(22-Nov-2020, 04:22 PM)iFly4rotors Wrote:  
Well, the VSWR is about 6.000 
 

@Krohsis, if you check in, point me in some direction.  Thanks.

6.000, WOW! that's a new record for a first try.  My first try was pretty bad at 4.2  

The direction I would point you in is a Gen 2....so easy.

At the risk of sounding like an A/H, pretty sure it was your soldering.  It didn't look very good, and then on top of it you desoldered an item that is super fussy about soldering it.  I'm far from a great solderer, but as I worked on it, each time it got better.  I could consistently get a VSWR of 1.2 -1.5 every time when I decided it wasn't worth the time and stress to build it when the Gen 2 is so good and so easy.  Jeremy, the designer, it took him several tries to get the touch right. 

If you plan to keep trying, you need to be uber careful with soldering the sleeve to the braid....that is where things go amok.  

Hi Krohsis,

It took three tries just to get a, Build #1, testable antenna. I am using the same sleeve and just keep re-soldering it. Before I move on to the next attempt, I will try a few things. H*ll, what have I got to loose. After all, this is quite an experiment for me.
My wife   has a saying: "You can't break what is already broken"...so, give it a shot. 

I have a theory, but won't know until I do a little experimenting. 

Yeah, you are probably right about soldering the sleeve {that is sort of a challenge to get it soldered without melting something}, however, the bond on the third one appears to be a solid, well bonded connection; but maybe not. 
  

I am going to try some things on this one before I attempt a fresh build; better than just tossing it. This is the diagnostic side of me. 
What I learn will be factored into Build #2. 

Hey, now I am REALLY having fun     Stay tuned...

Copper can be really tricky to solder. I use to solder copper sheet metal when I worked in a sheet metal shop many years ago. I know one thing, if it gets hot, its too hot.  I used to solder with an oxygen, acetylene torch and I cant imagine trying it with an iron. Good job on your first try man!.  It really is a feel and once you get it its like second nature. I'm enjoying this thread and once you get it figured out, I might have to try one myself.

Hi wllm,

Well, I don't generally have any issues soldering copper. I have soldered copper pipe for decades with no issues. That said, I had not soldered metal braded wire to the inside of a copper tube which turned out to be a little more challenging than I had expected.

The first attempt was particularly challenging {pictures in the previous posts were of this assembly}. It was also not very pretty. When I separated this connection (to salvage the copper tube), there were some places where the solder did not bond. NOTE: I broke the active element off before I even got it fully assembled. Bummer.  

The second attempt was much better and did have a pretty good bond. I was also trying to be more careful with the active element {I left the inner sheilding in place until the last step}. All was going well; or so I thought. Low and behold, I broke off the active element while removing the sheilding. Bummer. When I separated the tube connection on this one, the bond was much better. In fact, it appeared to be decent. 

These first two attempts were never completed to the point of being testable.

On my third attempt, I was much more careful with both the soldering and the active element. This time, the solder joint looks good and I managed to very carefully remove the inner shielding from the active element. WOW, I now have my first testable antenna. {it does not have any shrink wrap tubing yet}.

As indicated the VSWR is about 6.000 more or less, but fluctuates around that number. 

Now I had a thought that the passive element might be the issue. The copper tubing is actually thin wall so there is less copper in the 58mm passive element than a thick wall tube. As an experiment, I attached some metal wire braid to the passive element and doing just that brought the VSWR down to about 1.7xx. Drawing from this information, I believe that I can attach a copper sleeve to the original passive element and bring the VSWR down to a viable value.

(23-Nov-2020, 02:38 PM)iFly4rotors Wrote: Hi wllm,

Well, I don't generally have any issues soldering copper. I have soldered copper pipe for decades with no issues. That said, I had not soldered metal braded wire to the inside of a copper tube which turned out to be a little more challenging than I had expected.

The first attempt was particularly challenging {pictures in the previous posts were of this assembly}. It was also not very pretty. When I separated this connection (to salvage the copper tube), there were some places where the solder did not bond. NOTE: I broke the active element off before I even got it fully assembled. Bummer.  

