Rick, I was talking about the CM impedance rather than the Differential-Mode impedance. If you switch in parallel with each other the two 1:1 chokes which form the 4:1 Guanella balun, you have a 1:1
I've now run this experiment a further 3 times with pretty consistent results: on average, adding the water dropped the velocity factor by 1.8% and increased the matched loss by 0.25db/100ft at 26MHz
Problem solved .... I think. Just added some wetting agent - washing up liquid - to the water and re-sprayed. Losses jumped to 5dB/100ft at 26MHz! Steve G3TXQ I hope you document the test on your web
Ok, let me try the simple Executive summary: Taking a length of window-line fresh off the drum, and dowsing it with UK (midlands) rain water I see an small increase in attenuation at the top of the H
We're talking here about reported changes in loss that - if true - would be equivalent to a 5dB change between dry and wet on a 100ft of ladderline feeding a doublet on 10m. Are you folks trying to t
Bob, Perhaps I had better explain clearly why I am carrying out these ladderline tests. I believe that the "wet" ladderline losses reported by Wes Stewart, and those predicted by at least two of the
Now re-run EZNEC with the dipole at 25ft and at 55ft over average ground, and compare the losses reported by EZNEC with your figures; you'll see something very different! Orr's "logic" is way too sim
Run any FF 3D plot and look at the Average Gain figure; it will tell you what fraction of the total input power is reaching the Far Field. If you set the wire losses to zero, you'll be left with just
Joel, That'll teach me to read things more carefully - I'll modify the conclusions accordingly. I'm now waiting for some ice/snow conditions ...... but I don't think it'll be within the next few days
That's probably close enough for this sort of work! But it's maybe worth pointing out that an unmatched line does not have uniform losses along its length - the losses are higher at the standing wave
Dean, With respect, TLW doesn't agree with my results! Taking the " 450-Ohm Window Ladder Line" option, 60ft long, with a 50 Ohm load, at 29.5MHz TLW predicts a loss of 0.356dB - that's almost exactl
Jim, Thanks for pointing me in the direction of Zplots - I'd not appreciated what it can do, although I'm a big fan of AC6LA's TLD software. I just downloaded Zplots and ran open and short S11 tests
Yes it can - check the skin depth at 10MHz! Then try it again at 50MHz and you'll get 19 Ohms for 100ft! Steve G3TXQ S. Rohre _______________________________________________ TenTec mailing list TenTe
For future reference: http://ve3efc.ca/wire_ohms.html Steve G3TXQ Then try it again at 50MHz and you'll get 19 Ohms for 100ft! Steve G3TXQ S. Rohre _______________________________________________ Ten
On an unmatched line, losses vary with length because there are current peaks and troughs along the line. And because at HF losses are almost entirely copper losses, where the current peaks the losse
Jim, I'm comparing like for like: TLD's loss predictions for the line with a 50 Ohm load, vs my measured results with a 50 Ohm load. I'm pretty sure my line is equivalent to Wireman 551, and therefor
Well, I just spent two hours re-calibrating everything; results using Zplots were marginally better, but still not acceptable. Re-reading Dan's notes on Zplots' "Measure Transmission Line Parameters"
For anyone interested, web page updated with a further test to see the effect of ladderline in contact with a length of aluminium. Test 11 here: http://www.karinya.net/g3txq/wet_ll/ Steve G3TXQ
The water I used was collected rain water; I also tried tap water at one stage, but results between the two were indistinguishable. The line is still set up waiting for some heavy rain - I'm interest