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 End fed trials 
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Post End fed trials
From the unun, my end fed runs through some shrubs, along the shed roof, across the rotary washing line (about a foot away) to a fence post then up to the top of a 25' fibreglass pole, across the roof (on the roof) then to a small tree at the front. (about 10' up)

Decided today to get it away from bushes etc at the fed end.

Cut about 15' off, and mounted the unun on another fence post, so now it runs for about 10' about 18" from the fence before going up the fibreglass pole.

Took the unun off and fed the end of the wire straight to the analyser, and connected the outer braid of the normal feed to the ground of the analyser.

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Looks like the 9:1 is about the best compromise



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And then put the unun back and measured this at the feed point.




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Then this at the TX end of the coax.


To me, even adding in about 0.5dB for unun loss, and the loss for 15m of RG58, I am still getting more than 75% of my power into the antenna on most bands, or am I misreading it?

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Mon Jul 20, 2015 1:52 pm
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 End fed trials 
Silent Key

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Post Re: End fed trials
What's the unun?

Steve G3TXQ


Mon Jul 20, 2015 4:57 pm
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 End fed trials 
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Post Re: End fed trials
G3TXQ wrote:
What's the unun?

Steve G3TXQ



9:1

I tried others, before testing, but not as good, then when I checked at the end of the antenna, it looked as if the 9:1 would be the best.

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Mon Jul 20, 2015 5:01 pm
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 End fed trials 
Silent Key

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Post Re: End fed trials
How many turns, on what core?

Steve G3TXQ


Mon Jul 20, 2015 5:14 pm
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 End fed trials 
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Post Re: End fed trials
G3TXQ wrote:
How many turns, on what core?

Steve G3TXQ


It is a 140-43 core, and would probably be around 10 turns, but it is raining now...................................

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Mon Jul 20, 2015 5:19 pm
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 End fed trials 
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Post Re: End fed trials
Tried another unun this morning, roughly 10:1.

Better SWR curve, but without logical reason, much better on receive, especially on 40 and 80

Attachment:
10to1b.jpg
10to1b.jpg [ 65.21 KiB | Viewed 1375 times ]


No heating on 160 or 10 at all with the 100W signal generator. Didn't try the other bands yet.

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Tue Jul 21, 2015 8:35 am
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 End fed trials 
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Post Re: End fed trials
Sangoma wrote:
G3TXQ wrote:
How many turns, on what core?

Steve G3TXQ


It is a 140-43 core, and would probably be around 10 turns, but it is raining now...................................


No, wasn't a 140-43 core, it's one of the mauvish ones from SA, they seem to be almost the same as the 140-3; it is 9 turns.

Attachment:
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Tue Jul 21, 2015 8:49 am
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 End fed trials 
Silent Key

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Post Re: End fed trials
As we saw in the earlier thread, it can be very misleading to use low SWR as the main criteria for choosing a particular unun design.

You can't really deduce anything about the overall system efficiency from the SWR curves; you need to have measured the antenna impedance, measured the unun characteristics, and then calculated the efficiency.

Steve G3TXQ


Tue Jul 21, 2015 10:25 am
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 End fed trials 
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Post Re: End fed trials
G3TXQ wrote:
As we saw in the earlier thread, it can be very misleading to use low SWR as the main criteria for choosing a particular unun design.

You can't really deduce anything about the overall system efficiency from the SWR curves; you need to have measured the antenna impedance, measured the unun characteristics, and then calculated the efficiency.

Steve G3TXQ



Just put two of the ununs back to back, and very happy with the loss (or lack of it compared to others).


Attachment:
10to1final.jpg
10to1final.jpg [ 51.39 KiB | Viewed 1304 times ]





Continue to be happy with performance, especially changing back and forth between ununs lots of times now, and each time comparing with a vertical and another wire antenna.


I would like to have a remote receiver far enough away to get some sensible readings.

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Fri Jul 24, 2015 8:21 am
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 End fed trials 
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Post Re: End fed trials
...one of the Web SDR's, Hackgreen maybe?

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Fri Jul 24, 2015 8:39 am
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 End fed trials 
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ei9ju wrote:
...one of the Web SDR's, Hackgreen maybe?


I tried, never been able to hear myself!

Tried at work too, not successful, I would like something 1/2 to 1 mile away.

You eventually get a feel for it working other people, just takes a lot longer, and very hard to do comparisons.

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Fri Jul 24, 2015 8:55 am
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 End fed trials 
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Post Re: End fed trials
I can't hear myself (sometimes) on 40m on Hack green, but can on websdr.ewi.utwente.nl:8901.
Try that one. If all else fails I can try listening for you. I have the radio on (remote) pick a freq.

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Fri Jul 24, 2015 9:22 am
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 End fed trials 
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Post Re: End fed trials
Sangoma wrote:
ei9ju wrote:
...one of the Web SDR's, Hackgreen maybe?


I tried, never been able to hear myself!



As Alan has said, try the Dutch one for 40m, you're probably too close to Hack Green for it to register. Hack Green is good for 80m and 160m, although on 160m, the Stafford and Derby SDR are sometimes better.

If you can't hear yourself, try shooting a carrier, this usually gets displayed and obviously, the brighter it is, the better the signal. Try a standard set up, using the same frequency, at the same time of day, and then you will have a fairly decent comparison to use.

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Fri Jul 24, 2015 10:08 am
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 End fed trials 
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Thanks, the weather is too hot still to go out and change ununs!

Just completed the two I made for testing with covers etc.

Took a couple of analogue power meters, adjusting them both to show 100w on each band, with a coupler, then put the ununs back to back between the two meters.

I was losing about 15W, which is less than .75dB, so halve that and it agrees fairly closely with the spectrum analyser.

So it looks as if the worst case, coax loss and a 2:1 swr(for coax loss), on 10m I should still get 75W at the antenna, On 20m will be about 85W.

Probably not the correct way to work it, but it does make it look like it is worth trying for a while.

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Fri Jul 24, 2015 1:53 pm
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 End fed trials 
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Post Re: End fed trials
Too hot, it's Pi$$in& down here in Tamworth.

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Fri Jul 24, 2015 2:17 pm
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