3D Printed Potting Mold

[amaff]

I'm going to be putting together a couple shielded loop antennas for some DF work out of some RG58, but I didn't really like the open solder joint at the bottom of the design I'm replicating. So I designed and 3D printed a hot-glue potting mold so I can protect and support that joint better, since these are going to get treated pretty roughly.

Basic design of the antenna I'm borrowing:

CAD Model of 1 of mold halves (in this case, the half the glue will go in...)

.

 

Took less time to print than design, because I'm not a drafter by any means, but I can fumble my way through drawing up useful parts.
Cable for display purposes here:

 

 

 

I'll come back and update this once I get to use it and see how it does.

[SteveShannon]

Very nice!!

[amaff]

I couldn't help at least trying it with 2 'cables' in the mold and the concept will definitely work. My implementation was a bit crap tho lol

But, a couple lessons learned: 

-Mold release is important. I need to use it. I really didn't think the hot glue would stick to the PETG that well, but boy howdy did it. I pretty much had to destroy the mold to get it apart. Not a massive deal (I've already printed another couple of them), but I wasn't sure whether I'd even get the thing out at all. But using small screw drivers to split the mold apart split the glue around the wire.

-It was designed for a 'hollow' in the middle for the glue to go in. Without that hollow, only a tiny bit of glue went around, so, again, it was easy to tear up. It should hold together with a 'real' piece with the gap there.

-I'm REALLY happy with how it sealed up around the outer sheath of the RG58. I'll need to do a proper job clamping the halves together to keep it pushing apart.

Taped over the open hole to keep the glue in the mold:

The destroyed mold and what was left of the glue 'sheath'. Ugly, but it should work in the real application. It'd look better with black glue, but...meh. I'm not gonna go buy new glue for this haha

[amaff]

It's not perfect, it could probably use a bit more room in the center cavity to get another 1 or 2mm of glue in there, but it worked really well! I really dig the concept and will definitely be using it again.

The setup:
 

After cleaning a little flash up, I threw it in the chest freezer to cool. This is what popped out WAY easier than last time (I used a little silicon spray lube on the mold this time):

Again, it's not perfect (and honestly, I probably just cut a bit too deep into the flashing), but it's a lot more sturdy and protected than it was just off the soldering iron:

 

 

 

[nokones]

This is the Laird Yagi antenna I use for DFing with a VHF/UHF Part 90 cert. radio for the receiving radio.

I am a member of the DF Team for one of my radio clubs.

[amaff]

After all that, I...forgot the hot-glue potted antenna at home 

But I did get to use a different one I made (BNC T connector and a, modified obviously, loop of RG58 with BNC connectors at each end) on a SAR exercise today in conjunction with the L-Per.

The LPer got us close but with the low brush, our group was struggling to find the ELT. So I busted out the trusty UV-K6 and tried it out.
I'll be damned if it didn't walk me right up to the thing. I know in theory that they're really sensitive, but I was shocked at just how sensitive, and just how easy it was to follow it to the transmitter.

Obviously, having a plane in the air also doing DF to walk your team onto the target helps get you pretty close, helps cancel out the downside of this antenna working whether or not you're pointed directly at, or directly AWAY from the target. It ain't cheatin' if there's no rulebook lol

 

[WRYZ926]

I have an Arrow Antennas hand held 2m Yagi and 2m loop for this type of stuff. So far all I have used either antenna was for chasing down RFI issues. They work fine. I like seeing the home brewed antennas and other options for commercially available antennas.

[amaff]

The commercial ones were a bit more than I wanted to spend on an experiment. Might end up making a few more because the other adults were really impressed at how cheap it could be done, and how effective it was. A lot of talk on the trip down the mountain about being able to split into smaller groups to speed up triangulation as well.

[Northcutt114]

OK...sooo after some googling. We're talking about "fox hunting" in this thread? 

[amaff]

Basically.

Very specific aluminum and sometimes fabric foxes, though. 

[Northcutt114]

11 minutes ago, amaff said:

Basically.

