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Friday, June 21, 2013

Radio - Base CB

Hello, Frank here.

Last time we talked about mobile CB radios. For a base station most of the equipment will be the same - power cable, radio and coax cable. What you will need different this time is a power supply. Since almost all CB radios operate off of 12 volt or 13.8 VDC, then you are going to need a separate power supply that produces this voltage.

In most cases, you will also need a base type antenna. If you have a metal roof, you can get creative and stick a magnet mount antenna, (the kind used on a vehicle) on your roof, and it will work okay. But most choose to go a different route. I am going to talk about two antennas - the 108 and the A99. I will also give some examples of power supplies. 

Next I am going to give a formula that will be used through all levels of radio communications. And guess what it is? P = E x I.  Now, you need to remember this. P equals power or watts. E equals voltage. I equals current or amps. Alright. If your radio uses four watts of power (P) and the voltage is 13.8 (E), then divide P by E and get I, which in this case is about .3 amps. So, you will need a power supply that produces .3 amps. Most amateur power supplies are rated with their output in amps. Now, you might say, that is not a lot of amperage. You will need more than .3 amps
to transmit. But then, 4 watts is not a lot of power. Another rule: The rule of 80. The maximum you ever use of any piece of equipment is 80% of maximum rated output. So, in this case, go ahead and purchase a power supply that puts out at least 2 amps minimum. 80% of 2 amps is 1.6 amps. You need .3 amps for a 4 watt radio to listen, so there is power to spare with this set up, but not a lot. Something else to remember, you cannot have too much amperage, but you can have too little. 

This is a side note here. If you are never going to add any more equipment to your system, then a 2 amp power supply will work fine for years to come. But - if you have plans to add more power to a CB radio or you might buy a manufactured radio that uses more power, like an 11 meter radio, or most ham radios, then you might want to buy a larger power supply now. Remember, you can't have too many amps. Universal Radio and Bells CB both have many power supplies and a lot of information. I have done business with both companies and am satisfied with their service and products.

Example: Let's say you purchased a 30 amp power supply, which is a good choice for long-term planning. This is, of course, at 13.8 volts. Everything we are talking about here is.
Then go back to the formula of P = E x I. You have 13.8VDC (direct current) times 30 amps, equals 414 watts. That is your usable wattage output. Now figure in the rule of 80 - 414 times 80% equals 331 watts, which you can use very comfortably with a 30 amp power supply. We'll talk a whole lot more about P = E x I. Learn it now. Look up above to see what P, E, and I mean.

There are many, many antennas sold by many, many dealers. Every antenna promises the maximum output and the best reception. I'm going to recommend the classic 108, which is a stainless steel, whip antenna. 108 means one hundred and eight inches in length. It is actually a 102 with a six inch spring attached to the bottom. Wa-la! giving you 108 inches. To mount this antenna you will need a trucker mirror type mount, because it will probably go on a pole attached to the outside of your house. We'll talk more about attaching the antenna to the pole in just a minute. By the way, the 108 antenna, in my opinion, is the best antenna made for mobile operation. It really looks cool on a jeep. Again, my personal opinion.

Next is the A99 made by Antron. It is about 16 feet long, comes in three fiberglass pieces and is a standard in the industry. It comes with a radial plane kit. Some will say the kit is needed and others will say it's not. This antenna is a pole mount only and if you use the radial plane kit, you will need to go a little higher because the radials point downward at an angle. The mounts that come with this antenna, will mount poles about an inch and a half in diameter. Do some research and find the exact size, because you want the pole to be smaller than the mounts call for. The same is true with mounting the 108. 

Now you are going to need some cable or coax. It is actually called coaxial cable. On each end of the cable you will need a PL259 connector. Of course, it depends on how far your antenna is up in the air as to how much cable you need. Buy a few extra feet. Depending on the length needed and the power used, a standard cable is RG-8X. If you're running high power, and greater length than, let's say 25 feet, then you will need a different coax cable. We'll talk more about that when we talk about high power equipment.

Okay. Now, you've picked out a power supply that will cost you any where from $50 -$100. You have chosen your antenna. A 108 antenna will cost at the most, $50. An A99, with radial attachment, will be, maybe $130. Without the radial attachment, less. Pre-made coax cable with connectors on each end, let's say, 25 feet - $35 or $40 or less. Now you need a radio.

