70MHz SSB Transceiver GW4RWR
Introduction
My original intention was to make separate front-end, mixer and transmit boards to equip the FT-225RD for 70MHz, but I decided that a dedicated 4m radio was worth having. USB/CW modes were required, and the radio's performance should be at least as good as my modified FT-225, i.e. be contest-capable. Being dedicated for this band, it would always monitor 70.2 when I’m in the shack, and would avoid tying up the HF radio with a transverter and all associated cables.
The cabinet is galvanised steel, so tough as old boots and it should outlast me. Covers are brushed steel from an industrial air con, recovered from a skip at work.
The front panel switches control AGC slow/fast/off, Band, Freq counter, MOX, RIT/OFF/XIT. Knobs for LSB/USB/CW, Clarfier, AF gain, Power o/p, RF gain, MIC gain.
The rear panel has separate Tx/Rx sockets, suitably spaced to mount a CX-520 relay. Phono sockets carry PTT out to switch an external amplifier, and ALC back to the IF board from the amplifier's directional coupler. A 3.5mm socket connects to the CW keying line. The DC power connector is Yaesu fit, allowing me to use the same leads that fit the FT-707 and FT-225RD.
The modules
I learned the hard way that it's far easier to modify a project if it's split into discreet boards, and the easier each one is to remove, the better. Single boards save space, but are not good for prototyping. I leave them to the experts
