RF Cafe Software
About RF Cafe
1996 - 2016
BSEE - KB3UON
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 Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
Try Using SEARCH
to Find What You Need.
There are 1,000s of Pages Indexed on RF Cafe !
November 1929 Radio-Craft[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles from Radio-Craft.
You've heard of the World's Fairs, the most familiar probably being the 1933 Chicago World's Fair where the theme was "A Century of Progress." World's Fairs have been held in various cities worldwide since the late 1790s. In 1929, the World's Fair was held in the United Kingdom, but the "Radio World's Fair," which began its annual run in 1924 (click on stamps thumbnail), was held in New York City. Surprisingly little exists on the Internet about the events. It was more of a trade show to introduce new products than it was a fair, as can be seen from the photos. Radios with decorative wooden cabinets were becoming popular as the number of commercial broadcast stations was growing rapidly. Remote control in the day meant a handheld unit with a cable attached to the main system. Crosley introduced its first gendered radio model - the Monotrad (see photo).
Some of the New Things Displayed at Madison Square Garden
The Eveready "30" Receivers
The Eveready "Model 34" Console.
The National Carbon Co.'s line of Eveready receivers presents the same chassis, the "Model 30," in a choice of consoles. The receiver, a R.F.L. design. has variometer tuning in the antenna circuit, and six stages, using four 27s and push-pull '71s. All console models have the Eveready dynamic reproducer built in.
Silver A.C. Short-Wave "735"
Chassis of the "Round-the-World Six," a 17 to 650 meter factory assembled receiver.
This receiver is designed to take short-wave reception off the breadboard and into the parlor. Its circuit is similar to that of the D.C. "735" which is also available; the latter uses one '22 in an untuned R. F. stage, and four 12As. The A.C. model uses a '24 with its superior characteristics in the first stage, and has a '45 push-pull output. The audio channel and power unit are the same as in the "Model 722" - "Band Selector Seven". The "735" A.C. model lists at $64.90, factory assembled. without cabinet or long wave plug-in coils.
Set Tester And Checker
The Weston "Model 533" Counter Checker.
Thirteen ranges are combined in the new Weston "Model 547" Set Tester, which measures both A.C. and D.C. voltages up to 750, by means of its two selector switches. Three 3 1/4-inch meters are incorporated in the panel. The instrument, with the necessary tools and testing accessories, weighs ten pounds and fits in a carrying case 12 3/8 x 9 x 3 3/4 inches. Its net (dealer's) price is $93.75.
The counter rube checker is adapted for operation from any standard A.C. lighting circuit, with considerable tolerance of input voltages; and is designed to test quickly all the latest A.C. as well as D.C. rubes for their characteristics.
Brandes And Kolster Remote Tuners
The Brandes "Model B15," with its selector tuner above. The Kolster and Brandes receivers of this season incorporate a new method of automatically-selective tuning.
The Kolster "K-45" has no knobs or dials on the front; its dial may be seen through a small window in the top. and the tuning buttons are on the side. In addition. there is a remote-control box, led by a cable to the set, which has six buttons for as many stations, volume control, switch and pilot lights. The list price of this de luxe set is $500; other models range down to $200.
Above, the remote-control tuning box of the Kolsrer "K-45;" at the left, the automatic selector built into the set itself.
By modern house-wiring methods, any room can be equipped with a receptacle, thus allowing a convenient disposition of the tuning box wherever desired.
The Brandes brings the selector tuning system into a lower price range. This line has also four tuned circuits and '45 push-pull amplification. The "Model B-15" illustrated lists for $125.50; the line covers the field from $85 to $165.
De Forest Audions
In the line of new tubes presented by the de Forest Radio Co., an improved heater design has been incorporated to reduce the hum of the A. C. filament current. The heaters now used are made of "crolite," a new synthetic ceramic; and the filament is completely shielded from the cathode. In the 410 power tube, as in the new D.C. screen-grid audion (the 422), oxide-coated filaments are used to give longer life than with the thoriared-tungsten commonly used. In the new 424, the A. C. screen-grid audion, other characteristics have been retained, but the grid bias has been doubled.
The Crosley "Monotrad" in a table-type metal cabinet, designed to take the speaker as shown or on top.
In the Crosley line of mass-production price receivers, the newest arrival is the Monotrad, a seven-tube A.C. screen-grid receiver, listing at $62 without accessories. Its chassis, illustrated below, has the new Crosley triple-range control, a completely-shielded gang condenser carbon-type amplification control and Mershon condenser. It is intended for use in any of the many cabinets designed for the Crosley line.
