Students learning Morse code have had a
variety of commercially made practice instruments available to them
over the years to assist in their studies. Such devices included purely
mechanical sounders that simulated the audio of a working sounder (fig.
1), inexpensively made sounder/key combination sets identical in
function to the more robust instruments for commercial use, a variety
of perforated tape devices such as the Instructograph, Teleplex, AA
Transmitter, and others, a rotating painted cylinder device called the
‘Natrometer’ (fig. 2
), as well as a variety of 78
RPM and later 33 RPM
records and tapes.
Fig. 1: “No. 1 Mechanical Telegraph Instrument” is
the name for this
device in the 1912 J.H. Bunnell catalogue. Bunnell made another variety
of mechanical sounder, and a number of other manufacturers also made
such purely mechanical instruments including Manhattan Electrical
Supply Company, and British companies.
Fig. 2: Natrometer. A clock motor drives a rotating
painted in dielectric (insulating) paint. The unpainted surface is in
the shape of continental code characters. A stylus in contact
with the surface of the drum automatically travels from one line of
Morse code to the next higher line and then back down the lines of code.
Current generation Morse code practice instruments employ
microprocessorcontrolled random character generators capable of almost
any sending speed. PC based software programs for learning Morse
code are also widely available. Among the most unusual Morse code
practice devices were those manufactured by The Omnigraph Manufacturing
Company in New York City between 1900 (1
) and 1931 (2
). As best as can
be determined, the Omnigraph company never produced anything other than
Morse code practice devices, and did not produce commercial devices
such as telegraph keys or sounders of any sort. Omnigraph
advertisements were featured in numerous telegraph, radio and
electrical publications of the day including QST, The Wireless Age,
Modern Electrics, The Electrical Experimenter, Journal of the
Telegraph, Radio, Electrician and Mechanic and probably others (3
Omnigraphs were also marketed by major retailers of the day including
Sears and Roebuck, J. H. Bunnell, Manhattan Electric Supply Company
(‘MESCO’), and Wholesale Radio Service Company (New York City).
The factory occupied several different New York City addresses over the
30+ year span of the company existence, judging from the addresses
listed in the numerous advertisements during this time period.
The 1914 and 1919 U.S. Department of Commerce rulebooks stated that
commercial and amateur radio license examinees undergo a code test
that: “shall consist of messages with call letters and regular
preambles, conventional signals and abbreviations, and shall in no case
consist of simple, connected reading matter. The test will be conducted
by means of the Omnigraph or other automatic instrument wherever
)”. The demise of the company and
instruments was undoubtedly related in part to the superior
capabilities, versatility, and reliability of perforated tape devices
such as the Instructograph. As dazzling as Omnigraphs were to watch in
use, they were finicky and temperamental instruments to use. The
multi-disc Omnigraph devices (see below) although ingenius in design,
allowed for, at best, pseudo-random code generation, limiting overall
utility. Although company advertisements boasted a 45 minute running
time on a single winding, a properly functioning and adjusted
instrument would begin to slow noticeably after about 20 minutes
running time (5
The company manufactured a number of instruments of varying complexity,
all of which had rotating aluminum discs with Morse code characters
incised into the edges of the discs as raised teeth. As the disc
rotated, a tracking stylus in contact with the teeth was displaced by
the raised teeth, and allowed an electrical contact to make and break a
circuit, producing the Morse code characters. The instruments varied
only in whether the discs turned by use of a hand crank or were
motor-driven, and in the numbers of discs that could be stacked,
necessitating a cam mechanism which raised and lowered the tracking
stylus in the multi-disc models. Some instruments included keys,
sounders, or buzzers integral to the devices, although the company also
sold ‘stand-alone’ sounders, buzzers, batteries, and hookup wire
produced by other manufacturers as accompaniments to their instruments.
