This page contains summaries of valved designs common in the 1950s and 1960s and would make fun projects for home constructors. There is no reason why they cannot be customised for the additional HF bands that we currently can use.
1. VFO -
I built this as a penniless student in 1960 when first licenced and made thousands
of contacts on CW (full break in) and rather less on AM running around 5W output
Switching has been omitted for simplicity. Grid blocked keying was used which is
shown elsewhere on this site. The PA was modulated on AM using a simple design based
on a pair of 6L6 valves in push-
For a really minimilist design the first buffer can be omitted but this requires multiplying by two for 28Mhz in the VFO anode circuit. A drive level control will be required and the grid current in the PA must be metered. The intermediate tuned circuits can be ganged together as shown or tuned with individual controls.
Tunable IF Receiver with Crystal Controlled Converter
By today’s standards this design has a number of issues which could be significantly improved, particularly in respect of gain distribution. However, in 1960 it performed much better than its predecessor which used 6K8 mixers with no SSB filter. The new design allowed me to operate in the presence of nearby strong transmissions on the same band with significantly reduced intermodulation and blocking problems.
The fast break-
Details of the grid block keying, receiver mute and electronic T/R switch can be found here on this site.
Details of break-
There are alternative beam deflection mixers to the 7360 at rather lower prices although the performance may not be quite as good.