Matched pair of SFT307 (OC44N, 2N2614) germanium PNP transistors, black TO-1, Fuzz

You are buying one matched pair of SFT307 vintage germanium PNP transistors, new (never used and soldered).

The producer catalogue data is: (“Towers’ International Transistor Selector”)

• Ucb max = 18V
• Uce max = 18V
• Ueb max = 12V
• Ic max = 100mA
• Ptot = 150 mW
• Tj max = 85ºC
• FT min = 3MHz

We tested these transistors to a specific gain range and leakage. The gain was measured by our own method (if interested E-mail us for details) with collector current of 1mA. All measured data (at Tamb=19°C / 66°F) are shown below.

These vintage germanium PNP transistors (intended originally for computers) have very low leakage (easy to bias) and are excellent for vintage radio, amp, classic Fuzz-Faces and other guitar effects units!

Measuring a germanium transistor with a simple digital multimeter (at the terminal usually labeled E-B-C-E) always shows a higher gain than actual. A multimeter current of 10 microamps delivered to the base of the transistor under test is comparable to the collector-to-base leakage (Icbo) of (any) germanium transistor. The transistor amplifies both currents, in which case the multimeter shows a larger gain (for poor quality transistors over 300%).

Our method to check quality of germanium transistors is via two measurements of the base current. By this the gain is calculated and also conclusions can be made for what the measured transistor can be best used.

• 1. Supply voltage to collector-base. Measure the leakage current Icbo.
• 2. Then the base current Ib is measured at fixed collector current Ic (eg. at 1 mA, fixed by a resistor connected to the emitter).
• 3. Finally the gain Hfe = Ic/(Ib+Icbo) is calculated.

Note that additional testing of the transistors will likely lead to variants in results due to ambient temperature of the room and handling of the component. When the temperature rises by 10°C (or 10°K), the leakage increases by 2 times and also the gain increases by several %.

If you buy more than one item, please do not pay until we issue you an invoice for combined shipping. The shipping will have a tracking number.