Need-a Date?
Dating early Japanese radios - Part II

Part II - Radios that expose their build dates easily


This major manufacturer of everything from light bulbs to nuclear power equipment began using an 8-digit serial number scheme in 1958 that makes it easy for collectors to discern the month of production for any given radio. Here's how it works, at least for radios built after roughly October or November 1958:

The first digit reflects the year of manufacture
The next two digits indicate the month of manufacture
The remaining five digits are the radio's actual serial number

This gives us the formula: YMM##### (the #'s being the serial number)

Here's a sample:

Label from a pretty Penney's radio made by Toshiba in November 1958
s/n 86

Now for the exception:

The first Toshiba radios to use this type of serial number employed a slightly different formula that only leaves one digit to represent the month, as follows.

The formula: YYM##### (the #'s being the serial number)

Here's a sample:

Label from a gorgeous 6TP-219 made by Toshiba in August 1958
s/n 638

Okay, this deserves a little explanation. I'm walking on kind of thin ice here because I haven't seen many radios that use this earlier scheme, but I will offer my somewhat educated hypothesis anyway. Hopefully other collectors will write me and share any serial numbers they have that fall within this range so we can eventually pinpoint the period these dates were used. The earliest Toshiba transistor radios from 1957 and early 1958 were not exported and none of the samples I have seen sport the serial number labels shown above, (therefore do not use this dating scheme). I believe the Penney's and 6TP-219 shown above were amongst the first Toshiba radios to be exported to North America, and it's quite possible that Toshiba introduced this serial number label along with these models. If, as I'm speculating, these shipments began in the summer of '58, it is not hard to understand why the company might first have experimented with noting the last two digits of the year followed by a single digit for the month. However, along comes October and, in addition to preparing for Halloween, the folks at Toshiba had to make a decision. They could eat up a fourth digit to properly note the double-digit months at the end of the year, but leaving only four digits for the serial number would limit their dreams of selling large numbers of radios. Or, they could opt to expand the number to nine digits. I won't go as far as to suggest that the fact it would cost money and be a hassle to change the stamp they had set up to print 8-digit numbers was a factor in the decision they reached, but the company obviously settled on dropping the first of the two digits they were using for the year. After all, within context there was no mistaking the decade anyway. Not many dealers, salespeople, or service staff would really think a 6TP-243 transistor radio would have been made in 1948. And, if it came from 1968, somebody should have spotted a funky DeLorean whiz past with Michael J. Fox at the wheel. This brings up a good point when looking at dates in early transistor radios; context counts because date stamps are often abbreviated in one way or another.

Note: With the exception of the exception included above, this method for determining the production date of Toshiba transistor radios has long been noted on the opening page of the Toshiba section you'll find at Bob Davidson's unsurpassable Transistor Radios in Galaxy M31 site. In turn, as stated on Bob's site, the inspiration behind this dating scheme was none other than that good Canadian boy Fred Mason. In all honesty, I can't remember when or where I started reading the dates on these labels. I've been accused of trying to date everything and everybody before. Regardless, I think they deserve a credit here. A big round of applause for Fred and for Bob, please!



There are a couple of models made by Yaou that make dating an absolute breeze. These have inspection dates stamped right on the product label. While there is no guarantee that the inspection date matches the actual date of production, it's got to be pretty darn close.

This label is from a Yaou 6G-908


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