The second attempt was much better and did have a pretty good bond. I was also trying to be more careful with the active element {I left the inner sheilding in place until the last step}. All was going well; or so I thought. Low and behold, I broke off the active element while removing the sheilding. Bummer. When I separated the tube connection on this one, the bond was much better. In fact, it appeared to be decent. 

These first two attempts were never completed to the point of being testable.

On my third attempt, I was much more careful with both the soldering and the active element. This time, the solder joint looks good and I managed to very carefully remove the inner shielding from the active element. WOW, I now have my first testable antenna. {it does not have any shrink wrap tubing yet}.

As indicated the VSWR is about 6.000 more or less, but fluctuates around that number. 

Now I had a thought that the passive element might be the issue. The copper tubing is actually thin wall so there is less copper in the 58mm passive element than a thick wall tube. As an experiment, I attached some metal wire braid to the passive element and doing just that brought the VSWR down to about 1.7xx. Drawing from this information, I believe that I can attach a copper sleeve to the original passive element and bring the VSWR down to a viable value.

On the issue of the VSWR fluctuating reminded me of something we hadn't talked about.  Your readings will be different inside vs outside, proximity to things in your shop, and even touching the coax feedline.  Always do your final tuning checks outside and at least a few steps from buildings, etc.

(23-Nov-2020, 03:41 PM)Krohsis Wrote: On the issue of the VSWR fluctuating reminded me of something we hadn't talked about.  Your readings will be different inside vs outside, proximity to things in your shop, and even touching the coax feedline.  Always do your final tuning checks outside and at least a few steps from buildings, etc.

Hi Krohsis,

Thanks. I will go outside and test it, before doing anything else.

Now we are in debug mode. I am confident that I will figure out how to get things reeled in closer.

Yeah, I don't give up easily. What I learn, I will share. 

I appreciate all of your help and assistance.

Thanks    

Well, continued good luck, Buddy!

One thing we know, the design is sound, so if results suck there is no one to blame but ourselves....

(24-Nov-2020, 12:20 AM)Krohsis Wrote: Well, continued good luck, Buddy!

One thing we know, the design is sound, so if results suck there is no one to blame but ourselves....

Yeah, I got that one. I have been working on the passive element. I got it down to 1.6-1.7 VSWR. I should have stopped right there, but no, I had to keep tinkering towards 1.3...then I messed it up. The positive thing is that I am learning how to tune these things.  Still working on the first build; first coax and first copper tube sleeve. It might surprise you, but a I had to lengthen the passive element. 

If I can fix it, good. If not start to work on number 2.   

Yeah, I don't give up that easy. 

(24-Nov-2020, 02:33 AM)iFly4rotors Wrote:  It might surprise you, but a I had to lengthen the passive element. 

  Been there, done that!  Trust me, it seems like the correct path, but it isn't.  

Remember where I said the design is solid....it is.  And if you build it right, it works.  Altering the design will disappoint.  If you are altering to get a reading you screwed up somewhere.

This design was created by two engineers at SpaceX, yes rocket scientists.  And done so with highly sophisticated test equipment at SpaceX.

Remember, you are looking at 3 things for the tune.

1. VSWR
2. SnR, (signal to noise ratio).
3. The frequency of resonance....915mhz
Not necessarily in that order of importance.

Properly tuned they will come together.

Well, I think that I have done enough to this one.

I will try one more build with the thin wall copper tubing that I have. 

It might be this particular tubing; it has thinning walls than what I have used in plumbing.
Now, if the thickness has a bearing on the antenna, then the copper pipe that I have might be too thin   

I am NOT buying from eBay right now, so buying from them was not an option.

First, I picked up some 1/4 inch copper tubing at the hardware store, but it was too small.
Next, I went to Amazon and bought these tubes K&S Precision 3404 Round Copper Telescopic Tubes.

I will see what other copper tubing I can find.

(24-Nov-2020, 12:55 PM)iFly4rotors Wrote: Well, I think that I have done enough to this one.

