The JPC-12 - Third time's a charm?

The comments kept on coming on my last video, including one from @LA5PPA / Lasse with some instructions on how to tune the antenna. Also ‪@HAMRADIODUDE‬ made a video inspired by my attempts on tuning this antenna, so I had to give this another go.
Could I get it to tune now?
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Note: The antenna design is now open source and can be found on Thingiverse.
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[@HAMRADIODUDE]

I'm glad you did give it another go, regardless. Good job.. enjoy the POTA . I'll be hydrating

[@slorznovitch]

Finally found a reference for 10 meters. I would have never thought of removing the rods and coil and just using the whip. Thank you!

[@LB0FI]

You’re welcome!

[@F4LDT-Alain]

Extremely useful video for a new JPC-12 owner, thanks a bunch. 73 from Paris, France.

[@LB0FI]

Glad it was helpful!

[@drabfab3014]

So glad I watched this, I had totally forgotten to stay hydrated with setting up my antenna. Super useful information.

[@LB0FI]

Happy to help, I sure hope you picked some of the other advice as well. See you down the bands! PS: Sarcasm doesn’t come across well on a keyboard.

[@drabfab3014]

It was indeed a good and informative video, just thought that part was kinda funny.

[@philhayward8696]

Top marks Morten for persisting with the antenna rather than just thowing it in the "too hard basket" and writing it off as a faulty product......it shows the hallmarks of a reviewer that your viewers can trust. Cheers ZL2VTH

[@LB0FI]

Thanks! I’m still not completely sold on the antenna, but we’ll see with a POTA tomorrow.

[@DNL1200GSA]

Thanks for the video. Great explanation and instructions. I had mine working for the first time today. It’s fiddly, frustrating and now you’ve motivated me to persevere with it. Thanks. I’ve just subscribed! 73

[@LB0FI]

It's not a half bad antenna, but it's cumbersome to tune. Once it is tuned it actually performs pretty well.

[@thomasobert5261]

Many of those matches look more broadband than I expected. I’m going to buy one. I really don’t mind any extra tinkering. Every location has different ground conductivity and surrounding objects, so most similarly constructed antennas will give a similar experience. Most modern radios show SWR so its pretty easy to trim. Thanks very much for the good info and hi-res video.

[@LB0FI]

It is by no means an easy antenna to tune, but if you follow these guidelines it will be easier at least. And yes it is pretty broadbanded.

[@Overlanding4Fun]

Good video. It is always good to see people be able to work out technical issues that they are having. I am a big believer in KISS method, so I get your concern about this might be to much for a new ham. I just release a video myself yesterday on the antenna. I am looking for an antenna that was small and compact that I could take on a trip out to the desert. I got great results with it on 20 and 40 during a POTA activation in Indiana. I banged out 50 voice QSOs in an hour across the US and Canada with 2 of them in Europe. The only issue I had was with the provided radials, but once I split them apart, the SWR came in to line. I will be replacing them with some homemade ones.

[@LB0FI]

Looking forward to your video.

[@revbikerbigd8664]

Found list in comments! Thx👍🙏 ps they are at 3 months postings!

[@skydeclair]

Can we see more of the pos'za cat!

[@KS0JD]

Good luck on the POTA event. 73

[@LB0FI]

Thanks!

[@robpinter5431]

Thank you for the video, has anyone posted the tuning instructions for download?

[@LB0FI]

You can find them in the comments.

[@PhilG8PJH]

Have a look at KB9VBR , he uses a aluminium window mesh instead of radials, I tried it with my portable ground spike and 17 foot whip, and it tunes all bands from 20 to 6 like a dream just by adjusting the whip length. With my slide winder it will do 30 or 40.

[@LB0FI]

The only issue with that is that we don’t use window mesh here.

[@revbikerbigd8664]

Where are these instructions at in English, can't find them, would love to print them out ! Thx for doing this video,very helpful 👍🙏

[@NamasenITN]

Your furry helper might introduce strong em fields, as he started moving after you pet her.😂

[@EA4EVK]

Hi there! Could you tell me where to find that sheet?? I’m my instructions manual doesn’t come so many configurations. 73!

[@mikedodds7547]

Any ham that likes tux cats is OK by me😀 And the antenna video was good too!

[@LB0FI]

Thanks!

