144MHz SSB Transceiver GW4RWR
Summary
In 2001 I bought an FT-225RD. That classic radio has done me very well, both for operating and as a learning experience. But it had a few features that I didn't need, such as FM, repeater shift, tone burst, VOX. It also covers 4MHz, whereas I'm only interested in the lowest 500kHz. This radio is my alternative version. No PCBs, rather the double sided Cu boards were carved with a sharp knife or a 'Dremel' engraving machine.
Front panel:
From left to right, the front panel switches are AGC slow/fast/off, EXT VXO, n/a, MOX, RIT/XIT, Band, LSB/USB/CW/AM. At the right side is Clarifier, RF gain, TX Power, MIC gain, AF gain. I should have put the mode switch on the right side, which is where the IF modules are located. The mode switch connects to about twenty wires, some of which are shielded, and they take up quite a bit of space. In retrospect, it would have been tidier if I had used a simple four way switch and used TTL closer to the IF board to actually do the switching.
Green LEDs indicate Clarifier, External VXO, TX and sequenced PTT out to external amplifier. There's also sequenced output for TMA rx isolate and antenna Tx/Rx relay. It's tidier to have the sequencer inside the radio than in a separate box.
The frequency display gating time is a little annoying at 1s, but I got used to it. The display's rear mounted, but the 2mm panel hole is infilled with dark blue perspex which is flush against the front panel.
Rear panel:
Separate Tx/Rx panel plugs, spaced to accommodate a CX-520 relay if the radio is operated stand-alone.
'RCA' sockets for three sequenced ground-on-transmit lines. 3.5mm sockets for external loudspeaker, and CW key.
BNCs for ALC in, AF line-out, External LO in, two spare - maybe for buffered Rx IF out, and -30dBm RF o/p to an analyser?
The modules
Separate units make it much easier to swap out modules to try something else.
Audio:
I replaced the original LM386 with a car radio IC, which has lower noise and higher output. On the same board is the CW sidetone and 'soft start' rx to get rid of loud clicks that used to be deafening if I was wearing earphones. I intend to add a CW filter on this board.
The future:
I have two more 10.7 2.4kHz filters. I think an HF radio should be next; 14,18 or 28MHz? I find 28 is the more interesting band, although there's more activity on the lower bands. Unfortunately 14MHz seems to be contests all weekend and rubber-stamp "59" contacts during the week.
How about two parallel RF and IF stages, for diversity rx? Or stick with mono AF and use the spare ssb filter for an RF clipper. Suggestions please?
