Double-conversion HF desktop receiver. PLL synthesized, frequency range 0.1-30 MHz in 1 MHz bands. Ideated in Japan.
Reference market : ham-radio
|Frequency coverage||0.1000 ~ 30.0000 MHz|
|Modulation mode||CW / RTTY / LSB / USB / AM|
|Sensitivity||CW / SSB||
10.0 uV (0.1~1.6 MHz, 10dB S/N)
0.5 uV (1.6~30 MHz, 10dB S/N)
40.0 uV (0.1~1.6 MHz, 10dB S/N)
2.0 uV (1.6~30 MHz, 10dB S/N)
> 0.6 KHz (-6dB)
< 3.0 KHz (-60dB)
|SSB / RTTY||
> 2 KHz (-6dB)
< 6 KHz (-60dB)
> 4.4 KHz (-6dB)
< 10 KHz (-60dB)
|Image rejection||> 70dB|
|IF rejection||> 70dB|
|AGC||Off, fast, slow|
|Frequency stability||100 Hz/h max after warm-up|
|Intermediate frequency||1°||70.455 MHz|
|Memory||4 regular memories|
|Display||100 Hz frequency resolution|
|Antenna||SO239 50Ω connector|
|Power supply||100~230 VAC|
|Power consumption||50 W|
|Audio power||1 W with an 4~8Ω load|
Jack external speaker
Jack (IF output)
Jack (external VFO)
|Mechanical and environmental data :|
|Dimensions||340 (W) x 140 (H) x 300 (D) mm|
 With optional 2° IF mechanical filter
This JRC receiver adopts a classic double frequency conversion configuration, with the use of a VFO combined with a PLL synthesizer that divides the tuning field into 30 segments of 1 MHz each selectable through the convenient rotary control on the left of the front panel . The frequency reading is twofold, digital through the display with a resolution of 100 Hz, and mechanics through the graduated scale that shows signs of reading of 1 KHz. Among the features: BFO to move the detection point within ±2.5 KHz, noise-blanker (NB), AGC time constant selectable between slow-fast or excludable response, RF-gain, RF attenuator, fine tuning control (RIT), active audio filter, 4 memories that can be activated by a row of dedicated buttons on the right side of the front panel.
In the apparatus there are three positions for filters at the level of the 2nd IF. Two have pre-installed the devices corresponding to the bandwidth of 2 and 4.4 KHz respectively for the RTTY / SSB and AM. The third position is free and on this it is possible to install as an option the mechanical filter, with a narrow selectivity, for the CW. The tuning knob is coaxial with a displacement of 100 KHz/revolutions and 33 KHz/revolutions respectively.
Performance and practical notes :
The NRD505 is an receiver now part of the vintage world, marketed in the '70s using a fully solid-state electronics including 66 integrated circuits (IC), 54 bipolar transistors, 18 FET and 103 diodes. A complex circuit structure due to the need to implement the PLL synthesizer and associated control networks. Again on the internal circuit, the four memories of which the receiver is equipped use a CMOS-type RAM powered by a buffer battery, those who come into possession of the NRD-505 must remember this aspect. Interesting in perspective is the possibility, through a switch on the front, to choose between internal or external VFO. This allows you to upgrade the equipment by combining, for example, one of the DDS kit synthesizers made available by fans for this purpose. It is pointed out that originally the input for an external VFO was designed to interface the NSD-505 transmitter, a pair of devices that together constituted a complete amateur radio station.
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