A student could purchase the Omnigraph instrument alone, however for a
few dollars more, the student could obtain a package that
included a learner’s manual, a battery, a sounder or buzzer, some wire,
and a straight key. Although the company advertisements described
5 models of Omnigraphs, (Table 1
), in reality, at
least 15 distinct
instruments were advertised or produced over the years.
TABLE 1: Omnigraph Company Instrument designations
|No. 1 Omnigraph
||Transmitter only or
|Two versions (figs. 7,9)
|5 and 15 disc versions
|5 disc model-four types (figs. 12-15).
15 disc model-six types (figs. 19-24.)
|No. 3 Omnigraph
|Single disc transmitter model
with hand crank.
|One version (fig.
Similar to Omnigraph No. 1 (fig. 7)
but larger size wooden base.
|No. 4 Omnigraph
|5 disc model with key, buzzer,
and provision for headphones
||Two versions, (included in No. 2
variations, above). (figs. 13,15)
|No. 5 Omnigraph
|Single disc model with hand
crank and clock motor
|Two versions (figs. 10,11)
The instruments were mounted on wooden bases, which on most models
measured 5” X 10-1/2”. Many but not all instruments bore a company
identification label. Some were decals applied to the wooden bases
while others were metal tags attached by small pins hammered into the
The company supplied Omnigraphs to others who affixed their names to
the instruments including the National Wireless Institute (a
study-at-home correspondence school) in New York City, and A. W.
Gamage, Ltd., London. Most Omnigraphs have the notation
‘Patented’ or ‘Pat.’ embossed into the wooden bases. A c. 1910
Omnigraph catalogue has a diagram of a No. 5 instrument bearing the
patent date Oct. 25, 1903. The only instrument with a patent date
encountered by the author was a 5-disc instrument bearing the patent
date of Oct. 23, 1904. To the best of the author’s knowledge, there has
been no research on the patents held by the company nor on the
individuals who designed instruments. Discs The unique feature of the
Omnigraph instruments is the use of rotating aluminum discs with raised
teeth on the edge in the shape of the actual Morse code characters.
Discs were of at least 3 different types (figs. 3
) and a fourth type
that appeared in an advertisement (fig. 21
which has never been
seen by the author.
Fig. 3: A typical disc from a multidisc instrument.
Notice the 5
concentric holes in addition to the central spindle hole. In use,
besides the central spindle post, a second post must be fitted into one
of the 5 holes to align all the discs in the stack in a uniform manner
to allow for coherent messages that were spread over more than a single
disc. This disc is marked 9-O, representing the 15th disc of the
9-series of discs. (The letter ‘O’ is the 15th letter of the alphabet).
Transcription of the Continental code reads: “SEE SILAS FLA HEY ABOUT 5
AND 35 SIG W LEE”
Fig. 4: A typical disc used on a single disc
Omnigraph instrument. A
single central spindle hole holds the disc onto the rotating platter.
This particular disc is marked “6”. Transcription of the American
Morse reads: “HR STMH FM NEW YORK 21 TO ADH. YES SIG LH”
Fig. 5: An unusual disc, with a central spindle hole
and two alignment
holes. This disc is one of a complete set of 15 found on the instrument
shown in fig. 23
. This disc is the last disc
(‘O’) from the series, and
bore no numerical designation. The character consisting of 4 short
dashes at approximately the 2:00 position on the disc is the Morse
character denoting a new paragraph (6). Translation of the Morse
“ON SALE CAN YOU SEE? ANSWER SIG L RICHARDS”
The discs were all 3-1/8” in diameter and were either thin (1/32”) or
thick (1/16”). Thin discs were used on the single disc instruments, and
had a single central hole for the spindle, whereas thicker discs were
used on the multidisc instruments, and had alignment holes in addition
to the central spindle hole. Close inspection of the discs indicates
that production involved cutting the discs, analogous to a locksmith
duplicating a key. Such an arrangement would produce a disc with closer
dimensional tolerances than stamping discs from a die.
