[TowerTalk] Fwd: RG-59

[Hans Hammarquist]

 Hi Jeff,


Something is definitely wrong. You should have no problem using the RG59 for your dipole. 



It is not the easiest thing to get a good contact with the shield on the RG59 as the braid sometimes is made of steel or stainless steel. The "real" shield is the aluminum wrap under the braid.


If nothing else use F-connector to make sure you have a good contact with the cable and then go from there. I am sure that will help.


Just my penny thought,


73 de,


Hans - N2JFS

 

 

-----Original Message-----
From: felix1063 <felix1063 at comcast.net>
To: 'Grant Saviers' <grants2 at pacbell.net>; towertalk <towertalk at contesting.com>
Sent: Sat, Aug 11, 2018 12:07 am
Subject: Re: [TowerTalk] RG-59

I should have mentioned that the shield on the RG59 is shorted with the center conductor at both ends.  My results with the dipole element cut for 80 meters is that the dipole is un-tunable with an antenna analyzer.  In fact, the antenna does not tune to anything from 1.8mhz to 14.5mhz.  At the cut frequency, the impedance is 50 ohms, but the SWR is greater than 10:1.   I have used RG58 with good results.  I used RG59 because it's diameter is larger than RG58 and should produce a larger bandwidth.

What am I doing wrong?

--jeff WB7AHT

-----Original Message-----
From: Grant Saviers <grants2 at pacbell.net> 
Sent: Friday, August 10, 2018 9:35 AM
To: felix1063 at comcast.net; towertalk at contesting.com
Subject: Re: [TowerTalk] RG-59

Yes, assuming you mean using the shield as the conductor.  The larger the diameter, the greater the bandwidth, thus RG59 shield helps a bit. 
The formulas for diameter vs bw are in most handbooks.  The RG59 insulation reduces the velocity factor and thus the antenna will be electrically longer by a few percent than the usual dipole formulas calculate.  NEC based modeling software can model the effects of thin insulation like on RG59.

Otherwise, it is a dipole and a choke is a good idea.

Grant KZ1W


On 8/9/2018 16:14 PM, felix1063 at comcast.net wrote:
> Has anybody ever used RG-59 as the radiating elements in a dipole?  If 
> so, what were the results?  Was it easy to tune? Did the bandwidth of 
> the dipole change appreciably from using a piece of stranded wire?  Was a balun used?
>
> 
>
> Thanks,
>
>   
>
> --jeff
>
> Wb7aht
>
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