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A Century of Amateur Radio and the ARRL:

from The ARRL Letter on June 12, 2014
Website: http://www.arrl.org/
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A Century of Amateur Radio and the ARRL:

Let's continue our stroll through ham radio in the early 1950s.

TVI was the major technical problem facing radio amateurs during the 1950s, and the ARRL led the fight. Articles appeared in QST, authored by George Grammer, W1DF; Phil Rand, W1DBM; and others. The League worked with TV manufacturers to reduce TVI problems in future TV designs. Hams started using low-pass filters at the output of their HF transmitters, and band-pass filters at the output of their VHF and UHF transmitters. Yet the TVI problem persisted for many years.

In addition to TVI, there was ITV -- interference from TV receivers, caused by strong radiation from the horizontal oscillators at 15.734 kHz and multiples thereof, well into the HF range. As you tuned across a lower HF band, there would be raspy "markers" every 15.7 kHz.

In the early 1950s, a few hams started working with amateur television (ATV), building complex equipment to generate NTSC video signals. They were successful, but usually there were only a few stations near enough to make contact -- sometimes only one other ATV-active ham. Although it was an excellent technical accomplishment, ATV never caught on in a big way in the 1950s.

Military surplus equipment and its conversion to amateur use continued to be of considerable interest, with articles in QST detailing how such conversions could be made. New vacuum tubes that had been developed for military use during the WW II years found great utility in ham equipment, particularly the tubes developed for high-power HF and VHF/UHF transmitters.

These surplus tubes were very inexpensive. One popular one was the 1625, the 12 V filament equivalent of the 807, a workhorse tube that was good for 75 W or so. They sold for 25 each, or four for $1. The 813 was another popular tube for higher power, A pair could run 500 W input.

The ARRL continued the push to get more hams on the VHF/UHF bands. Ed Tilton, W1HDQ, wrote many articles about the VHF/UHF equipment he designed and built, including a 2 meter station for Novices. QST began publishing a box listing of states worked on 50 MHz (with maximum path lengths noted), and the first 50 MHz Worked All States (WAS) awards (48 states back then) were earned.

A new idea -- voice-operated transmit (VOX) -- appeared in the early 1950s, so phone operators could chat back and forth quickly, rather than taking turns transmitting long monologues. A few AM operators used VOX, but the idea was quickly put into use by SSB enthusiasts. The earliest VOX switches required the operator to use headphones, so the VOX would not be triggered by the receiver audio, but anti-VOX circuits were soon published in QST that would allow use of the station speaker.

Next week: A continuing look at Amateur Radio and its advances in the early 1950s. -- Al Brogdon, W1AB

Source:

The ARRL Letter

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