FT-221 improvements- CW
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If you change Q07 (PB-1460) to BF199, carrier leakage in CW may be reduced by
10-15db. Key on/off ratio will be about 50dB.
If you change the transistor Q01 also to BF199, a further 5dB improvement can
be reached giving a 55db on/off ratio.

This was tested with the following set-up:

Converter 10.7MHz to 500KHz (2xBC547 with 11.2MHz xtal).
Siemens 3D344a2a "Pegelmesser-selektiv" (selective voltmeter) with +20 - 120dB

The signal output from Q08 was also changed, 100+120 ohm voltage divider with
1nF directly to Q07.
I believe that a better figure for keyed carrier on/off ratio would be
preferred, but the achieved value is acceptable.

CW MS modification will also be tried, a new PCB for keying must be built,
using an LM324=MC3403CP

73 jan-martin LA8AK @ LA5IV

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