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*I am experimenting with a ? MYANTENNA ? 80m end-fed with a 49:1? UNUN? on loan*
*I substituted a heavy gauge #12 wire for the wire that came with the antenna.*
*
*
*I started to alter the length of the _#12 wire_ (140 feet now) attached to the MYANTENNA? 49:1 UNUN.*
*But first I wanted to see how it performed on the HF bands 3.5 to 29 MHz.*
*Not too bad,? but? 40m was a higher SWR (between 2:1 and 3:1) than I wanted.*
*Here is the overall? "RETURN LOSS (dB)" and "SWR"? curves:? 3? to? 30 MHz*
*
*
*So if I make it a bit shorter - maybe 130 ft - it may do better overall on more HF bands.*
*Or, I can add a loading coil or capacitor to work better on some bands.*
*The original ? MyANTENNA? (130 ft)? had a loading coil which lowered the resonances on 10/15 meters.*
*One can also mess with various lengths of wire on the "counterpoise" socket on the UNUN.
*
*Here is the expanded? 80m? graph? and the expanded? 10m graphs*
*As you can see, I wanted to make it "long" to work well on the low part of 80m band for CW and digi modes.
*
*
*
*
*
*It also tunes up easily on the 10m band with no additional tuner needed, but I prefer a _10m vertical_ for low-angle DX .
*
*
*
*Not bad for one wire and a UNUN.
*
*de k3eui*
*
*
*
*
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Barry,
Looks like you've got some decent readings that your antenna tuner can grapple with reasonably.
I was curious as to how you have the antenna placed. How high above your ground is it? Do you have it horizontal or sloping?
In my 50+ years of hamming, I could only have dreamed of using a VNA analyzer on my antennas. I love playing with wire antennas now, and the endless fiddling with seeing immediate results with my nanoVNA.
73,
Stan Weber - WB5UDI
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Can you please be more specific on the install configuration. I've also had a lot of mixed results and had to look the the UNUN cores on off the shelf unun's more. That being said, more information on the 49:1 UNUN would be appreciated. Lately I'm winding my own.
Andy
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Stan
You raise good points.
I am using the space I have available.
The 140 ft #12 wire attached to the MyANTENNA 49:1 UNUN is about 20 ft above Chester County ground and is horizontal the whole way and runs 50 ft north-south in one direction and make a right angle turn on a tree limb to another 90 ft run east-west.
It is set up only for NVIS prop and I don¡¯t care about any bands other than 80m and 40m since verticals do far better on 20m and 10m
de k3eui
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The 49:1 UNUN is whatever MyANTENNA sells.
I did not open it or examine it.
I took off the counterpoise and put it back on (30 ft wire) and it made very little difference since the coax itself served the function of a counterpoise.
It is fed with about 70 ft of RG213 at this moment, or I use a different 100 ft RG213 at times.
I did substitute a beefy #12 insulated wire for the light wire that came with MyANTENNA kit.
de k3eui
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I've seen other kits which supply 130 ft with a 56:1. (and since you went with a heavy wire you are a little long on your trim yet - its seen in your traces) If its high enough a counterpoise isn't necessary - but grounding at entrance is recommended. (NPFA 70, article 800) Keep trimming.
Andy
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Addressing your first plot from 3 to 30 MHz: Your worst case return loss
(RT) shows roughly 4 dB at the low end and pretty much 5 dB for the rest of
the plot. At low points of the RT I'd expect something considerably less
than that. If it were me, I'd start looking for loss in the system. It'd
start with the 49:1 and use a 9:1 instead. Remember, system loss will make
otherwise marginal to bad systems "look good" in both SWR and RT.
Dave - W?LEV
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On Wed, Feb 21, 2024 at 11:47?AM Stan - WB5UDI <stan@...> wrote: Barry,
Looks like you've got some decent readings that your antenna tuner can
grapple with reasonably.
I was curious as to how you have the antenna placed. How high above your
ground is it? Do you have it horizontal or sloping?
