Executive Summary
Still trying not to waste your time.......or am I?
If you look elsewhere on the blog, you'll find the earlier version of a KX-2 handheld antenna bracket. It's been fun, but some people can't work metal, or don't want to leave a bracket on their radio, and, quite frankly, the kit could use a few creature comforts.
The REV.2 bracket uses a Gemsproducts Side KX KX-2 radio mounting plate that snaps on the radio. This way, the handheld system can be quickly attached and removed from the radio, without requiring leaving a bracket screwed on to the radio, or any other modifications to the radio.
The REV.2 bracket also includes a safety lanyard (guess why) so that there is no need to keep a death grip on the radio while operating.
Lighter antennas can be held by adding a Kydex bracket to the mounting plate. To avoid potential stress and large flexing issues, more serious antennas are probably better supported with a metal bracket. I describe both versions below.
Why?
I have several years of handheld KX-2 operations under my belt, and I'm a convert.
Family vacations here tend to be a blur. There are opportunities to get away for an hour of free (radio) time, but often that's it. Getting to a good spot, setting up and getting back in an hour sucks.
And sometimes you can operate from very good spots if you are inconspicuous. I'm thinking particularly of salt water piers or bridges, elevated pedestrian walkways and the like. Think clandestine.
So why not buy a KH-1? Well, let me count the ways, four in particular.
1) More bands (and probably a better tuner).
2) An ability to use a sturdier antenna mount with longer antennas that can buy you 3 to 6 dB of gain (you can stay QRP and still be louder if QRP IS YOUR THING)
3) A more powerful radio, offering over 3dB more output; and
4) DUH, I already have a KX-2 I'm pretty fond of.
Mix this all together and you're looking at potentially up to 10 dB of ERP improvement.
The pocket-sized KH-1 is a clever set up, but I've always got a small sling or backpack, the KX-2 kit fits in it fine, so I have no need for a maximum dimension of 6-8 inches. And YES I'm rationalizing, but it's saving me a grand and I'm louder :)
I've found that the Gemsproducts Side KX KX2 mount makes a great adapter for mounting a serious HT-style antenna to the KX-2 for handheld ops. No radio modification is required and the bracket installs in a few seconds.
This is an image of the KX-2 mounting plate from the Gemsproducts.com website. The plate costs about 30 dollars and is a slick design. Removing one of the thumbscrews from the KX-2 makes it easy to snap this mounting plate off and on the radio, with access to every port and feature remaining available.
Note that this use of the Gemsproducts mounting plate has not been acknowledged, encouraged or endorsed by them. For my applications the mounting plate is fit for purpose, but the following description is my experience, and not a recommendation.
THE NOT SO FINE PRINT
It is always up to you to determine what is safe for you to do, keeping in mind the need to follow RF safety regulations and the safety of humans, animals and other people's property.
Walking around with an 8 foot antenna can be hazardous to you and others, and especially be mindful of electrical or physical entanglements that might arise and AVOID THEM.
Nevertheless, have fun.
Why KYDEX?
I built the first version of this new mount using Kydex because I wanted to avoid metal-working if at all possible.
Kydex can be scored and snapped into the shape needed for the antenna mounting bracket, and the snapped piece can be bent to include the required 90 degree bend with the application of a little heat and a cheap sheet metal press, or using any of the tricks known to bend metal without a jig.
These pictures show the build details.
Start with a piece of Kydex. This piece is 0.08 inches thick. Thicker would be better, but it's all I had. The sheet is scored at 2 inches, and the scored piece is snapped off.
Cut the scored Kydex strip to your desired length, and heat the strip in the area you want to bend it, heating before bending using a heat gun with a narrow focused tip if possible.
I used an inexpensive Harbor Freight sheet metal brake, and if you can get access to one that's the easiest way to go. If not, look at YouTube for all sorts of great ideas about how to make a clean bend in metal without special tools. Hot Kydex will bend more easily.
Here I scored the strip to a length of 5 inches, broke off the desired length, and bent the strip at 1 inch from the top for the antenna mount.
Next, I used the mounting plate as a template to drill 4 mounting holes for the antenna bracket to the mounting plate, and drilled a 3/8 inch hole in the top (horizontal) 1 inch section.
Add the four mounting screws. I think they were 6-32 by 1 inch but use what you want - and you're about ready.
Note the antenna mounting hardware to the right. This is simply a 3/8 -24 bolt of the right length to mount your 3/8-24 coupler (like the kind used on a mirror mount).
There is no need for insulators as Kydex has insulating properties good enough for our needs.