Very specific aluminum and sometimes fabric foxes, though. 

I don't know enough to know what that means. But when I saw the Quansheng with the wiggidy wiggidy wack antenna, I got interested. 

[amaff]

10 hours ago, Northcutt114 said:

I don't know enough to know what that means. But when I saw the Quansheng with the wiggidy wiggidy wack antenna, I got interested. 

This was a Civil Air Patrol exercise, simulating looking for a downed airplane with its Emergency Locator Transmitter going off (that's what you're hearing in the video), coordinating air and ground assets, and attending to a cold / injured pilot, and getting them off the mountain.

[WRYZ926]

Fox hunting is a good way to train for emergency situations like amass described.

[Northcutt114]

22 hours ago, amaff said:

This was a Civil Air Patrol exercise, simulating looking for a downed airplane with its Emergency Locator Transmitter going off (that's what you're hearing in the video), coordinating air and ground assets, and attending to a cold / injured pilot, and getting them off the mountain.

That's legit, man. Thanks.

So let me get this straight, though. You had a fixed wing aircraft on station and a $30 CCR won the day? 

[amaff]

26 minutes ago, Northcutt114 said:

That's legit, man. Thanks.

So let me get this straight, though. You had a fixed wing aircraft on station and a $30 CCR won the day? 

That's probably overstating things. Real world, they would have walked us right onto the target if we needed them to. And honestly, they pretty much did.

To explain:
Because we were running an exercise, the people who set it up were free to be a bit diabolical.

The actual "aircraft" structure (a bunch of tarps laid out in the shape of an airplane, nice and visible from above) our plane talked us right onto.

Our victim was displaced from the plane (as though they had gotten out in the cold to seek shelter overnight). But the REAL trick was that the ELT was displaced away from the "aircraft" a small distance, and we didn't actually realize that until after we packed up our "aircraft" target and we were all going "hey...who picked up the ELT? The plane's still up and says it's still on, so turn it off!" and none of us had it.

The plane's a hell of an asset, but trying to pick out a fairly small orange box (see the last photo) that's in scrub grass, brush, and red rocks from 1000' up at ~100 mph is not exactly easy.



I happened to be with the crew packing up the plane when we realized no one had actually found the ELT, and had my UV-K6 at hand. Another part of our group, hearing on the radio what was going on, was un-packing our 'official' DF gear that we had already packed up, assuming we were done. But I called out that I'd found it before they were really able to get set up. They'd have had no trouble finding it with that either, but it was nice to have a real-world test of some easily packable back-up gear.

[Northcutt114]

54 minutes ago, amaff said:

That's probably overstating things. Real world, they would have walked us right onto the target if we needed them to. And honestly, they pretty much did.

To explain:
Because we were running an exercise, the people who set it up were free to be a bit diabolical.

The actual "aircraft" structure (a bunch of tarps laid out in the shape of an airplane, nice and visible from above) our plane talked us right onto.

Our victim was displaced from the plane (as though they had gotten out in the cold to seek shelter overnight). But the REAL trick was that the ELT was displaced away from the "aircraft" a small distance, and we didn't actually realize that until after we packed up our "aircraft" target and we were all going "hey...who picked up the ELT? The plane's still up and says it's still on, so turn it off!" and none of us had it.

The plane's a hell of an asset, but trying to pick out a fairly small orange box (see the last photo) that's in scrub grass, brush, and red rocks from 1000' up at ~100 mph is not exactly easy.



I happened to be with the crew packing up the plane when we realized no one had actually found the ELT, and had my UV-K6 at hand. Another part of our group, hearing on the radio what was going on, was un-packing our 'official' DF gear that we had already packed up, assuming we were done. But I called out that I'd found it before they were really able to get set up. They'd have had no trouble finding it with that either, but it was nice to have a real-world test of some easily packable back-up gear.

And all I did yesterday was sit on a park bench and miserably fail a POTA activation. Congrats for getting out there and getting stuff done. Thanks for your service!