Experimental QRP Transmitter by I. Tsapiv (UB5DT):
This simple two-stage telegraph transmitter has been developed for a QRP experiments on the amateur HF bands.The rock bound exciter on the 6П3С (6L6) vacuum tube utilizes circuit known as the "Three-point" (or Tritet in common notation). The crystal controls the frequency of oscillation - 3510kc in this case. Signal output is taken from a separate tuned tank circuit L1C4 in the plate circuit of exciter; this tank should be tuned to 3510kc or 7020kc.
The second stage on the 6П7С (6BG6) tube acts as an amplifier or frequency multiplier (doubler or tripler) depends on an inductance of the L2 coil and bias voltage on the signal grid of this tube.
If you would like to use this transmitter on 80m band as well as on 40m with a noticeable lowered power, you have to connect an antenna to the "A1" connector and pull the amplifier tube (6BG6) out from the socket. For the general power output on 7020kc and QRP operations on 14040kc and 21060kc that tube has to be back and antenna switched to the "A2" output connector.
Several interesting QSO's has been obtained using this transmitter in October 1966. For example, UA0MX and K2AGU on 14Mc, and F9MC on 21Mc with a power level as low as 1.7 Watt.
Measured Power:
frequency | single stage (6П3С) | both stages |
---|---|---|
3510kc | 8 W | - |
7020kc | 3 W | 18 W |
14040kc | - | 6...8 W |
21060kc | - | 1,5...2,5 W |
Several interesting QSO's has been obtained using this transmitter in October 1966. For example, UA0MX and K2AGU on 14Mc, and F9MC on 21Mc with a power level as low as 1.7 Watt.