W1RST "Tiny Tim" Transmitter-Receiver

June 1, 2009

The "Tiny Tim" is a portable CW transmitter-receiver for 80 and 40 meters, published in QST for April, 1955. It later appeared in at least one edition of the ARRL "Mobile Manual." I don't endorse putting this rig on the air, as the transmitter probably won't meet current FCC spurious-emission regulations, and the receiver will radiate into the antenna. I've always admired its simplicity, the essence of QRP.

Tiny Tim exterior
The "Tiny Tim" Portable

I believe the author, Stu Cowan, W1RST, went on to publish CQ Magazine. If you're an ARRL member, you can download the complete article from ARRL's archive. I've taken the liberty of posting brief descriptions of the transmitter and receiver, and their schematics.

The Receiver
The receiver covers 80 and 40 meters using plug-in coils. A type-3A4 tetrode serves as a regenerative detector, followed by a type-3V4 audio amplifier. There is no rf stage, so the detector will be pulled by antenna swaying, and will radiate a signal. The author used the rig on his sailboat, presumably with a stable antenna.

Tiny Tim receiver schematic and parts list.

The Transmitter
The transmitter uses a single type-1J6G dual triode as a push-pull crystal oscillator. Its output is link coupled to the antenna by means of a plug-in coil for each band.

Tiny Tim transmitter schematic and parts list.

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