I will try one more build with the thin wall copper tubing that I have. 

It might be this particular tubing; it has thinning walls than what I have used in plumbing.
Now, if the thickness has a bearing on the antenna, then the copper pipe that I have might be too thin   

I am NOT buying from eBay right now, so buying from them was not an option.

First, I picked up some 1/4 inch copper tubing at the hardware store, but it was too small.
Next, I went to Amazon and bought these tubes K&S Precision 3404 Round Copper Telescopic Tubes.

I will see what other copper tubing I can find.

The tubing I linked to was used in the development, I believe.  Wall thickness/total amount of copper matters.  If you remember, I had issues on my first couple attempts using a tubing cutter.  The tubing cutter created a ridge inside the newly cut passive element.  To get room enough in the sleeve to slide over the coax, I would ream out this ridge.  Doing so changed the properties enough to cause problems.  I recommend buying the tubing I mention in the tutorial.  But if not from there at least dimensionally the same.  If you are boycotting Ebay, perhaps you can buy direct from the same company, I don't know.   

If you are using tubing that is different, you finding a different length may actually work, as you would need to make the different copper tube be the same as the recommended tubing electrically.  Find that sweet spot without more sophisticated equipment than you are using would be more lucky than finding a Unicorn in Antarctica. 

On the analyzer screen, I am assuming that the SNR value is in the S11 (dB) box {the one to the right of the VSWR box}. 

What value(s) are we looking for here   
What is the best value and what are acceptable values 
Is there anything else on the analyzer screen that I should be aware of or strive for; target and range 

this has been an awesome thread to watch. I had no idea antenna were so fussy.

might be worth while creating some kinda jig to hold everything in place as you're soldering so you can get repeat performance. would love to see how you're actually doing all of this.

(24-Nov-2020, 03:24 PM)TStroFPV Wrote: this has been an awesome thread to watch. I had no idea antenna were so fussy.

might be worth while creating some kinda jig to hold everything in place as you're soldering so you can get repeat performance. would love to see how you're actually doing all of this.

Hi TStroFPV,

At this point, I am using one of those 6 clamp octopus things when soldering. 

"Repeat"    Yeah that is funny since I haven't settled on a method that I like yet.  

I find it interesting, if not a little frustrating, the challenge with soldering the copper sleeve to the wire ground sheilding of the coax.      I have soldered electronics since I was 18 years old and have soldered {they call it "sweating" in the plumbing world} more copper pipe than I care to mention; all with no problem. I learned how to solder early on and have never had a problem doing it; until this stuff. I think the challenge is trying to heat up the metal without melting the inner "plastic" insulation on the coax. If you just put the heat to it, you could melt that insulation. I should probably cut some of the copper tubing and just try different techniques until I get something worked out that works for me. 

I don't have a set up to be able to video anything yet, but I am getting a lot of still pics {obviously I will only be posing those which provide insight}.

Yeah, I am not giving up; more to come... stay tuned 

(24-Nov-2020, 03:05 PM)iFly4rotors Wrote: On the analyzer screen, I am assuming that the SNR value is in the S11 (dB) box {the one to the right of the VSWR box}. 

What value(s) are we looking for here   
What is the best value and what are acceptable values 
Is there anything else on the analyzer screen that I should be aware of or strive for; target and range 

Yes, I believe S11 display is for SNR, I would have to go to the shop and look as I haven't used it for awhile.  Bigger number is better, much under 18db would be considered less than optimal/not so good....I believe I'm getting a SNR of 28ish on the antenna on my Super G+, my best attempt of the Gen 3 build.  Jeremy has been getting around 35db, but he is a rocket scientist after all....

You also want to look at the graph on page 2 of the analyzer and see that the dip for VSWR dips down at  915mhz....it also shows that on the main screen but it is much easier to visualize for me on the graph.  You can have a very low VSWR (1.1-1.5) and look at the screen and see that it is resonating at for instance, 650mhz or 1.2ghz.  Low VSWR at the targeted frequency is what you want.