Drake R - 7 A
Manufactured by R. L. Drake.
In 1979 Drake introduced the original version of the R-7, which was initially designed as a receiver with analogue display covering the amateur radio bands. Soon the digital display was installed as a standard option, and with the number of options integrated as standard, the list price rose from US$1295 to US$1800:
- DR-7: Frequency counter with digital display and extension of the frequency coverage from 0.5 - 30 MHz.
- AUX-7: Additional board, that allows the selection of 8 additional 500 MHz ranges with the AUX switch, for each range the corresponding range has been defined by means of diodes on a RRM - 7 frequency range module.
- NB-7A: Noise Blanker.
It is uncertain whether copies of the original R7 were actually sold without the option of digital frequency display.
- Principle: Triple conversion superhet, IF 48.05 MHz, 5.645 MHz, 50 kHz
- Operation modes: A1 with BFO, USB / LSB, AM (A3)
- Frequency range: 10 kHz - 30 MHz
- Frequency display: digital display, 100 Hz
- Frequency memory: none, external VFO optional
- Signal processing: RF gain, preamplifier, attenuator, AGC 3x, PBT, opt. noise blanker, notch filter
- Features: switchable antenna inputs
- Sensitivity: AM (A3) <2 μV, SSB <0.5 μV / Selectivity: 0.5/1.5 kHz, 1.8/3.6 kHz, 2.3/4.4 kHz, 4/8 kHz (-6/-60 dB)
- Mains operation: 110, 120, 220, 240 V
- 345 x 117 x 330 mm, weight 8.3 kg
- RV-75: an external VFO, an additional tuning knob, allows to switch between two frequencies
- MS-7: the external loudspeaker
The anthracite - black front panel of the 34 x 12.1 x 31.5 cm wide tabletop receiver is dominated by blue backlit dial elements.
The display elements are positioned above the transverse trim. On the far left is the blue backlit S-meter calibrated in S-units, next to it the indicator lamps for RIT and fixed frequency operations. Next to the UP / DOWN keys to select the 0.5 MHz ranges the red LED frequency display, the reception frequency is indicated with an accuracy of 100 Hz.
Below the trim on the left, the range switch for the preselector, only the portion of the shortwave spectrum between the two orange digits can pass through the bandpass filter. To the right of this, in two rows of push-buttons, are the controls for the various special functions, below the switch for up to 8 additional frequency ranges, the bandwidth switch with 5 positions, and a double control. Its outside ring is used to shift the filter passband (passband tuning) and thus also to select the sideband for SSB reception, the inner knob is used for fine-tuning activated by pressing the RIT (Receiver Incremental Tuning) button. However, even with the main tuning knob, precise tuning is no problem, the RIT might be used for RTTY reception.
At the right, you find the large main tuning knob, in a sector-shaped blue backlit dial you can read the operation frequency to 5 kHz on two transparent plastic discs, for the 1 kHz digit there are markings on a metal ring outside the tuning knob, an arrangement similar to the Drake R-4C. Normally (except perhaps in direct sunlight) the frequency read off the red LED display above the tuning knob.
To the right of the tuning knob and the frequency dial is a special feature of the Drake R-7, an antenna selector switch: signals from two external antennas can be switched to two different receivers, this makes the R-7 a candidate for receiver comparisons. Below this is the notch filter control, and at the bottom right is the RF/AF gain control in the form of a double potentiometer. The RF gain can be reduced with the RF gain control in case of overloading at high antenna input levels, the main switch is combined with the inner knob, the volume control, called AF gain.
For practical use, an external antenna is connected to the MAIN antenna socket by means of a chinch plug and the antenna selector switch in the upper right area of the front panel is set to the second (MAIN/Alt) or third position. After switching on with the volume control/AF gain knob, make sure that the RF gain control is fully turned up, otherwise the received signal will be attenuated. As described in the manual, none of the 12 function keys other then the AM key should be pressed, the AUX-PROGRAM selector should be set to OFF and a filter of 2.3 kHz (usually installed as standard) or 4 kHz should be selected for AM reception. To listen to Austrian Radio Intl. on 6155 kHz, the BAND (preselection) switch is now set to 5 (6.155 is between 4.5 and 7 MHz), the range 6000 - 6500 kHz is selected with the UP/DOWN keys and the tuning knob is set to 6155.0 kHz. For single sideband reception, switch from AM to SSB/CW and select the appropriate sideband with the PBT knob, the default setting is for LSB and USB each marked with a dot.
The reception performance of the Drake R-7 was excellent at the time of its introduction and can still easily keep up with those of modern tabletop receivers, the large signal stability is good, especially with a full choice of IF filters installed, almost any signal from CW to AM can be demodulated without any digital DSP circuitry tinkering with the signal. Frequency stability after warm-up is good, though not one hundred percent like modern PLL designs. Unlike the newer NRD receivers, Drake's R-8 or the remote-controlled AOR 7030, comparing multiple parallel frequencies in different shortwave bands is not quite as quick and easy as the set has no direct keypad frequency entry, though the number of shortwave stations offering broadcasts on 5-8 frequencies in parallel has dwindled to a handful over the past decades anyway. For search reception in one band, the Drake R-7 leaves little to be desired with the possibilities of signal tweaking by means of passband tuning and notch filter, adjustment of the AGC constant and, if available, a nice IF filter selection.
In you plan to acquire a used R-7 / R-7A you have to be patient, sets are rarely offered on the second-hand market, at amateur radio fairs and also on ebay.
Triple conversion superhet with high first intermediate frequency.
The set is equipped with semiconductors.