It is not an easy task to design a highly sensitive radio receiver that also has a wide dynamic range. However this is an important requirement for many radio communications systems, particularly where mobile radio communications units may come into close proximity with each other.
To achieve the required level of performance a number of methods can be used. The front-end stage of the radio receiver is the most critical in terms of noise performance. It should be optimised for noise performance rather than gain. Input impedance matching is critical for this. It is interesting to note that the optimum match does not correspond exactly with the best noise performance. The amplifier should also have a relatively high output capability to ensure it does not overload. The mixer is also critical to the overload performance. To ensure the mixer is not overloaded there should not be excessive gain preceding it. A high level mixer should also be used (i.e. one designed to accept a high-level local oscillator signal). In this way it can tolerate high input signals without degradation in performance. Care should be taken in the later stages of the receiver to ensure that they can tolerate the level of signals likely to be encountered. A good AGC system also helps prevent overloading and the generation of unwanted spurious signals.
A radio receiver with a good dynamic range will be able to give a far better account of itself under exacting conditions than one designed purely for optimum sensitivity. With the exacting requirements needed for today's radio communications systems where mobile radio communications means that transmitters and receivers come into close proximity, good levels of sensitivity are needed along with the ability of the radio receiver to tolerate high signal levels, either on or off channel. Only when the radio receiver has a good dynamic range will the required performance level for the whole radio communications system be achieved.


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HARRIS RF 1310 / A  EXCITER 100mw output


eciSpecifications for the RF-590A
Specifications are subject to change without notice.
Frequency Range  10 kHz to 29.999999 MHz in 1Hz steps
Frequency Stability + 1 part in 10 6– Standard + 1 part in 108– 
Optional External Frequency Standard 1/5/10 MHz, 0.5 VRMS
Channel Memory 100-channel capacity
Modes of Operation
   USB (J3E, A3J), LSB (J3E, A3J),
2-ISB (B8E, A3B) (optional),
      CW (A1A, A1), AM (A3E,A3),
FM (F3E,F3)
Sensitivity For 10 dB (S+N)/N, above 50 kHz
SSB: 0.35 μv
CW: 0.15 μv (300 Hz)
AM: 1.5 μv (6 kHz)
IF Bandwidths 
Mode 3 dB BW (kHz) 
USB   2.8 
LSB    2.8 
CW    0.3
CW    1.0
AM    3.2
AM    6.0
AM/FM 16
 In Band: –50 dB or better for (2) –7 dBm signals within the IF passband
Out of Band: –50 dB or better for (2) 0 dBm signals separated 30 kHz or more
Reciprocal Mixing ≤ –107dBc in 3 kHz @ ≥ 100 kHz 
separation Image and IF Rejection –100 dB Spurious Rejection Internal ≤ –123 dBm, external –80 dB
Maximum Signal Input
Receiver protected to 100 watts available power input
AGC  Range: < 3 dB audio output variation for 1 μv to 1v input
Attack Time: <20 msec
Hang/Decay Times:
Short, <30 msec.; 
Medium, 200 + 50 msec.;
Long, 2.5 ± .5 sec.
Data BFO + 9.99 kHz in 10Hz steps
Hum and Noise < –50 dB
Ultimate (S+N)/N 50 dB
Audio Outputs Line Output: –16 to +10 dBm/600 ohms
Phone: +10 dBm/600 ohms
Internal Speaker:
2.0 W/8 ohms
External Speaker: 2.5 W/8 ohms
Operating: – 10 ̊C to +55 ̊C
Non-Operating: – 62 ̊C to +71 ̊C
Humidity 0 to 95%
\    Installation
Power Supply
115/230 VAC + 20%, 47 to 420 Hz,
Power Consumption 75 watts
Size 5.25”H x 19”W x 19.5”D max
(13.3H x 48.3W x 49.5D cm)
Weight 40 lb (18.2 kg)


1 comment:

  1. HARRIS RF 591A

    As a preselector, the RF-591A provides extra receive system selectivity required when operating in the presence of strong undesired RF signals. Such signals could be caused by transmitters located in close proximity to receive antennas. The RF-591A filters these interfering out-of-band signals to prevent distortion and overload conditions at the receiver. Low level in-band signals are amplified to enhance receiver performance. When the input Radio Frequency (RF) signals exceed safe operating limits, circuits in the RF-591A activate to protect the system.

    When used as a postselector, the RF-591A is inserted in the signal path after the transmit exciter to significantly reduce transmitter broadband noise output.

    This broadband noise may cause interference with receivers which are located in close proximity to the transmitters. Note that the RF-591A is inserted at the exciter output where in-band signals are low (typically 100 mW). A separate RF input and output are provided on the RF-591A rear panel for the postselector signal path.

    The pre/postselector may also be configured to work with a transceiver.
    In this application, the RF-591A performs both the preselector and postselector functions and the signal path is automatically controlled by the transceiver keyline.

    The pre/postselector is a digitally tuned highly selective filter which may be tuned locally or by remote control. Frequency range is from 10 KHz - 29.99 MHz. The pre/postselector operates as a bandpass filter from 2.0 - 29.99 MHz and provides a set of low pass filters for operation below 2.0 MHz.

    Selectivity is accomplished by three cascaded bandpass filters modules and gain is provided by two low distortion amplifiers. All three bandpass filter assemblies are identical and interchangeable. When operating between 2.0 - 29.99 MHz, each filter assembly has approximately 20-dB selectivity at +10% from the tuned frequency. Passband loss in each assembly is 5 dB nominal.

    A high power input attenuator network is used to guarantee 50 ohm input impedance antenna termination.

    The gain of the pre/postselector is distributed between two low-distortion amplifiers. The first amplifier provides +10 dB of gain and the second provides +13 dB of gain.