February 27, 2021

A SSB CB Thrift Store Score!, by Tunnel Rabbit

My advice is to keep checking the thrift stores. I went to town to sell eggs, and turned some of the egg money into a single-sideband (SSB) Citizen’s Band (CB) radio ($5), and 100 feet of new 75-ohm coaxial cable ($2.50). I can now get on the air for only for only $8.50! If I land one more of these, then I will consider modifying my Kenwood 830S 10-meter rig to 11 meter. I would then have a 100-watt rig with SSB capability to talk to my mobile SSB CBs. Having SSB mode CB would give me yet another redundant communications system. I want a pile of at least three of these before I do the ‘mod’, as “3 is 2, 2 is 1, and 1 is none.” These old sets may not last in the field, but they are not my ‘primary’. But they could become an ‘alternate’, and  are already a ‘contingency’. Some of my friends also have SSB-capable CB radios.

For almost a decade, I’ve been collecting old CBs to hand out to select neighbors to provide for a low power net. Because this a rare find, a CB with SSB is a keeper. This one was produced for Sears by Toshiba, or Sharp around 1972. It is a 23-channel crystal set. It is a high-quality build. It’s exterior appearance is very good. It was stored in conditions, likely a cool, dry, and clean place that is conducive for good operation, later. Perhaps decades later. However, in my experience, only about half the old dusty CBs that I run into actually work. This one had no dust on it.

CBs are usually stored poorly. The ‘dust of ages’ can sometimes be blown out, and corrosion from oxidation removed with a spray. This one would be worth that kind of attention, and work. Fortunately, initial bench testing indicates that it turns on, receives, and transmits. That is a good start. Regardless of how it performs on the air, or doesn’t, as it might prove to be ‘off frequency’ on some or all channels. The price was right ($5). And the P.A. (Public Address) part of the CB may still work. Use one, or two CBs with P.A.s, and you’ve got a one-way, or two-way intercom-telephone system. Crude, but effective for shorter distances. The audio can be amplified with a 12 vdc computer speaker amplifier if need be. We need the audio to be intelligible at the other end. Some CB P.A.s are not as powerful as others, and an amplifier would be necessary. Or, if you happen to have a box of these, then grab another one out of the box.

Even if only the P.A. works, if someone shows up at the front gate and their intent is unclear, we can now ask them to leave, politely, without revealing the location of the Observation Post (OP). If all we had was a hammer, then everything would look like a nail. It would be good to have the means to be able to deescalate the force needed to deter an enemy threat, and avoid the use of a hammer. A bull horn would giveaway your location. There is more than one way communicate, or to skin a rabbit.  Sometimes it is better to speak softly before using the big stick.

Why am I so excited about SSB CB?

Is the old CB adequate for your commo needs? Will it provide adequate coverage of your area of operations (AO)? Here is a ‘rule of thumb’ to estimate the maximum range of CB radio. Typical vehicle-mounted antennas are not long cumbersome 8-foot whips, but 4 feet in length, or shorter:

  • For every 1 foot of antenna length, the 4 watt CB will have 1 mile of range.
  • For every 1 foot of antenna length, the 12 watt SSB CB will have 2 miles of range.

CB base station antennas can be about 8.6 feet in length, twice the length of most CB antennas mounted on vehicles. and also have a ground plane to match and maximize it’s performance. The ground plane part of the antenna on a vehicle is barely adequate, or most likely would produce a radiation pattern that is semi-directional, because of their location on the vehicle. (Top-center is deal, but a bumper mount is poor.)

Base station antennas can also be mounted above the house, or on a tower — greatly increasing the range. A common man’s expedient ‘tower’ could simply be a long 20 foot wooden post secured in the ground, anchored with 2 or 3 bags of pre-mixed concrete. It’s ground plane radials can then be full length. and at a 45 degree angle from the base of the antenna. This would create the best radiation pattern possible for a quarter-wave antenna. We could also be tempted to build a high gain 5.5 dBi J-pole. That might give us another 50 percent increase in range. The air-choke should be at least 4 coils, and 6 inches in diameter.

The range of an [effectively] 12-watt SSB CB mobile to a SSB CB base station can be as much as 15 to 20 miles. This is approximately twice the range of a standard 4-watt CBs using the same antennas. The range of two SSB CB base stations could easily be greater than 20 miles, especially if one of the base station antennas is located 50 feet or more above surrounding obstacles. IMHO, covering an AO of 20 miles in diameter is all most people would need.

If you are going to use CB, then pay the extra. Or haunt the thrift stores in the hope of ‘lucking out’. Get a CB with Single Side Band, and get twice the range, and 100 times less traffic. (Since there are 80 SSB channels, as there are few who own SSB CBs in this day and age.) If you really need more than 20 miles of range then build a higher tower, and a better antenna, or high gain yagi antennas can be used.

For every 5.5 dBi gain, the range might increase as much as 50%. The correlation between watts of radiated power, and range is not directly proportional. The antenna used can have more bearing on the effective range than the power of transmission. A quarter-wave antenna is usually a good choice. However, if it not sufficient, a yagi that offers 11 dBi of gain could double the range from 20 to up to 40 miles in some situations. In my case, I might use a powerful old Kenwood ham set. It would make one heck of a good CB.

