Joel On The Road

Me and my 100R

Okay, folks, time to afflict you non-ham radio operators with some of my radio nostalgia. This story ran in November, 1998 QST:

In the art world, when a “one of a kind” masterpiece surfaces, collectors battle for the right to possess a unique treasure. Ham radio collectors are no less frenzied. And as the author discovered, mythical, legendary and lost treasures are occasionally recovered–even by mere mortals!

By Joel Thurtell, K8PSV

It’s 1958. You’re a hotshot engineer at Zenith. Your boss gives you a longterm assignment: Design the best amateur radio receiver money can buy. What kind of radio would you build?

Central Electronics 100V, left, and 100R, right.

Wait! Zenith in the ham radio business? Sure, they made television sets and delved into military electronics. But who ever heard of them manufacturing ham radios back in the fifties?

Well, they did it, but under a different name. Their ham radio products were marketed under the Central Electronics logo. In truth, everything they sold sprung from the fertile brain of ham radio entrepreneur Wesley Schum, W9DYV or his chief engineer, Joe Batchelor, W4EGK — even the fantastic receiver that would be designed by that hotshot engineer at Zenith.

Zenith promotional photo of Central Electronics 100R

Central Electronics leaped into ham radio history in September 1952, when QST ran Schum’s ad promoting a little gray box that transmitted a then little-used mode of communication called SSSC — single sideband suppressed carrier. We now call it simply single sideband, or SSB, and everybody knows it’s the dominant mode on the amateur high frequency bands.

But in the early 1950s, single sideband was an exotic form of communication. Our standard ham receivers were not designed to demodulate single sideband signals. And for years, many ardent AM operators rejected the new mode.

Sideband transmitters in those early days were home-built. It was Schum who conceived of manufacturing a low-cost kit of parts which would give the builder a usable, low power single sideband transmitter. Schum called it the “10A,” and began shipping kits from his garage in Chicago. Schum became a missionary for sideband, traveling around the country and speaking to every ham radio club willing to give him a little time on their programs.

He recalls receiving a standing ovation from Chicago’s Hamfester’s Radio Club after he demonstrated the 10A. But the going was often rough. Doc Holt, W9VVN, remembers the Hamfester’s Club meeting differently. “The initial response of the audience was one of skepticism and even derision,” recalls Holt. “Many of my ham buddies who were steeped in the AM phone tradition called it ‘silly sideband’ or worse yet, ‘duck talk.’ ”

Bill Van Slyck with Central 100R. Zenith photo.

A few curious hams bought 10-As. They discovered that sideband signals, even barefoot 10-watt signals, could get through when AM was fading or lambasted by interference. Soon, more hams bought 10As. Schum found more garages for assembling the rigs.

Meanwhile, over in Cedar Rapids, Iowa, the head of Collins Radio Co. was listening. Art Collins was used to being king of the pile-ups with his 1,000-watt plate modulated Collins KW-1.

“A guy in Indiana was pinning Art’s ears back with reports much better than Art was getting with his KW-1 and rhombic farm,” recalls Schum. The Indiana ham was driving a pair of 811As with a Central 10A. His power output was less than the KW-1, but single sideband was more effective.

Central 200V transmitter, left, 100R, right. Joel Thurtell photo.

Collins called Schum. He wanted Schum to sell him a 10A.

Problem was, there were no factory-wired units on hand.

Schum told Collins, “If you think you have anybody out there who could put a kit together, we could sell you a kit.”

Collins’ response: “I think we could manage, Wes.”

“I found out later they didn’t read the assembly instructions and went at it in typical ham fashion and it took them a month to get it running,” recalls Schum.

A few months later, Collins called to place another order. “We’d like to buy three of them, Wes, but no more kits.”

Central 100R rear chassis view. Zenith photo.

Business was good. The 10A was followed by the improved 10B, then the 20A, a bandswitching rig, covering 160 through10 meters, with 20 watts of RF output. Central also offered accessories such as the MM-1 and MM-2 station monitoring scopes, and the Model A and Model B sideband slicers to convert older receivers to sideband reception.

Meanwhile, Schum noticed a potential competitor. In Georgia, Joe Batchelor was converting military surplus BC-696 transmitters into sideband exciters. He sold dozens of the little rigs, even though they had no name. Batchelor said Schum was worried the little 696s would compete with his 10A. So Schum invited Batchelor to join him at Central.

Central 100R below the deck. Zenith photo.

Batchelor brought a novel idea to Chicago. How about a “look, ma, no hands” transmitter? A deluxe 100-watt output all mode transmitter which required no final amplifier tuning. Batchelor eventually patented his broadband coils, which were the major innovation in the Central 100V transmitter and 600L linear amplifier. The 100V had a permeability tuned oscillator which was extremely stable and a small oscilloscope for monitoring the transmitted signal’s quality. It could transmit CW, phase modulation, double sideband with or without carrier and single sideband with or without carrier. It also would do radio teletype. It used the phasing method of generating a single sideband signal with circuitry which ensured longterm carrier and unwanted sideband suppression rivaling or surpassing that achieved by filter generators. But the big advantage of the phasing system was audio quality. The final tubes were two 6550s — highly linear audio tubes. If you liked hi-fi, you’d love the 100V.

Batchelor and Schum always wanted to produce a receiver which would match the marvelous 100V. Such a receiver would have to be like its desk mate — revolutionary.

But first, they had to deal with production problems — the complex 100V turned out to be a handful– like a talented but temperamental child.

