Well we spent the better part of a weekend preparing the case internals and mounting the LCD. All said, it turned out well enough. I am quickly learning that adapting an existing case to a new project, can in fact be just as much work as building a nice cabinet from scratch! Modern factory equipment fits together with very fine tolerances and grafting something “Alien” into said environment tends to get tricky if you’re wanting everything about the case to close back up correctly. This is a picture of the LCD mounting. This was done with small wing brackets made of PCB material. This was the second attempt, the first was with made with a set of home made aluminium brackets. Which were a failure, as the front panel could not sit flush with the case.
The next thing to do was add some ground plane surface area to work with. So some PCB material was cut to size. Given a spray coat of protective PCB lacquer and the result looks something like this. The rig is not a large one and I’m quite concerned about having enough raw “space” for building circuits using “Dead-Bug” or “Manhattan” style. So I wanted to be able to build circuits both top and bottom. To this end I had to use the brass PCB stand-off spacers to lift the PCB material up from where it would normally mount on the chassis. So that there would be enough room underneath for circuit components. You will note that my stand-off spacers are not fixed with bolt nuts. But instead yet more stand-off spacers are used. This is because I pulled all these brass spacers from very old PC’s many years ago and for the life of me can’t find another nut or bolt to match the thread pattern! Well, at least not in my junk-box that is. No harm done. It’s functional and I had plenty.
I didn’t have a double sided PCB board. So I simply used two sheets of single sided material back to back. Making a mental note that it is probably a very good idea to electrically join the ground-plane areas. Just so I don’t get any strange unpredictable capacitance effects. Having the top and bottom boards “separate” could make experimental life easier later on if I need to remove one or the other.
The board underneath is not cut to the exact same size and shape as the top piece simply because it was the off-cut from the top board. Waste not, want not.
Those with sharp eyes will note that an additional rotary switch has snuck into the front panel in these photos. The original band switch was connected to a shaft that activated various PCB mounted stage switches. So when the original board was removed the knob and shaft went with it. Since I plan on all the front knobs and controls being functional I needed to replace it.
Next I wanted to add another PCB and a power transformer to the otherwise unused area of the original receiver. This radio is going to be a home QTH desk job. So I’ve decided to try and incorporate the power supply into the radio. To this end a multi-tap transformer went atop another slice of PCB material. Power supply to be built later.
Then I needed somewhere to mount my radio logic Ardunio board. So this was done over the top of what will be the power supply underneath. All the mucking about broke a couple of wires of the LCD display. No matter. The ribbon cable is not long enough anyway. So that’s the next job.
If one looks closely at the photo of the logic board and PSU area. You can see a problem waiting to bite the unsuspecting constructor – Hard! The left most corner of the PSU PCB material is sitting under a plastic protrusion from the front panel. This is in fact the integral front panel headphone socket. This is bending the PCB material down and placing preasure on the front panel where none should be. Look up from that point and you can see one of the front panel self-tapping screws holding the bezel in place. The result being the front panel was miss-aligned to the case body when assembled. Worse still, it resulted in that particular bezel mount point snapping off under the lateral force. So that front panel mount point had to be Super-glued back on. And it remains to be seen how strong it will be. Gluing plastics is tricky. A small section of the PSU PCB material was trimmed away with a nibbling tool to clear the headphone socket. Now the case can be reassembled and everything aligns properly.
So the day finished looking like this. Not too bad. At least the case fits back together nicely with proper alignment. I’m probably going to need to more ventilation holes. The case by the way, is predominantly made of plastic. In this last picture the main tuning knob is held in place for the “Photo Shoot” by a blob of Blue-Tack. The tuning pot that I had available with a splined shaft to match the original knob was just not long enough in the shaft to reach. So I’ve got a couple of 100K linear pots on order with a longer spline shaft which I think will be suitable.
Next up… Fixing up the LCD ribbon cable and cleaning up the shack work bench. Now that should take a day or two!!