Discs were available for both American Morse and Continental code. The
number of characters on any individual disc varied from 12 to 36 (4
with the lower number of characters allowing for slower code speed in
the beginning lessons and the closer spaced characters for more
advanced lessons. The speed of rotation of the discs, of course was
user modifiable, allowing further control of sending speed. Code was
sent using the ‘Farnsworth Method’ indicating that the individual Morse
code characters were uniform in dot and dash length and spacing with
slower code speeds achieved simply allowing more time between
individual characters. The thicker discs could be used on the single
disc instruments but the thinner discs were physically incompatible
with the multi-disc mechanism, which required a second alignment hole.
Practice sessions included code groups, random characters, numbers,
punctuation, and short messages (fig. 6
Fig. 6: Transcription of the full disc series of
Continental code for
the 7-series of discs. (Transcription courtesy of Mr. Lynn
AS HOOKER OFF LB NJ SEPT 15 TOT
OPR STR BRITTON VIOLENT RAIN AND
RAGED AT ASBURY SE OF US THIS MNG
THE TOWN AVON. 2 LIVES IN PERIL
ON SHIP KENNEDY BEACHED HERE. B
DENTY KEY ESCEBETTS FRANK R. MILLERS
JOHN Z. WORTON SAMUEL T. CORBIN
POCKET OF ROB BENTLY SAVED,
HUSSARS ARRESTED WHILE AT SCUTARI
HIGGINS ON STEAMSHIP XE MEYER.
HATTARAS WED. 5 AM SEVENTEEN HUNDRED
|WT IS ZN
HOPING FOR ? S FORD IS A VYGD
|. IT WAS
STATED IN ADVICE S. MURAD WAS PUT
D’S NO IS 496 ADSMEAT 370N
|SEA-AIR AVE 7 AM (SIG C HAROLD EBLIN.
Discs that were used on multidisc instruments (5 or 15 disc models)
were designated with an alphanumeric numbering system consisting of a
number followed by a letter between A and O accounting for the 15 discs
in the series. Other discs (fig. 4
) were designated
simply by a number.
A set of 15 discs exists that is labeled A through O with no number
designation (fig. 23
It is not known with certainty but it is suspected that the discs for
single-disc instruments were numbered whereas the discs for instruments
employing multiple stacked discs bore the alphanumeric designations.
Alphanumeric discs are known up the ‘9’ series however it is unknown if
more than 9 sets of discs exist. The lowest numbered series of discs
(series 1 and 2 for example) had simple code groups whereas the highest
numbered series (8
) had more
complex messages including numbers
and punctuation characters.
Nine sets of 15 discs may exist for both Morse and continental code for
a total of 135 discs for each code. The highest numbered disc
encountered by the author is ‘19’, suggesting that at least 19 numbered
Discs from the “2” series exist for both Morse and Continental code,
and transcription indicates that the messages were completely different
indicating that the Morse and Continental code discs were not simply
same messages in Morse and Continental code.
Morse discs were identical in appearance to Continental code discs and
the company made no attempt to differentiate one from the other based
on appearance. The only way to tell Morse from Continental discs is to
visually inspect the discs, looking for the characteristic Morse
characters that were distinct form the continental code characters.
In addition to the discs that were included with the initial purchase
of the instrument, additional discs could be obtained at modest cost.
The company also permitted students to exchange their discs for
different ones for a 2 cent per disc postage and handling fee. If one
ordered 5 extra discs for a 5 disc instrument, it is suspected that the
student would receive the first, second, or third set of 5 discs of a
15 disc sequence.
Transcription of the discs has demonstrated that sometimes the company
mislabeled the discs. A 7-L disc owned by a collector is the same as a
7-I disc in the author’s collection. Other collectors have other discs
with the same messages on discs with different alphanumeric
designations suggesting incorrect labeling. The author has several
alphanumeric discs with the letter crossed out and another letter
stamped next to it as a correction. Another disc has the letter
designation on the disc upside down. The finding of inconsistent and
erroneous labeling of discs suggests that disc labeling was not
automated, and that human errors were not rare in labeling discs.
