Ships main and reserve receiver
R.L. Drake print the folder with
specifications, but this receiver has never been in production.
On October 2000, I discover the
MR-3 prototype Serial 000X
Click on left margin for prototype
picture
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to enlarge pic Picture: R.L. DRAKE Company |
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FOLDER DESCRIPTION
The MR3 is a solid state, broadband receiver which embodies several unique state-of-the-art design features. The unique design offers excellent sensitivity, selectivity, very high dynamic range and digital frequency readout combined with general coverage capability.
A high overload and intermodulation to a minimum.
The MR3 synthesizer is tuned by pulses from a shaft encoder as the main tuning knob is rotated. This circuit features a variable frequency tuning rate. Slow tuning provides tuning at a rate of 1250 Hz per revolution of the tuning knob. The frequency change per revolution increases as the speed of tuning increases. The variable BFO provides a plus and minus 3 kHz range. A clarifier allows fine tuning of the received signal. These features combined provide a tunable band tuning capabilities while also allowing ease of fine tuning a signal.
While normal sensitivity meets the CEPT specifications, an internal preamplifier may be switched in for improved reception. This preamp increases receiver gain by about 10 dB and improves sensitivity by about 5 dB.
Other features include a notch filter for eliminating interfering heterodynes, switchable ACC with three selectable time constants, VFO lock, speaker on/off switch, and capability of operation from AC or DC power. Accessory items include a noise blanker, 600 ohm balanced output line amplifier for RTTY operation, rack cabinet enclosure, internal DC-to-DC isolation power supply, and eight programmable crystal controlled channels.
FOLDER SPECIFICATIONS
 | Frequency Range: 10 kHz to 30 MHz |
| Modes of Operation: USB, CW, RTTY, AM, (LSB with BFO) |
| Frequency Readout: Six digit readout to 100 Hz. |
| Frequency Selection: Band switched in 10 bands. Incrementally stepped up and down in 500 kHz increments within each band. Continuous tune over each ofthe 500 kHz range and fine tune with clarifier. |
| Frequency Stability |
| Long Term: Less than 100 Hz in any 8 hour period at a constant temperature between 0" and 40°C with a +- 10% change in mains. |
| Short Term: Less than 20 Hz in any 15 minute period with a temperature variation of 7°C per hour over the range of 0" to 40°C with a +- 10% change in mains. |
| Sensitivity: Meets
CEPT and MPT 1201. (a) Antenna impedance 10 ohm in series with 250 pF. |
|
Freq. MHz |
Condition |
EMF micro V | S+ N/N dB |
| .10 - .16 | A1, Narrow | 30 | >=10 |
| .16 - .525 | A1, Narrow | 20 | >=10 |
| .16 - .525 | A2/A2H, Intermediate | 30 | >=10 |
| .525 - 1.6 | A3, Intermediate | 30 | >=10 |
| 1.6 - 4 | A2/ A3/ A3H, Wide | 30 | >=20 |
| 1.6 - 4 | A3A/A3J, SSB | 6.3 | >=20 |
(b) Antenna impedance, 50 ohms unbalanced.
|
Freq. MHz |
Condition |
EMF micro V | S+ N/N dB |
| 4 - 30 | A1, Narrow | 1 | >=10 |
| 4 - 30 | A2/ A3/ A3H, Wide | 16 | >=10 |
| 4 - 30 | A3A/A3J, SSB | 3.6 | >=10 |
Above EMF values are open circuit voltages.
| Selectivity |
Position IF Bandwidth (kHz) -6 dB -60 dB Very Narrow .5 1.1 Narrow 1.7 3.6 Intermediate 2.3 4.2 Wide 8 16 SSB 2.3 4.2
| Spurious Response: All spurious response, including image and IF are at least 70 dB below level obtained with 1 micro Volt EMF wanted signal. |
| RF Blocking: Greater than 100 dB relative to 1 mi cr o V (desired signal at 60 dB above 1 micro Volt with blocking signal removed 20 kHz and its amplitude adjusted to reduce desired signal 3 dB). |
| Cross Modulation: 90 dB relative to 1 Mi cr o V (desired signal at 60 dB above 1 Micro Volt with undesired signal removed 20 kHz and its amplitude adjusted for cross modulation products 30 dB lower than desired signal). |
| Intermodulation: test signals, each separated by at least 30 kHz from the wanted signal, must be at least 10 millivolts.) |
| Automatic Volume Control: Audio output rises less than 6 dB for RF input change from 3 micro Volt to 300 mV (100 dB). Attack time; 1 millisecond. Three selectable release times; 2 seconds, 400 milliseconds, and 75 milliseconds. Also AVC OFF. |
| Audio Output: 2.5 watts with less than 10% THD. |
| Hum and Noise: Greater than 60 dB below rated output. |
| BFO: Fixed frequency derived from a 40 MHz standard or variable +-3 kHz range from front panel control. |
| Power Requirements: 100/120/200/240 VAC +- 10% 50/60 Hz, 60 watts or 11 to 16 VDC, 50 watts. |
| Size and Weight: 5.25"H x 19"W x 14"D (13.3 x 48 x 35.6 cm) 19 Ibs (8.6 kg) |