A simple coupler to 27 MHz

Since I had problems with the antenna tuning and therefore the stationary relationship was excessive, I have designed a coupler to 27 MHz that works like a charm. It is a very simple and readily available components assembly. Such is the degree of adjustment that have come to doubt the stationary meter as reflected wave in the needle of the instrument or move. Measured by a dummy load insertion, losses are negligible.

I hope you like it as much as me.

For the realization of this coupler I used two variable capacitors commonly used in radio recorders. These have the advantage of incorporating four sections (two AM and two FM) and its partners trimers allowing us a great number of combinations and a variety of settings. For mounting at hand I used the two sections of parallel FM (20-60 pF in total) and thus I managed to adjust a vertical antenna 5/8 with an initial ROE of 1: 2.5 to 1: 1.1. Despite having a dielectric of these capacitors they are holding polyester smoothly exceeding 120 W peak power SSB.

Depending on the type of antenna and equipment, using switches S1 and S2 can be enabled or not capacitors, as low or high band of 27 MHz is used.

What Are CB Radios Used For?

In the first category we find the groups and clubs signaling responsible for security at events like racing (or rally) cars, marathons, foot races, trails, horseback riding, etc …, counting also with the voluntary and spontaneous assistance in scenes of accidents or natural disasters. Commercial use is also given to convoys and special vehicles.

SUVs and 4 × 4’s and campers, almost always require a CB radio in operation for members of the expedition or so the computers can communicate with each other during their excursions. To be the most interactive mobile telephony CB allows an entire group to be informed of any risk or contingency.

Sometimes we use the CB as a stealth tool aboard our vehicles. The material used for this is simple and just an AM / FM radio and antenna, usually medium or small in size.

We are also walkers and hikers on foot equipped with portable radios (walkie-talkie). Some more efficient models work with AM / FM / SSB. When the contact is not possible in AM / FM SSB can pass and we can solve the communication problem. These laptops can also change the antenna to improve performance.

Portable CB Radios

Do not confuse these portable CB radios with walkies PMR446 that are designed to run only on FM and overshort distances (3 or 5 km.)

  1. The Citizens Band is fun and entertaining

Use for leisure and recreation of the CB is completely opposite to the utilitarian. The teams will remain lit for hours, almost all day in their homes. For this use it is typically installed as fixed CB equipment in a room or hall dedicated to the radio.

  • Those who use only SSB, the DXers or “amateur” (to distinguish them from genuine amateurs, who have had to overcome tests and are holders of a specific license), often using all types of transmission and we find out the frequencies assigned to the service legally Citizens Band. There is a certain tolerance from the authorities to this situation and, for now, is allowed to stand.

For this use of the equipment the chosen CB is usually multimode (AM / FM / SSB) and preferably with dual display (channel and frequency). Some of these operators prefer to display only equipment transceivers designed for the amateur radio service that have been manipulated to cover the band of 27 MHz.

Other users prefer search only communications in AM / FM and SSB even for local contacts, from fixed or mobile stations (cars) so that they have them at their disposal all day and the possibility to chat, organize trips or, why not stay for a drink. Sometimes they cited regularly to organize games like “fox hunting” which is no more than a sport-finding test on a hidden vehicle emits beacon signals or music on a particular channel and the other participants, using measurements signal intensity, they will have to find the hiding place. Usually ends with a laugh or lunch or dinner, allowing closer relations between friends.

Using the CB from home

DX lovers lurking, like hunters, waiting for rare or distant contact from mobile or fixed stations and emissions from ships. Almost always directional antennas, large, are used to make such contacts and even cover impressive distances.

In such contacts are expeditions. This is a similar installation to that fixed to generators or batteries are used. The islands or places of difficult unusual access are preferred. The aim is to make as many contacts during a given period of time. If the spread accompanying the results are satisfactory. Ends with the exchange of QSL cards (cards with pictures of the place or the seasons that serves to confirm the contact).

But we do not believe that this is only the DX for older people. Many young people approach the practice of exploiting the contacts far and recovered old CB radio with AM / FM ‘abandoned’ by their parents.

A Large number of DX practitioners  quickly become licensed amateur unfinished necessarily leaving the 27 MHz, 11 meters, the Citizens Band.

  1. Citizens Band is also useful and fun

The last category is where we find people of the road. Trucks use CB to contact peers in established channels and often using channel 19 for listening. When problems or traffic information is displayed, the news spread quickly.

The CB has always been faithful companion on the road

French truckers prefer the AM / FM radio with an antenna type of ML145 or K40. Spanish and Portuguese truckers and tractors prefer multimode stations with antennas of 1200. The height of the antenna site is not always easy to determine because fiber booths and height must not exceed a limit. Therefore we often see antennas placed on mirrors or rear of the tractor for heavy vehicles.

The campers have the same problem to install the antenna. In this case they usually hold them on the metal surface of the engine hood, the side of the vehicle, and often choose antennas designed for marine use not requiring installation with ground planes. The talks will mainly focus on travel plans, escapades in previous trips, search for sites and traffic information. It has been proposed that such users to use the channel 2 for your contacts.

In any vessel Citizens’ Band radio is an excellent complement to the mandatory marine VHF. On board, the CB can be an additional security tool that enables communication with other ‘nautical bars’ and fixed or about near shore mobile stations. recent developments in technology have also seen drones use them to communicate on longer flights although laws on drones use is becoming stricter on their usage.