All CB radios operate on AM, which is amplitude modulation. They all operate around 26 to 27 Mhz (megahertz). This is the operating frequency. All manufacturers make a good, solid radio. You can find one from $75 to $125. Some have weather (NOAA), some have alarm clocks, some the dials change colors, others light up at night and during the day, some have echo, some have talk back, some have SSB, some have adjustable power, adjustable microphones, adjustable input power - there are many, many choices to pick from. Like I said before, if you want to talk to your buddy half a mile down the road with no hills in the way, any radio will do. If you want to talk to somebody a long ways away, then not any radio will do.

Talk back and echo, I think, are a little silly. Lighted dials come in very handy, especially in a mobile situation, and sometimes they just look cool. A weather option is your choice. SSB (single side band) is necessary if you want to talk long distance. 

Cobra makes the 148, which is a classic SSB radio. Galaxy makes a handful of SSB radios: 949, 959, 979. Uniden makes the Bearcat 980. These are all strong contenders for single sideband radios. The Uniden is a new radio. It hasn't been out long, but it is well worth a look. My personal preference is the Galaxy line of radios. All of these radios tend to cost a little bit more than your average non-SSB radio, and work well in a mobile environment. Having the same radio in your house and your car means you become more familiar with the knobs and it's operation. Something to think about.

Now, we have a radio, an antenna, cable, and a power supply. That's about all you need. There are some things I cannot tell you on a blog. You are going to need a pole to put up your antenna. Some people use fiberglass. You can purchase these at some Army/Navy stores. Hardware stores that carry fencing supplies that come in 10 foot sections work pretty good too. I like to have the pole attached to the ground, attached to the side of the house and just far enough above the roof line so that the antenna will fit. Mount the pole in it's chosen place; mount the antenna to the pole; connect your cable to the antenna; run your cable into your house however you choose; READ THE RADIO MANUAL; READ THE RADIO MANUAL; connect the cable to the back of your radio; connect your radio to the power supply, which is real easy - red connects to red, black connects to black; turn the on/off switch in the appropriate direction - which is normally also your volume; and you are in business. If you purchased an SSB radio, most CB SSB is conducted on the LSB (lower side band). It is usually done between the frequencies of 30 & 40. Example: Channel 34 LSB.

Now, CAUTION. During a thunderstorm or electrical storm unplug your radio antenna connection. Some people also disconnect their power supply. Depending on how you ran your coax into your house, put your antenna connection into a glass jar, because lightening can and will fry your radio and all associated equipment. CAUTION. If you choose to pep up your radio and run more power, then you can do RF (radio frequency) damage. If you don't know what you are doing then don't do it. With 4 watts of power this is not a concern. 

I have talked on my SSB CB radio from southeastern Oklahoma to Grants Pass, Oregon; Ontario, Canada; and southern Florida. I hope you enjoy your CB radio. But if you do want more options, or more power, then in a couple of posts we are going to be talking about 10 meter and export radios, which are on many of the sites I have given you before. 

We'll talk more later. 73, Frank



2 comments:

  1. You are way off on your power supply advice. The typical 4-watt CB radio may only draw 0.3 amps during RECEIVE, but they draw far more during TRANSMIT! Check the specifications. Most CB radios come with 2-amp fuses installed in their power cords. They will typically draw 1.5 to 2 amps during transmit. Your rule of 80 is good advice. But a 1-amp power supply will overload and fail when someone attempts to transmit with their CB radio. As a miminum, I would go with a 5-amp "regulated" power supply that can put out 13.8 volts DC. Unregulated power supplies will work on receive, but trying to transmit will cause the voltage to dip down to 10-11 volts. They are a waste of time & money. The power supplies sold for Amateur Radio use are regulated and hold their voltage output steady at 13.8 volts DC during the higher current draw of transmit. The MFJ-4225MV power supply is small and works well.

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  2. You are correct. One amp is too small, my error. Uniden recommends a two amp power supply, minimum, for the 29 LTD Classic. Thank you for the correction.

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