The QMX Gets a Paddle Mount
Executive Summary
If you're a fan of handheld QRP cw rigs, you may envy Elecraft owners' ability to mount Elecraft paddles directly to an Elecraft radio.
I do. But I often use GM0EUL Academy paddles on my KX2 and KX3 because Peter has developed a paddle mount with two axes of motion This is a big advantage over the KX fixed mount. And an especially big advantage if you operate the KX2 as a handheld - a favorite vacation mode for me.
But for a number of reasons, the QMX often gets the call, either as a primary or backup rig. And I'd like to use the Academy paddles mounted to it. So what to do?
I solved this problem with my (tr)uSDX by drilling and tapping holes in a side panel so that I could directly attach the panel mount to the cabinet. You can see that HERE. Intermingling of the Species...The tr(u)SDX Gets an Academy!
But if you've built a QMX, you know how packed the cabinet is. It might be possible to drill and tap the cabinet, but I was looking for a simpler, safer way to use the Academy with the QMX. I think IMHO this is it.
Some Background
If you're not familiar with the Peter's paddle or the mount, look below.
The blue fixture next to the Allen wrench is the paddle mount. On an Elecraft radio, the two thumbscrews thread into the panel to hold the panel in place.
Admire the mount for a moment.
The first advantage of this mount is the adjustable hinge between the swing arm and the mount base. This adjusts with the Allen wrench.
The second advantage comes from the Allen screw mount of the paddle (orange) to the mount swing arm (blue). The paddle can swivel to most any orientation you want before tightening it with the second Allen screw.
Two degrees of freedom more than an Elecraft mount.
But how to get that on the QMX?
A Hairbrained Idea
What if there was a "secondary panel" attached to the QMX cabinet (the "primary" panel ")?
If the panel was thick enough that the thumbscrews could penetrate the secondary panel without hitting the primary panel, we might have a winner.
If we had a clean method to attach the secondary panel to the primary panel, Bob might be your uncle :)
The Secondary Panel
How to make a secondary panel? Not having to do metalworking would be a big plus.
The junk box yielded some scrap FR4 sheet that was just a bit thicker than the free length of the paddle mount thumbscrews, so that was where I started.
How big should the panel be? Here's where it got tricky. It could be the same size as the mounting flange on the paddle mount. But I decided to make it almost the length of the QMX panel and a bit thinner.
Why that large? I was considering using a removeable adhesive to mount the secondary panel, as the larger surface area between the two panels would provide more hold strength.
Why else? If the secondary panel runs the length of the primary panel, multiple mounting positions can be available for the paddle, or for any other add-ons you might like to attach to the QMX. The paddle mount mounting holes are 1 1/2 inches apart, so I drilled a series of holes separated by 1/2 inch to enable those features.
The mounting holes need to be 4-40 threaded, so per the standard, use a 3/32 inch bit to make the holes to tap. Remember that this is fiberglass, not metal. Take it easy and go slowly when tapping, there's a lot less resistance than when tapping metal.
To mount the secondary panel I used two-sided carpet tape. Amazon's finest has held well on projects requiring less adhesion, and it would allow for relatively easy removal of the secondary panel if things didn't work out, or if access to the radio internals was needed.
The protype secondary panel looks like this.
You can see in the picture that no matter how many times I work on projects like this, I continue to overestimate my ability to eyeball a straight line of holes.
That's why it's a prototype. Peter's bracket has some adjustability, so any misalignment can be minimized with that.
Note the bracket sits on an exposed surface of one side of the carpet tape.
Next I trimmed the carpet tape around the panel with a sharp blade. That yields a peel and stick mounting panel that can be easily attached to any smooth surface.
You may be skeptical about carpet tape's ability to hold the bracket to the panel. I was. So I fastened the prototype to a metal radio shack shelf.
Several efforts to dislodge the bracket failed. I needed to drive a flat blade screwdriver under the mount to pry it off. A bit of GooGone took care of a minute amount of residual adhesive.
Back at it. You're about done. Peel the backing from the second side of the carpet tape and slap the panel on the QMX.
Add the paddles to the bracket, and Bob really is your uncle! This is my preferred orientation for handheld operation, obviously YMMV.
Yep, it's stupid simple, but it's taken me way too long to figure it. I remain a big fan of handheld operation of little QRP rigs, and attachable paddles generally. I'm an antenna mount away from finishing my handheld QMX.
The usual fine print: I write about my experiences. These aren't recommendations, they are thought experiments to help you come up with something that you deem safe and suitable for your use. Have fun.
As always if you have any ideas for improvements or other feedback, shoot it in, and with your permission, I'd love to share it here.
72 Scott KA9P/ZF2SC
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