The author’s experience and the anecdotal experience of other
collectors is that most discs encountered are the thicker discs used in
the multidisc instruments. The 6 thin discs in the author’s possession
are all American Morse.
The Clock Motors
Another feature of some of the Omnigraphs is their use of a
spring-driven windup clock motor. An interesting adaptation is the use
of a flying-ball governor mechanism to maintain constant speed in the
face of a marked increase in the instantaneous loading, as when the
stylus tracking mechanism moved from one disc to a higher disc in a
stack. In reality, the sending speed slowed as the tracking stylus
moved to a higher disc, and frequently would flub the first character
on the higher disc. As the stylus descended the stack of discs,
frequently it would skip the adjacent disc and track to a lower disc,
although this may have been secondary to wear on the cam mechanism. The
clock motors on different instruments varied slightly in design over
the years but all had the flying ball governor, and a friction speed
control mechanism. An experienced clock repairman indicated to the
author that the clock motor resembles a Seth Thomas clock mechanism of
the era with the addition of the governor, and that most likely Seth
Thomas provided the clock drives to the Omnigraph company. The motor
mainspring is presently an off-the-shelf item from clock repair parts
sources and can easily be obtained and replaced on existing instruments
The Simplest Omnigraph
The simplest Omnigraph device consisted of a single disc mounted on a
platter which was rotated by use of a hand crank (fig. 7
Fig. 7: “Omnigraph Transmitter No. 1”, the simplest
device the company
produced. The user had to supply his own battery, buzzer or sounder,
wire, and key.
Advertisements in 1909 listed this model as “The Omnigraph Transmitter
No. 1”. The single disc supplied with the instrument had American Morse
characters which sent the nonsense statement: JOHN QUICKLY EXTEMPORIZED
FIVE TOW BAGS, which incorporates all 26 letters of the alphabet into
one sentence. No numerals or punctuation were included. An
instruction booklet “How To Become An Excellent Operator” was included
with purchase of the device. Additional discs could be purchased for 5
The same device on a larger base was known as “The Omnigraph #3” in a
c. 1910 catalog (fig. 8
Fig. 8: “Omingraph Transmitter No. 3” is the same
instrument on a
larger wooden base. From a c.1910 Omnigraph Company catalogue.
A device similar to the simplest Omnigraph (above) incorporated an
inexpensive sounder and key identical to the J.H. Bunnell “Morse
Learners’ Outfit” advertised in the 1900 Bunnell Catalogue, and were
undoubtedly supplied to Omnigraph by Bunnell. (fig. 9
Fig. 9: Omnigraph transmitter with integral key and
instrument is missing the hand crank used to turn the platter
containing the disc.
There was no separate model number for this device, and it was regarded
as a version of “The Omnigraph Transmitter No. 1.” The 1903 MESCO
catalogue listed this device as “Omnigraph Learner’s Set”. A ‘press
release’ in the April 16, 1901 issue of The Telegraph Age described
this device suggesting that it may be the first instrument produced by
Single Disc Omnigraph with hand crank and motor
Due to the inconvenience of having one individual hand crank an
instrument while another listens to the code, (or even worse, trying to
crank it yourself
while attempting to copy Morse code), the company supplied a device
that allowed both for hand cranking and motorized disc rotation (fig.
Fig. 10: “Omnigraph No. 5” is the company
designation for this model.
