First written on 01 Jan., 2003
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.
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
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
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.
|hFE||70 -- 240||100 -- 320|
Figure 2 shows my implementation example.
I put all the things into a small aluminum box (W/D/H=70/50/40 mm).
My great thanks to Toru KATO, JG1RVN, for his crystal support.