Make up a coax connector assembly.
I used a 5 inch piece of RG8X with a 3/8 inch ring terminal to connect to the antenna side, a BNC connector on the other end for the KX-2 connection, and added a bullet connector to the antenna side shield for a counterpoise wire.
In addition to being an easy connection point for the counterpoise, the bullet's use will allow the radial to unattach if you're walking around and the counterpoise gets snagged. (a good thing)
If you don't like soldering BNC connectors, just hack 5 inches off a BNC jumper, crimp on the ring and bullet connectors, and you're good to go. Additional detail of the coax assembly can be seen in the picture of the aluminum bracket version described in the next section.
Put the radio in the mounting plate and you're ready to go handy!
Note that the aluminum bracket is the old whip mount, it just hadn't been removed yet.
The antenna mounted to the radio in this picture is a Buddistick Featherweight whip.
This is a 6 foot whip that costs $8.50 from Buddipole, plus another $3.50 for a 1/4-20 to 3/8-24 adapter. This routinely tunes to an SWR of less than 2 to1 for me on 20-10 with a 17 foot counterpoise, and almost always to less than 1.5 to 1 on 17-10.
5 bands, 12 bucks, and about 3 dB better than a 4 foot whip. What's not to like about it?
But there is going to be some flex when you use Kydex. And antennas bigger than the Featherweight will make that issue much more apparent.
This picture shows the worst case flex in the Kydex bracket when using an 8 foot tall, heavy slider coil MFJ-1898 vertical. This antenna is frequently my handheld antenna of choice, and this much flex is not acceptable.
Thicker Kydex would help. I didn't have any. And an additional support between the mounting plate and the antenna bracket probably would as well.......
If you look at the top of the bracket you can see that I added a 3/8 inch spacer between the bracket and the antenna mounting plate. This eliminates a lot of the bracket flex, and gives some flexibility to use an antenna heavier than the Featherweight.
I suppose you could carefully use this with the MFJ 1998, but this led me back to using metal for version 2 the antenna bracket.
The Metal Bracket Version
Nothing special going on with using a metal bracket but it does a great job of eliminating flex in the mounting plate/bracket assembly.
The procedure for building the bracket is pretty much the same except:
1) the stiffer aluminum bracket can be 1 inch wide rather than 2. I used a 5 inch long by 1 inch wide by 0.125 inch thick piece of scrap aluminum that was laying around;
2) two screws seem sufficient to hold the antenna bracket to the mounting plate;
3) because the bracket is aluminum it requires the two white insulators above and below the bracket to insulate the antenna from the bracket;
4) the use of the insulators (from standard mobile mount sources) requires that the antenna mounting hole be 1/2 inch diameter rather than 3/8 as in the uninsulated Kydex bracket; and
5) because some recent wintery operation in Iceland had me wishing that I didn't need to hold the radio all the time, I added a second large hole to the bracket to accept a lanyard. This is a real convenience, and can save the day if you accidently let go of the radio. You need to be aware of where the center of gravity of the radio and antenna is, especially with the antenna extended, but worst case the antenna hits the ground and not the radio. That's almost always a win.
Post metal bashing, the aluminum antenna bracket looks like this.
After a bit of paint, the assembled aluminum bracket looks like this. That's the lanyard extending towards the bottom right.
And the completed and mounted handheld system looks like this.
Notice that in this configuration, the antenna center of gravity has been oriented forward over the radio. This is a design choice. It saves a bit of space, and eliminates any chance of your hand contacting the antenna mounting bolt. You can see the detail of the forward mounted bracket below.
That hadn't been a problem for me with the Kydex bracket, but why wait to do that experiment?
Final Thoughts
I was please with how well the Gemsproducts Side KX mounting plate supported the antenna.
The big advantage of the plate-based system is not having a bracket always attached to the radio (as with my first system).
Having the plate there allows for addition of other features, if you are so inclined. I'm shopping for a good pushbutton that can be mounted to the plate and used as an external Push to Talk switch that can be activated by my left (holding the radio) hand to eliminate the need for pushing the panel button to PTT when using the internal mic.
I'm also working on a hand strap that would eliminate the tedium of holding the radio quite a bit.
I'm sure you'll find other great ideas.
If nothing else, it's a cheap way to try out handheld operation before you invest in that KH-1 !
And with a 6 to 8 foot antenna, you'll be 3 to 6 db louder, you can add 3 more dB of power by cranking the KX-2 to 11, and you'll be $900 less poor :)
Cheers, have fun de Scott ka9p/zf2sc.
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