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Hi, attached is a small qrp CW transceiver schematic.
I do not understand how TX can be activated this way.
When key is connected do GND no power flows to the buffer amplifier according to this schematic, so how is the TX activated?
Since I would like to build it European/US style I would like to know suitable replacements for the three types of BJTs, are 2n2222, 2n2907 and BD139 suitable types?
BC237 and BC227 will work just as well, they only carry a small current. BD139 should be OK as the PA transistor. Be careful that you find a compatible FET though. If the FET isn't available, you can use almost any analog switch (DG..., CD4016, CD4066 etc.)
BC237 and BC227 will work just as well, they only carry a small current. BD139 should be OK as the PA transistor. Be careful that you find a compatible FET though. If the FET isn't available, you can use almost any analog switch (DG..., CD4016, CD4066 etc.)
Brian.
I thought the FET, since it is used as a switch, can be mpf102/j310/2n7000 or similar.
Have you got any idea of a European alternative for this FET? It will save me trouble.
Thanks a lot!
Almost any FET can be used but make sure it is a depletion mode device. The 2N7000 series are enhancement mode types so if it works (unlikly) at all you may find it is in reverse!
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