reverted to 6V6s for both VFO isolator/amplifier and multiplier. The tuned capacitors in these circuits were mounted behind the controls labelled OSC PLATE and DOUB PLATE as in the original transmitter. Plug-in coils were used in the original to enable the transmitter to cover the frequency range mentioned earlier. In this case the transmitter was only required to cover the 7, 10 and 14MHz bands and some experimenting showed that this could be done without changing coils. The multiplier stage doubles the 3.5MHz VFO output to 7MHz and this is used to drive the PA stage on 7MHz and 14MHz. On 14MHz the PA stage operates as a doubler. On 10.1MHz the multiplier stage triples the 3.666MHz VFO output to 10.1MHz to drive the PA. The general design of the transmitter is shown in the following block diagram,
Block diagram of the modified Harvey transmitter The original antenna link coupling arrangement was replaced with a Pi output circuit for greater harmonic suppression, availability of components and ease of
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