WJ-1000A | Watkins-Johnson

Watkins-Johnson » WJ-1000A

High performance, triple-conversion, HF desktop receiver with last IF in digital technology. Frequency range 0.005-30 MHz all-mode. Ideated in USA.

Reference market : ham-radio / professional

General :
Frequency coverage 0.0050 ~ 30.0000 MHz
Modulation mode CW / LSB / USB / ISB / AM / AM-S / FSK / FM
Tuning step 1 Hz
Receiver :
Sensitivity CW [1] 28 uV (0.005~0.02 MHz, pre. OFF, 16dB S+N/N)
1.27 uV (0.02~0.05 MHz, pre. OFF, 16dB S+N/N)
0.5 uV (0.05~0.5 MHz, pre. OFF, 16dB S+N/N)
0.35 uV (0.5~30 MHz, pre. OFF, 16dB S+N/N)
SSB/ISB [2] 0.56 uV (0.5~30 MHz, pre. OFF, 10dB S+N/N)
AM 1.6 uV (0.5~30 MHz, pre. OFF, 10dB S+N/N)
Selectivity [3] CW
300 Hz
0.35 KHz (-6dB)
0.45 KHz (-60dB)
3 KHz
3.0 KHz (-6dB)
3.8 KHz (-60dB)
IF-filter ultimate attenuation [4] 80 dB
Group-delay < 0.1 ms (300~3050 Hz band)
NF (Noise figure) 14 dB (preamplifier OFF)
11 dB (preamplifier ON)
Dynamic range [4] 99 dB (20 KHz spaced signals, 14 MHz)
75 dB (5 KHz spaced signals, 14 MHz)
Blocking [4] 123 dB (100 KHz spaced signal, 14 MHz)
IP2 (2nd order intercept point) +60 dBm
IP3 (3rd order intercept point) +30 dBm (preamplifier OFF)
Image rejection 90 dB typ
IF rejection > 85 dB (90 dB typ)
Spurious carriers < 0.4 uV (referenced to RF input)
AGC Adjustable
Frequency stability ± 1ppm with temperature from 0°C to +50°C
Synthesizer settling time 10 ms
Intermediate frequency 45.455 MHz
455 KHz
25 KHz
Features :
Memory 100 regular memories
Display 1 Hz frequency resolution
Antenna BNC 50Ω connector
Power supply 97 ~ 253 VAC
Power consumption 35 W typ
Audio power 1 W with an 8Ω load
Audio output Jack 6.35 mm headphone
Connections RS232C / RS485 / RS422 (control)
BNC (IF 455 KHz output)
BNC (monitor 455 KHz output, BW 8 KHz)
BNC (frequency reference input)
Terminal jack (audio)
Mechanical and environmental data :
Operating temperature from 0°C to +50°C
Dimensions 482 (W) x 133 (H) x 508 (D) mm
Weight 6.78kg

[1] 300 Hz bandwidth
[2] 3200 Hz bandwidth
[3] Standard values, 58 bandwidths are available between 0.056~8 KHz
[4] This parameter, not in official data, was obtained with direct tests

Description :

The WJ-1000A was one of the first receivers for the amateur market to implement the SDR technology in hybrid form, ie. adopting a triple frequency conversion with the last digitized to perform the filter and demodulation functions. The equipment has professional characteristics both in terms of RF performance and reliability, the producer WJ in fact works in the military as well as in the civil sector, always linking its name to products of the highest quality. The receiver offers a lower frequency limit of only 5 KHz, although tuning can go down to zero under the operational aspect, thus covering even the lowest radio frequencies with substantially constant sensitivity and dynamics over the entire range. In fact, this model, starting from hundreds of KHz and up to the upper limit, guarantees a precision in the detection of the amplitude displayed by the S-meter. Equivalent to a measuring instrument with reading both in S points and in dBm. The AGC operates in analog and digital sections for a total of 100 dB, the response time is extremely rapid, taking 5 milliseconds while the release time is selectable between slow, medium and fast in the interval of 0.01 ~ 5 seconds so as to adapt to each type of emission. After the ADC conversion stage operating at 100 Ksps for 16 Bit a DSP processor is responsible for defining selectivity, with high attenuation slope bandpass filters, and making the PBT, notch, BFO adjustable functions available (within ±8 kHz in 10 Hz steps), multi-mode demodulation including also the ISB (independent side bands with two audio outputs) and the synchronous-AM.

The WJ1000A has 58 different bandwidths to choose from a minimum of 56 Hz to a maximum of 8 KHz, the form factor of the filters is always better than 1.5:1 at 6/60 dB. In the following table the nominal bandwidths referred to 3 dB:

Hz Hz Hz Hz Hz Hz Hz Hz
56 113 225 450 900 1800 3600 7200
63 125 250 500 1000 2000 4000 8000
69 138 275 550 1100 2200 4400  
75 150 300 600 1200 2400 4800  
81 163 325 650 1300 2600 5200  
88 175 350 700 1400 2800 5600  
94 188 375 750 1500 3000 6000  
100 200 400 800 1600 3200 6400  

The front-end module is characterized by excellent levels in IP2 and IP3 parameters, to change the dynamic range at the input you can insert a 10 dB preamplifier or a 15 dB attenuator. However, there is not a preselector stage that is only provided as an optional accessory (model HF-1000PRE), this integrates eleven preset bandpass cells with a width of less than one octave and can be switched off when necessary.

The internal clock uses a high stability TCXO with a maximum deviation of ±1 ppm for a temperature change of 50°C. An input is dedicated for an external master clock reference that accepts 1, 2, 5 or 10 MHz signal. The receiver automatically adopts this reference and detects its presence. The audio is usable for loudspeakers, headphones and via fixed-level outputs on 600Ω for connection to recording systems. The volume control is also separate for audio intended for the speaker and headphones. Two the IF outputs both at 455 KHz but with different bandwidth, this makes it possible to connect instruments that display the spectrum around the tuned frequency or even specific demodulators that make use of the selectivity determined by the user. A multi-standard interface on a 25-pin connector with baud rates of 75 ~ 9600 bps allows remote use of the WJ-1000A. The apparatus has standard size measurements so as to be possibly mounted in a 19-inch rack.

Performance and practical notes :

Certainly the WJ1000 is a superior class receiver for reliability and repeatability in performance, it is also taken care of in every detail both in terms of electronics and mechanics. Being born in the first half of the 90s this Watkins-Johnson (WJ) model inevitably suffers from some weaknesses when compared to the recent SDR, more flexible on some aspects, but nevertheless expresses an ergonomic that perfectly fit the needs of the operators who prefer a traditional front panel instead of the combination of monitor and mouse. It should be noted that the receiver is in practice the version for the civil market, with few but significant variations, of the WJ-8711A model of the same manufacturer. Apparatus that was originally intended solely for military and government users.

Valuation :

Dynamic range
Spurious response
Signal functions
Control functions
User friendly

Stars: 1=insufficient, 2=just sufficient, 3=mediocre, 4=good, 5=excellent

Review :

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