 100Ft. This is due to the RF Power Loss, in heating the Coax, which increases faster than the Improved reception, gained by the higher Antenna.
    7. The ONE THING that can improve Range, and effective Comms, when using CB Radios is, instead of an AM Radio, you use a SSB (Single Sideband) CB Radio. This is due to the lack of a Tx Carrier, and the elimination of the Opposite Sideband. An AM CB Radio puts 5 Watts into the Carrier, and 5 Watts into 100% Audio Modulation, 2.5 Watts into each of the two Generated Sidebands. So If we eliminate the Carrier and one Sideband, you now have 12.5 Watts of RF Power, All of which is put into a Single Sideband, and none is wasted on a Carrier, that carries NO Audio Information, and a second sideband that only carries Duplicate Audio Information, as the one you want. You also get the benefit, of Double, the number of available Selected Channels. (Upper Sideband & Lower Sideband for each of the 40 CB channels) You really want to put the RF Power into where the Audio Information is.

    Ok now lets look at the Mobile setup. You have a "Burb" which is mostly a Metal Body and Frame. This is good, very good, considering many of the New vehicles are mostly PLASTIC, these days.

    1. As you have noticed, the old 102" Standard CB whip Antennas seem to work best on Mobiles. There is a very good reason for that, in that 102" inches is very close to 1/4 Wave Length, for the 27 Mhz CB Band, and tends to Match the 50 Ohm Output Impedance of the Radio, itself.
    2. Also you have noticed, that there are a bunch of other Antenna Systems out there that use Multiple Radiators, usually mounted on the Wing Mirrors of 18 Wheelers, that purport to have better TX and RX Capabilities. This is mostly CB Marketing BS. Yes, There is a REAL Antenna System, called CoPhased Verticals that DOES give an antenna gain advantage, over a single Vertical whip Antenna. HOWEVER it does so by making the the Antenna Pattern NOT Omni-Directional, but into a figure "8" with Gain Lobes to the Front and Rear, and sacrificing the Gain to the Sides. Not real useful, when your traveling, and do not know where the next station you my want to have Comms with is located. These systems are designed to use very exact dimensionally, Coax Phasing Harnesses, as well as Exact Radiator spacing, in order to work correctly. these parameters are rarely meet on 18 wheelers and therefor, are not better than a good 102" whip Antenna, installed correctly.
    3. The thing that makes ANY Antenna System work, is "How good is the RF Ground... Understanding this ONE THING, can Make or Break ANY Radio Installation. This goes back to how much METAL is in the Body and Frame of the Vehicle. Mounting of the Antenna, is also an important design criteria for CB Radio Installations. As you have already noticed, a 102" whip, mounted on the Bumper of your Burb, works pretty well, because the RF Ground is the whole Metal Frame of the Vehicle. what you may NOT know is that by mounting the Vertical Antenna on the corner of the vehicle, causes the Antenna Pattern to get real "Lumpy" when compared to the Standard Omni-Directional Antenna Pattern. The correct place to mount the antenna is in the middle of the largest section of flat Metal on the vehicle. On a Burb, that is in the middle of the Roof. You ask, "Why is it that you almost NEVER see such installations?" Simply, because if that is where the whip is mounted, it gets knock off, when driving under Low Overpasses. It is a practical thing, rather than what is Best for the Radio System. Smart Operators will use a correct Mounting, and then sacrifice some Gain, but bending the whip over when in motion, with a String to lower its profile.
    4. Using a SSB CB Radio is better, for the same reasons, in the Mobile, as it is in a Base Station.
    5. Antenna Coax has little effect on Mobile Installations as you rarely have more than 15 Ft, between the Radio, and the Antenna, and the loss difference at 15 Ft, between an RG-8 type, and an RG-58 type, is not significant in operational capabilities.

    Ok, that concludes CB Radio 101 Lesson 1.

    Now lets consider a Prep'ers Comms System that can add some good capabilities, to what you will have, IF you follow the above. Read up on the SECURE Phone Comms Systems, that many Monkeys have been using for local AoO Comms. iDen/ISm Secure Comms.... UpDate... This system has many good features, that are NOT available to a CB Radio system. These are Un-Scannable, and they are Un-DFable. CB transmissions are Not SECURE and are both Scannable, and can be DF'd.(Direction Found) These are dirt Cheap. They have a single drawback. They have a limited Range. (2 Miles Max. in Dense Terrain) Something to consider as an addition to a CB System.

    If you really want good Comms, you might want to look into Ham Radio. There is NO Morse Code Requirement, any longer. Just basic Radio Technology and Rules. The Tests are ALL Multiple Guess, and you only need 75% Correct to Pass. If 10year olds can pass these tests, ANY High School, or GED Grad, can memorize the answers, and Pass, as well. If that is something you are interested in, @ghrit, can steer you to a Site, that will help you get up to speed, and Licensed.

    If you need any further information, please do not fear to ask, Here, or elsewhere in the Comms forum. We have a good bunch of Monkey Comms folk, here that can help you out.

    Not bad for a Sunday Night Post.... ...... YMMV......