In my 50+ years of hamming, I could only have dreamed of using a VNA
analyzer on my antennas. I love playing with wire antennas now, and the
endless fiddling with seeing immediate results with my nanoVNA.
73,
Stan Weber - WB5UDI
-- *Dave - W?LEV*
--
Dave - W?LEV
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maybe just fold a bit over to get it a tiny bit higher?? so 20m is better into place??
and getting the mid dip on the 40m band inside the band??
that does not do much on 80 ... maybe lifts a bit more to midband but i think digi mode will still be usable
without cutting .. just folding over it will not hurt much ... at least its worth a try
a small loading coil about 8 feet from the base (first max current spot on 10m) will not lower the 80m resonance that much (cause on 80m it is near a voltage spot at the end) but can finetune your 10m resonance (cause there it is at a current spot) ... on the other hand a coil or cap (or both) at the centre may influence all uneven resonances but not the even resonances
similar to a centre loaded off centre fed dipole you can do the same thing on an end fed wire (add a load at centre ... maybe a cap and a coil combined ... NO NOT A TRAP!!)
sooooo .... a lot of possible solutions to get more bands with low swr on a single wire
dg9bfc sigi
Am 20.02.2024 um 17:04 schrieb Barry K3EUI:
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Show quoted text
*I am experimenting with a ? MYANTENNA ? 80m end-fed with a 49:1 UNUN? on loan*
*I substituted a heavy gauge #12 wire for the wire that came with the antenna.*
*
*
*I started to alter the length of the _#12 wire_ (140 feet now) attached to the MYANTENNA? 49:1 UNUN.*
*But first I wanted to see how it performed on the HF bands 3.5 to 29 MHz.*
*Not too bad,? but? 40m was a higher SWR (between 2:1 and 3:1) than I wanted.*
*Here is the overall? "RETURN LOSS (dB)" and "SWR"? curves:? 3 to? 30 MHz*
*
*
*So if I make it a bit shorter - maybe 130 ft - it may do better overall on more HF bands.*
*Or, I can add a loading coil or capacitor to work better on some bands.*
*The original ? MyANTENNA? (130 ft)? had a loading coil which lowered the resonances on 10/15 meters.*
*One can also mess with various lengths of wire on the "counterpoise" socket on the UNUN.
*
*Here is the expanded? 80m? graph? and the expanded? 10m graphs*
*As you can see, I wanted to make it "long" to work well on the low part of 80m band for CW and digi modes.
*
*
*
*
*
*It also tunes up easily on the 10m band with no additional tuner needed, but I prefer a _10m vertical_ for low-angle DX .
*
*
*
*Not bad for one wire and a UNUN.
*
*de k3eui*
*
*
*
*
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I'm looking back at this and thinking about your configuration. Its much like an inverted L but on its side - so yet not, but the second half may still be experiencing some loading. Its understood that you are space limited, that's always the drawback, can you reduce the 90 degrees at all (?) or convert it to an inverted L ? As is I'd think that since you are not concerned about 10/20/30m that the supplied unun should be "ok". And yes I've used good 9:1 unun's on these but a tuner as well. (my first was a failure due to a poor one off of ebay)
All of the bands (except 30m) were resonant lower, this looks like trimming alone could do - no coils required, keep it simple.
Here's my approach to trimming. Find your current resonance near your primary target and do a reverse length calculation. Compare the actual length calc to an online calculated length at that resonance. The diff should be the velocity factor and site specific influences. Recalculate for your target from above. Cut longer in stages and fold back - keep the fold back twisted so that it doesn't resonate. I know you know this but I've added it for reference to other "new ticket" readers.
Andy
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On Wed, Feb 21, 2024 at 10:27 AM, Barry K3EUI wrote:
I am using the space I have available.
The 140 ft #12 wire attached to the MyANTENNA 49:1 UNUN is about 20 ft above
Chester County ground and is horizontal the whole way and runs 50 ft
north-south in one direction and make a right angle turn on a tree limb to
another 90 ft run east-west.
