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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post 9:1 unun and 40m wire antenna. (LW-40 and similar)
I know this is a compromise antenna so please let's not slag it off.

Have you tested one of these on an analyser? If you have can you please share the results.


Thanks Andy

https://www.avera.eu/sigma-lw40.html

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Fri Mar 27, 2020 2:58 pm
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
I was once feeble minded enough to buy one. Heaven knows why.

Did it work? Well if my atu could tune it then sure, it worked. I cut it up for wire in the end.

If you really want a random wire, put up a random wire...a tenners worth of of wire from moonraker will do. If you feel the sudden need for the unun again, a tenners worth of bits and you can make one. If you cant then I will and I wont charge you 80 euros. But if you are starting to be convinced that the length and unun are magic and that rare dx is at your fingertips, a cold shower is called for.

Having said that, weve all been there and just HAD to spend the money so we know...

Good luck.

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Sat Mar 28, 2020 7:22 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
David and all,

I don't need one, nor will I buy one. I don't use HF much (currently have a trapped inverted L for LF end and a trapped vertical for the higher HF end). My interest stems from that annoying amateur trait of giving it a go. So I can see me making a replica.

Interestingly, I've emailed several companies who advertise similar antennas (NB none are site sponsors) asking for a copy of an analyser 'sweep' all have replied saying words to the effect of 'WE DON'T HAVE THAT'

So I conclude, either they have no idea how it 'works' or they do and they're not prepared to show the facts. Unfortunately the annoying amateur trait now kicks in and I can see me producing one just so I can test it on the VNA and in use to 'see' the magic in person.

I am a candidate for the job of 'patron saint of lost causes' I consider it a duty to experience these things.

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Sat Mar 28, 2020 8:58 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
I have been using home made versions for many years now.

They work well between 7 and 18 Mhz, above that a vertical works better, and the performance drops of a lot below 7 MHz

I use them in an inverted L configuration, with the feedpoint as far from the house as I can get it, and intentionally using the coax as part of the antenna. ie put your 1:1 at the shack end, and peak the SWR with clip on ferrites on the coax.

There is no way the one in the link will handle 400W digital on all bands (nor does it claim to, it says 400W max, just need to read it the right way)
It should handle a 100W rig OK though.

I agree they are simplicity itself to make.

The matching units sold on here by G4ICD are extremely well made, amd rated correctly for power.

I can't see what wire the linked one is made from, at first I thought it was stainless, which would make the price OK.

There are 3 ways commonly used to make a 9:1 unun, haven't noticed much difference in performance, which to use depends mainly on power and the highest frequency you want to use it on.

Building it yourself, if you can and want to, does give you the advantage of experimenting, and you can always try a 49:1 on the same wire.

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Sat Mar 28, 2020 8:59 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
Sangoma wrote:
I have been using home made versions for many years now.

They work well between 7 and 18 Mhz, above that a vertical works better, and the performance drops of a lot below 7 MHz

I use them in an inverted L configuration, with the feedpoint as far from the house as I can get it, and intentionally using the coax as part of the antenna. ie put your 1:1 at the shack end, and peak the SWR with clip on ferrites on the coax.

There is no way the one in the link will handle 400W digital on all bands (nor does it claim to, it says 400W max, just need to read it the right way)
It should handle a 100W rig OK though.

I agree they are simplicity itself to make.

The matching units sold on here by G4ICD are extremely well made, amd rated correctly for power.

I can't see what wire the linked one is made from, at first I thought it was stainless, which would make the price OK.

There are 3 ways commonly used to make a 9:1 unun, haven't noticed much difference in performance, which to use depends mainly on power and the highest frequency you want to use it on.

Building it yourself, if you can and want to, does give you the advantage of experimenting, and you can always try a 49:1 on the same wire.

