[GCARC] Fwd: FW: SWR and ladder line

[Chuck Colabrese]

Tony, 
This is common with 450 ohm ladder line. Or as a lot of people call it "window line". I've used it here for a long time. The water soaks the plastic dielectric and the line's characteristics change. The 600 ohm "ladder line" that Tom is suggesting has mostly air between the conductors, and is not affected as much by the rain. 
You have to change your tuner settings when it rains with the 450 ohm window line, but, as long as the tuner handles it, live with it. It's normal. 

Here's a link to some forums on qrz.com where the problem is discussed. A lot of different opinions. 
http://forums.qrz.com/archive/index.php/t-279751.html 

Here's something else to consider... How long is your run of RG-8X ? Since this is a multi-band antenna, the SWR at the tuner is going to be quite high on certain bands/frequencies, so, the losses in that section of feedline might be quite high. If it's short, (less than abt 40 feet) I wouldn't worry about it. For 40 to 100 feet, you might consider changing that to something like RG-8 or RG-213, or even 9913 or LMR-400 for a run longer than 100 feet. 
73, Chuck, WA2TML 

----- Original Message -----

From: "Tom Gorman" <tom.gorman2178 at gmail.com> 
To: "Tony" <kd2afy at comcast.net> 
Cc: gcarc at mailman.qth.net 
Sent: Sunday, March 30, 2014 9:43:15 PM 
Subject: [GCARC] Fwd: FW: SWR and ladder line 

Tony, 

You might want to switch to 600 ohm ladder line if SWR variations with 
moisture are adversely affecting your operating during storms such as this 
weekend, especially on contest weekends such as this. 

Read eham reviews of both K4NA and W5KG on page 2 of 4 of website 
www.trueladderline.com Their rain and moisture problems were both 
minimized when they switched from 450 to 600 ohm ladder line impedance. 

BTW, you might also have better results with a 4:1 balun with RG8. Check 
with the engineering folks at Balun Designs, www.balundesigns.com 

They can recommend a 4:1 current balun for ladder line that works very well 
with 600 ohm low loss ladder line. Possibly their Model #4111. 

Hope this helps... 

73, 
Tom, KE2ES 



---------- Forwarded message ---------- 
From: Jeff - Comcast <jeff.garth at comcast.net> 
Date: Sun, Mar 30, 2014 at 8:41 PM 
Subject: [GCARC] FW: SWR and ladder line 
To: gcarc at mailman.qth.net 


I am forwarding this for Tony because he sent it to the wrong address. 



D. Jeffrey Garth 

621 Greenbriar Drive 

Williamstown, NJ 08094-1149 

73, KC2WCS 

Club Publications 

www.w2mmd.org <goog_162360365> 



"Choose a job you love, and you will never have to work a day in your life" 
- Confucius 



From: Tony [mailto:kd2afy at comcast.net <goog_162360365>] 
Sent: March 30, 2014 20:07 
To: gcarc-bounces at mailman.qth.net <goog_162360365> 
Subject: SWR and ladder line 



I'm hoping to tap the collective knowledge of the group on this one. I have 
an antenna which is fed by 450ohm ladder line into a 4:1 balun to RG-8x 
coax. I know there is no water in the balun or coax. Why does the SWR of 
the antenna change dramatically in rain or snow? It's not a problem per se, 
the tune handles it nicely, but it perplexes me. 



73, 

Tony 



Tony Otlowski, KD2AFY 
Assistant EC/ Net Control Manager/Asst. Skywarn Coordinator 
Gloucester County, NJ ARES/RACES 

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