It is set up only for NVIS prop and I don¡¯t care about any bands other than
80m and 40m since verticals do far better on 20m and 10m
de k3eui
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56:1? That¡¯s kind of a weird ratio. 49:1 is easy, it¡¯s 7:1 turns ratio (impedance goes as the square of the turns ratio). 64:1 would be 8:1 turns.
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On Feb 21, 2024, at 7:47?AM, Andrew Harman <Nexus9d9@...> wrote:
?I've seen other kits which supply 130 ft with a 56:1. (and since you went with a heavy wire you are likely a little long on your trim yet) If its high enough a counterpoise isn't necessary - but grounding at entrance is recommended. (NPFA 70, article 800) The other option for a coil at the feed point is also sometimes used - but you knew that.
Andy
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15:2 ratio?
Approx.
Cheers,
Paul
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On 22/02/2024 14:34, Jim Lux wrote: 56:1? That¡¯s kind of a weird ratio. 49:1 is easy, it¡¯s 7:1 turns ratio (impedance goes as the square of the turns ratio). 64:1 would be 8:1 turns.
On Feb 21, 2024, at 7:47?AM, Andrew Harman<Nexus9d9@...> wrote:
?I've seen other kits which supply 130 ft with a 56:1. (and since you went with a heavy wire you are likely a little long on your trim yet) If its high enough a counterpoise isn't necessary - but grounding at entrance is recommended. (NPFA 70, article 800) The other option for a coil at the feed point is also sometimes used - but you knew that.
Andy
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I consider a 56/1 wideband transformer to be a utopia (I could be wrong). The fact of presenting measurements by joining two transformers head to tail does not assume anything about the operation of a single transformer. Let's push the absurd and suppose that in the boxes they are 1/1 transformers, you will always have very encouraging measurement results. -- F1AMM Fran?ois -----Message d'origine----- De la part de Andrew Harman Envoy¨¦ : vendredi 23 f¨¦vrier 2024 12:58
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Jim, The 56:1 can be seen at the Myantennas website. They have a similar transformer with the 49:1 and state it can be in the horizontal L config. On the 49:1 kit there is a disclaimer on the band coverage. These are typically a 3 core kernel.
Fran?ois, A 49:1 is 2500:50 ohms and a 56:1 is 2800:50. Saying the "boxes" are 1:1 -- that is if fact absurd. The end to end testing is INSERTION LOSS. You may want to look at some articles at Ferrite Corporation on how insertion loss testing may be performed. My local club president was the chief engineer at Ferrite until he recently retired - he has steered us to many of their papers and videos over the years.
Andy
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The end to end testing is INSERTION LOSS. Ok, it is the testing insertion of the *two boxes end to end*. This doesn't tell us anything about the functioning of any *one* of the boxes. Even if it's Uncle Sam who does the measuring -- F1AMM Fran?ois -----Message d'origine----- De la part de Andrew Harman Envoy¨¦ : vendredi 23 f¨¦vrier 2024 13:45
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I have an end-fed antenna with switch-selectable 49, 56 and 64:1 ratios. It's covered with heat shrink so I haven't looked inside. Checks out OK with VNA.
73, Don N2VGU
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If one had a lossless transformer for an End Fed Halfwave EFHW one would expect low SWR on the harmonic multiples of the fundamental frequency, such as 80 40 20 and 10 meters. I attribute the low SWR readings at other frequencies because of the resistive loss in the ferrite.
I consider these EFHW designs another example of broadband lossy designs such as the Tilted Terminated Folded Dipole T2FD antenna which uses a resistive termination. One could follow a trick used by Barker and Williamson in the design of their T2FD by using stainless steel wire. The higher resistance of the steel wire would also result in a lower SWR at the expense of efficiency.
Choosing an antenna is a compromise - a mix of cost, complexity, frequency agility and size but as the saying goes TANSTAAFL - "There ain't no such thing as a free lunch".