The chassis of the Crosley "Monotrad."
Majestic Receiver Models
The post-colonial console design of the "Model 181."
The Majestic line incorporates, in its "Models 91 and 92," the latest type of power detection. These receivers, with built-in super-dynamic reproducers, list at $137.50 and $167.50.
The "Model 181," illustrated above, is a striking accomplishment in cabinet work, and reproduces either radio or phonograph records through a '50 push-pull amplifier. List, $316.50.
Zenith Remote-Tuner System
The Zenith "50 Screen-Grid" Chassis (above) and Automatic Tuner (below, right).
The newest Zenith designs Incorporate the "Model 50" chassis, with its five tuned R.F. circuits, and two push-pull audio stages, with '45 output. All embody the Zenith automatic tuning system, to which has just been added (in the "Model 55") the remote tuner illustrated. This operates at the turn of a button, its pilot light automatically indicating the station which is on; and gives also volume control. The set operates a 12·inch dynamic reproducer. The "Model 55" is priced at $700 in its Italian Renaissance cabinet; others down to $175.
Champion Radio Tubes
A new method of merchandising of interest to buyers, as well as sellers, is utilized in the packing of Champion tubes. Not only is there the new system of packing the complete tube equipment for a given receiver in one carton; but the individual tube is in a stout container of a design which permits a demonstration test of its characteristics without removing it or breaking the seal by means of a test adapter furnished by the manufacturers.
Hammarlund Amplifying Units and Transformers
The Harnmarlund Manufacturing Co. has just added to its extensive list of radio components several important units; among them a three-stage R.F. band-selector, known as "BS-3," to work ahead of an amplifier; a three-stage screen-grid R.F. amplifier, "RF-3," to follow the former; a shielded, polarized R.F. choke, SPC, and a family of audio-frequency transformers.
The band filter comprises a three-gang "Midline" condenser and matched filter coils; this affords pure 10-kc. selectivity ahead of the amplification. The amplifier also contains a three-gang condenser and matched, shielded coils. Both units are factory assembled and sealed.
In front, the "Battleship" condenser of the band filter; behind it, the coils in their shields.
The first-stage A.F. transformer, "AF-2," has a ratio of 1 1/2-1; the push-pull input type, "AF·4," 2-1 on each side. Both have very large primaries, and cores of special-alloy laminations to insure a flat characteristic. The output transformer types are "AF-M" for magnetic reproducers and "AF-D" for dynamics.
A complete power supply unit, "PS-45," is designed to operate a receiver with push-pull '45 amplification. It comprises two heavy chokes and a power transformer with primary tapped at 80 volts for use with an automatic voltage regulator. The high-voltage secondary is a center-tapped 750-volt winding with a rating of 100 milliamperes; and there are a 5·volt and two 2 1/2·volt windings. The new voltage divider is "RHQ-30" and the condenser block "CHQ-30."
The new A.F. transformer in its steel housing for sub-base mounting.
Jewell "581" Test Panel
The Jewell Electrical Instrument Co. has designed a laboratory panel, suitable for shop or jobber's use, to facilitate complete testing of receivers and other radio apparatus in the shortest time. It is furnished with high-resistance precision meters and gives in addition to tube readings, condenser capacities and high-voltage secondary readings. Dealer's price $159; with work bench, $208.87.
Readings of the seven large (5 inch) meters of the Jewell Test Panel are visible at a glance. It is a time-saver; and time is money, even in the radio business. There is a tube socket at the lower right for testing rubes apart from a set.
"General" Wood Cabinets
The increasing vogue of individuality, in cabinets to take standard receiver chasses, has promoted the production of many very artistic designs. The Wood Cabinet Corporation presents a line, of which the "Model 108" is illustrated; it is designed to accommodate any popular set, with speaker above.
An attractive and somewhat modernistic piece of cabinet work.
Best Electric Motor Chassis
The "BBL" electric motor, designed for small-cone reproducers, incorporates a tapped winding with a switch, which matches the output impedance of the receiver without resorting to a special transformer, as well as a separate volume control. It is now available in a separate cabinet, at $35 list, as well as in chassis form at $22.50.
The magnetic reproducer unit of the "BBL" motor will drive a 12-inch fixed-edge diaphragm.
1933 Chicago World's Fair: "A Century of Progress"
Posted November 6, 2014