Agree with above, I bought a couple of G4ICD ones, and have used them to pretty good effect for what they are.
You can indeed make your own, I could have done that myself, not that difficult, but bought them on one of his "sell off" bargain clearances, and the construction and materials used are very good.
They do not like a lot of local RF noise floor though to be fair, if you have a relatively quiet RF environment fine, if its rather noisy, possibly not the antenna for you.
The two I have are one for 20 meters, and one for 40 meters, of course if you just own one of them you can adjust the radiating wire length to suit within the frequency bandwidth range of the 9:1 unun transformer.

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Sat Mar 28, 2020 9:09 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
G0BHD wrote:
Sangoma wrote:
I have been using home made versions for many years now.

They work well between 7 and 18 Mhz, above that a vertical works better, and the performance drops of a lot below 7 MHz

I use them in an inverted L configuration, with the feedpoint as far from the house as I can get it, and intentionally using the coax as part of the antenna. ie put your 1:1 at the shack end, and peak the SWR with clip on ferrites on the coax.

There is no way the one in the link will handle 400W digital on all bands (nor does it claim to, it says 400W max, just need to read it the right way)
It should handle a 100W rig OK though.

I agree they are simplicity itself to make.

The matching units sold on here by G4ICD are extremely well made, amd rated correctly for power.

I can't see what wire the linked one is made from, at first I thought it was stainless, which would make the price OK.

There are 3 ways commonly used to make a 9:1 unun, haven't noticed much difference in performance, which to use depends mainly on power and the highest frequency you want to use it on.

Building it yourself, if you can and want to, does give you the advantage of experimenting, and you can always try a 49:1 on the same wire.

Agree with above, I bought a couple of G4ICD ones, and have used them to pretty good effect for what they are.
You can indeed make your own, I could have done that myself, not that difficult, but bought them on one of his "sell off" bargain clearances, and the construction and materials used are very good.
They do not like a lot of local RF noise floor though to be fair, if you have a relatively quiet RF environment fine, if its rather noisy, possibly not the antenna for you.
The two I have are one for 20 meters, and one for 40 meters, of course if you just own one of them you can adjust the radiating wire length to suit within the frequency bandwidth range of the 9:1 unun transformer.


Round about 26m wire will work well between 7MHz and 18MHz, and up to 50MHz and down to 1.8MHz with less efficiency, and only using an internal tuner.
Roughly doubling the length imroves the efficiency down to 3.5MHz

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Sat Mar 28, 2020 9:20 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
Sometimes you see adverts for 49/1 high impedance matching transformer for long wire aerials. I'm assuming that these should work better that the 9:1 unun which seems to be a glorified dummy load! As I'm no expert on long wire matching units which one is better?

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Sat Mar 28, 2020 9:43 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
TF3SI wrote:
Sometimes you see adverts for 49/1 high impedance matching transformer for long wire aerials. I'm assuming that these should work better that the 9:1 unun which seems to be a glorified dummy load! As I'm no expert on long wire matching units which one is better?



TF3SI wrote:
Sometimes you see adverts for 49/1 high impedance matching transformer for long wire aerials. I'm assuming that these should work better that the 9:1 unun which seems to be a glorified dummy load! As I'm no expert on long wire matching units which one is better?



The 49:1 work best for single band 1/2 wave end feds, as you get a proper match.

They also work OK on the harmonics.


The 9:1 work better if you want all bands from one piece of wire.
They are not glorified dummy loads, they are just as efficient as the 49:1 when the impedance matches exactly.

Basically they just reduce the impedance variation by a factor of 9 to bring the impedance presented to the radio within range of the internal tuner.

Both are inefficient when there is a big mismatch, and when there is a larger mismatch, power is lost in the unun, which will heat it up and make the problem worse (you would see the SWR at the radio rising duting an over, that would tell you the cores are getting hot)

Obviously, in a situation like that, the efficiency would be low, so they would approach the effect of using a dummy load, but I have never made a contact on a dummy load, and I have made thousands with a 9:1 unun :)

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Sat Mar 28, 2020 9:53 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
TF3SI wrote:
Sometimes you see adverts for 49/1 high impedance matching transformer for long wire aerials. I'm assuming that these should work better that the 9:1 unun which seems to be a glorified dummy load! As I'm no expert on long wire matching units which one is better?

