Loading Coils & SWR Curves - Signature 12.4 Ham Radio Vertical
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- Опубліковано 20 сер 2024
- It's important we understand where an antenna tunes and what is the 1.5:1 bandwidth, particularly for Amplifier users and those without an ATU. We look at the Signature 12.4m in this example. 73, Callum.
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Man that’s a nice looking antenna!
Mike, you need to move and have one!
Those are some impressive SWR-curves. I like :-)
Me too Anton!
A great vid on the SWR and b/width explanation Cal. I have just looked at your WSPR coverage...... flipping'eck.... flipping awesome.....
Yes, I left it going...!
line goes down, happy ham.
That looks like a great antenna Callum. I only wish my HOA would let me install one, for sure I would put in a order.
Another great video, keep it coming 🎙️🎧📽️
Cool, thanks
Excellent work. 👍🏻
Hope the addition to the shop is coming along nicely.
Thanks 👍
My 12.4 arrives tomorrow. It will take a few days to get everything sorted out in my backyard for it.
Good luck!
Hi Cal,
Had no doubt that the Signature 12.4 would become an awesome antenna. Stay safe. 73 WJ3U
Tnx Don!
The 80M result is what I would expect to see, typically with a coil to electrically lengthen the antenna at 80M, the resultant bandwidth is about 100KHz, this is the result of typical wire sizes used to wind the coil. It’s worth noting that Q=wL/R where w=2.pi.f so you can work out what the actual Q is if you can measure the coil resistance and inductance or because R is the denominator, you can use that to lower the Q and widen the bandwidth, so if the coil wire size was made smaller, then R would increase and Q would be lower giving you more bandwidth.
Good point.
Just like magic Cal 🙂
Yes mate!
As a coil moves up.... it requires more Henry to get the same result. You come up against the fact the ohmic losses start to out weigh the benefit of the coil pulling your current up the wire (your wiggles).... cheers
Got a 12.4 on its way!
YES!
How about a 17-foot telescoping whip mounted on top of a 5:1 matching transformer at which the analyzer reads 1.0:1 SWR (wait for it), EVERYWHERE!? Tested every band my General Class in the USA allows with a Rig Expert AA 55 ZOOM Analyzer.
Good video.
KD8EFQ/73
Everywhere? Yeah, I had that once on an antenna and I couldn't get anyone to hear me :)
So if 1 coil gives 100kHz, if we add 2 more do we get 300kHz? (Kidding!) Great video. I just got tracking info my Signature 12.4M is in the US and should be here any day now. '73
Look out for User Guide Video (just the main points and 10 mins only) uploading now..
@@DXCommanderHQ Timely. The XYL just called me and said "You got 2 packages from the UK ... 1 heavy and 1 long box". I wonder what they could be? 😁❤️👍
"Known-good coax..." Any tips for testing a piece of coax to verify that it's good? I know there are purpose-built coax tester gizmos, but what could we do if we only have a multimeter, dummy load, SWR meter, and maybe (or maybe not) an antenna analyzer?
Stick the dummy load on the end of it, meter and tx on the other end, and check over all bands. Should be perfect VSWR. Wiggle the plugs as you do it in case of any iffy connections!
Agree with Andy, that’s how we did it years ago, painstaking in comparison with the magic of analysers and VNA on the market I know. Record the figures on a graph or spreadsheet. 👍🏻
Multimeter is normally just fine (mine kept going open circuit).
Great stuff as always. Can one save a sweep with the Stick 230 for later viewing with AntScope ?
It will directly attach with the Bluetooth - I haven't played much with AntScope yet but think you can download from the app?
I have no idea... Sorry!
Callum, I asked this on IG re SWR. Is the recommended element length based on Region 1 or between Region 1 & 2? Asked differently: is the SWR table based on the final recommended cut lengths? See, I have been studying the guide! Lee N5BE.
OK, so the user guide has the exact dimensions.. THE curves will move up and down appropriately. I did test this for both Region 1 and Region 2.
How does tuning the 80m element affect the 30m band? US general class 80m phone is 3.8-4Mhz. If I move the center up to 3.9 will that hose up 30m?
Thanks.
Shouldn't do.. The long story is that by adjusting the coils AND the amount of foldover on the 80m element should keep the 30m tune fairly balanced. See user guide for probably better explanation :)
@@DXCommanderHQ Yup, my fault for not checking out the manual. Just watched your new vid. Enjoy your time off!
@ David Casler I have a cb base station setup. Would the window line make a difference in hearing other and does it handle power better than the thickest coax i can find? i also planned to top out the tallest tree on my land and putting my cb antenna on the top of it. The putting the antenna in the tree, will this hurt me any? the antenna is 18 foot ground plain type.
Hmmmm. Dave, are you hiding upstairs at Callum's shop??? 🤣
Hey Dave, wake up fella.. Question for you! ANd stop reading that User Guide!
One more sad fact you are up against.... is if you could stand up 1/4 wave towers for each band without any wire guy wires starting to bring in real world capacitive loading. You would see the tuned dip gets narrower the lower you go. This becomes a pain in the butt for Broadcasting Services on LW that want to push out full 10khz audio. It needs a totally flat response for the full 20khz. That is not easy to get down there. But boy your groundwave goes further for the same power. The reverse happens as you go up in frequency. Your tuned dip gets wider.
Wow. That's amazing.. So flat for 20kHz.. Gosh!
@@DXCommanderHQ Bad SWR on a broadcast service effects audio response. Also makes the TX see reflected power if its more like tighter Q aka smaller tuned dip. Even though the carrier is 1:1..... The sidebands are out at thier audio freq +/- the carrier. They are really seeing a higher swr IF the aerial has a hi Q. The Sidebands are the ones getting your audio to air and operate at about 1 tenth of the carrier power. You need to be nice to them.
Yes Callum... dead flat is preferred atleast for the total bandwidth of the audio high fi the station engineer wants. Where to roll that off does start a massive debate. As the fact AM radio has the reputation for being low fi.... 80% of that blame is the reciever.
Another trick we do is to add wire to the tower to trick SKIN EFFECT into thinking the tower is wider. This helps. Try using thicker for your 80m element first. Then two on opposite sides of the pole. So the two elements approx 4inch apart look like FLAT Ribbon thanks to skin effect.
Thats my advise and suggestions to help with wider dip down low. 73