Amateurs Turn Back the Clock on Television Technology

The GB2KZ commemorative test pattern, as received in New York by the Antique Wireless Association's museum curator Ed Gable, K2MP. [AWA Photo]

NEWINGTON, CT, Mar 27, 2003--This amateur television story perhaps should carry a small-print warning at the bottom of the screen reading, "Professional operator. Do not attempt!" On February 8, 1928, John Logie Baird--a recognized leader in TV development--used an electromechanical system to transmit a 30-line TV signal on HF to an amateur, Robert Hart, 2CVJ, in Hartsdale, New York. Earlier this year, Amateur Radio operators in the UK and the US celebrated the 75th Anniversary of that inaugural transatlantic TV transmission by recreating the event on 15 meters.

"We did six days of on-air testing over a four-week period, lasting about two hours a day," reports Antique Wireless Association Museum Curator Ed Gable, K2MP. The AWA Museum (W2AN), in Bloomfield, New York, was on the receiving end of the transatlantic circuit. "Two of the days there was zero propagation. Another day wasn't much better, but I received signals that could be displayed on a scope, but could not resolve any pictures."

Behind this year's effort to recreate Baird's accomplishment was the Narrowband Television Association (NBTV), made up largely of hams in the UK.

Don't let the "narrowband" part throw you. While the necessary full-carrier AM signal for 30-line resolution TV is 12 kHz wide, that's considerably slimmer than the several MHz or so signals today's TV stations transmit (obtaining hundreds of lines of resolution). Even so, this kind of experimenting is not for the faint-of-heart, and taking up 12 kHz on a busy 15-meter band might not pass muster with current FCC rules--see §97.307(a)--although, like 30-line TV, that's not entirely clear. As one FCC official put it, it's not recommended but not necessarily illegal. The UK's Radiocommunications Agency apparently had no qualms, however.

Peter, G4JNU, Vic, G3SDQ, and Ted, G3GMZ, of the Narrowband TV group on the UK transmitting end of the transatlantic commemorative test. The cartoon-character head atop the monitor was dubbed "Stooky Bill." [NBTV Photo]

Gable says that on February 6, the right combination of circumstances came together. The QRM melted away, the selective fading disappeared and the signal peaked above S9. "We had good conditions and got very good pictures," he said. "That was probably the best day." On the actual anniversary weekend, propagation was good, but, Gable said, QRM from a European operating event often meant there were several SSB signals in the TV signal passband at any given time--"an intolerable situation," as he characterized it. Gable said that, on average, it took 30 minutes of transmit time to get 30 seconds of good picture.

Gable's observations resonate curiously with those penned in 1928 by "The Old Man"--ARRL cofounder Hiram Percy Maxim, W1AW. Maxim described his own initial experience with "low-scan" TV in a commentary "Rotten Television," which appeared in the January 1929 issue of QST. "For about a half a second, actually, I had the picture," The Old Man wrote in his inimitable style. "It was a rotten picture. It flickered and it was fuzzy and foggy, and about the time I was wondering how and why they picked on a cow to televise, it suddenly dawned on me that it was a man's face I was looking at."

Inside the GB2KZ shack, which included a modified Yaesu FT-101E transceiver (in front of chair) to drive the linear and a 625-line PAL camera with a 625-to-30 line converter. The 30-line monitor and camera are near the end of the table, next to the camera. [NBTV Photo]

For their commemorative transmission, the NBTV folks replicated Baird's original contraption--which he called a "televisor." It consisted of a spinning disk with 30 offset holes around the perimeter. With the disk spinning rapidly in front of a flat-panel neon gas tube, it creates a 30-line raster. The neon tube's soft orange glow was modulated in intensity (black to full orange) by the receiver's audio output. "Now, turn that neon light source on and off in sync with an identical spinning disk in front of a photocell at the transmitter, and you have a crude but functional 30-line TV," Gable explains. Synchronization typically was accomplished using a simple rheostat in series with the motor.

Since the flat-panel neon tubes today are rare and valuable, the modern-day replication substituted orange LED arrays, that, Gable said, simulate the tube very well.

Searching for another New York amateur station to be on the US side, the NBTV group located the AWA Museum and Gable, who describes himself as its "very willing and enthusiastic" curator. Gable received equipment from England. He also modified a Kenwood R-1000 receiver so it exhibited flat audio response over 12 kHz.

On the UK side, the NBTV group had constructed a TV transmitter that could put out 400 W of wideband AM. It was crystal-controlled on 21.310 MHz. The NBTV group celebrated the anniversary date with events at UK's Amberley Museum with Baird family members and former Baird employees among those in attendance.

The GB2KZ signal display showing the test pattern. Sitting atop the display is the 625-to-30-line converter box. [NBTV Photo]

"The [receiving] equipment was capable of producing very usable pictures but needed very good signals--something difficult to achieve on the crowded 15-meter band with a required 12-kHz bandwidth," Gable said. When the gods smiled down on this enterprise, Gable was able to receive the 30-line signal from the UK.

Back in 1928, The Old Man was anything but pleased at the nascent technology. "Why don't they mention that the definition is rotten in the little pictures and many times worse in the ones where you use a magnifying glass to get them bigger?" he grumbled.

"And why don't they explain that the only way we can get bigger pictures and better definition is by using enough modulation on the carrier to take up half the broadcast band," he went on, "and that even if we had transmitters to send such stuff and receivers to receive it--which we haven't--the Federal Radio Commission would let anybody have that much of the ether?"

A wider view of the receiving end at the AWA Museum in New York showing the modified Kenwood R-1000 receiver and the "televisor"-- a mechanical disk scanner and magnifying apparatus. The orange LED array is just visible on the disk's right-hand edge. [AWA Photo]

On August 3, 1928, the Federal Radio Commission--the forerunner of today's FCC--did authorize amateurs to transmit television pictures in the 160 and 5-meter bands.

Gable says the obvious limitations of the early electromechanical TV experiments were the reason no commercial transatlantic TV service ever was established. The 30-line electromechanical TV service did meet with some success in Europe, however.

Gable recounts that Baird tried again in 1929 with transmissions from Berlin to London with better success, but no commercial venture resulted. "We know that there was regular mechanical TV service in the 1927/30 era in England, Russia, France, Germany and the US and perhaps others," Gable said.

As for The Old Man, he predicted--quite accurately as it turns out--that "a new system will have to be developed for all this, and that some smart aleck will develop it." TV in the late 1920s, he concluded, was the stuff of experimentation "for those who are willing to plug hard and expect very little in the way of immediate results."

One must wonder what Maxim would have made of high-definition TV, which, we're told, is right around the corner. For his part, The Old Man wasn't impressed. He decided to give up on TV and go back to 20 meters to "see what the little dots and dashes are saying."