[@John_Henry83]

Did you ever try this antenna out in a actual POTA activation? Where can we find that list to tell you how to tune the antenna on different bands,.

[@LB0FI]

Yes, I have tried it several POTA activations, I have a total of four videos on this antenna. As for the list, I can't find that anymore, so you will need to take notes from the video unfortunately. Thanks for commenting!

[@tcwaite88]

Where did you find the cheat sheet that you are referencing in the video?

[@LB0FI]

Everything is explained in the beginning of the video. It was posted in the comments on the previous video of this antenna.

[@Stewart-HA5RV]

This might be a good antenna but it seems like a bit of a pain in the Ar$3 to me... I think I'd stick with a EFHW (80m-10m) and a DX commander 80/40 upwards. I think those two (and variants) alone are the best compromise between effort/efficiency when it comes to multi-bands antennas and avoiding tuning or automatic tuner.

[@LB0FI]

You are comparing two or three very different antennas for two or three very different use cases here. Sometimes you are space compromised, or just have too many people around for the two options you talk about, and then having something a little bit more flexible than a hamstick could be a good thing.

[@Stewart-HA5RV]

​@@LB0FI Yes, that's true. I'm thinking of just the antennas alone - assuming that space etc don't matter. By the way you can use a EFHW vertically too - obviously that requires either a very long pole or only using higher bands. It has an advantage of a very low take off angle. Ultimately there are pro's and con's always I suppose.

[@fjrempel]

This helped. Thank you. 73, KK7BN

[@LB0FI]

You're very welcome!

[@muskrat1949]

Just bought my JPC-12. The slider is extremely hard to slide up and down. Do you have any suggestions to make it easier without taking it apart?

[@LB0FI]

I just borrowed that antenna, so I don’t know unfortunately.

[@muskrat1949]

@@LB0FI thanks

[@jessgypin-ko5ds]

Good work dust you vna screen

[@LB0FI]

I hope you are aware that this video is almost a year old, and shot in the middle of pollen season.

[@jessgypin-ko5ds]

@@LB0FI 👍😆

[@jessgypin-ko5ds]

Look above. I hoped you would understand that it was meant as good humor. You did figure it out.

[@regularguy519]

Add a link for the tuning cheatsheet.. or scan it, upload it somewhere and send us link plz

[@LB0FI]

I have something even better, I have a video on it. Besides that there’s a comment on the previous video with the complete list.

[@docdancel]

hi. can i have a copy of the "manual" that you used. thanks

[@LB0FI]

I have two options for you. Check the comments in the other video or take notes.

[@tulenik71]

The problem of this antenna (and dipole variant, too) is not bad engineering or manufacturing. There is only one problem: the manual is idiotic. I don't speak Mandarin (only all slavic languages, English, Old English, French, Old French and Latin :D ) so I don't know if the chinese manual is any better, but English version is basically unusable. What I did was similar to your attempt - it was crystal clear I must first find some "reference settings" (and the best attempt is having whip and/or tubular sections as long as possible with shortest possible coil length involved) and then fine tune changing the length of the whip. It was almost immediately clear the coil must be taken out starting with 17 m band. The measurements did take like 2 hours. Basically my results are identical with the document by DO1HFS. What I did I bought JPC-7 version (dipole - so I have 2 coils and in vertical arrangement I can tune 60/80 m) with spare whip and bottom segment with ground rod and HF connector for JPC-12, so I have both vertical/dipole options. I made a set of 8 10 m radials instead of that crap provided with JPC-12. I didn't use dipole arrangement for now, but when I will have some time, I will make the measurements.

[@LB0FI]

Manuals are absolutely an issue with a lot of Chinese products unfortunately.

[@lesleyjohnson317]

Hi ? Can you pass on that list (notes) on to us as well please.

