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Boxing Up the MMR-40

 

Boxing Up the MMR-40

Filed in Kits on Dec.11, 2009

I’ve been told that the site is getting a little stale, so I better get another post on.  I usually wait until I have more progress, but here’s what’s been happening lately.

I’ve seen a couple of examples of people packaging up their QRP kits into old CB Radio Chassis.  I was able to locate a used CB through Craig’s List.  It cost $10.00, but I think just the parts alone are worth that.  It has the SO239 antenna connector, a speaker, microphone, meter, several switches and potentiometers, and a few RF transistors for salvage.  So I’ll try to put the MMR-40 into the chassis, and include metering circuits and a digital frequency readout.

Here is what I’m starting with (excuse the fuzzy pictures, I had low light while doing some of this):

Cobra CB to start with

Here is a top view of the complete CB.  Notice the nice RF final that should come in handy someday!

Cobra Top View

And it has a nice, big speaker that should enhance the MMR-40 sound over the tiny computer speaker I’ve been using during construction.

Speaker

So, after completely gutting the old radio, I went to work making a new front panel insert that I can put holes in appropriate places and cover up the old holes.  I used a 6″x6″ piece of printed circuit board, and trimmed it to size by scoring the copper and the substrate, then putting it in a vise with a couple pieces of plastic aligned along the score.  Then I just bent the circuit board over until it snapped off.  A piece of sandpaper smoothed the sharp edges.

Trimming the faceplate

So here is the faceplate and the face it will cover…

Blank Faceplate

Next, I went to work cutting the hole for the meter.  It’s a little tricky cutting a square hole, and I still don’t have it down, but here is what I tried this time… I marked the hole and drilled the corners.

Mark Hole

Then I used a coping saw with a very narrow blade to rough out the rectangle…

Cutting Meter Hole

By using a needle file to smooth up the cuts, here is how it turned out…

Meter Fit

To be continued on next post…

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