All HF bands transmitter design (experiment)
by sv3ora

Schematic of the transmitter section below.



Below is a version where the final BJT is used as an RX mixer. This idea has not been fuly tested.



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