Colin,
The minimum 70 feet is a specification from W8AMZ, whose version of the G5RV
Howard and I are using. I have no idea where that comes from nor do I think
it's meant to be a universal spec for all G5RV's. I imagine he has his
reasons for such a spec but I haven't seen them listed anywhere. When I
bought the coax for mine, I just happened to get a 75 foot run to make sure
I'd have enough. Then, when I bought his version, I saw his requirement and
just left the coax in tact even though I don't need that much. Lou WA3MIX
Lou Kolb
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Radio/TV Ads, Video narrations
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www.loukolb.com
----- Original Message -----
From: "Colin McDonald" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, August 20, 2012 12:09 AM
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
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