Mike N2MS
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On 02/23/2024 7:12 AM EST Fran?ois <18471@...> wrote:
I consider a 56/1 wideband transformer to be a utopia (I could be wrong). The fact of presenting measurements by joining two transformers head to tail does not assume anything about the operation of a single transformer.
Let's push the absurd and suppose that in the boxes they are 1/1 transformers, you will always have very encouraging measurement results.
--
F1AMM
Fran?ois
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In my modeling of an EF wire, be they 1/2-wavelength or not, a 9:1 is far
more in order than a 49:1 or even higher ratios. Reason is for any
"reasonable" and amateur typical heights above soil surface, the
interaction of the ground very noticeably lowers the free space feed
impedance. What's more, some sort of counterpoise, even the outer surface
of the coax feed, is absolutely required.
Dave - W?LEV
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On Fri, Feb 23, 2024 at 11:58?AM Andrew Harman <Nexus9d9@...> wrote: Jim,
The 56:1 can be seen at the Myantennas website.
Andy
-- *Dave - W?LEV*
--
Dave - W?LEV
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I just substituted a 9:1 Palomar Engineering UNUN with 100 ftRG213 (counterpoise) and changed the wire length to 155 ft in a large horizontal loop (around my back yard).
Everything looks better than the 49:1 UNUN and 130 ft wire on 80m and 40m, but we will test more thoroughly
de k3eui barry
Phila PA
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On Fri, Feb 23, 2024 at 09:33 AM, N2MS wrote:
I consider these EFHW designs another example of broadband lossy designs such
as the Tilted Terminated Folded Dipole T2FD antenna which uses a resistive
termination. One could follow a trick used by Barker and Williamson in the
design of their T2FD by using stainless steel wire. The higher resistance of
the steel wire would also result in a lower SWR at the expense of efficiency.
I've used them before - great company. In my application and if I remember the part number correctly it was the BWDS1.5-80 with the stainless steel wire. I had that installed as a backup to a CMV-604 vertical for a KC-135 mission east of Halifax from Niagara Falls. It was mounted in a horizontal dipole configuration at 35 ft. The stainless steel wire model was chosen for strength and durability in icy and high wind conditions. Mind you this was a dipole. The SWR was very low and almost perfect in fact. During operational testing, unexpectedly, Minot ND had to ask us to turn down our power. Moving antennas to different locations over the years I was in Combat Comm we learned that the soil conditions do play in a large part. The same antenna was unpredictable over a thin soil, high rock or heavy clays. Having a switchable transformer as was mentioned would have been sweet for us or even having an assortment to play with. Testing the antenna Z (without its transformer) in each specific installation would be the most ideal however when elevated could be impractical. Back to EFHW, a couple of years ago I played with inverted "L"s. As I previously stated I first used a 9:1 and found the core to be garbage giving me both poor band coverage and extremely high SWR. I had a few 4:1 Balun Designs transformers kicking around and rewound one as a 9:1, beautiful results because they use a premium core. But I relocated that for Field Day and It wasn't as impressive (soils again?). Another ham there loaned me a 49:1 with better results. So as they say, "individual results may vary". Andy
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What is a premium core? An inverted-L typically has a impedance <50 ohms and a endfed halfwave is high impedance, so neither a 1:9 nor a 1:4 transformer could be right. 73 Peter, DJ7WW -----Original-Nachricht----- Von: "Andrew Harman" <Nexus9d9@...> An: " [email protected]" < [email protected]> Back to EFHW, a couple of years ago I played with inverted "L"s. As I previously stated I first used a 9:1 and found the core to be garbage giving me both poor band coverage and extremely high SWR. I had a few 4:1 Balun Designs transformers kicking around and rewound one as a 9:1, beautiful results because they use a premium core. But I relocated that for Field Day and It wasn't as impressive (soils again?). Another ham there loaned me a 49:1 with better results. So as they say, "individual results may vary". Andy ?
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Barry K3EUI
Stan - WB5UDI
Donald S Brant Jr