Rycom R1307A/GR
VLF Receiver

This receiver is what I use to receiver frequencies between about 3 kHz to 830 kHz. I think it was designed to provide accurate field strength measurements of various transmitters. It is an all-mode receiver that be used to listen to about anything one might find in the VLF range. I've used this receiver to receive WWVB, BFSK, NDB's (Non-Direction Beacons), European longwave broadcast, LowFER transmissions, and many more interesting transmissions. I've received all of this with nothing more then a 20m long Inverted-L antenna. The only thing lacking in this receiver is an Automatic Gain Control (AGC). It does have a precision switchable front-end attenuator to keep signals within a linear region.

Additional Photos:

• Front View
• Top Inside View 1
• Top Inside View 2
• Bottom Inside View 1
• Bottom Inside View 2
• Nuvistor (1 of 3 Nuvistors)
• ID Label
• Dial
• Meter
• Rear 1
• Rear 2
• Rear 3

Input Characteristics
• Input Impedance: 3K or greater.
• Level: 100uV to 30V.
• Frequency Range: 3 kHz to 830 kHz.
• Modes: AM, CW, MCW, SSB, FM and FSK.

Receiver Characteristics
• IF Center Frequency: 2.215 MHz.
• IF Selectivities: 1 kHz, 2 kHz, 4 kHz and 8 kHz.
  (a) Passband ripple: +/-1 dB maximum.
• Detectors
  • AM detector used for amplitude modulation and modulated carrier wave.
  • Product detector used for single sideband and carrier wave.
    • Injection oscillator control.
    • Crystals for upper sidebands and lower sideband.
    • Beat frequency oscillator for carrier wave. BFO adjustable +/- 7 kHz from center IF frequency.
  • Limiter: Frequency descriminator, used for frequency modulation and frequency shift keying. 0.9 volts per kilohertz, nominal output.
• Local Oscillator.
  • Termal Stability: +/-100 Hz (constant environment one hour warmup).
  • FC sensitivity: 500 Hz, minimum shift per volt input.
  • Dial error: +/-2 kHz maximum. +/-500 Hz nominal.
• Internally generated harmonics of input signals: nominal -60 dB (0 dB meter reference, with attenuator set 40 dB below input signal).

Output Characteristics
• Impedance
  • Audio output: 600 ohms.
  • FM output: 5k ohms or greater.
  • IF output: 200 ohms or greater.
• Level
  • Audio output: adjustable, 10 volts maximum.
  • FM output: 0.9 volt/kHz nominal centered at approximately _8V DC>
  • IF output: 1 volt PP nominal.
• Frequency Response
  • Audio output: determined by IF selectivity switch and audio bandwidth swithc ( 2 kHz, 6 kHz and Flat).
  • FM output: dc coupled, determined bu IF selectivity.
• Signal to Noise Ratio: 36 dB nominal measured at IF output J7 with 4 kHz selectivity and MONITOR in AM position.

Mechanical Characteristics
• Size: 19"W, 15"D, 9-3/4"H.
• Weight: 35 pounds.
• Mounting: 19 inch relay rack.

Power Requirements
• Voltage: 98 to 130V AC 48 to 62 Hz, single phase.
• Current: 0.6 amps.