TT2/J

Cosy MUTO, JH5ESM
First written on 01 Jan., 2003

Introduction

The Tuna Tin 2 tiny transmitter, designed by Doug DeMaw, W1FB, was first appeared in May 1976 issue of the QST magazine.

This is a Japanese modification of TT2.
Instead of 2N2222A, Toshiba 2SC1959 and 2SC2120, which are for audio driver and 1[W] output stages, respectively, are employed.

• Original article by W1FB (PDF file from ARRL Web)
• "Tuna Tin 2" QRPp Transmitter by New Jersey QRP Club
• NORCAL'S BACK TO THE FUTURE PROJECT

Circuit Description

Figure 1 shows the entire circuit of the TT2/J.
Maximum ratings of the transistors are summarized in Table 1.

A cheap 7.000[MHz] crystal is frequency adjusted up to 7.006[MHz] by 20pF TC.

Different from the original, the final stage is changed to zero-bias operation.
Load impedance of Q₂ is 200Ω, which is stepped down to 50Ω by T₁.

In addition, a 220Ω resistor is inserted at the base of Q₂ for better load condition of OSC stage.
Q₃, the keying transistor is another addition.

At 13.5[V] supply voltage, 400[mW] output power is obtained.
However, collector efficiency is approximately 34[%] which is half the original.
Entire supply current are 130[mA].

Fig.1 Schematic of TT2/J.

An Implementation Example

Figure 2 shows my implementation example.
I put all the things into a small aluminum box (W/D/H=70/50/40 mm).

Fig.2 Implementaion of TT2/J

Acknowledgment

My great thanks to Toru KATO, JG1RVN, for his crystal support.