The coax isn't part of the antenna.
It is purely a link from the ladder line to the ATU.  A random length is preferable.


David W Wood

Ham call - G3YXX
FOC # - 1685
Licensed - 1969
 
-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]] On Behalf Of Colin McDonald
Sent: Monday, August 20, 2012 5:09 AM
To: [log in to unmask]
Subject: Re: Tom's G 5 R V

granted, the recommendation for using 75 feet of 50 ohm coax is something 
your antenna designer stated.
However, most antennas based on the G5RV design do not specify a certain 
length of 50 ohm coax to feed it.
Where does the magic number of 75 feet come from? it's not a quarter wave, 
or a half wave on any of the frequencies the G5RV style antenna covers...
I've now seen several installations where a short pig tail, or any various 
length of 50 ohm coax is used and the antenna plays perfectly fine.
does the extra long length of coax somehow reduce swr or increase bandwidth 
or make the antenna more efficient?  I would think any gain in efficiency 
would be off set by loss in the coax over 75 feet.
those are just my thoughts.
But if you have a technical explanation as to why they work better with 75 
feet of coax, please explain if you would.
I'm curious to know why.

73
Colin, V A6BKX
----- Original Message ----- 
From: "Howard, W A 9 Y B W" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, August 19, 2012 7:51 PM
Subject: Tom's G 5 R V


>I have been out of town until about an hour ago.  I just read all the =
> posts in regard to your antenna Tom.
>
> For the antenna to work properly you need about 75 feet of coax between =
> the window line and your radio.  The excess coax can just be coiled up =
> in your shack or outside the RV at a convenient place.
>
> I know you really don't need to buy a new antenna, however, the G 5 R =
> V's from W 8 A M Z are made very well. The connections at the top where =
> the window line connect to the two legs of the antenna are sealed in =
> epoxy.  The bottom end of the window line is terminated in an S o 239 =
> connector which is also sealed in epoxy therefore all the connection =
> points will not get any moisture in them.  The 450 ohm window line is =
> copper coated steel wire which is insulated and will not break from =
> movement in the wind.
>
> I own one of these and I feel it is of high quality.  The regular size =
> is about $70.
>
> Get the wire off the ladder, cut the P L 259 connector off the coax =
> pigtail check for continuity.  If there is still a short, cut the =
> pigtail completely off the window line and make a new pigtail and =
> install it be sure to water proof all connections.
>
> Again, 75 feet of coax between window line and radio, a must!!!
>
> In general, it seems like most agree on what you should do.
>
> 73
>
> Howard #3 

--
I am using the free version of SPAMfighter.
SPAMfighter has removed 3721 of my spam emails to date.
Get the free SPAMfighter here: http://www.spamfighter.com/len

Do you have a slow PC? Try Free scan http://www.spamfighter.com/SLOW-PCfighter?cid=sigen