Tom:
Don't use coax if you can avoid it.

It is preferable to use twin 75 ohm for a horizontal dipole.

David



-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of T Behler
Sent: 28 December 2007 03:21
To: [log in to unmask]
Subject: Re: more G5RV stuff

    Thanks, Steve, for this very helpful information.

I fully realize that the G5RV is a compromise antenna at best, but right 
now, it's the only thing I have to get on 40 meters with at least some 
degree of effectiveness.

Perhaps a resonant coax-fed  dipole will be in my future once the Spring 
weather gets going here in the north country of Michigan.

73 from Tom Behler:  KB8TYJ

----- Original Message ----- 
From: "Steve Forst" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, December 27, 2007 10:05 PM
Subject: Re: more G5RV stuff


> Tom,
>
> First, good news on the  power supply.  Sounds like no problem.
> I think your G5RV sounds typical.   Following is a link  to a site with 
> some
> computer modeling of the G5RV.  If I'm following this correctly, the first
> batch of numbers shows swr's for all bands for a 102 ft. long dipole fed
> with coax, or 300 ohm  twin lead, or 450 ohm ladder line.   Some of the
> numbers are pretty high as you would expect.
>
> Then comes a batch of numbers showing  that same  dipole fed with coax, 
> but
> with a 300 ohm section (typical G5rv).   You can see how the numbers 
> change,
> and the examples you gave seem to  be in this ballpark.
>
> The G5RV is what it is, and while I used one  in the '80's, I  prefer coax
> fed resonant  dipoles.  To each his own.
>
> Here is the link:
>
> http://www.qsl.net/k2hq/g5rv.htm
>
>
> 73, Steve KW3A
>
> ----- Original Message ----- 
> From: "T Behler" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, December 27, 2007 9:09 PM
> Subject: more G5RV stuff
>
>
>> Hi, all.
>>
>> Can someone tell me what an acceptable SWR picture would be for a 
>> 102-foot
>> G5RV antenna?
>>
>> I re-oriented my G5RV antenna today, by making the ladder-line run pretty
>> much vertically from the antenna feed-point at the top of my 35-foot
>> tower,
>> to the coax that then goes into my shack from the base of the tower.  I
>> checked the connections between the ladder-line and the coax feedline, 
>> and
>> they still seem to be good.
>>
>> My SWR's are a bit better, and the auto-tuners on both my IC746 and
>> Kenwood
>> TS480 now tune the antenna on 40 meters (which I couldn't say before), 
>> but
>> the SWR's still seem quite high to me.
>>
>> On 40 meters, I get an SWR anywhere from about 5 to 1 down to about 4 to
>> 1.
>>
>> The antenna has its best SWR readings on 20 meters, which you'd expect,
>> but
>> even here, I can't get the SWR to go much below about 1.8 to 1 in the
>> center
>> of the band.
>>
>> Again, at least now, the auto-tuners in both of my HF rigs will tune the
>> antenna, but I'm wondering whether it's even safe or wise to use the
>> antenna
>> under these conditions.
>>
>> 73 from Tom Behler:  KB8TYJ
>>
>>
>>
>
> 

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