Antenna Cable

Discuss antenna construction, problems, tuning, designs...

Moderators: Sir Nigel, Nina, pcs, 5r, phpBB2 - Administrators

Post Reply
Polo_Thug
Regular poster
Regular poster
Posts: 24
Joined: Sun Nov 21, 2004 9:40 pm

Antenna Cable

Post by Polo_Thug »

Just was wondering is it okay to mismatch cables...I have a RG8/U 13 AWG that going into my amp from my transmitter and a RG58?U 20 AWG thats coming out my amp in connect to my comet antenna....Just want to know if thios is okay
User avatar
pcs
Site master
Site master
Posts: 3132
Joined: Fri Jan 18, 2002 1:00 am
Location: Radio Land
Contact:

Post by pcs »

Just make sure it is all 50 ohms.
Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
User avatar
Dr. No
Regular poster
Regular poster
Posts: 23
Joined: Sun Jan 27, 2002 1:00 am

Post by Dr. No »

Marko is correct on the match. both RG-8 and RG-58 are 50 ohm cables.

If you are running more than 25 feet from the amp to the antenna, you are loosing some of the power that could be running out the antenna instead of the heat generated by the high relative loss that RG-58 gives you at 100 mhz.

You do not need to waste money on RG-213 or high quality RG-8 if you are running under 30 meters or 100 feet, but here are some suggestions: Under 40 feet, use Belden 9258 RG-8/X (mini coax) . The loss will be less than 1 Db. It is the same size as the 75 ohm cable that is common in Cable TV apps the diameter is like that of RG-59. only a little bigger than RG-58.

Over 40 feet, Times Wire and Cable LMR-240 is very good, lower loss than RG-8/X it approaches that of the larger RG-8. and is only 10 cents a foot more than RG-8/X. I would use LMR-240 up to 125 feet, RG-213 over that length.
Holliday
New registered user
New registered user
Posts: 3
Joined: Mon Apr 04, 2005 6:12 pm
Location: Leamington

75 ohm

Post by Holliday »

Is it a huge crime to use 6 or 11u for the antenna? It wont hurt the PCI MAX will it?
User avatar
Dr. No
Regular poster
Regular poster
Posts: 23
Joined: Sun Jan 27, 2002 1:00 am

Re: 75 ohm

Post by Dr. No »

Holliday wrote:Is it a huge crime to use 6 or 11u for the antenna? It wont hurt the PCI MAX will it?
They are both 75 ohm cables. spend a few dollars on the correct stuff.
User avatar
pcs
Site master
Site master
Posts: 3132
Joined: Fri Jan 18, 2002 1:00 am
Location: Radio Land
Contact:

Post by pcs »

Cable is really quite cheap so there's no reason not to get
the correct one.
Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
Holliday
New registered user
New registered user
Posts: 3
Joined: Mon Apr 04, 2005 6:12 pm
Location: Leamington

Post by Holliday »

The catch is I have thousands of feet of 6 & 11, and hardly anytime to take a lunch break let alone shop. So in the mean time..... basically I'm looking for pros and cons 75ohms, as 50ohm materiel is fairly foriegn to me. If I use rg11 or 6 to get me by for now, am I going to wreck anything?
User avatar
pcs
Site master
Site master
Posts: 3132
Joined: Fri Jan 18, 2002 1:00 am
Location: Radio Land
Contact:

Post by pcs »

If it is just going from a low powered PCI MAX to antenna,
75ohms is ok.
Best regards,
Marko - PCS Electronics
--------------------------------------------------------
Turn your PC into a FM radio station!
http://www.pcs-electronics.com
fax +386 4 2316 128
User avatar
Fission7x
Regular poster
Regular poster
Posts: 21
Joined: Sat Jul 03, 2004 2:51 pm

Post by Fission7x »

Holliday wrote:The catch is I have thousands of feet of 6 & 11, and hardly anytime to take a lunch break let alone shop...
Don't forget the click, click, here it comes in the mail method.
In the time it takes to post a few notes to a forum, your new coax could be on it's way!
You could possibly try the upper left hand corner of this screen??!!
Fission
Post Reply