How to date early Japanese tr radios

by Fred Mason


EARLY JAPANESE TRANSISTOR RADIOS: HOW TO DATE THEM
--------------------------------------------------
PART ONE: CAPACITOR DATE CODES


INTRODUCTION
------------

Many collectors are now actively collecting early Japanese transistor radios.
Unlike American sets, information about manufacturers and models produced is
extremely difficult to come by.  Current transistor radio catalogs give dates of
production that may differ wildly from the actual production dates.  In
addition, there is little information available about different models and
manufacturers which can help to identify and date an individual set.

This short series of articles will help the interested collector to identify key
features of early Japanese sets in order to pinpoint relatively closely when the
set was made.  You may be surprised at what you find when looking for
interesting
radios; early sets contain many features which show the quick evolution of
portable radio design as this new consumer product entered the market.

This article discusses the most accurate method of dating so far encountered
(barring an actual production date stamped somewhere inside the set); date codes
on certain brands of tubular capacitors used on many early sets.  This
information will be of extreme interest to collectors of early Sony and
National(Panasonic) sets, but also applies to many other sets manufactured by
both large and small makers.  At the end of this article is some further
information which may be of interest to Toshiba collectors, as well as a request
for information from you all out there, in order to extend this research.

The next article will discuss other features such as transistor type and code,
tuning and i.f. capacitors, earphone jacks, and other characteristics of early
sets which point to particular dates of manufacture.

CAPACITOR DATE CODES: THE BACKGROUND
------------------------------------


Over the last 10 years I have slowly gathered some nice examples of early Sony
radios, and have become obsessed enough with them to spend some time examining
them, in order to be able to figure out when they were made and in what order.
Fortunately, Sony sold radios in Canada as early as early 1956 (perhaps earlier,
but that's another article), and quite a few models were sold here that never
made it to the United States.

In examing the innards of many of these sets, I noticed that a certain brand of
tubular capacitor (NIPPON CHEMICON) often displayed a 7 digit number.  Comparing
many sets, I began to suspect that the number was actually a date code.  A
lengthy examination of all sets in the collection and some correspondence on the
Internet with some other collectors who kindly examined their sets and critiqued
my work resulted in this article.  Although the majority of sets discussed are
SONY, these codes show up often enough on other sets to make the hunt worthwhile
if you only have other brands at hand.

CAPACITOR DATING: CHEMICON
--------------------------

CHEMICON tubular capacitors can be found with three brand names:

        CHEMICON
        NIPPON CHEMICON
        FOX CHEMICON

The capacitors in question are tubular, either shrink wrapped in black plastic
with white lettering, or silver with black lettering and a clear plastic tube
on top, or cardboard tube with yellow colouring and brown or black lettering.
There is often a stylized crest as a logo.  On some of the larger capacitors
the words NIPPON CHEMICON appears on two lines within the crest.  So far, the
codes have been found on capacitors of 30 and 100 micro farad caps.

Perversely, the codes seem to be usually on the side of the capacitor facing
the circuit board; however there are often capacitors mounted vertically,
allowing them to be twisted into a position to view the code.

CHEMICON codes are of the form:

        "MMYYDDx"

        where

        MM = Month (01 to 12)
        YY = Year  (56 to 61 found so far)
        DD = Date (highest is 25 so far)
        x  = Unknown (production line? hour? etc.)

Thus, the code "0656257 is June 25, 1956, which matches well with the radio,
which is a SONY TR-72 manufactured by TOKYO TSUSHIN KOGYO before the name was
changed to SONY Corporation in early 1958.

In over 100 capacitors examined, all codes found match the format described
above.

CAPACITOR CODING: "TITL" or "KADOMAX"
-------------------------------------

A second brand of capacitor has been found with a slightly different coding
method.  These caps are gray, and have been found on several Sony TR-86s.
There is a logo which is circular with slight dash marks from the circle
towards the centre of the circle, at the 1 and 7 o'clock position.  Presumably
Japanese script across the centre of the circle looks slightly like "TITL"
slightly italicized.  All writing on these caps is blue.

Subsequent information indicates that these are KADOMAX caps; which are also
light gray body with blue writing.  The STANDARD sets included are KADOMAX, and
use this coding info.  More subsequent information comes via the case for a
PANASONIC AM/SW portable which has the TITL logo on it, indicating that TITL is
actually NATIONAL.  In addition, several early NATIONAL sets all have the
relevant capacitors.

