Skip to main content

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…

Comments

Post a Comment

Popular posts from this blog

Building the W8NX Short Trap Dipole

Image
  Building the W8NX Short Trap Dipole Filed in Antennas on May.31, 2021 For the past five years, I have been operating the lower bands (30, 40 and 80 meters) with a trap dipole that was modeled after a web article written by John DeGood NU3E. [1] While the antenna performed well, a monsoon storm last summer beat it up enough that the antenna wire broke at the center balun. So I climbed the tower and lowered the remains of the antenna to the ground for repairs. On closer examination, I discovered that the relentless Arizona sun had taken its toll on the traps. The insulation on the exposed ends of the coax had rotted away. They were still working, but would need to be rebuilt and weatherized to insure good operation many years into the future. Since I was going to have to rebuild the antenna, I started thinking about whether this antenna met my current needs and wishes. I had been wanting to get on 160 meters at this QTH for some time, but my small back yard w...
Read more

Yaesu G-450XL Rotator Repair

Image
  Yaesu G-450XL Rotator Repair Filed in Antennas on Dec.30, 2007 In December of 2007, the rope support for the center element of my Cushcraft A3 broke, requiring me to climb the tower and bring the beam down for maintenance.  At the same time, at had been noticing that the rotator control was not indicating correctly, it was very erratic.  So I brought the rotator down for maintenance, as well. The first step was to mark the side of the case, where the top and bottom of the clam shells connected together.  This would allow me to assemble it in the correct alignment when the time came.   Marked Case of Rotator Next, I took the top cover off.  All of the bearings between the clam shells in the depression on the outside were safely stored.   Top Removed A little inspection revealed what the problem was.  The center gear had broken away from the shaft it was pressed onto.  I tried re-pressing it back onto the shaft, but it was to...
Read more

Kenwood TS-790A Light Replacement

Image
 I noticed a while back that my TS-790 meter displays had gone dim.  While I had the radio opened up to adjust the master clock. I decided to replace the burnt out incandescent lights with new white led lights. I neglected to take any pictures until after the work was done, but this will show where the lights are located, and which led bulbs I used to replace them. To access the 3 bulbs for replacement, I removed the top cover.  This and the bottom cover had already been removed in a prior repair in my case.  So I don't know if the bottom cover needs to come off or not. There are two screws on each side of the front faceplate.  I removed the top screw and loosened the bottom screw to allow the faceplate to tilt forward off the edge of the bench.   Faceplate Screws   Be careful when tipping the faceplate forward.  I managed to break one wire out of a connector on the bottom right side.  I was able to reattach the wire with the faceplate open....
Read more