All HF bands transmitter design (experiment)
by sv3ora

Schematic of the transmitter section below.



The VXO arrangement varies the frequency to an adequate range even at 160m, but does not change the output level much, which is good. The combination of TX tune and RIT, makes the transceiver capable of transmitting at either sideband, so you double the chances for a contact. TX tune and RIT controls almost don't affect each other and they have adequate and quite even spread.



The version above uses a relay and a separate receiver mixer can be used.

The low pass filter design is shown below.

Band
Input/output capacitors
Inductor
160m
820pF
5.56uH
80m
820pF 2.58uH
60m
820pF 1.61uH
40m
820pF 1.05uH
30m
820pF 542.3nH
20m
820pF 291.2nH
17m
820pF 186.2nH
15m
820pF 132.7nH
12m
820pF 102.9nH
10m
820pF 78.5nH

The filter schematic is shown below. All coils implemented with 1mm enameled wire. Coils are wound onto appropriate diameter drills, then the drill is removed.



Pictures below, show how to wind the coils. They are all close wound with 1mm enamel copper wire.


160m


80m


60m


40m


30m


20m


17m


15m


12m


10m