Tuesday, July 6, 2010

23 cm

The next amateur band is 23 cm, or 1240 to 1300 MHz. It should also be mentioned at this point that 1,000 MHz is equal to 1 gigahertz, or GHz. The 23-cm band may thus be referred to as 1.24 to 1.3 GHz, if desired. The 23-cm band is becoming quite popular in many areas of the United States and Japan. Numerous amateur fast-scan-TV repeaters operate near the 1265 MHz range, and Phase-IV OSCAR satellites are slated to use the lower portion of this band for uplink signals. Equipment for 23-cm operation can be relatively inexpensive if the amateur shops carefully and plans his moves. Inexpensive varactor-tripler circuits for translating a 432-MHz signal to 1296 MHz may be constructed with minimum effort, and the results are quite gratifying. Receiving downconverter "front ends" for 23 em are available in kit form, or preassembled from several sources listed in monthly amateur magazines. Such converters usually feature high-gain, low-noise, rf sections, and relatively low purchase costs. A substantial'amount of 23-cm equipment is slated to become available for amateur use in the near future, thus activity on this band is destined to significantly increase. The long-distance communication record on 23 em stands at 1,000 miles-a feat accomplished by using emperature-inversion and signal ducting propagation.