Radio Pages

Panasonic / National Panasonic,
Matsushita Electric Industrial Co. Ltd., Osaka
DR - 22 / RF - 2200

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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.
Panasonic developed several multi band shortwave radios in the medium price segment, it seems, that the same technology has been used in several other Japanese shortwave radios - the innards of the Miramo / Sanwa 6090 and even of some Pan Crusader sets have some resemblance with sets originating from Matsushita production plants.

Double conversion superhet,

Analog dial 10 kHz

AM, CW/SSB (BFO), FM

Sensitivity

Selectivity -6/-60 dB

S Meter, RF Gain, Crystal marker

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, below the signal strength meter, You find another row of switches, they operate the AFC in FM mode, the narrow and the wide I.F. filter and the 125 kHz and 500 kHz signals of the calibration system. Just below are the knobs for volume control and separate controls for bass and treble.
At the right of the main tuning knob, You find the shortwave bandswitch for the shortwave bands SW 1 - 6, just below the bandswitch for FM, mediumwaves and shortwaves and the R.F. gain.

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 search fo a station on a known frequency is a bit more challenging: First You have to calibrate the main dial to the nearest 1 MHz or 0,5 MHz point and then work out the correct frequency. Tune the set to the nearest lower 0,5 MHz mark, e.g. to receive the BBC on 6.195 MHz tune to 6 MHz and for 11,805 MHz to 11.500 MHz. Activate the 500 kHz marker, You will hear a whistle in the region around 6 MHz, slowly use the main tuning dial to tune to "zero beat", that means until the whistle disappears. The pointer of the signal strength meter should read maximum towards the left side. The fine tuning dial should be set to 000 during this procedure.
After You switch off the 500 kHz calibrator, the fine tuning dial is moving again. Tune up to 195 and You should hear the BBC on 6.195 MHz. You might use the 125 kHz calibrator signal to check Your dial's accuracy on every 125 kHz, the receiver is muted for this procedure.
Dr-22 / RF-2200 dial set to 6155 kHz
The set is equipped with a BFO to receive CW and single sideband emissions. When switched on, You will hear a whistling noise, with the main tuning knob set to slow speed You can tune in to a CW transmission for a beat note with good readibility. With single sideband signals, You have to detune the set until readibility of the speech is optimal, the set is not very stable to listen to music in single sideband or ECSS mode (reception of one single band of a AM transmission under difficult conditions. In case of interference by a nearby station, try the narrow I.F. bandwidth filter - this may help, but as in other consumer grade receivers of this era, the filter skirts are not really steep and the I.F. filters quite wide.

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.
In the FM band, the DR-22 / RF-2200 has a single conversion superhet design.

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.
The technical concept of the shortwave recepetion section with the integrated crystal calibrator and a linear fine tuning dial dating from the seventies has made sense, when Panasonic engineers had the task to construct a portable receiver with an acceptable accuracy. Nowadays, the tuning arrangement is awkward, most not so technically minded people would find it very difficult to operate the set with acceptable results.
From my point of view, the DR-22 / RF-2200 makes a fine collector's item to document the development step from a simple analog to a PLL synthesizer receiver design, and it's still a useful radio, but if You really have to rely on informations from the shortwave bands, I would recommend You go and get a tiny portable with a digital frequency display and a decent number of memories.

Variants sold in different regions of the world: 
DR-22 / RF-2200 BSFM 87,5 -108 MHz
RF-2200 
Cougar 2200 

further literature:
d/e: Panasonic DR-22 at www.radiomuseum.org

© Martin Bösch 10.7.2010