The first Batchelor broadband couplers were inefficient. “The first 100Vs didn’t ship until late 1958,” said Schum’s good friend, Nick Tusa, K5EF. “During that time, they endured VFO problems, bad HF oscillator crystals and the continual problem getting the Batchelor couplers to a state where they were reproducible with consistent results.”

By 1958, said Schum, “We didn’t have the working capital to produce over a million dollars of backlog in orders for the 100V. We had run ourselves out of money. The (100V) buyers didn’t pay cash … Instead of getting money in hand … you got a purchase order — the dealers had my working capital!”

Schum eventually worked out a takeover with Zenith in control. New capital flowed in, the 100Vs — by then performing beautifully — were almost selling themselves. An updated model, the 200V, went on the market.

With Zenith came new talent. Now Schum and Batchelor outlined what they wanted in a receiver that would properly complement the 100V: It must have high sensitivity, selectivity, stability. It must transceive with the 100V. It must resemble the 100V.

Bill Van Slyck, W9EMB, was head of special products at Zenith. He assigned two top engineers — including Jim Clark, a former Hallicrafters receiver deisgner — and two technicians to the receiver project. “They worked several years on this thing,” recalls Van Slyck. “We spent a quarter of a million dollars when you think of all the company overhead.”

He told Clark’s team, “Build the best receiver ever built, with an emphasis on single sideband.”

It would be called the “100R.”

Clark’s engineering notes indicate a prototype was in use by 1960. Follow-up tests were conducted through 1961.

Schum took it home and played with it. “It worked well — I transceived with it one Sunday afternoon with a 200V.”

It covered the ham bands, 160 through 10 meters. The second intermediate frequency was at 50 khz with six tuned circuits for great selectivity without crystal or mechanical filters. The PTO could be owner-adjusted quite easily. It had three degrees of selectivity for AM, two each for upper and lower sideband and one position for CW. Once gain, it featured a Batchelor creation: the bifilar compressor was an RF-derived AGC system which made the front end virtually immune to strong signal overload. Together with low noise RF, mixer and IF tubes, the receiver had impressive sensitivity, better than .6 microvolt through 40 meters and less .9 microvolt on 10 meters.

Ray Osterwald reviews receivers for Electric Radio magazine. He calls the bifilar compressor “true genius.”

“It probably would be tough to overload, even with a gain antenna on 40 meters at night,” said Osterwald.

Schum recalls planning to have five more prototypes built with production and sales to begin in 1962.

Central’s transmitter sales were brisk, but a new president at Zenith decided amateur radio was not good for the corporation.

“I think they experimented with the (ham radio) market and found it wasn’t deep enough for them,” said Schum.

Late in 1961, orders from Zenith: Close Central Electronics.

Wes Schum remembers the trash bins. Central’s records — everything from design plans to sales receipts — went to the landfill.

Including parts for the next five 100-R prototypes.

The lone 100-R prototype vanished.

Years passed. Schum longed to re-establish what he calls “Central Headquarters.” He had a couple of 200-Vs, and some other Central equipment. And a friend donated a 75A-4.

Whatever happened to that lone 100R?

I run a small used ham radio equipment business. [This story was written in 1997; I no longer have the radio business — JT] Over the course of my buying and selling of old ham radio equipment, I had heard a yarn about a receiver companion to the 100V. I too longed to own it. I had owned 100Vs and 200Vs at different times, and always loved the transmitters. I would usually run a Collins 75A-4 as a receiver, but it was not a perfect match. Rumor had it that some ham had managed to acquire the 100R prototype. How many times had I sat in front of my 100V and wished for a matching receiver. It would be wonderful, but … It was a dream, that’s all.

Then one day in September 1997 my phone rang.

I sipped coffee and waited for the answering machine to take the message. “Joel, this is Bill Van Slyck in Chicago. I have a receiver you may be interested in — ”

Turns out Van Slyck bought the 100-R along with a matching speaker and 100V transmitter from Zenith as the electronics giant pulled the plug on Central. All three units had sat in his basement unused.

One hitch. Van Slyck had a little auction going. A collector from New Orleans was on his way to make an offer for the 100R.

I drove to Chicago, and there it was — the mythical 100R was real after all!

The New Orleans collector paid Van Slyck a visit, too. I figured they’d top my offer. End of story. But the next day I had a phone call. Bill Van Slyck, accepting my offer.

Another rushed trip to Chicago. Next day, I was in my shack cabling the 100R to my 100-V transmitter together. Transceive with the 100V!

And thinking. Van Slyck assured me that “there is only one,” but still, I wondered. Was there another stray 100R out there?

Who would know for sure?

I called Wes Schum.

“You got a one and only,” said Schum.

Then he hit me. My rival on the 100R deal, the “New Orleans collector” Van Slyck mentioned, was Schum’s good friend, Nick Tusa. And Schum was with him.

“I am preparing my second ham shack with a 200V, and I was looking forward to buying that receiver,” Schum said. “I wanted to get the 100R and 200V on the air at headquarters.”

He offered me a deal: Send him the 100-R on loan. He would tune it up, make detailed notes on its design and performance. Thus, after playing it, photographing it and talking about it to anyone who’d listen, I packed it up and shipped it to Wes Schum.

The 100-R is on line at headquarters and Wes has overhauled it. He even sent the PTO to Nick Tusa for repair. Now he’s comparing its performance with his Collins 75A-4, the main competition when the 100-R was conceived.

Does that venerable 75A-4 stand a chance?

Stay tuned — that’s another story.

*The staff at QST voted this piece best article in the November, 1998 magazine.

Reprinted with permission of QST