Details about COLLINS 51J-4 General Coverage Communications ReceiverSee original listing
Jul 25, 2013
[ 16 bids ]
San Diego, California, United States
Used: An item that has been used previously. The item may have some signs of cosmetic wear, but is fully ... Read moreabout the condition
Collins 51J-4 Communications ReceiverGENERAL - Collins 51J-4 Receiver (RACK MOUNT) is a complete coverage superheterodyne receiver capable of AM and CW reception in the frequency range of 0.5 to 30.5 megacycles. The set covers the tuning range in 30 bands, each band one megahertz wide. Three stages of intermediate- frequency amplification and a crystal filter produce the desired degree of selectivity. The receiver also features a low impedance AVC, a good noise limiter, two stages of audio amplification and a 100 kHz frequency calibrator. The receiver employs dual conversion on most bands and single or triple on others in order to obtain full coverage economically with a minimum of image and other spurious responses on all bands. Band 1, 0.5 to 1.5 MHz uses triple conversion, bands 2 and 3, 1.5 to 3.5 MHz, use single conversion, and bands 4 to 30, 3.5 to 30.5 MHz, use dual conversion. Each band is numbered on the band's center frequency. For instance, band 1 covers 0.5 to 1.5 MHz, band 2 covers 1.5 to 2.5 MHz, and so on.
OPERATING RANGE ......... 540 kc to 30.5 MHz
TYPE OF RECEPTION ....... AM, CW or MCW
CALIBRATION ............. Direct reading in Megahertz and Kilohertz
TUNING .................. Linear tuning with uniform bandspreadFREQUENCY STABILITY ..... Dial calibration at room temperature is within 300 cps if the nearest 100 kc calibration point is used to adjust the fiducial.
TEMPERATURE RANGE ....... -20øC to +60øC
SENSITIVITY ............. Band 1 - Less than 15 uv gives 10 db s/n Bands 2 to 30 - Less than 5 uv gives 10 db s/n
SELECTIVITY ............. 1kc, 3kc, 6kc
SPURIOUS FREQ RESPONSE .. Down at least 40 db
AUTOMATIC VOLUME CONTROL Less than 8 db increase in audio power output with an increase in r-f signal from 5 to 500, 000 uvS-METER ................. Meter calibrated in 20, 40, 60 db above AVC threshold and -10 to +6 db audio level with 6 mw as reference
NOISE LIMITER .......... Series type ahead of the first audio stage
AUDIO POWER OUTPUT ..... Band 1 - at least 0. 5 watt for 15 uv signal Bands 2 to 30 - at least 0. 5 watt for 5 uv signal
AUDIO FREQUENCY RESPONSE +/-3 db from 200 to 2500 cps
AUDIO DISTORTION ....... Less than 10 percent at 0. 5 watt output
AUDIO OUTPUT IMPEDANCE . 4 and 600 ohms
I-F OUTPUT IMPEDANCE ... 50 ohms
R-F INPUT IMPEDANCE .... Designed to operate into a high impedance whip or single-ended antenna
POWER REQUIREMENTS ..... 85 watts at 115 volts 45/70 cps. Same power required when reconnected for 230 volt 45/70 cps operation
DIMENSIONS ............. Panel - 10-1/2 inches high, 19 inches wide, notches for standard rack mounting
WEIGHT ................. 43 pounds
This receiver, S/N 4779 was restored by Howard Mills, W3HM Radio Labs in 2001. The following was performed:
.Clean chassis, gears, slug rack, and cams.Polish all IF cans, PTO cylinder, BFO can, crystal-phasing cover, knobs, handles, escutcheon, and meter case
.Wire brush all tube shields and other corroded metal parts
.Replace 2 conductor AC line cord with 3 conductor cord
.Disassemble PTO, lubricate, clean, set end points
.Clean and lubricate gear train and rack slots with Teflon
.Test and Replace all weak/bad tubes
.Re-whiten all lettering and index lines
.Clean and lubricate all controls and switches with DeOxit
.Completely align receiver per Collins instruction manual
.INSTALL PRODUCT DETECTOR AND IMPROVED AVC MODIFICATION
I have tested every single band with signal generator. The receiver works very well and is in good condition (see pictures). Volume control is a little scratchy sometimes – probably needs a shot of DeOxit.
Included will be the 51J-4 receiver – S/N 4779, Original Collins 51J-4 Instruction Manual and Howard Mills, W3HM 51J-4 Receiver Restoration documentation for S/N 4779, dated February 2001.
I pack very well. I will ship and insure free of charge in the Continental USA. Split costs for shipments to Hawaii, Alaska and Puerto Rico. Would rather not ship international.