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July 1967 Electronics World
Table
of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
from
Electronics World, published May 1959
- December 1971. All copyrights hereby acknowledged.
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This "Mac's Service Shop"
column, which appeared in a 1967 issue of Electronics World magazine, captures
amateur radio's pivotal shift toward solid-state technology. The discussion between
shop owner Mac McGregor and technician cum Ham radio operator Barney Jameson highlights
how semiconductors enabled radical size and weight reductions in equipment, transitioning
bulky tube-based kilowatt stations into compact tabletop units. SSB transmission
and silicon diodes provided key efficiency gains, though transistors still faced
limitations in high-power transmitter applications due to cost and availability
constraints. The article anticipates future advancements through FETs and integrated
circuits that would improve signal handling and enable truly portable operation.
Notably, they acknowledge Japan's emerging dominance in electronics manufacturing
and suggests ham radio participation correlates with national technological capability.
The piece ultimately portrays solid-state devices as catalysts for experimentation
and home construction, predicting continued miniaturization and reliability improvements
that would transform amateur radio operations.
Mac's Service Shop: Ham Radio and Semiconductors
 By John T. Frye
Solid-state devices have materially changed amateur radio equipment, and even
greater improvements appear imminent.
When thunder from the July storm started to roll, Mac and Barney grounded the
antennas, opened the service bench switches, and started for the front office to
comfort Matilda, the office girl, who was deathly afraid of thunder and lightning.
Just as they stepped through the door there was a blinding flash of light followed
almost immediately by a snapping sound and a great bellow of thunder.
"To quote Thomas Hardy: 'How can such a heavenly light be the parent of such
a diabolical sound?' "Matilda asked with a nervous giggle. "Why don't you two talk
about electronics? That always quiets my nerves. In fact, it usually bores me so
much sleep comes as a defense mechanism."
"Always glad to oblige a lady," Barney replied, perching himself on a corner
of her desk. "Mac, I've been wanting to talk to you about the love affair hams have
with semiconductors. Right from the beginning, those two have gone together like
guitars and folksingers, and you don't need a crystal ball to see a lot more conventional
and exotic semiconductors in the future of ham radio."
"It's not hard to understand why hams would take to solid-state diodes and transistors,"
Mac mused. "For one thing, the tiny size of these devices goes along with the modern
trend toward more compact and lighter amateur radio gear. I can remember a few years
back when a kilowatt ham transmitter was a truly impressive affair, occupying two
six-foot racks and weighing upwards of half a ton. But the days when a ham could
take over a spare upstairs bedroom or the basement for his ham shack are going fast.
The average small, functional, modern house doesn't have a spare bedroom; and if
there is a basement, it's likely serving as a playroom or bar. Today's ham has to
make do with a corner of the living room, den, bedroom, or even the kitchen. To
meet his needs, the modern kilowatt radio station has been compressed until it fits
neatly on a table top and weighs less than a hundred pounds."
"You're right, of course, but it's only fair to say that the switch from AM to
SSB transmission accounts for much of this saving in weight and size. In that kilowatt
AM station you were talking about, one of those six-foot racks held speech amplifier
and modulator equipment, together with the husky power supply needed for the latter.
Getting rid of the modulator cut the size of the transmitter in half. Since an SSB
transmitter need not supply a power-consuming carrier, it imposes much less demand
on the power supply. Current peaks drawn under modulation are of very short duration
so that the average demand on the power supply, even when the transmitter is inputting
2 kW p.e.p., is modest."
"I know," Mac said. "I never cease to marvel at how those table-top linears can
get around 3000 volts out of a transformer only slightly larger than the power transformer
for a color TV receiver. Of course, I know it's done by using voltage-doubling circuits
employing series-connected silicon rectifiers. You certainly couldn't do it if you
had to use mercury vapor 866's for rectifiers. Their filament transformer alone
would take up more space than all the silicon diodes and would weigh a whopping
lot more."
"Silicon and germanium diodes replace bulky tubes lots of other places in SSB
transmitters and receivers," Barney said. "They are used as audio rectifiers in
the vox and anti-trip circuits and in the balanced modulators that suppress the
carrier, and as r.f. rectifiers in the automatic level-control circuits that limit
drive to the linear amplifiers so as not to exceed what the amplifier can handle
in a linear fashion. A diode rectifies a sample of the r.f. output and feeds it
to a milliammeter to provide an r.f. output indicator. Other diodes provide a.g.c.
voltage for the receiver or transceiver. Zener diodes provide voltage regulation
of critical low voltages in the vox and other circuits."
"How about transistors? Are hams making much use of them ?"
"So far, they have used transistors chiefly outside the station receiver and
transmitter. The first uses were for code practice oscillators and mike preamplifiers,
including speech clipping and limiting circuits. But lots of hams have been experimenting
with flea-power transistorized transmitters and with transistorized communications
receivers. As far as completely transistorized transmitters are concerned, the chief
stumbling block has been a lack of reasonably priced transistors that can efficiently
handle a couple of hundred watts input up to 30 MHz. I know there are transistors
that can do this, but they are not available to hams, at least not at a price they
can afford. While I keep hearing rumors about other solid-state transceivers on
the drawing boards, as far as I know there is only one amateur-band transceiver
on the market that is completely transistorized - except for the final amplifier
tubes."
"Well, how about receivers? We have plenty of transistors that can handle any
power requirements there."