The 10-meter band is basically dead during this solar minimum, and the ability to talk to local license-free mobile units would be of greater utility. ‘Ham Shacks in a Box’, such as the Yaesu FT-817, and other radios like it, can access CB frequencies, but my old boat anchor would require a bit of surgery to perform that trick. With the surgery, it could kick out 100 watts, and that is enough brute force power to push a signal into RF holes, or over hills and dales, and around obstacles such as trees. At the very least, the mobile station could copy the base station ‘in the blind’. They could hear the base station, even if they could not talk back to the base.

Imagine if that 100 watts was pumped through an 11-dBi yagi, and pushed out at 750 watts! Please do not tempt me! However, that would be foolish, as low power is our friend. We do not want intercept stations to take note of unusual signals and zero in on us. It is better to make do with lower power radios that just satisfy our communication needs. In my opinion, the SSB CB is that sensible balance between a useful range and a relatively low PEP (Peak Envelope Power) need to get the job done.

Fire It Up!

It’s time to drop the ‘smart’ phone, and fire up your dusty CB to see if it still works. Without the test equipment, the only way to check for good and reliable operation is to get out there and use it. Simply attaching an antenna or dummy load and turning it on and seeing if it ‘keys up’ is only a preliminary test. If functions on the bench, then it’s time to see how far she’ll transmit, and how it sounds on the air. We are also testing the antenna and cable and the connection at the battery. The old cable should be replaced, and all connections inspected, and corrosion and debris removed. Use a SWR meter to verify that the antenna, cable, and connections are good, before doing a ‘field test’. If 8 miles of range is all you need, then an inexpensive 4 watt CB on a quarter wavelength base station antenna that is 8’6” can talk to another base station CB up to 8 miles away.

My next homemade CB antenna will be made from 3/4″ diameter tent poles. Firestik KW7 is a 7-foot antenna, and only costs about $25. However, consider that most other CBs you may talk to will only be using 4-foot antennas. Most conversations could then be had at a maximum of 4 to 6 miles. I therefore highly recommend a CB with SSB if you have others nearby with a SSB-capable CB. It can still talk to standard CB too. Or buy 2 or 3 for the family. The added COMSEC that these radios provides with their SSB capabilities, in addition to their superior range, is well worth a $150 price tag. And they are very easy to use.

COMSEC (Communications Security)

The communications security (COMSEC) that SBB mode CB provides is hard to find elsewhere, and it comes in a familiar, easy to use package. Most scanners scan frequencies in the AM or FM modulation usually associated the radio service. CB typically uses AM, or amplitude modulation. Therefore, most scanners will not be able to hear SSB in an intelligible way. Most typical scanners cannot scan for SSB CB transmissions. Of course, high-end scanners and some modern SSB CB could scan SSB, yet these are not common. We can further improve COMSEC by using a horizontally polarized antenna with SSB. By doing so, we add yet another layer of security. The range of the radio using this method could be shortened versus vertically polarized antennas. In some circumstances, such as in pine forests, it may however be improved. Try it both ways. If the horizontal antenna, that is typically a dipole, still provides adequate range, then the increase in security is worth the trade-off. Vertical antennas that receive horizontally polarized signal have difficultly hear this kind of antenna most when the transmission is relatively nearby. This means that even if they can hear SSB, then you’ll sound weak and far away even if you are close by. [Editor’s Note:  Sun Tzu would approve!]

The farther away the receiver is, the less the polarization is a facto, since radio waves will bounce off objects and tend to change orientation. If we are using 12 watts of power sent out of a horizontal antenna, then the receiver using the standard vertically polarized antenna will receive our signal as if we were transmitting with only 1.2 watts if they are nearby. Our 12-watt signal is attenuated by 20-dBi. That is significant reduction, and it make us hard to direction find (DF). Yet if the horizontally polarized antenna is ‘talking’ to a vertically-polarized antenna 10 miles away, it could still be heard. Ideally, a horizontally polarized antenna should be used by all who are on your local ‘circuit’. You’ll want to all be on the same wavelength if possible. Fortunately we can still talk to mobiles that by their application in a vehicle requires vertically-polarized antennas. The range could decrease by 20 percent or more. A horizontal dipole can also be a more stealthy antenna, great for attic installations. An attempt to DF will usually end with a visual confirmation by identifying the antenna on a rooftop or on a tower. They’ll be looking for a typical vertical antenna tower. They are less likely to spot the thin wires of a horizontally polarized dipole antenna.

Always remember that low power is our friend. Any way that we can obscure the signal reduces the likelihood of becoming intercepted and found. Weak signals are hard to hear and hence rard to ‘DF’. Ideally, we would wish to use only enough power to have reliable communications, and no more power than that.

Ideally, I would want to use 1-to-5 watts through a high gain yagi, or another directional antenna, polarize it horizontally, and keep transmission bursts to no longer than 5 seconds before making a ‘break’, and then resume transmitting again with another 5-second ‘burst’.

Even though the SSB CB may not offer variable power controls, we can use the aforementioned techniques to improve COMSEC. Brevity codes will reduce air time, but they will not prevent someone for DFing you. If the threat condition is high, then think carefully about if you should transmit at all, or how you can further reduce your RF footprint. There are many other techniques that can be employed to reduce the risk as well, but this is beyond the scope of this article.

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