At $7 around 1915, it came with a total of 3 discs and a learner’s
manual. This instrument is also missing the hand crank as is fig. 9
The logic behind supplying such an instrument is unclear, inasmuch as
the hand-cranked mechanism would seem completely superfluous in the
face of the convenience of motorized use. Despite the ease of having
automated disc turning, the user was still limited to a single disc at
a time, and by having to change the disc after every use. It must have
been very tedious for the student to listen to the same disc over and
over, and to have to change every disc by hand. It is speculative, but
undoubtedly at least some students thought to turn the disc over, thus
playing the disc backwards, generating new characters. The letter A
(.-) for example would then become N (-.). A c. 1930 company catalogue
illustrated a slightly different version of this instrument on a
smaller base and with a more compact design (fig. 11
Fig 11: “Omnigraph No. 5” on a smaller base with
more compact design
than fig. 10
Five Disc Model
The 5 disc model was designated “Omnigraph No. 2 Junior” in the 1924
J.H. Bunnell catalogue. The five disc model (fig. 12) was probably the
most popular model (4), and incorporated the clock motor, a stack of 5
discs, and a cam mechanism to move the stylus from one disc to the next
Fig. 12: “Omnigraph No. 2 Junior” is the company
designation for this
model, and is reported to be the most popular model sold (4
the purchase price of $12.50, or for $14 the device
came with a key and sounder, battery, wire, and a learner’s manual.
When the stylus arrived at the highest disc, it would travel down the
stack again from the highest disc to the lowest disc and then ascend
again. An adjustable mechanism allowed the user to decide whether to
play the entire disc before moving to the next disc in the stack, or to
play a segment of the disc before moving to the adjacent disc. 1/5,
2/5, 3/5,4/5 or the entire disc could be played before moving on to the
next disc. By allowing less than a full disc to play before moving to
the next disc, the user could create nonrepeating messages much longer
than the sum of all of the characters on the 5 discs. For example, if
the user wished to play only 2/5 of the disc before moving on to the
adjacent disc, then when the disc reached the highest level, it would
begin to descend down the stack of discs again, and would play a
different 2/5 segment of each disc on the way down. At the lowest disc,
the stylus would begin to ascend the stack of discs again, this time
playing a 1/5 segment of the disc that had already been played with the
last 1/5 segment of the disc that not been played. This ingenius
pseudo-random character generator design would allow continued playing
of different 2/5 disc segments for many, many hundreds of characters
before repeating the message. By adjusting the device to change discs
after 1/5 of a disc, then 2/5, 3/5, 4/5 or a complete disc, students
could produce a nearly infinite number of non-repeating characters
before repeating. Of course shuffling the disc order, flipping the
discs over, or rotating one or more of the discs ‘out of phase’ with
each other would allow even more variety. Nevertheless, students may
have relatively quickly memorized segments of discs, diminishing the
utility of the device as a learning tool. The company also
manufactured a 5-disc device with a key and buzzer (fig.
Fig. 13: Omnigraph No. 2 Junior with integral
buzzer, key, and
provision for use with earphones.
The governor is missing from the spring motor as is the cover for the
Advertisements for the 15 disc version of this device show earphones
being used. The small cylindrical object next to the buzzer is a
primitive coupling transformer for use with the earphones described in
a c.1930 company catalogue as “induction coil #21”. The primary winding
is in series with the buzzer, and the secondary is connected to the
earphone terminals. The audio heard in the earphones would be the same
frequency as the buzzer and would be expected to mimic the raspy audio
quality of spark transmitter signals of the era. A similar coupling
device is present on the Natrometer (fig. 2
is also present on a
similar device advertised in a c.1919 Gamage catalogue. The buzzers
included on the Omnigraph devices so equipped were almost certainly
manufactured by Signal Electric Company of Menominee, Michigan.
Another version of the 5 disc model had the discs stacked on top of the
motor (fig. 14
) in a compact arrangement.
Fig. 14: Compact 5-disc device. Advertisement from
an issue of QST
As best as can be determined, there was no separate model designation
for this device. A version of this model included a buzzer and key
) similar to fig. 13
use by the New
York Wireless Institute, and which bore their name (fig.
