01/1980 html

Presenting the Drake R 7 receiver A synthesized, general coverage receiver. it offers a wide range of features. Covering the frequency range of 0 to 30 MHz. this receiver is at home in both the ham snack and the laboratory.		Drake R.7 VLF/HF Receiver Claimed specifications Sensitivity: 1.8-30 MHz less than 0.2 uV for 10 dB S + N/N with preamp on; lees than 0.5 uV with preamp off. From 0.01 to 1.5 MHz, less than 1.0 uV. Dimensions (HWD) 4.6 x 13.6 x 13 inches (116 x 346 x 330 mm). Weight: 16.4 Ibs (8, 34 kg) Power requirements: 100 to 240 V ac. 50/60 Hz. 60 watts, or 11 to 16 V dc at 3 A (13.8 V dc nom.). Price class: $1300. Manufacturer: R. L. Drake Company, Miamisburg. OH 45342. Tel. 513-866-2421.
R. L . DRAKE R-7 RECEIVER The beholder of this fine new product may regard it initially as just another "super-duper signal scooper." but it is. in fact, anything but just another fancy receiver. The Drake R-7 (model 1240) is a synthesized general-coverage (0. to 30-MHz) unit with no gaps in the frequency coverage. The utility of this new product can be used to advantage in the ham shack or laboratory , with or without the many available options. Among them arc the MS-7 speaker, i-f filters for 300, 500 and 1800 Hz One can also purchase filters for 4.0- or 6.0-kHz bandwidths. Other accessories are the NB-7A noise blanker and AUX-7 range program/fixed-frequency board. The latter permits programming eight additional) 500-kHz range segments in the 0- to 30-MHz range. irrespective of the existing e l even 500-kHz range increments. Specific Circuit Features The receiver front end employs a high-level doubly balanced mixer As an enhancement to image rejection. the first i-f is derived at 48 MHz by means of "up-converting." Front-end bandpass filters are used from vlf through hf. A broadband preamplifier can be switched in from the front panel at all frequencies above 1.5 MHz. This adds 10 dB of front-end gain when it is needed. multi position antenna selector switch is located on the front panel. It enables the operator to receive simultaneously with the R-7 and a TR-7 for split-frequency reception. Other positions can be used to select alternate antennas and outboard vhf and uhf converters. This receiver can be used for transceiving when utilized with the TR-7. (c) QST - January 1980 - p 49	A tunable i-f notch filter is included in the circuit. It is used for reducing unwanted heterodynes from interfering strong signals. Electronic passband tuning is still another feature of the R-7. It can be adjusted for use with any of the filter bandwidths listed earlier. There are three selectable agc time constants in addition to an "off" position. Also, the receiver is equipped for digital and analog frequency readout. A front-panel switch enables the operator to use the internal counter as a 150-MHz external frequency counter, if desired. A 25-kHz calibrator is included f or alignment of the analog dial. A low-distortion "synchro-phase" a-m detector is included in the receiver. This circuit permits a 3-kHz a-m sideband response when using a 4-kHz filter. The technique provides better interference rejection than is possible with conventional systems. The principal application for amateurs would be in the monitoring of international shortwave broad-casts, but amateur a-m diehards might appreciate the feature also! Performance As one might conclude from reading the specifications for the R-7, the receiver dynamic range is excellent. The worst-case numbers were obtained on 80 meters with and without the preamp switched in. They arc. with the preamp actuated: Noise Floor Blocking IMD - 139 dBm 112 dB 91 dB Without the preamp turned on: Noise Floor Blocking IMD -133 dBm >120 dB 100 dB		The tests were based on the W7ZOl measurement techniques described in July 1975 QST. These numbers equate to a third-order input intercept of -2.5 dBm on 80 meters with the preamp turned off and +17 dBm with the preamp turned on. The League’s product-analysts engineer reported difficulty in identifying the IMD responses, as they were among other responses within the receiver. presumably caused by the frequency synthesizer. Our present measurement capability prevents us from making definitive 1.0 noise-floor measurements. In actual amateur service at W1FB (two short blocks front W1AW), the receiver performed extremely well in the presence of very strong signals. There was no evidence of overloadi ng when W1AW was operating. Image rejection appears to he excellent: Drake rates it at greater than 80 dB (48.05 MHz first i-f, 5.645 MHz second i-f and 500 kHz third i-f). The antenna input impedance is 5 50 ohms R. The Audio output is rated at 2.5 watts with less than 10 percent total harmonic distortion (THD) in-to a 4-R load. The frequency drift checked out at 85 Hz after a 30-minute warm-up period. This is quite good. considering the power supply is built in and the heat from the m any active devices contained in the circuit. - DougDeMaw. W1FB