RF Cafe Software
About RF Cafe
1996 - 2022
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 ...
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January 1939 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.
I have been scanning and posting Radio Service Data Sheets like this one featuring the ERLA Model 4500, dual-wave, T.R.F., 4-tube, A.C. receiver for many years now. There are still many people who restore and service these vintage radios, and often it can be difficult or impossible to find schematics and/or tuning information. I usually attempt to find somewhere on the Internet of an actual existing example of the radios, but could not for the ERLA Model 4500.
Band-Selector Switch: This receiver is designed for operation on two different frequency bands. The frequency ranges of these bands are : 1,720 to 540 kc., and 4,200 to 1,500 kc. Selection of the desired frequency band is made with the band-selector switch knob which is located on the lower right-front of the cabinet. When the band-selector switch is placed in the maximum left-hand position the receiver is operating on the 4,500 to 1,500 kc. band. For operation on the 1,720 to 540 kc. band place the band-selector switch knob in the maximum- right-hand position. To Align the Variable Condenser: It is important when aligning to follow the procedure carefully, otherwise the receiver will lack sensitivity and the dial calibration will be incorrect. (1) Connect the high output side of the oscillator to the receiver antenna lead and the ground to the chassis. (2) Place the band-selector switch for operation on the broadcast band; tune the receiver to exactly 1,400 kc. on the dial and set the service oscillator frequency to 1,400 kc. Then bring in the 1,400 kc. signal to maximum output by adjusting the trimmer condensers located on top of the gang condensers. Note: Generally the rear gang condenser section trimmer bas to be adjusted to minimum capacity.
Posted February 2, 2017
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 185 Radio Service Data Sheets as of April 12, 2017.