TITL codes are of the form

        YMMDDx
        or
        YMM DDx (note the space)

        where

        Y  = last digit of the year
        MM = Month
        DD = Date
        x  = unknown

A sample code found in a SONY TR-86 (cream colour) is 901240 which would
translate to Jan. 24, 1959, if valid.  The date is certainly in keeping with
the radio, however, because of the very small sample, conclusions about TITL
dates must remain tentative.

SONY DATING CHART
-----------------

The following chart indicates what capacitor codes were found in each set
examined, where CHEMICON capacitors were found.  Each line is a separate set.
Where more than one date code was found, it is shown as such, indicating the
range of dates found in a particular set.  The TR-86 sets were dated using the
TITL capacitor dates; all others contained CHEMICON capacitors.

Some other sets from SONY contained ELNA caps; these do not show dates.
Examples of sets with ELNA caps are the TR-84 and TR-710 sets.

(G) = Gendis model, sold in Canada
*   = cap date in a single set
-   = missing serial number

MODEL      S/N      1956........1957........1958........1959........1960........
--------------------------------------------------------------------------------
TR-72(G)  Wood AM 7 Transistor table model
         10056      |....*......|...........|...........|...........|...........
not (G)  29707
|...........|......*....|...........|...........|...........
         34799
|...........|..........*|.*.........|...........|...........
           -
|...........|...........|...........|.*.........|...........
         52079
|...........|...........|...........|..*........|...........
         53070
|...........|...........|...........|..*........|...........
         54489
|...........|...........|...........|.**........|...........
         54789      |...........|...........|...........|.**........|...........

TR-6(G)   Large Horizontal AM Cream
           -        |...........|....**.....|...........|...........|...........

TR-61     Small Horizontal AM
         10149      |...........|......*....|...........|...........|...........

TR-74     Large Square AM/SW
         20421
|...........|.......*.*.|...........|...........|...........
         15925
|...........|...........|.**........|...........|...........
         18977      |...........|...........|.*.*.......|...........|...........

TR-63(G)  Small Vertical AM ?
           -
|...........|...........|*..........|...........|...........
Green    91771      |...........|...........|...*.......|...........|...........

TR-75(G)  Large Horizontal AM
RedBrown 16797      |...........|...........|...**......|...........|...........

TR-608(G) Large Horizontal AM
Wht/Gray   16544
|...........|...........|....*......|...........|...........
Wht/Grn      -
|...........|...........|.........*.*...........|...........
Wht/DkGrn  32300
|...........|...........|...........**..........|...........
?            -
|...........|...........|...........|...**......|...........
Wht/Red    49315
|...........|...........|..........*|...*.*..*..|...........
Wht/Grn    51006    |...........|...........|...........|....*.*....|...........

TR-88(G)  Large Horizontal AM/SW
           44891    |...........|...........|......**...|...........|...........

TRM-88(G) Large Horizontal AM/MB
            38917   |...........|...........|........*.*|...........|...........

TR-881A   Large Horizontal AM/MB
            2038    |...........|...........|.........*.*...........|...........

TR-86 Small Vertical AM Cream
              -
|...........|...........|...........*...........|...........
Cream      59986
|...........|...........|...........**..........|...........
Cream      77846    |...........|...........|...........|....*......|...........
Black      80789    |...........|...........|...........|....*.*....|...........

NOTES ON SONY DATING CHART
--------------------------

* There is an anomaly with the serial numbers for the TR-74 model; the earlier
set has the higher serial number.  Re-examining the earlier set, the serial
number is a small label, and there is definite evidence that there was another
label on the speaker, which was removed.  Was it re-labelled at the factory?

* There is another anomoly with the serial numbers of the TR-88 and the TRM-88,
comparing production dates.  Did Sony carry separate numbers for two models of
what is essentially the same set?  Apart from the frequency ranges, the dial
plate is silver colour on the Marine Band set and gold colour on the Shortwave
set.  Model TR-881A is the same set again, different knobs, and the addition of
fine-tuning knob concentric with the tuning knob, and one additional earphone
jack, but has a much lower serial number compared to the TR-88s.

* Given that the largest range of dates in any particular set is two months,
what is a reasonable guess for the actual production date of the radio?  I
would feel comfortable assuming that the set was actually produced within 60
days of the latest date.