Fig. 15: Compact 5-disc Omnigraph with integral key
and buzzer made for
the New York Wireless Institute. (Photo courtesy of Mr. Lynn Burlingame
Fig. 16: Label on device shown in fig.
Although the New York Wireless Institute was a study-at-home
correspondence school, advertisements mention an on-site ‘post
graduate’ course. It is unknown how many students actually studied at
the ‘campus’. Of note, the address of the New York Wireless
Institute was 258 Broadway.
Between about 1910-20 the Vibroplex Corp. factory was located directly
across the street at 253 Broadway. Students enrolled in the Wireless
Institute ‘post graduate’ course of study wishing to purchase bugs
conveniently do so at the Vibroplex factory. Of interest, a c.1930
Omnigraph catalogue listed Vibroplex bugs for sale including the #4
model (“Blue Racer”) for wire work and the #6 model (“Lightning Bug”)
for wireless work.
A typical 5-disc model Omnigraph was listed in a c. 1919 A. W. Gamages
(London) catalogue (fig. 17
) under the name “The
Dictamorse No. 1” and
bore a Gamages label (fig. 18
Fig. 17: Typical No. 2 Omnigraph listed in a c.1919
Fig. 18: Detail from fig. 17 showing the Gamage
label on the device.
The label reads, “A.W. Gamage London”
15 Disc Model
The fifteen disc model was listed in company advertisements as “The No.
2 Omnigraph” incorporating the same driver motor as the other models,
but with a more elaborate cam mechanism for changing the discs (fig.
Fig 19: “Omnigraph No. 2” is the name the company
gave to the fifteen
disc model. This instrument is probably on a replaced wooden base.
A version of this model advertised in 1909 as “The Omnigraph No. 2
Improved” used a battery powered motor and rheostat in lieu of the
wind-up motor (fig. 20
Fig. 20: “Omnigraph No. 2 Improved” is the company
designation for the
electric motor driven version of the No. 2. Omnigraph.
An elongated drive belt connected the drive shaft of the electric motor
to the rotating platter. A total of 60 discs was included with this
model. At $10 in 1909, this amounted to nearly a weeks’ wages for a
typical worker, making the purchase of this instrument a very serious
decision. A slightly different version of this instrument with a
different design cam mechanism also allowed for hand cranking (fig. 21
Fig. 21: Another version of the “Omnigraph No. 2
Improved” with a
different type of cam mechanism and a provision for hand cranking the
instrument. Notice the different style discs with large holes. The
author has never seen these discs such as these and wonders if they
were ever produced.
A slightly different version of the 15 disc model advertised as “New
Omnigraph No. 2” in 1910 employed the wind-up motor and also had the
capability of hand cranking the device if desired (fig.
Fig. 22: “New Omnigraph No. 2” from a 1910
advertisement. The 15-disc
instrument could be powered by either the clock motor or a manual hand
crank. Notice the user wearing earphones. Auxilliary equipment such as
a buzzer or oscillator must have been present and not illustrated.
As with the single disc device that has both motorized or manual drive
), the author
wonders why the hand crank mechanism is
included with motorized capability. It is possible that the company
knew that the clock motors wound down very rapidly and that students
working in pairs probably represented a more efficient way to use the
instrument. In addition, a human could probably crank the machine more
forcefully, minimizing the slowing that occurred when the cam mechanism
moved the stylus from one disc to the next higher disc.
A version of the 15 disc model exists that has the hand-crank
and no motor drive, with extra stacked discs where the motor would be
normally located (fig. 23
Fig. 23: Hand crank instrument with no clock drive.
instrument was never advertised to the best of the author’s knowledge,
and contained 30 Morse discs with 15 in use and 15 spares. This
instrument contained the unique discs shown in (fig. 5
The company also supplied a 15 disc device with a buzzer and straight
key, to the New York Wireless Institute (fig. 24
Fig. 24: Omnigraph #2 with integral key, buzzer and
earphones. from a 1920 advertisement in QST for the New York Wireless
Institute. Similar to fig. 13
, except with 15
discs. Students enrolling at the institute received this
instrument according to the widespread advertisements for the school.
