Yes I think the 3d printable designs that we find for all those antennas are very similar to the one you made. I want my coil to be “all in one” piece to replace the red base piece: double M10 nuts + coil + BNC connector. It has to be strong. I don’t really see how it would be possible for me to make such a part, except for 3d printing it.
That’s why I proposed this one in a message above:
This design is probably a good candidate for this purpose. We just need some modifications to accommodate a bnc socket instead of a so239, and maybe a little change in the pitch of the helix to be compatible with the crocodile clip method.
I received one of these ‘5.6M QRP Antennas’ as described in the original post. The telescopic whip is not useable as the brass insert with the M10 thread is not firmly crimped. With the thread gripped firmly in a vice (with soft jaws) and the whip collapsed, the tip moves around freely 5 - 10mm. It’s definitely not rigid enough to use unsupported, and even with support, I don’t want to trust the electrical connection.
These telescopic whips are cheap and likely to vary in quality - it looks like I got a bad one. obviously I should send it back, though I’ve already marked the base with ANT - GND symbols and reworked the counterpoise wires, so it’s no longer as delivered.
Has anyone encountered this and found a work-around?
I have found that reporting the condition of such items usually results in a request for a photo and the offer of a replacement item at no charge. And a request not to return the faulty one.
You could try improving the crimping already in place. You can see numerous points where the metal has been deformed by a point to crimp the thread to the outer. Try using a hammer and centre punch to re-crimp those points. Or add more crimp points.
I effected the same repair on a very old pair of Leki aluminium walking poles when the joint mechanisms worked loose. Smack with a hammer tightened up the same type of joint and they continued to support my vast bulk for several more years.
I 3D-printed a base without any coil and found that a heat-set insert worked quite well to fix the antenna in the 3D print. I would recommend trying that instead of the double M10 nuts. My motivation for making a 3D-printed base was not to make a coil, but to get a BNC connector, banana plugs for the radials, and a neat way to fasten a tent plug. You can see some pictures here.
Why do you want 2 M10 heat inserts? I think it should be possible to make a dipole from this whip as well, but I only needed a single one for the vertical.
I added two banana plugs for the radials, but that is also more than strictly needed. I have used it successfully with radials in only one of them. Nonetheless, it is somewhat convenient to have several radial sets and be able to use two of them.
I want two M10 because the ground spike is also M10 and I want to keep that long ground spike. Even with this one I found the stability a bit mediocre when activating in the fresh snow.
The two radials connectors are probably a nice addition because I like mine with a lot of radials, like 8 or 10. And connecting two groups of 4 sounds much easier than one of 8.
Mine arrived on Monday with some other bits and pieces. Bag had a hole in it but they hadn’t tried to put it through the letter box. Thankfully nothing lost, although one seller had only sent half the mini DIN connectors I had ordered.
Tried the antenna out last night on GW/NW-044. The weather was awful, couldn’t see a thing so had to sit at the side of the path to make sure I didn’t get lost in the fog.
I was worried the whip would bend over in the wind however it was fine in my slightly sheltered spot.
Almost fully extended, the SWR was about 1.5 on 20m. I might’ve been able to get it better but it worked and I made 5 contacts. On 15m, I was able to tune it so the SWR meter was showing 1.0 and got USA, Canada, Brazil and Tenerife in the log - although I was running 50W.
So it worked, and it was convenient to set up.
The ribbon cable radials worked OK, although they get tangled easily so I will replace with 3x wire radials and see if that is easier.
I will also try to find a way to mount the base of the antenna above the ground (maybe a threaded insert or cap for the bottom few sections of a travel pole) to see if that improves performance because ultimately I want to use it with QRP.
I have 2 of the cheap antennas - bought the first one about 2 years ago but usually default to my JPC-12 so I have 40 meters but I have always wondered whether the coil on the cheap whip would be less to carry and easier and quicker to setup in the field than the JPC-12. Yes, I could make one but at a price of NZ$26 on Aliexpress made for purpose, why would I bother.
Anyway, any experiences with these coils would be much appreciated…or I might just pull the trigger and buy one
Here is a link to this particular coil if anyone is interested.
So had mine out today up GM/SS-254. I was using my tr(uSDX) with Kanga pocketmatch. Got about 10 QSO’s as far as Ukraine. V happy with it and impressed it stood up to the wind today, about 20 mph.
I made 2 groups of radials, 2x2.5m and 3x2.5m.The first tests are promising. I can tune all bands from 40 to 10m with SWR <1.2.
For 40 and 30 m I connect only 2 radials, and lay them in the opposite direction.
From 20 to 10 m, it’s 5 radials, in a star shape.
Audio comparison on 40m, EFHW (20m long, 6m mast) vs vertical whip + coil. WebSDR is located at 250 km.
In the audio sample you can hear in order: EFHW broadside to target - Vertical with radials in the axis of target - EFHW again - Vertical with radials in the axis of target - Vertical with radial perpendicular of target.
All audio sample are recorded with only a few seconds interval.
The EFHW is clearly wining on this one, beating the (high today) noise floor easily. However, the compromised vertical is not ridiculous and I believe contact can be made. Of course it’s variable and different results may be found in different conditions but it gives an idea. Maybe more test in the future.
Well, I answered my own question. Does the Aliexpress coil for $NZD26 or 13 Euro, allow the Aliexpress Whip antenna to tune 40 meters. I had always been on the verge of buying one of these coils without any input from anyone who had used one. So I took the punt and purchased one. Here it is set up in my wife’s garden just outside of my shack a couple of hours after it arrived in the post.
I set the NanoVNA for 7.070 Megs to 7.350 Megs and the result was in the range of 1.6 to 1.9 SWR. Now this has been achieved by shortening the whip by just one section. The radials are stock standard and just thrown out in 4 directions. While this result is sufficient for most purposes I am sure that I could get it down further with a bit of adjustments to the radials.
Anyway, thought I would share this with you and I will update any further findings as I take it out and try to make contacts.
Mine arrived the other day. I had to extend the whip all the way out (for 20m, it’s not quite fully extended) but it gave a really low SWR. I managed to qualify the summit on 40m no problem.
I’ve also swapped the radials to larger diameter silicone wire so they are less prone to getting tangled and so easier to deploy.
Not used it yet for SOTA but did take it on a trip to Namibia last summer. The whip is poor quality and the crimp at the base on mine is now loose, the top couple of sections came apart after a few deployments. Still it worked as really there is not much not to work if it stays mechanically together.
As mentioned earlier, I have made a 3D-printed base for this antenna. I used banana plugs as the connector for the radials. This has proven very practical in the sense that the antenna is easy to set up, even with mittens, but they also fall out easily. Do you know about any other practical alternatives to banana plugs that sit better?
I guess I could try to find better banana plugs or try to fit a slightly too-large plug into a slightly too-small hole, but I am also interested in other options. For example, AUX connectors seem to sit slightly stronger than banana plugs, but I don’t need two channels, and I am unsure about their power rating.