[@LB0FI]

Lasse LA5PPA found this information somewhere on the net about a year ago and it has been of great help for tuning the antenna It is DO1HFS who made it in German so I use google translate to English. He also recommends adapting the radial set if you want to optimize for a particular frequency band 6m: Earth spike/radials/feed point/telescopic Extend the telescopic 3-4 sections. An average SWR of 1.2-1.7 is possible without further changes. Fine adjustment via telescopic 10m: Earth spike/radials/feed point/telescopic Fully extend the telescopic. An average SWR of 1.2-1.5 is possible without further changes 12m: Earth spike/radials/feeding point/2x aluminum rod/telescopic Fully extend the telescopic. An average SWR of 1.2-1.7 is possible without further changes Fine adjustment via telescopic 15m-1: Earth spike/radials/feeding point/4x aluminum rod/telescopic Screw all four aluminum rods together and screw onto the feeding point. Telescopic except for one link Extend completely and screw onto the aluminum rods. Without further changes an average SWR of 1.2-1.5 possible 15m-2: Earth spike/radial/feeding point/3x aluminum rod/telescopic Just screw three aluminum rods together and screw them onto the feeding point. Fully extend the telescopic and screw onto the aluminum rods. An average SWR of 1.2-1.5 is possible without further changes 17m: Earth spike/radials/feeding point/4x aluminum rod/telescopic Fully extend the telescopic. An average SWR of 1.2-1.7 is possible without further changes Fine adjustment via telescopic 20m: Earth spike/radials/feeding point/4x aluminum rod/coil/telescopic Extend the telescopic completely and place the coil between the four aluminum rods and the telescopic install. Place the pickup sled on the top red mark for 14MHz. An average SWR of 1.1-1.4 is possible. 30m: Earth spike/radials/feeding point/4x aluminum rod/coil/telescopic Extend the telescopic completely and place the coil between the four aluminum rods and the telescopic install. Place the pickup sled about EIGHT clicks below the top red mark. An average SWR of 1.1-1.5 is possible. 40m: Earth spike/radials/feeding point/4x aluminum rod/coil/telescopic Extend the telescopic completely and place the coil between the four aluminum rods and the telescopic install. Place the pickup sled on the lower red mark for 7MHz. If necessary, the slide can be moved by one or two Coil turns are pushed up. An average SWR of 1.1-1.4 is possible.

[@lesleyjohnson317]

Thanks Much aprpeciated.

[@Lennymc39]

​@@LB0FIThanks for sharing these instructions and thanks to LA5PPA & DO1HFS for compiling them.

[@charlieoscar09]

Thankyou for the video.....Persoanlly i think these Chinese aerials are awful and getting lots of negative feedback. Good Luck with yours keep the videos coming

[@LB0FI]

It's not a half bad antenna, it is just very cumbersome to use it.

[@BrekMartin]

Pretend it’s a quarter wave monopole, just like any other since the dawn of radio.

[@LB0FI]

Electrically or physically?

[@BrekMartin]

@@LB0FI Electrically in this case, but if you can get your hands on the 1964 ARRL Antenna Handbook, a remarkably similar antenna with equally similar loading coil is described on page 308 (right down to the hardware used for the sliding contact), so when there are videos titled PAC12 fail and whatnot, I can’t read it any way other than “user fail”. I do happen to be aware that physical quality of the thing is surprising for a mass produced China thing.

[@LB0FI]

@@BrekMartin Thanks for commenting.

[@MrHowardPhillips]

I am still rather suspicious of this antenna. Getting a usable impedance match is one thing, but does it radiate? It's easy to get a good match off a dummy load, but what makes an antenna good is how well it radiates.

[@LB0FI]

Everything in this hobby is a compromise. And yes it radiates, but no, it does not radiate as well as a quarter wave, but you get the benefit of a more compact kit. And that being said, there's not really any magic in this, it's a vertical with a loading coil.

[@JohnTarbox]

What is your cat's name? I hope she likes ham radio as much as LB6QJ's cat Odin. ;-) DE WA1KLI

[@LB0FI]

Her name is Kathinka, but we usually just shorten it to Tinka. She loves wire antennas and radials more than radio itself :)

[@WilliamLee-eh6hy]

So why did they use 3/8 x 20 threads instead of the fairly standard 3/8 x 24 threads on all their stuff. Now it is incompatible with all my other coils and whips. Very stupid ... cant even use it on my mag mounts ... sending it back for refund as all my mounts are 3/8 x 24 thread.

[@LB0FI]

The mounts are M10 - metric. Get an adapter.

[@HAMRADIODUDE]

I do not eat grass

[@LB0FI]

The mower is Shawn, not Sean 🤣

[@KevinFraser411]

Thank you, the instructions are helpful. 73 de ZS6KB.

[@LB0FI]

You are most welcome!