Need help on How to test transmission line
 

Hi fellow amateurs,
I am using 746Pro for 6M with direct coax to my 5 el antenna. I used to
get 1:1 SWR but recently, the SWR runs a little over 1:2 and my output
drops to 30W.When stations in FN20 were working EU, I could hear
nothing. My signal can still be received because I was able to make
contacts despite 1:2 SWR as far as FM5AA. But I know something is wrong
with the line or the antenna. I checked all the connections and they
seemed to be ok.

Can someone help by directing me to a source where I can read about
troubleshooting transmission line? Or can someone who has experience in
this give me step by step instruction on how to diagnose the problem,
e.g., is it the PL 259 at the rig side, or the antenna side, or
somewhere along the line, or is it the antenna altogether. I have an
ohm meter and a small swr/pwr meter box.
Thanks in advance.

73, steve

Need help on How to test transmission line
 

Need help on How to test transmission line
 

"Dave" wrote in message
. ..
wrote:

Hi fellow amateurs,
I am using 746Pro for 6M with direct coax to my 5 el antenna. I used to
get 1:1 SWR but recently, the SWR runs a little over 1:2 and my output
drops to 30W.When stations in FN20 were working EU, I could hear
nothing. My signal can still be received because I was able to make
contacts despite 1:2 SWR as far as FM5AA. But I know something is wrong
with the line or the antenna. I checked all the connections and they
seemed to be ok.

Can someone help by directing me to a source where I can read about
troubleshooting transmission line? Or can someone who has experience in
this give me step by step instruction on how to diagnose the problem,
e.g., is it the PL 259 at the rig side, or the antenna side, or
somewhere along the line, or is it the antenna altogether. I have an
ohm meter and a small swr/pwr meter box.
Thanks in advance.

73, steve

Steve, If you can locate someone who owns an antenna analyzer you should
be able
to analyze your problem. I use the MFJ 259B.

Someone in your local radio club should own one, antenna analyzer, or have
access to one.

BTW, a 2:1 VSWR is not BAD. It indicates that the antenna is receiving 90%
of
the available power. However, ICOMs are designed to power down on low to
moderate VSWR. Note: I run about 30:1 on 75 meters.


what about coax losses at that VSWR?

Need help on How to test transmission line
 

gravity wrote:

"Dave" wrote in message
. ..

wrote:


Hi fellow amateurs,
I am using 746Pro for 6M with direct coax to my 5 el antenna. I used to
get 1:1 SWR but recently, the SWR runs a little over 1:2 and my output
drops to 30W.When stations in FN20 were working EU, I could hear
nothing. My signal can still be received because I was able to make
contacts despite 1:2 SWR as far as FM5AA. But I know something is wrong
with the line or the antenna. I checked all the connections and they
seemed to be ok.

Can someone help by directing me to a source where I can read about
troubleshooting transmission line? Or can someone who has experience in
this give me step by step instruction on how to diagnose the problem,
e.g., is it the PL 259 at the rig side, or the antenna side, or
somewhere along the line, or is it the antenna altogether. I have an
ohm meter and a small swr/pwr meter box.
Thanks in advance.

73, steve

Steve, If you can locate someone who owns an antenna analyzer you should

be able

to analyze your problem. I use the MFJ 259B.

Someone in your local radio club should own one, antenna analyzer, or have
access to one.

BTW, a 2:1 VSWR is not BAD. It indicates that the antenna is receiving 90%

of

the available power. However, ICOMs are designed to power down on low to
moderate VSWR. Note: I run about 30:1 on 75 meters.



what about coax losses at that VSWR?



What coax?? I didn't say I used coax. I said I run about 30:1 VSWR on 75 meters.

I use 600 ohm open wire tuned feeders. My TL Loss, approximately 150 feet, is
measured at slightly over 1 dB. I've been a ham since before coax became
commonly used. g

Need help on How to test transmission line
 

if the OP has no antenna or coax problems, he might invest in an antenna
tuner.

http://www.ocarc.ca/coax.htm

example follows.

100 watt transmitter
30 watts out
50 feet Belden 9913
2:1 SWR
26 watts to antenna

Gravity

Need help on How to test transmission line
 

I've been a ham since before coax became
commonly used. g

are you bragging about being old? ;-)

Gravity

Need help on How to test transmission line
 

gravity wrote:
i had no easy way to run twin lead through my window, so i used RG 58. my
losses were bad.

At any hardware store, you can buy a drill that will put
a hole through glass. That's pretty easy.
--
73, Cecil http://www.qsl.net/w5dxp

Need help on How to test transmission line
 

gravity wrote:
I've been a ham since before coax became
commonly used. g

are you bragging about being old? ;-)

Before WWII, coax wasn't all that popular.
--
73, Cecil http://www.qsl.net/w5dxp

Need help on How to test transmission line
 

gravity wrote:

I've been a ham since before coax became
commonly used. g


are you bragging about being old? ;-)

Gravity



Among other things! Have I told you about my grand kids??? g

Need help on How to test transmission line
 

"Cecil Moore" wrote in message
.com...
gravity wrote:
i had no easy way to run twin lead through my window, so i used RG 58.
my
losses were bad.

At any hardware store, you can buy a drill that will put
a hole through glass. That's pretty easy.

i considered a replacement (acrylic) pane for the window, but i couldn't get
permission for that.

the joys of renting.

Gravity