en:e-629
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+ | ====== E-629: Shortwave Receiver Collins 51J-4 ====== | ||
+ | **E-629**, **Shortwave Receiver Collins 51J-4**; manufactured by [[Collins|Collins Radio Company, Cedar Rapids, USA]]. | ||
+ | After WWII, [[Collins]] presented their first all wave receiver covering all frequencies from mediumwaves to 30,5 kHz shortwaves, the 51J - after a short time in 1949, the 51J-1 appeared and was built in small production numbers. After major technical improvements, | ||
+ | |||
+ | The Swiss Army acquired 84 of these sets to be used on high power stations, in embassy communications and for monitoring, the Swiss sets seem to originate from a late production batch as all sets are equipped with S-line knobs. | ||
+ | |||
+ | {{: | ||
+ | |||
+ | ===== Technical Data ===== | ||
+ | * [[Principle]]: | ||
+ | * [[Modes]]: [[A1]] with BFO, [[A3J|SSB (A3J)]] with BFO, [[A3|AM (A3)]] | ||
+ | * [[Frequency range]]: 500 kHz - 30.5 MHz in thirty ranges of 1 MHz | ||
+ | * **Analog dial**, linear analog dial, accuracy better then 1 kHz. | ||
+ | * [[Sensitivity]]: | ||
+ | |||
+ | ==== Power Supply ==== | ||
+ | * [[Mains]]: 115 / 230 V; 85 W | ||
+ | |||
+ | ==== Dimensions ==== | ||
+ | * 536 x 317 x 333 mm, 24.9 kg | ||
+ | |||
+ | ==== Accessories ==== | ||
+ | * 75 ohms asymmetrical antenna connector for a **L-Antenna**. | ||
+ | * headphones | ||
+ | |||
+ | ---- | ||
+ | |||
+ | {{: | ||
+ | ===== Operation ===== | ||
+ | The Collins 51 J-4 is a typical " | ||
+ | |||
+ | In the centre of the front panel, You find the analog linear drum dial displaying the selected 1 MHz segment with 100 kHz marks. Underneath, just next to the main tuning knob, you find a window displaying a segment of a circular dial calibrated in 10 kHz marks, between the 1 kHz-lines you can read a tuned frequency with an accuracy of around 500 Hz.\\ | ||
+ | Due to the circuitry, in some 1 MHz segments marked with red lettering on the MHz drum, you have to read the frequency off the red numbers of the circular kHz dial. | ||
+ | |||
+ | In the lower row of controls you find from the left to the right the mains switch, in the " | ||
+ | |||
+ | The round signal strength meter in the right upper corner indicates the level of an incoming signal in dB and can be set to indicate the AF level. Three smaller switches below the signal strength meter will activate the internal 100 kHz - calibrator, the AGC (automatic gain control) and the Noise Limiter. | ||
+ | |||
+ | In the left upper corner of the front panel, you find the controls for the crystal filter, the rotary switch activates the [[BFO]] used for [[CW]] and [[SSB]] reception and another knob controls the BFO pitch note. A small metal lever is used to switch the three IF bandwidths of 1,5 / 3 and 6 kHz. | ||
+ | |||
+ | Only the 51J-4 version is equipped with the famous mechanical Collins IF filters, I consider the 3 and 6 kHz filters as very useful for AM reception, in some situations they are even better suited then the filters found in the R-390A. Another special feature of the Collins 51J-4 is the " | ||
+ | |||
+ | ^Position Selectivity^Filter 1,5 kHz (-6/-60 dB)^Filter 3 kHz (-6/-60 dB)^Filter 6 kHz (-6/-60 dB)^ | ||
+ | |0|1.2-1.6 / 4|2.8-3.4 / 8.5|5.7-6.3/ | ||
+ | |1|1.3-1.55 / 3.5|2.27-2.75 / 6.4|3.0-4.0/ | ||
+ | |2|0.8-1.2 / 3.0|1.2-1.5 / 5.5|1.25-1.6/ | ||
+ | |3|0.3-0.5 / 2.65|0.3-0.5/ | ||
+ | |4|0.1-0.3 / 2.5|0.3-0.3/ | ||
+ | |||
+ | ===== Technical Principle ===== | ||
+ | {{: | ||
+ | The HF circuit of the 51J-4 is nearly as complicated as the mechanical synchronisation of the preselection using very impressive gears. | ||
+ | |||
+ | The RF signal from the antenna input first has to pass a tuned circuit and a RF amplifier stage (V101: [[de: | ||
+ | |||
+ | In the **0.5 - 1.5 MHz** frequency range, which in fact can only be used from 540 kHz up due to the IF of 500 kHz, the 51 J-4 acts as a triple conversion receiver: the RF signal is converted to a 11.5 - 10.5 MHz intermediate frequency in the first mixer (V102: [[de: | ||
+ | |||
+ | In the **1.5 - 3.5 MHz** frequency range, the receiver acts as single conversion receiver; the signal is fed directly to V106 ([[de: | ||
+ | |||
+ | In the other shortwave bands from **3.5 up to 30.5 MHz** , the receiver operates as a double conversion superhet: after the first HF amplifier stage (V101: [[de: | ||
+ | |||
+ | After that, the 500 kHz IF signal first has pass through the switchable crystal filter and then the bank of mechanical filters (with two 500 kHz IF amplifiers V301: [[de:6BA6]] and V302: [[de: | ||
+ | |||
+ | The second system of the V110 ([[de: | ||
+ | |||
+ | The mains rectifier is a [[de:5V4G]] (V115), a [[de:0A2]] (V116) acts as voltage stabilizer. | ||
+ | |||
+ | ==== Valve setup ==== | ||
+ | V001 and V002 ([[de: | ||
+ | V101 ([[de: | ||
+ | V301 ([[de: | ||
+ | V110a ([[de: | ||
+ | V115 ([[de: | ||
+ | |||
+ | ==== Development ==== | ||
+ | |||
+ | |||
+ | ==== Field use ==== | ||
+ | Most sets used by the Swiss Army have been modified with a S-meter zero knob next to the signal strength meter, so you can recognize them easily. | ||
+ | {{tablelayout? | ||
+ | |{{: | ||
+ | |Usually, You find Dekaware knobs on the Collins 51J-4 / R-388A.|Only the sets from the latest series made by Collins have been equipped with the newer S-line knobs, like in this example of a set having been used by the Swiss Army.| | ||
+ | |||
+ | ==== Variants ==== | ||
+ | |||
+ | {{gallery>: | ||
+ | ===== Manuals ===== | ||
+ | * {{ : | ||
+ | |||
+ | ==== Additional information ==== | ||
+ | * [[http:// | ||
+ | * [[https:// | ||
+ | * [[http:// |
en/e-629.txt · Zuletzt geändert: 2019/04/05 22:04 von 127.0.0.1