Panasonic / National Panasonic,
überarbeitet am 21.10.2010
In the middle of the seventies, Matsushita - Panasonic did present their first
world band radios as a reaction to the efforts of Grundig, Nordmende and Sony in the
field of travel multiband radios.
The Panasonic DR-22 / RF-2200 is a portable shortwave receiver with the dimensions 32 x 19,5 (the rotable ferrite antenna included 22,5) x 10 cm, the double conversion receiver is constructed with a conventional design, a crystal calibrator and a linear fine tuning dial allow tuning in a known frequency with high accuracy.
All necessary controls of the RF-2200 are located on the front panel,
on the top face, there are two eyelets for a carrying strap and a rotable
ferrite antenna very useful for mediumwave reception - You won't have to turn
the whole set to make profit from the directional effect of the ferrite antenna.
The speaker grill takes most of the left part of the front panel, at it's top, You find the mains switch, the switches for the dial illumination (in those days, dial illumination was realised with conventional bulbs and consumed nearly as much battery power as the rest of the conventionally designed circuity) and finally the BFO switch.
In the right part of the front panel, You find at the top the signal strength
meter and next to it the coarse frequency dial, a red mechanical sign indicates the
active part of the dial corresponding to the selected waveband. Below the frequency
dial moving behind the fixed dial pointer line, You find the main tuning knob with
a fine tuning dial marked from 0 - 1000. This fine tuning dial can be used in
conjunction with the crystal calibrator to read a frequency with a quite good
accuracy of around 5 kHz. The main tuning knob is equipped with a finger pit,
the tuning speed can be switched mechanically from slow to fast.
At the left face of the cabinet, the sockets for earphones and cassette recorder are located, at the rear, the mains socket, the set can be switched from 110 and 220 V, and two screw sockets for aerial and earth.
Reception on a random frequency or search for an interesting signal is uncomplicated:
Pull out the telescopic antenna, switch the set on, make sure that R.F. gain is
set at maximum and adjust volume control for a slight noise on an empty channel.
Select KW1 / SW1 and search for signals of broadcasters in the 49 m band somewhere
in the vicinity of the 6 MHz mark.
The Panasonic DR-22 / RF-2200 is a double conversion superhet: the signal from
the telescopic or ferrite antenna will run through a R.F. amplifier, in a first
mixer, the first intermediate frequency is generated and this signal is amplified.
In the second mixer, the second I.F. signal is generated, it will pass the I.F. filters,
drive the signal meter amplifier and will be demodulated. The crystal calibrator
acts based on a 4 MHz crystal signal with 1/4 and 1/8 divisors.
Reception performance is that of a shortwave consumer grade receiver of the
seventies: reception on mediumwaves is fair, in the FM band, selectivity is not
sufficient for the conditions in the crowded central European FM bands, in USA
and Japan, the selectivity is good enough.
© Martin Bösch 10.7.2010