MARES Annual Dinner Night – Floral Fantasy


Come and join us to a MARES Annual Dinner at Bayou Coffee House, Cyberjaya. It is opened to all – radio amateurs, SWL and anybody who wishes to participate and have a good time. Do not miss out the chance to meet up with old friends and make new ones.

Date: Saturday 31 July 2010

Time: 7:30PM (+8 GMT) – Dinner time

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Common Causes of High SWR


There are many things other than the antenna that can cause high SWR. SWR meter readings take into consideration the antenna, the coaxial cable, the mount, the mounting location, the vehicle and objects in the antennas near-field environment. We broke our list of common high SWR causes into six primary categories. The order of the categories does not imply that one is more common than the other, however, the list within each category is arranged based upon our experience and shows the most common causes higher on the list than the lesser common causes.

ANTENNA RELATED

  • Antenna was not tuned in its final mounting location
  • Antenna tip installed AFTER the antenna was tuned
  • Testing or tuning with doors, hood or trunk open (altered ground plane)
  • Antenna not mounted vertically
  • Incompatibility between antenna and vehicle for undetermined reasons
  • Insufficient tuning range due to antenna/installation incompatibility
  • Antenna tested/tuned inside garage, carport, etc.
  • Antenna was tuned then moved to another mounting location or vehicle>
  • Ground plane and no-ground plane antennas used with wrong coax cable type
  • Antenna grounded to vehicle chassis ground circuit
  • Internal antenna issue (verify base to tip continuity)
  • Antenna not designed for use with CB radio

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Simbol Skema Peralatan Elektronik


The schematics symbols for most major electrical components can be found in this table. However, each component may have numerous possible representations. In cases where there is more than one common symbol, pls ask help from pakcik google.

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Antenna Basic Theory.


Antenna

An antenna is a device that transmits and/or receives electromagnetic waves. Electromagnetic waves are often referred to as radio waves. Most antennas are resonant devices, which operate efficiently over a relatively narrow frequency band. An antenna must be tuned to the same frequency band that the radio system to which it is connected operates in, otherwise reception and/or transmission will be impaired.

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Transistor Circuit Test And Fault Finding Using A Multimeter


* some of the key points to note and hints and tips for testing and fault finding a transistor circuit including those in a radio with a multimeter.

One of the main uses for multimeters whether they are analogue multimeters or digital multimeters, DMMs is to test and fault find circuits like those in a transistor radio. Multimeters are ideal items of test equipment for finding many faults in a transistor circuit. However to use a multimeter to test a circuit and find faults it is necessary to have a little knowledge about the circuit, and also to adopt a logical approach in tracking down any faults that may exist.

Warning!! Some transistor equipment may be mains powered. Only qualified persons should attempt to repair mains powered equipment or equipment that contains high or hazardous voltages. High voltage can kill so be warned!

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Walkie-talkies in Amateur radio


Walkie-talkies (also known as HTs or “handheld transceivers” ) are widely used among amateur radio operators. While converted commercial gear by companies such as Motorola are not uncommon, many companies such as Yaesu, Icom, and Kenwood design models specifically for amateur use. While superficially similar to commercial and personal units (including such things as CTCSS and DCS squelch functions, used primarily to activate amateur radio repeaters), amateur gear usually has a number of features that are not common to other gear, including:

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Coaxial cable how it works.


Like any electrical power cord, coaxial cable conducts AC electric current between locations. Like these other cables, it has two conductors, the central wire and the tubular shield. At any moment the current is traveling outward from the source in one of the conductors, and returning in the other. However, since it is alternating current, the current reverses direction many times a second. Coaxial cable differs from other cable because it is designed to carry radio frequency current. This has a frequency  much higher than the 50 or 60 Hz used in mains (electric power) cables, reversing direction millions to billions of times per second. Like other types of radio transmission line, this requires special construction to prevent power losses.

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