The worst exception to this rule is the red TR-608, S/N 49315, where the range
of cap dates is from December, 1958 to October, 1959!  Was it returned for
repair?  The set is in excellent shape, but has been disassembled at least
once.

OTHER MANUFACTURERS DATING CHART
--------------------------------

As above, this chart shows the range of dates for each individual set examined
which contained CHEMICON (or TITL/KADOMAX/NATIONAL/PANASONIC) capacitors.

*   = cap date in a single set
-   = missing serial number

MODEL      S/N     1956........1957........1958........1959........1960........
--------------------------------------------------------------------------------
SILVER    7T-3      large black plastic horizontal AM 7 transistor
        80901710   |...........|....*.*....|...........|...........|...........

SANWA     3BP-16    large black/grey painted wood AM/SWx2 8 transistor -
                   |...........|.......*..*|...........|...........|...........

STANDARD SR-F22     small vertical plastic AM 6 transistor ivory
           109222  |...........|...........|...*.*.....|...........|...........
mint green 106423  |...........|...........|....*.*....|...........|...........

STANDARD SR-G24  thin, wide AM 7 Transistor
          2026392  |...........|...........|........*..*...........|...........

GLORITONE T-71      small red horizontal plastic AM 8 transistor -
                   |...........|...........|......*....|...........|...........

NATIONAL  AB-235    White/Olive Green  plastic AM horizontal 6 transistor
          72059    |...........|...........|.......*...|...........|...........

NIVICO    6TA-1     grey horizontal plastic AM/SW 6 transistor
          11738    |...........|...........|...........|.*.**......|...........

HITACHI TH862R      "Marie" small black plastic horizontal AM 8 transistor
       14446312    |...........|...........|...........|....*......|...........

SHARP     BX-326    large grey horizontal AM/SW 8 transistor
AG 25768           |...........|...........|...........|...........|*..........

NOTES ON OTHER MANUFACTURERS DATING CHART
-----------------------------------------

* Except for the HITACHI Marie, these are all fairly large sets.  In fact, only
the Standard SRF-22 sets are pocket style verticals. The CHEMICON capacitors
are quite large, and shoehorning them into small sets would have been
difficult.

* The NIVICO and STANDARD sets have TITL (or KADOMAX) Caps.

* The SILVER shows many signs of early manufacture; a sticker stating that the
set is produced with licensing from RCA in the States, early earphone jacks,
very thick case etc. The caps in this set are very large, and look like they
came from a tube set.

FINAL NOTES AND A REQUEST FOR ASSISTANCE
----------------------------------------

- These sets show a clear progression of features and sophistication when
organized and examined in the chronological order the above charts indicate.  In
particular, there is a fairly strong correspondence between date and the type
codes of the transistors in an individual set.  This will be discussed in the
next article.

- One of the additional methods of dating a set I am researching involves the
serial numbers of TOSHIBA sets.  If any collector with any number of
TOSHIBA sets
would forward information as indicated below, I can report on whether there is
an actual production date coded within the serial numbers.  Surprisingly enough,
TOSHIBA is the only brand I've found to date that may have an actual production
date on their products.

- Obviously this type of information is only as good as the data it is based
upon.  Although in over a hundred sets examined there have been no capacitor
codes which don't fit the suggested coding scheme this article proposed, there
can never be enough data to be absolutely certain.  I invite any collector who
wishes to generously contribute to this research to examine their sets and
forward the following information to me:

BRAND
MANUFACTURER (if known, and if different than above)
MODEL NUMBER
SERIAL NUMBER
STYLE, COLOUR
TRANSISTOR TYPES
CAPACITOR TYPES
CAPACITOR CODES

The preferred method to reach me is via the Internet where my e-mail address is

fredm@helix.net

Alternately, my mailing address is:

Fred Mason
PO Box 643
Fort Langley, BC Canada
V1M 2S1

I will post updates to this article, based upon information received and further
research, on the Internet.  Watch the newsgroup "rec.antiques.radio+phono" for
posting details.  Alternately, I will endeavour to keep non-wired collectors
posted via this publication.


ACKNOWLEDGMENTS
---------------

Thanks to the collectors who contributed to this; Robert Ross, George Kaczowka,
Smitty at Gasoline Alley, Darryl Rehr, Dean McIntyre, Al Reilly, Mark Brauer,
and some others who remain anonymous.




Copyright @1997 Fred Mason

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