Manufactured by Sangean, Taiwan.
More popular than the travel radio RK 665 was its sister model RK 670, which came with a built-in cassette recorder.
The Siemens RK 665 was developed by Sangean around 1992 as ATS-818. Its sister model RK 670, which has an integrated cassette recorder in similar cabinet dimensions, was more popular: with this set, exotic station IDs could be recorded at the push of a button.
The Siemens RK 665 has a plastic cabinet measuring 300 x 190 x 80 mm and has a weight of 1.8 kg, it is quite bulky for a travel radio. To power the set, four D cells UM-1 or a 9 V external power supply are needed. Three UM-3 AA cells are required to operate the quartz clock and to store the transmitter memories.
The set is switched on with the red power button at the top right of the front panel; the volume control is located on the right-hand side of the set. At the bottom right of the front panel are the switches for timer operation, the IF bandwidths and the BFO. Below are the controls for tone, RF gain and the BFO control, which activates the heterodyne oscillator for A1/single sideband reception.
The frequency ranges are called up with the keys below the display: the FM key selects the FM radio band, the MW and LW keys call up the medium- and longwave ranges, and the SW key calls up the shortwave range. With the Meter key followed by a numeric key, the shortwave broadcast bands can be accessed directly. The last received frequency in each bradcast band is stored, so that there is an additional frequency memory, in addition to the nine frequency memories.
To store the received frequency, press M and the memory location number; a stored frequency is called up directly by pressing the corresponding numeric key.
To access a frequency, first the FREQ key must be pressed, then the frequency is entered and confirmed with ENTER; you can continue tuning with the rotary tuning knob.
AUTOSCAN UP/DOWN activates an automatic station scan, which stops as soon as a station with sufficient signal strength is tuned. Touching the UP/DOWN keys again stops the scan or continues the station search.
With the SSB ON/OFF switch, the BFO can be activated to receive CW or SSB transmissions, for example from radio amateurs; ECSS reception (i.e. receiving an AM shortwave station in SSB mode tubed to zero beat) is difficult due to low frequency stability and wide tuning steps.
A ferrite antenna for long and mediumwave reception is built in. For VHF and shortwave reception, in addition to the built-in telescopic antenna an external antenna can be connected.
With the built-in digital clock, a SLEEP timer can be programmed for 90 to 10 minutes until the set is switched off, and the radio can also be used as an alarm clock.
Double conversion, microprocessor control with PLL synthesis circuit.
The set is equipped with semiconductors.