Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old October 17th 05, 05:26 AM
Jon L
 
Posts: n/a
Default antron 100 antenna question

Hey Jack! When checking the coax with the ohm meter as you described,
what sort of a reading shoud you get, and I suppose you should set it
to DC, but at what voltage? I know these are basic questions, but I am
sure I am not the only one who is unsure. Thanks for the reply in
advance! Have a great week! Jon.

  #2   Report Post  
Old October 17th 05, 06:51 PM
Dungeon Master
 
Posts: n/a
Default antron 100 antenna question

Jon,
When checking a coax with an ohm meter. With the coax disconnected on
both ends, measure from shield to ground. This must be an infinity
reading. Now measure the center conductor end to end. This shouldn't be
over a couple ohms at the most. The same for the shield measurement. If
you have a dummy load, connect it to one end and you should read around
52 ohms with the meter. It's best to do that from both ends to ensure
the connectors are good. The only way better to test is with either a
megger or a TDR time Domain Reflectometer.
If you have you atenna connected, you'll find that with most fiberglass
base antennas, you'll have a reading from 40 - 150 ohms do to the
tuning curcuit inside the antenna.
I hope this helps a little.....
73 de Dungeon Master

  #3   Report Post  
Old October 17th 05, 07:33 PM
Jan Panteltje
 
Posts: n/a
Default antron 100 antenna question

On a sunny day (17 Oct 2005 10:51:15 -0700) it happened "Dungeon Master"
wrote in
.com:

Jon,
When checking a coax with an ohm meter. With the coax disconnected on
both ends, measure from shield to ground. This must be an infinity
reading. Now measure the center conductor end to end. This shouldn't be
over a couple ohms at the most. The same for the shield measurement. If
you have a dummy load, connect it to one end and you should read around
52 ohms with the meter. It's best to do that from both ends to ensure
the connectors are good. The only way better to test is with either a
megger or a TDR time Domain Reflectometer.
If you have you atenna connected, you'll find that with most fiberglass
base antennas, you'll have a reading from 40 - 150 ohms do to the
tuning curcuit inside the antenna.
I hope this helps a little.....
73 de Dungeon Master

Small correction:
There is a difference between 'rsistance' and 'impedance'.
For example when I measure the 'resistance' (with the Ohm meter) from
my 1/2 wave GPA, I measure a dead short.
This is because there is a little transformer in it, you measure the Ohms
of the wire in the primary.
the *impedance* however is around 50 Ohms (I would hope).

There is a simple way to measure impedance too, in a bridge:
http://web.telia.com/~u85920178/antennas/bridge.htm

The reason is that for DC a transformer is almost dead short....





  #4   Report Post  
Old October 17th 05, 07:10 PM
DrDeath
 
Posts: n/a
Default antron 100 antenna question

"Jon L" wrote in message
oups.com...
Hey Jack! When checking the coax with the ohm meter as you described,
what sort of a reading shoud you get, and I suppose you should set it
to DC, but at what voltage? I know these are basic questions, but I am
sure I am not the only one who is unsure. Thanks for the reply in
advance! Have a great week! Jon.

Set the meter on ohms. You should get infinity between the center conductor
and ground. You should get a reading very close to zero when checking ground
to ground or center to center.
On your previous post on swr meter use, place in line close to radio. Place
switch to for, key mic and adjust to where it says cal, the switch it to
ref. That will give you your swr reading.


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Inverted ground plane antenna: compared with normal GP and low dipole. Serge Stroobandt, ON4BAA Antenna 8 February 24th 11 10:22 PM
SkyWire Loop Antenna [Was: Wire loop.] Question RHF Shortwave 0 September 21st 05 10:15 AM
Poor quality low + High TV channels? How much dB in Preamp? lbbs Antenna 16 December 13th 03 03:01 PM
Poor quality low + High TV channels? How much dB in Preamp? lbbs Shortwave 16 December 13th 03 03:01 PM
Question for better antenna mavens than I Tony Meloche Shortwave 7 October 28th 03 09:16 AM


All times are GMT +1. The time now is 05:13 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017