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Radio Data Sheet 344 National Union "Presentation" Radio Model G-619
February 1947 Radio-Craft

February 1947 Radio-Craft

February 1947 Radio Craft Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

National Union "Presentation" Radio Model G-619 (the Radio Attic) - RF CafeNational Union Radio Corporation, located in Orange, New Jersey, had been producing radios since its formation in 1929 when this Radio Service Data Sheet for its Model G-619 "Presentation" tabletop set appeared in a 1947 issue of Radio-Craft magazine. That they survived the Great Depression which began in the year of their founding is a testament the tenacity of its management, design staff, and production workers. This 5-tube radio had a very nice mahogany case with a unique reverse-lettering dial glass plate. A few years ago I posted an advertisement by Union Radio from a 1945 issue of Radio-Craft appealing specifically to women engineers and technicians because of the severe shortage of men available while serving in the armed forces during World War II.

Radio Data Sheet 344 National Union "Presentation" Radio Model G-619

Radio Data Sheet 344 National Union "Presentation" Radio Model G-619 , February 1947 Radio-Craft - RF CafeCircuit:

Superheterodyne - Tuned r.f. stage - a.v.c

Tuning:

Broadcast Band

Power Supply:

105-125 volts, 60 cycles

105-125 volts, direct current

Approx. 30 watts consumption

Preliminary

(a) Adjust the DIAL POINTER along the dial cord to the position opposite the first right-hand punch mark on the dial backing-plate, with the tuning condenser gang completely out of mesh (Minimum Capacity); (b) Set VOLUME CONTROL to the FULL ON position; (c) Maintain SIGNAL GENERATOR output at MINIMUM consistent with a readable Output Meter indication; (d) OUTPUT METER across voice coil; (e) Follow sequence indicated below.

Service Notes

Hum Modulation:

On Early Production runs Condenser C-18 consisted of two .05 uf units. One ground terminal was connected to CHASSIS, the other to B-. Disconnect the CHASSIS terminal of the .05 Condenser now connected to Pin No. 1 of the 12SA7GT tube and connect this lead to Pin No. 5 of either of the 12SK7GTs or to any other convenient B-point. This effectively bypasses the a.c. modulation hum to B- instead of to chassis.

Oscillation:

Remove one side of Resistor R-2 (in grid circuit of 12SA7GT) now connected to a.v.c. bus and reconnect to cathode No.5 pin 1 of i.f. -12SK7GT

Reinstalling Chassis (After Alignment):

(a) With chassis still on the bench, set dial pointer at the minimum capacity end of travel.

(b) Slide chassis into cabinet and adjust its position so that the dial pointer is opposite and in line with the FIRST calibration mark at the right-hand end of the GLASS DIAL SCALE.

(c) Tighten the chassis hold down screws.

(d) Tuning should now track so that peak signal is attained at the proper frequency calibration on the glass dial scale.

Radio Service Data Sheets

These schematics, tuning instructions, and other data are reproduced from my collection of vintage radio and electronics magazines. As back in the era, similar schematic and service info was available for purchase from sources such as SAMS Photofacts, but these printings were a no-cost bonus for readers. There are 227 Radio Service Data Sheets as of December 28, 2020.

 

 

Posted November 27, 2020
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RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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