Projects, past & present

Yaesu FT-901DM - extension boards

This had been the main station rig until 2010. A real heavyweight, but virtually indestructable. However it had one or two minor faults and I had been unable to do any diagnostics as the PCBs are mounted vertically and inaccessible.

So, I explored many avenues to try to source a set of extender boards, but failed. So the next task was to 'manufacture' a pair of boards. It required a very simple layout, but it was to be double sided. I decided to use a laser print and transfer the image (as a mask) to double sided copper board. Meanwhile I had great difficulty locating the connectors (0.156" spacing) but eventually found an advert for a company dealing in electronic items - particularly 'obsolete' components.

Two boards are needed - an 18pin and a 10pin. The 'artwork', for what it's worth, was soon completed and the next stage of printing the artwork and transferring this to the PCB surfaces.

Main HF rig, 2m TxRx & Ae Auto tuner

The 18way - double sided extender was completed successfully. As the PCB 'artwork' was very simple, alignment of the two sides was not a problem. I used a (Samsung) laser printer with glossy inkjet photo paper to produce a suitable transfer medium. The toner was transferred to (well cleaned & burnished) double sided copper clad board, using a househoil iron on maximum heat.

The etching took about 30mins in a fairly strong FeCl solution. The connectors were 20way, so I cut one end and after reducing it to just the piece with the mounting, glued (good ol' Araldite!) it to the cut end of the connector. I then glued two strips (cut PCB) to each side of the connector to give strength to the attached end-piece. All this was for aesthetics rather than functionality. After soldering the 36 pins to the copper strips, I applied a layer of spray paint followed by a layer of laquer - just to minimise the possibility of inadvertent s/ccts while testing.

The first fault, a problem with AM mode, was soon resolved. The extender bds were invaluable in solving the problem (actually a short between two of the IF boards connector pins).


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