The Omnigraph company advertised or produced at least 15 models of
telegraph learning devices over an approximately 30 year span early in
century (Table 1). There may be other devices or
variations thereof not listed here that may come to light, and the
author would appreciate hearing about the existence of any such devices
from readers. It should be noted that a number of the devices described
(above) are known only by their advertisements. Telegraph manufacturers
in the early 20th century are known to have advertised items that are
completely unknown today, and it is uncertain if they were ever
Devices similar to the Omnigraphs that appeared after the demise of
company had an incised wheel which would send “SOS” repeatedly and were
presumably of WW-II military origin.
Interestingly, in 1963, long after the demise of the company, a device
was advertised in CQ magazine identical in function to the Omnigraphs
). It consisted of a motorized circular wheel
with the Morse
code characters cut into the edge. Amateur radio operators could have a
custom message (such as their radio call letters) cut into the disc as
Inasmuch as the telegraph keys, sounders, buzzers, binding post
hardware and the clock drives included with the Omnigraph instruments
seem to be items supplied to the company by others, it is uncertain
exactly what portions of the instrument were made at the Omnigraph
factory itself. The wooden bases, the rotating platter, and the
aluminum discs may be all that the company actually produced.
The unique design of the Omnigraphs represented a continuation of the 19th
century American tradition of electromechanical innovation that also
produced the universe of telegraph instrumentation, fire alarm systems,
stock market tickers, nationwide time service systems, and innumerable
Given the explosion of the use of telegraph following the successful
demonstration by Samuel Morse in 1844, and the importance that instant
communication played in the economic, social, and military fabric of
and early 20th
centuries, the Omnigraphs
played a small but important role during the declining years of
Morse code takes advantage of the simplest property of an electrical
circuit: on or off. As such, this binary form of communication may be
rightfully regarded as the earliest form of digital communication, and
the necessary predecessor of digital communication as we know it today.
Notes and References:
1. An Omnigraph catalogue c. 1930 listed the company
1900’. The first Omnigraph advertisement the author could locate was
from a J.H. Bunnell catalogue from 1900.
2. No advertisements for Omnigraphs were found after
this year for the demise of the company.
3. Numerous radio and electrical publications and
from 1900-1931 were employed as reference materials and are too
numerous to mention individually
4. Friedman, Neil D. A Clockwork Omnigraph; CQ
Magazine Feb. 1981 p.
5. Martin, Fredric W (KI6YN). Personal communication.
6. Elwood, John (WW7P). Personal communication.
7. Friedman, Neil D. Omnigraph Disc Codes; Old Timer’s
Bulletin of the
Antique Wireless Association. Vol. 35, No. 1. (Feb. 1994). p. 54
8. Reinke, Roger W. I’ll Never Forget That Old
Timer’s Bulletin of the Antique Wireless Association. Vol. 37, No. 1.
(Feb. 1996). p. 39.
9. ‘Parks Code Wheel’; Parks Electronics Laboratories
Rt. 2 Box 35,
Beaverton, OR. CQ. Vol. 19, No. 5. (May 1963). p. 79
The author wishes to acknowledge the kind assistance of Mr. Lynn
Burlingame (N7CFO), Mr. Mike Feher (N4FS), Mr. Neil Friedman (N3DF),
and Mr. John Casale (W2NI), Mr. John Elwood (WW7P), Mr. Fredric W.
Martin (KI6YN), and Mr. Roger Reinke for providing references,
photographs and historical materials, and Mr. Edward Gable (K2MP) of
the Antique Wireless Association for his assistance accessing the AWA
David R. Pennes, M.D. (WA3LKN) is an advanced class amateur radio
operator and diagnostic radiologist living in Grand Rapids, MI. Dr.
Pennes collects and restores bugs and landline keys.