Working on the design and layout for the SB-
The original intention was to use low loss ceramic switches with a single set of circuitry to cover the three bands 50, 70 and 144Mhz and some prototype work showed that this could be accomplished electronically. However, it could not be fitted into the depth of chassis size that was available (another SB-
The next photo shows the final layout of a single transverter viewed with the rear panel on the left and the front panel on the right. It takes up one third of the chassis space of an SB-
The first photo shows the initial layout attempts with the switched arrangement in pencil on the left and the non-
Two days of work in the garage/workshop produced the chassis, front panel and bracing structures using fairly basic tools including a bench drill, vice mounted bending irons and a selection of files.
The chassis and front panel are made from NS4 Half Hard 16SWG aluminium which is very strong but too hard to bend. The remainder are made from a bending grade 16SWG aluminium.
All that remain to be made are the two horizontal cross bracings that join the front and back together at the bottom of the front and rear panels and the retaining angles for the (SB-
Two further days and the main drilling and punching is complete allowing assembly to commence. The long slots will each hold a receive converter RF stage on a tin plate base as they have solder in valve-
The rear panel holds the 11 way power connector, three RF output connectors, interfaces to three external transceivers, an interface to optional external linear amplifiers and the power and control interfaces to a separate 432MHz transverter.
After a lot of work the 50Mhz transmit section is working and the 50Mhz receive section is waiting on completion of the RF amplifier. The box at the lower right of the picture contains the solid state (J310) simplex and repeater crystal oscillators -