Sony TFM-151
Sony TFM-151
There's a whole lot happening in here. In addition to the ferrite bar antenna for AM reception, AM external antenna jack, and metre-long telescoping rod antenna for FM reception, there are also two large nuts above the left battery holder to which the user can attach a TV antenna as an FM external antenna. Another feature is the "line-in" and "line-out" connectors that allow one to hook up a record player or other sound equipment.
The 4" x 6" oval speaker is not the only component shared with the TR-74 and TR-741. As with its AM/SW siblings, the telescoping rod antenna on the TFM-151 does not tilt or swivel. This means when not connected to an FM external antenna, the TFM-151 could also be found in a "reclined" position on its handle as the user rotated the entire radio to achieve optimum reception when listening to FM.
Transistors: 2T203 x 3, 2T201 x 5, 2T76 x 2, 2T65 x 3, 2T85 x 2, [1T23 x 4, 1T51]
Power source: 4 x D-cells (UM-1) = 6V
AM band: 535 ~ 1605 KC
FM band: 88 ~ 108 MC
The photo above shows the second* earliest serial number I have seen to date. It was common during this period for Sony to begin models at number "1000" or "10000", so this is possibly the 154th unit off the production line. The earliest serial number I've seen to date is 1129*, and latest is number 2166*. Of course, I'd be more than happy to revise this information if and when somebody can show me a TFM-151 with a 3-digit serial number.
Note also in this photo that the circuit board is the earliest type marked "010-6". The board was revised to the "010-6A" version by the time production reached serial number 1439.
The early unit pictured above also differs from later production in that it continues to use the plain rectangular label common to the TR-74 and TR-741 with the early Sony logo to the right of the serial number. The label changed to a smaller one with serrated edges, (as though cut by pinking shears), by the time s/n 1439 was produced. You can see the later serial label in the photo at the top of this page, (the photo showing the insides of the unit with s/n 1599).
*
* While it doesn't prove anything, the above image of a pre-production prototype unit found in the first pamphlet Sony printed introducing the TFM-151 in late 1958 could be read to suggest that Sony may have pondered starting the serial number series for the model at "10000" instead of "1000".
* [07.04.15]: Thanks to Steve P. and Michael J. for contributing and expanding the range of serial numbers in my database. We've now spread the range by a whopping 25 digits/units on the early end, (from s/n 1154 down to 1129), and by 13 digits/units on the high end, (from s/n 2153 all the way up to 2166!) If all numbers between were used on units that actually shipped, (which may not be the case), we are currently at range of about 1,038 units!