On this night in late spring here in the midwaste, I mean, midwest, I suddenly recalled a couple of early day experiences back when I was a pimple faced announcer at the local FM just before the medium became popular.
It was (guess) 1961 when the first transistor AM/FM/SW receiver arrived, German made. It was physically beautiful at about 10″wide-by-7″high-by-3.5″deep, with royal blue art plastic pasted over a wood crafted case. The transistors inside were the silver can type not seen anymore. It was very sensitive, but there was a problem with audio distortion.
Next, about 1964, I saw an ad somewhere for a wrist AM/FM radio from (I think) Timex. I had mine right away and it certainly tuned in the stations on the tiniest speaker ever imagined, but the sensitivity was borderline and the level very miniature, so I returned and was given an honest refund.
Around the same time a Japanese AM/FM car radio went on sale at an oddball electronics store and I had mine somehow tapped into the car’s wiring, but it also had amplifier problems.
From crude beginnings we have all arrived wherever now is.
Wrist Radio
A wrist radio was my first electronic project which used a transistor. The plans were in some magazine and it was built inside a plastic clamshell pill box. It was tuned with an adjustable slug coil. I gathered the parts including a CK722 transistor ordered from Allied Radio. The hardest part to find was the N cell but a local TV repair shop had them.
It worked as well as could be expected for a single transistor radio and I never wore it on my wrist. It was mainly for show since at the time a radio that small was a “gee whiz” gadget. I don’t know what happened to the radio but I still have the earphone for it.
My dad wore a hearing aid and the audiologist knew I liked electronics and gave him a bag full of hearing aids and other stuff from which I salvaged the earphone. Dad’s pocket aid used mercury cells for the A supply and he accumulated a five pound coffee can full of them. I smashed them and recovered the mercury for my “collection”. Over those years I saved about a pound of Hg and I have it in a pill bottle to look at though I don’t play with it anymore. I would coat silver dimes with it to make them shine and passed them at the school cafeteria. They sure would shine for a couple of days then they turned yellow. No one cared in those days.
Neil
2N107
My first transistor was GE’s 2N107. It was marketed about the same way as Raytheon’s CK722. Both transistors were rejects of commercial germanium PNP transistors, and were directed toward the hobbyist market. They were very popular with hobbyists because of their “low” price. I paid $ 1.50 for mine. That was actually a lot of money at the time. They were lousy transistors, but they provided audio amplification for crystal radio earphones.
The “wrist radios” didn’t actually work because, due to their poor sensitivity, they required very long antennas to produce an audible signal.
More “Geekness”
Ermi is correct about the antenna. I recall using the old “crystal antenna” trick of connecting the antenna to the telephone dial finger stop to get a usable signal. My KnightKit AM broadcaster really made it sing though.
I recall the 2N107 and had a few in my collection. $1.50 sounds about right for the price but considering that I was earning 75 cents an hour working in a bicycle shop this was a two hour labor investment. My first FM BCB transmitter used a Philco 2N499 which cost about $5 but it was worth it for the joy of being able to broadcast.
Back then tie tacks were popular and I made one from a nice looking transistor by soldering a small nail to the back of it. It was the style which is similar to the TO-5 can with a pinched tab on the top. It was gold plated with gold plated leads and it actually resulted in some nice comments. It is still in my jewelry box though I haven’t worn it for years.
Our engineering honorary fraternity (HKN) required pledges to wear their colors. We had to make a lapel pin from a 22 Meg. 2 Watt resistor (Red, Red, Blue) and wear it. Because of what it represented, it was a badge of pride.
Neil