en:e-649
Unterschiede
Hier werden die Unterschiede zwischen zwei Versionen angezeigt.
— | en:e-649 [2019/04/09 18:17] (aktuell) – angelegt - Externe Bearbeitung 127.0.0.1 | ||
---|---|---|---|
Zeile 1: | Zeile 1: | ||
+ | ====== E-649: Watkins-Johnson WJ-521A-3 ====== | ||
+ | **E-649**, **Surveillance Receiver Watkins-Johnson WJ-521A-3**; | ||
+ | The surveillance receiver Watkins - Johnson WJ-521A-3 with the optional digital frequency display DRO-290 A1 has been used by the " | ||
+ | |||
+ | {{: | ||
+ | ===== Technical Data ===== | ||
+ | * [[Principle]]: | ||
+ | * [[Modes]]: [[A1]] with BFO, [[A3|AM (A3)]], [[F3|FM (F3)]] | ||
+ | * [[Frequency range]]: 20 - 80 MHz | ||
+ | * **Analog dial**, digital display DRO-290, max. 100 Hz | ||
+ | * [[Sensitivity]]: | ||
+ | |||
+ | ==== Power Supply ==== | ||
+ | * [[Mains]]: 220 V | ||
+ | |||
+ | ==== Dimensions ==== | ||
+ | * 90 + 45 x 483 x 478 mm; 8.2 kg | ||
+ | * in the cabinet: 270 x 534 x 682 mm; 36 kg | ||
+ | |||
+ | ==== Accessories ==== | ||
+ | |||
+ | ---- | ||
+ | |||
+ | {{: | ||
+ | ===== Operation ===== | ||
+ | The VHF surveillance receiver Watkins Johnson WJ-521A-3 has been presented to the public in 1967 and it saw use at the military radio traffic surveillance ("Air police" | ||
+ | |||
+ | The receiver WJ-521A-3 itself together with the digital frequency display DRO-290-A1 and the DAFC option, a high stability frequency synthesizer, | ||
+ | |||
+ | The left part of the frontpanel is taken by a panoramic display offering an visual survey on all R.F. emissions in a certain frequency segment. You can select the SWEEP WIDTH, the width of the band segment displayed up to 300 kHz, adjust the SM GAIN, the level of the signals displayed and move the most interesting signal in the middle of the display using the CENTER FREQ control. | ||
+ | |||
+ | The controls of the receiver itself are located on the right half of the frontpanel: At the right, just above the headphones jack, you find the AUDIO GAIN volume control combined with the mains switch, at it's left the main tuning knob. The receiver is equipped with a mechanical film dial with coarse frequency markings, you can also read the reception frequency from the nixie tubes frequency display, the option DRO-290-A1 is installed in all Swiss receivers. Of the two analog meters, one is used as signal strength meter and the second one as center indicator when the set is set to FM operation. | ||
+ | |||
+ | The modes switch lets you select between [[CW]] (A1), [[AM]] (A3) and [[FM]] (F3) mode, you can control the beat note in CW mode with the BFO control. In the position AM AGC, automatic control and in position AM MAN manual gain control is selected, the R.F. gain control is used to control RF gain in the AM modes. The set comes with three I.F. filters, filters with a bandwidth of 4, 10 and 50 kHz are installed. | ||
+ | |||
+ | {{ : | ||
+ | |||
+ | ===== Technical Principle ===== | ||
+ | The WJ-521A is a double conversion superhet, the incoming signal from the antenna is amplified and converted to the first IF of 10 MHz in the first mixer stage. | ||
+ | |||
+ | After the first IF amplifier Q+ with FET transistors, | ||
+ | |||
+ | For demodulation of frequency modulated signals, a solid state limiter and discrimator is used. The audio signal is amplified in two preamlifier and a final amplifier AF stage. | ||
+ | |||
+ | For the panoramic display, the 10 MHz IF signal is used: After a conversion to 2 MHz with the signal of a sweep oscillator, the signal is again mixed with a 2,205 MHz signal, to generate the 205 kHz signal to drive the vertical deflection plate. | ||
+ | |||
+ | ==== Semiconductor setup ==== | ||
+ | The set is solid state. | ||
+ | |||
+ | ==== Development ==== | ||
+ | [[Watkins-Johnson]] has developed the WJ-521A-3 in around 1967. | ||
+ | |||
+ | ==== Field use ==== | ||
+ | |||
+ | ==== Variants ==== | ||
+ | |||
+ | {{gallery>: | ||
+ | ===== Manuals ===== | ||
+ | * {{ : | ||
+ | |||
+ | ==== Additional information ==== | ||
+ | * [[http:// | ||
+ | * [[https:// |
en/e-649.txt · Zuletzt geändert: 2019/04/09 18:17 von 127.0.0.1