Bit unfair to call it a "glorified dummy load", it is just all compromise "matching" at the end of the day!
Want something better?, have the space?, stick something truly full size and resonant up!
No tuner required.
It's that simple really.

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Sat Mar 28, 2020 9:54 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
GD1MIP wrote:
I know this is a compromise antenna so please let's not slag it off.

Have you tested one of these on an analyser? If you have can you please share the results.


Thanks Andy

https://www.avera.eu/sigma-lw40.html


Just pointed Andy to a VERY good article, look at the K1RF pdf, it makes interesting reading.
Re 9/1 and 49/1 un/uns, most of the clearance ones we sold were 49/1 which offer commercial users multi resonant frequencies for day/night operations and NO TUNER, they are mainly used by overseas aid agencies, FEMA, Homeland Security and users of Codan and Barrett commercial transceivers (google them and see how big they are), these are used in areas usually in the middle of nowhere so have no noise floor problems, if used in towns/cities then we advise trying sloping vertical or sloping horizontal to reduce noise levels.
The 9/1 is used in many commercial applications and has been around for 50 years??? it is used in many of the terminated Commercial Rhombics we have built for overseas Mil business so has specific uses and applications.
It is no dummy load!!
Geoff G4ICD

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Sat Mar 28, 2020 10:09 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
Good reply.
We could of course debate "are antenna tuners and trying to get wide coverage out of whatever wire we have up in general" glorified dummy load compromises, in some circumstances! :)
They do what they claim to do, and no more.

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Sat Mar 28, 2020 10:16 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
G0BHD wrote:
Good reply.
We could of course debate "are antenna tuners and trying to get wide coverage out of whatever wire we have up in general" glorified dummy load compromises, in some circumstances! :)
They do what they claim to do, and no more.


And the difference is?
49/1 no tuner/matcher required for multiband use, as we have resonance!
9/1 tuner/matcher required for multiband use.
BTW, talking of ATU's Yaesu have an ATU that even has a fan on the rear, the FC20, shows where the RF is going

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Sat Mar 28, 2020 10:27 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
g4icd wrote:
G0BHD wrote:
Good reply.
We could of course debate "are antenna tuners and trying to get wide coverage out of whatever wire we have up in general" glorified dummy load compromises, in some circumstances! :)
They do what they claim to do, and no more.


And the difference is?
49/1 no tuner/matcher required for multiband use, as we have resonance!
9/1 tuner/matcher required for multiband use.
BTW, talking of ATU's Yaesu have an ATU that even has a fan on the rear, the FC20, shows where the RF is going

A tuner with a fan on!
I have never required a PSU with a fan on yet! :D
I am obviously selling myself short RF wise.

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Sat Mar 28, 2020 10:31 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
Thanks for all the feedback / comments. I guess I should apologise to the humble 9:1 unun - calling it a glorified dummy load. I know the 49:1 high impedance matching transformer works well. I was just wondering why some people us a 9:1 unum vs others use a 49:1. Now I know.

It's good to know that people are supportive and always willing to help people like myself in getting a better understanding of this hobby and particulate the various options on aerials which seems to be endless.

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Sat Mar 28, 2020 10:58 am
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 9:1 unun and 40m wire antenna. (LW-40 and similar) 
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Post Re: 9:1 unun and 40m wire antenna. (LW-40 and similar)
While we are at it. Here is the inside of a Sigma Euro Com 9:1 unun. Doesn't look too professional.

I found it trawling the www so hopefully the original poster is telling the truth.


Attachment:
sigma 9 to 1 unun.jpg
sigma 9 to 1 unun.jpg [ 24.04 KiB | Viewed 683 times ]

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Sat Mar 28, 2020 6:49 pm
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