"True, but again there are drawbacks - or have been until very recently. The
ordinary transistor is essentially a small-signal device. When one is used in the
r.f. stage of a communications receiver, it will do a fine job of amplifying weak
signals until a nearby ham fires up a full gallon on the same band. Then his signal
overloads the input of the transistor with resulting cross-modulation that does
an excellent job of swamping out the weak station. If that weak station happens
to be a rare ZA in Albania or a YI in Iraq, the ham is likely to be very disturbed
- to put it mildly!"
"I suppose you're thinking about the FET and its ability to handle both strong
and weak signals as the answer to this problem."
"Right you are, and I see no reason why an excellent, fully transistorized amateur
receiver cannot be built right now. It would have many advantages, including such
things as small size, light weight, practically no generation of heat, indefinite
transistor life as opposed to comparatively short-lived tubes, resistance to shock
and vibration, and simple power supply requirements that could be easily and economically
met by batteries for mobile or portable operation."
"Well, I'll hazard a guess that if U.S. manufacturers don't get on the stick
and come out with something like this at a reasonable price soon, they will be scooped
by the Japanese."
"You can say that again. I think the Japanese are beginning to eye the ham market
the way they did the CB market, and are both know what they did there in the way
of transistorized transceivers. Quite recently, I've run across several DX stations
who say they are using Japanese-made ham equipment. One thing is sure: the number
of Japanese amateurs is increasing rapidly. It used to be you had to listen long
and hard to hear a JA station, but now just about any time I point my beans northwest
I hear Nippon stations coming ill On ten, fifteen, or twenty meters - and with darned
good signals, too. Some of the fellows on the islands out ill the Pacific complain
that the Japanese are beginning to swamp them out the way U.S. hams monopolize the
bands in this hemisphere."
"These things sound like straws in the wind to me," Mac said. "We have long produced
most of the manufactured ham equipment, probably because the great majority of the
world's radio amateurs are located in this country. In no other country has the
home ham market been large enough to warrant the research and development necessary
for producing this highly specialized equipment. Now, with the ham populations of
other countries on the rise and with Americans' ready acceptance of imported electronic
equipment, this may be changed."
"Hey, that brings up an interesting chat I had with a ham in The Netherlands
the other morning. He suggested dart the number of active hams ill a country compared
to its total population was a good index of that country's electronics know-how
and its ability to produce electronic gear. He pointed out the high percentage of
hams in England, West Germany, Japan, and the United States as examples."
"He may have something there. We both know that the electronics industry has
always displayed an interest in amateur radio that goes beyond that segments being
an important market for electronic products. Take a look at the applications section
of any diode, transistor, grid-controlled rectifier, or integrated circuit manual,
and you will find several strictly ham suggestions. And hams return the compliment.
Practically every one of their magazines has a regular semiconductor column, or
something similar, in which new semiconductor devices are introduced or circuits
involving semiconductors are described. In addition, ham magazines often carry full-length
feature articles describing the use of semiconductors in ham gear written by top
men involved in the production, research, and development of solid state devices.
This is not surprising, considering how many of these people have ham radio for
a hobby."
"That brings up an important feature of solid state devices. They lend themselves
to experimenting, home construction, and kit construction. Transistorized gear is
almost invariably assembled on a printed circuit or Vector board. You don't need
a machine shop to bend chassis, punch socket holes, or cut out heavy metal areas
as you ordinarily do when building equipment using tulles. What's more, since distributed
capacitances are easily duplicated with this type of construction, you can build
a piece of equipment from an article and expect equivalent performance. The use
of IC's is going to make this even more true. No wonder hams who like to build and
experiment are in love with transistors!"
"Okay; let's not get carried away. How do you picture transistorized ham equipment
of the future?"
"Well, there's a limit to how much you can reduce the panel area of a ham transceiver.
No matter how small the components behind that panel, you still need room to mount
all the controls, jacks, dials, and meters necessary for operation. The panel of
my present transceiver carries fifteen of these components. Since many controls
require a comparatively close adjustment, the knobs cannot be made too small. The
tuning dial, for instance, has to be large enough for fine adjustment and for comfortable
operation hour after hour. The meter and frequency indication must be large enough
for easy reading. So 1 see the ham transceiver of the near future as not much smaller
in height and width but greatly reduced in depth.
"The use of FET's and IC's will produce better, more sophisticated, more trouble-free
equipment. The lower voltages required by transistors and their lack of heat generation
will greatly reduce component failure. Mobile operation, already stimulated by SSB,
will increase even more when solid state transceivers with their low current requirements
are in widespread use. We may still have to use compact ceramic-type tubes in high-
powered linears, but medium-power transmitters and exciters will be fully transistorized
and will take up touch less space than today's equipment ---"
His voice trailed off as he nodded to Matilda, sound asleep with her head resting
on her folded arms on her desk, oblivious to the intermittent growls of thunder
from the retreating storm. "I thought she was kidding!" he said in a hoarse whisper
to Mac.
Mac's Radio Service Shop Episodes on RF Cafe
This series of instructive
technodrama™
stories was the brainchild of none other than John T. Frye, creator of the
Carl and Jerry series that ran in
Popular Electronics for many years. "Mac's Radio Service Shop" began life
in April 1948 in Radio News
magazine (which later became Radio & Television News, then
Electronics
World), and changed its name to simply "Mac's Service Shop" until the final
episode was published in a 1977
Popular Electronics magazine. "Mac" is electronics repair shop owner Mac
McGregor, and Barney Jameson his his eager, if not somewhat naive, technician assistant.
"Lessons" are taught in story format with dialogs between Mac and Barney.
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