Thursday, February 26, 2009

High-End Receivers for Shortwave Listeners

Serious shortwave listeners, especially those who consider themselves DXers or DX-listeners may use very expensive communications receivers and outdoor antennas. Typically, a modern solid state communications receiver will be of the superheterodyne type in double, triple or, more rarely, quad conversion. It will feature multiple RF and IF amplification stages and may have at least one IF stage that is crystal controlled. It will usually have an additional BFO product detector for SSB and CW reception capabilities. The frequency coverage of receivers of this type is typically in the range of 500 kHz to 30 MHz.

The front panel controls are typically more comprehensive than those on a local broadcast receiver. Usual features include: signal strength meter; RF gain control; AVC/AGC adjustments; antenna tuner; bandwidth filters; BFO tuning; audio limiters or attenuators. Frequency display dials may either be analog (typically marked to fine increments for accuracy) or digital.
Three portable shortwave receivers

The older generation of vacuum tube-based communications receivers are affectionately known as boatanchors for their large size and weight. Such receivers include the Collins R-390 and R-390A, the RCA AR-88, the Racal RA-17L and the Marconi Electra. However, even modern solid-state receivers can be very large and heavy, such as the Plessey PR2250, the Redifon R551 or the Rohde & Schwarz EK070.

Modern medium quality shortwave radio receivers tend to be relatively inexpensive and easily accessible. Many hobbyists use even less-expensive portable receivers with good results. In general, any given shortwave radio will benefit from an external antenna — even a simple wire antenna — as long as the antenna is away from electrical noise sources. The standard shortwave receiving antenna is the dipole antenna which can be readily purchased or made by hand from a roll of wire and a couple of insulators.

(From Wikipedia, published under Gnu Free Documentation License)

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