    Ok,
     
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  4. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Sounds like you are intending to stick with CB. If so, the gear to hand might be just suitable, if still operable. If the distance from house to shop isn't too great (in excess of, say, 100 feet, you'll be good to go. More than 100, line losses start to have a noticable effect on signal strength.

    Practical matters, then. Back in the day, I used, variously, a simple base loaded coil whisker on the top of a small station wagon and on the roof of a pickup, a K-40 on a sedan, and a Firestik on the back edge of a pickup roof (and on the wagon occasionally) all with a variety of type certified and unmodified CBs. Tuned them with a SWR meter across the band to less than 1.2 to 1.

    On the base at home, used a 1/4 wave ground plane vertical, and later replaced it with a 5/8 wave vertical on an "opened up" rig that ran 20 watts SSB (according to the meter, uncertified) that was tuned to less than 1.1 to 1 across the ("expanded") band.

    I don't think CB will be too useful except for very local comms. Saying that, I was often able to talk to a guy 60 miles away on the base, but you have to know he had a rotatable quad on a tower. If skip was rolling, well, you never know what could happen, but depending on it is doomed to fail. Best I ever documented was 12 miles on the mobile, that in very open flat country in Montana. Hiding in a hollow as you indicate, line of sight will be short at best.

    Never used a power mike, all were hand held. My understanding is that they use speech compression to squeeze the last drop of intelligibility out so that a weak signal will, at the receiving end, be a bit more intelligible. Dunno 'bout that.

    The power supply isn't needed for a dedicated base station, they plug into the wall. However, if you want to take your mobile unit inside and set it up on the dining room table, you need the ps to supply battery voltage for the rig.

    Bear in mind that using the linear will want you to know what the power handling capacity is for the antenna and coax. Make certain the antenna will handle ALL the wattage that the booster can put out or bad things will happen. (Like burning out the finals in the rig, melting something inconvenient at the antenna, or other equally disabling/destroying parts and pieces.)

    Keep your coax out of the ground unless you know it is certified for underground use, and don't forget drip loops at the building penetrations. Avoid a sag in the middle that will accumulate water and possibly freeze.

    With the slot car ps, you will want to know it's output voltage, and also (since I suspect it is unregulated) you'll want a battery in the circuit for stability of voltage for the rig. Type certification does NOT imply immunity from voltage spikes. Again, bad things can happen. Additionally, be aware that they can be sources of RF noise that won't be good for either tx or rx, but other than that won't harm the equipment.

    Finally, the burb has a steel roof, yes? If so, it's an ideal ground plane for the mobile antennas. Center the antenna on the roof to the best extent possible for the most omni directional pattern possible. Don't try to use a mobile antenna on the house without supplying a ground plane, or they will not work. (I managed to make one function on a length of roof gutter, but hoo boy! that wasn't exactly a success over two blocks away and in only one direction.) Thinking along the same lines, mounting a mobile antenna off center on a vehicle simply alters the radiation pattern. Tx will be highly preferential in the direction of the most metal it "sees" to say if it is on the left rear bumper, the pattern will be heavily biased toward the right front. I do not know if rx is affected the same way, but suspect it is. If the burb's roof isn't metal, find someplace else to mount the antenna.

    As BTP notes, co-phased pairs on the big rigs works, and works well. The idea is to make the radiation pattern as close to omni as you can get it. Consider the rig, metal is in all directions, no matter where the antenna is located, thus a single antenna will be massively biased toward the most metal. To counter that, two antennas are used, one on each side of the rolling stock. They MUST be an optimal distance apart, just about 1/4 wave, which just happens to be around the distance between outrigger mirrors on the tractor. Not going to work well on a normal sized vehicle; the sticks will be too close together and the radiation pattern will be biased to the sides. Note also that using two antennas reduces the need for a ground plane, a good thing with aluminum and fiberglas cabs common these days.

    Go ham, and go high if you can. If a tower is not practical, go NVIS and bounce the signal over the hill.
     
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  5. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    @Jay Tx - Have you made any decisions or progress with your comms implementation?
     
    Last edited: Sep 1, 2013
  6. STANGF150

    STANGF150 Knowledge Seeker

    Is he still here even? o_O
     
  7. kellory

    kellory An unemployed Jester, is nobody's fool. Banned

    Last seen july 24. 2013
     
  8. BTPost

    BTPost Old Fart Snow Monkey Moderator

    Some monkeys come, and some Monkeys go, and some Monkeys really find a home here in the Tree....
     
  9. kellory

    kellory An unemployed Jester, is nobody's fool. Banned

    been less than a week guys, he could even be on vacation, or work issues. i wouldn't count him gone yet. give it some time.
     
  10. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Ah, hm. July 14 to Sept 1 is a week? I need to recalibrate ==
     
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  11. kellory

    kellory An unemployed Jester, is nobody's fool. Banned

    Mark your calendar, I made a mistake. mea culpa, mea culpa, mea maxima culpa...my bad.

    and that was july
    24 not 14.:rolleyes: (since we're making corrections)
     
  12. ghrit

    ghrit Ambulatory anachronism Administrator Founding Member

    Chortle. I claim dyslexic fingers.
     
    kellory likes this.
  13. kellory

    kellory An unemployed Jester, is nobody's fool. Banned

    That might fly, had you said Sept 41, however......:rolleyes::p
     
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