Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Coiling excess coax in mobile rig  (Read 3355 times)
KK4IKO
Member

Posts: 67




Ignore
« on: April 04, 2012, 12:41:53 PM »

I'm going to have about 9' of excess coax when I finish my mobile rig setup.  I've read lots of stuff on the effects of coiling the excess or not, but those folks can't seem to agree (mostly CBers) on what to do.  I'll be on 2 and 6 meters mostly.  Since I don't have the PL-259 installed yet, is cutting to fit an option?  The setup is a Larsen 5/8 wave mobile on a Larsen NMO mount going to an appropriate duplexer and then to the IC706MKIIG radio. 

No callsign yet, I'm taking the test on Saturday.
Logged
WB6BYU
Member

Posts: 13038




Ignore
« Reply #1 on: April 04, 2012, 01:00:54 PM »

 Cutting to fit will slightly decrease the coax losses:  by about 0.4dB
according to VK1OD's transmission line loss calculator:
http://www.vk1od.net/calc/tl/tllc.php

On the other hand, simply coiling it up is fine, and gives you the option
to pull it out for maintenance, or to set the rig on the outside of the car
when operating in the field, etc.
Logged
KB1GTX
Member

Posts: 460




Ignore
« Reply #2 on: April 04, 2012, 08:05:35 PM »

Go ahead and coil it.

The cb'ers got that don't coil the coax from instaling cb's on non metalic boats where the coax run worked as the ground plane.
Logged
AC5UP
Member

Posts: 3825




Ignore
« Reply #3 on: April 04, 2012, 10:27:40 PM »

I'd coil it, and I'd put the coil under a seat or somewhere else that offers some protection from being crushed. I'd also make the coil radius fairly large as that's less mechanical stress and good VHF practice involves gentle transitions from a straight run.......
Logged

Never change a password on a Friday                
W5DXP
Member

Posts: 3546


WWW

Ignore
« Reply #4 on: April 05, 2012, 04:31:50 AM »

I've read lots of stuff on the effects of coiling the excess or not, but those folks can't seem to agree (mostly CBers) on what to do.

Something else to consider: Coiling has an effect on common mode currents on the coax and is often used at HF as an "ugly balun" to reduce common mode problems.
Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
WA3SKN
Member

Posts: 5443




Ignore
« Reply #5 on: April 05, 2012, 05:42:36 AM »

9 Ft of coax is not that much, unless you are using RG179 or such... so there should not be a problem in coiling it.  But you can cut to fix, if desired, just to improve appearance.  And if there is any real problems (with common-mode, etc.) you will want to address it anyway!
Good luck with the test!
73s.

-Mike.
Logged
N4CR
Member

Posts: 1655




Ignore
« Reply #6 on: April 05, 2012, 06:52:28 PM »

Good luck on your test!!

You can just coil up extra coax with no noticeable effect. Larson makes exceptionally nice mounts and antennas. You'll have a great installation even with it coiled up. Don't make the coils too small but the diameter of a 2 liter bottle would be fine.

Welcome to the hobby!
Logged

73 de N4CR, Phil

We are Coulomb of Borg. Resistance is futile. Voltage, on the other hand, has potential.
N6AJR
Member

Posts: 9891




Ignore
« Reply #7 on: April 07, 2012, 12:24:54 PM »

If  it already has a connector  then coil it up and shtash it out of the way. If it has no  connector on it and it will be staying in this car, then cut it to fit, and save a bit of loss.
Logged
KK4IKO
Member

Posts: 67




Ignore
« Reply #8 on: April 08, 2012, 06:03:04 PM »

Thanks for all your help.  I passed my test, looking for my callsign in the next week or so.  I completed the installation and gave the radio a listen.  All I got was a weak conversation accompanied by lots of static on 147.45.  I would suppose the fact I live in a narrow north/south mountain valley with ridges on 3 sides didn't help.  Later this week, I'm going mountain-topping.
Logged
N4NYY
Member

Posts: 4742




Ignore
« Reply #9 on: April 08, 2012, 07:38:13 PM »

Quote
Thanks for all your help.  I passed my test, looking for my callsign in the next week or so.  I completed the installation and gave the radio a listen.  All I got was a weak conversation accompanied by lots of static on 147.45.  I would suppose the fact I live in a narrow north/south mountain valley with ridges on 3 sides didn't help.  Later this week, I'm going mountain-topping.


Do yourself a favor and do not be like me, where my work frequents parking garages, many of the 7 foot clearance variety. I cannot even put on a 2M magmount, or I will destroy it. Believe me when I say, you will forget.

Congrats on the license and stay the hell away from parking garages!
Logged
KK4IKO
Member

Posts: 67




Ignore
« Reply #10 on: April 09, 2012, 04:32:47 AM »

Good point about parking garages...never really thought about it because I use them very infrequently.  I'll put a reminder on the dash, LOL.
Logged
N6AJR
Member

Posts: 9891




Ignore
« Reply #11 on: April 09, 2012, 12:33:05 PM »

a small 2m antenna on a trunk lip mount will be ok for repeaters and will be below the roof line and no thought necessary...Smiley  my kind of antenna
Logged
W0FM
Member

Posts: 2052




Ignore
« Reply #12 on: April 12, 2012, 11:58:06 AM »

I like that, Tom....."NTN".  No Thought Necessary.  I think I'll make all my future projects the "NTN" variety.  Not getting any younger, ya know.  ;o)

73,

Terry WØFM
Logged
N6AJR
Member

Posts: 9891




Ignore
« Reply #13 on: April 12, 2012, 02:25:06 PM »

Heck I have a second one on the other side of the trunk lid for the 900 radio.  After the first time I ran it through the "free" car wash at the gas station, I realized I don't have to take them off there either.  On the other side of it, in my truck I have a ladder rack, 4 antennas on the roof and 4 antennas on the bed rails, and the tallest is over 10 feet, and it always wakes me up when I forget it is there.  The tallest is a 60 inch whip on a bed mounted DK 3, so it is a tough old  bird and it always reminds me that I have antenns upo there... ot does the word "twang" come to mind:)
Logged
KK4IKO
Member

Posts: 67




Ignore
« Reply #14 on: April 12, 2012, 05:16:34 PM »

Now if I could only get the forum guru to recognize the fact I have filled out his little form to change to my new callsign 2 days ago, I'll appear to be a little more official looking.

Anyway, just for the record, I'm now KK4IKO.

I have just one antenna, on the roof of my Cherokee.  A ham friend is going to help me get on the air this weekend.

You elmers are great!
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!