PC Programming Parts List
Q1 = 2N2222
Q2 = 2N2222
Q3 = 2N2222
Q4 = 2N2222
Q5 = Not Used
Q6 = 2N3906
D1 = 1N914
D2 = 1N751A
D3 = 1N914
D4 = 1N914
R1 = 47K
R2 = 47K
R3 = 10K
R4 = 12K
R5 = 470K
R6 = 47K
R7 = 47K
R8 = 47K
R9 = 100K
R10 = 100K
The abbreviation NC means no connection.
The DB9 connector can be Radio Shack part # 276-1538 or equivalent.
A good place to start looking for the 4 conductor plug is Tower Electronics:
1-800-662-3422. The 2N2222 can be substituted for any general purpose NPN
transistor, while the 2N3906 can also be substituted for any general purpose
PNP transistor. D1,3,4 are general purpose silicon diodes. D2 is any 5.1V zener diode.
All resistors are 1/4 or 1/8watt - 5% tolerence resistors. This PC programming cable can also be built with
SMT (Surface Mount Technology) parts if desired.
The interface is a bidirectional level converter, changing TTL-level to RS232, and vice versa.
The supply voltage comes from RTS, CTS and DTR and is stabilized with D2 to 5V. Q1 works as a simple switch,
getting the data viz R8 from the PC. In the opposite way Q2 drives the push pull stage Q6 and Q4.
This cable works with the Yaesu FT-50, VX-1R, VX-5R. The cable can also be adapted to work with the
FT-10 & FT-40 - which use a 3 conductor programming cable.