[TowerTalk] [Bulk] Re: G5RV vs 40M dipole

[Kelly Taylor]

If the choke bead is getting too hot, it doesn't mean you shouldn't use a
choke. It means the choking impedance isn't high enough. Either the beads
aren't the proper ferrite material or there aren't enough of them. With many
commercial bead chokes, it's sometimes a combination of both errors.

If anything, the heat is proof a choke is required, because if that energy
wasn't making the bead choke hot, it would be on the outside of the
feedline.

73, kelly
ve4xt


On 4/26/15 12:51 PM, "Bry Carling" <bcarling at cfl.rr.com> wrote:

> Yes there is no way a monster fan dipole would work here. Small lot. I did try
> one and it was too obtrusive as well as high SWR on every band contradicting
> all theory. First I have heard of using any "choke bead" for a G5RV. If it's
> getting hot then it's wasting a lot of your RF power.
> 
> Best regards - Brian Carling
> AF4K Crystals Co.
> 117 Sterling Pine St.
> Sanford, FL 32773
> 
> Tel: +USA 321-262-5471
> 
> 
> 
> 
>> On Apr 26, 2015, at 12:22 PM, Grant Saviers <grants2 at pacbell.net> wrote:
>> 
>> My G5RV at QRO stopped working when the purchased bead choke at the
>> coax/ladderline junction got so hot it melted the coax.  They need several
>> thousand ohms of choke impedance, usually not found in most of the off the
>> shelf bead chokes.
>> 
>> OTOH two 80/40/20 fan dipoles (at right angles) I modeled and built worked
>> super at 65' high.  They worked on 15m with a tuner (<2.5:1 swr) and perhaps
>> on 10m if the coax is cut for a match or there is enough loss.   I separated
>> the ends by 24" using 3/8 sq pvc rod which makes for mechanical complexity
>> and difficulty winding it up (I use 10" diameter concrete column forms).
>> Eznec models are reasonably accurate if you follow the recommendations on
>> modeling by Cebik, #108-111 at http://www.antennex.com/w4rnl/
>> 
>> re VE7RF's conjecture that the center of every dipole may not need to be
>> connected:  Since I had a working EZNEC model, I disconnected the
>> transmission line connections to the 40 and 20m dipoles and fed only the 80m.
>> There is coupling but very poor swr; 4:1 on 40m, 10:1 on 20m, 8:1 on 15m, so
>> it's not a good idea.
>> 
>> Grant KZ1W
>> 
>>> On 4/26/2015 1:26 AM, Steve Hunt wrote:
>>> The 51ft "G5RV" performs well on 40m, 20m and 10m - bands where the SWR(50)
>>> at the ladderline/coax junction is moderate. On other bands the SWR(50) is
>>> high, and how well it performs will depend on the length and quality of your
>>> coax run.
>>> 
>>> On 40m you will notice little difference compared to a half-wave dipole; on
>>> 20m it has a small amount of broadside gain over a half-wave dipole; and on
>>> 10m the azimuth pattern has broken into 6 major lobes, with best performance
>>> at 45 degrees to the direction of the wire
>>> 
>>> Using a good CM choke at the coax/ladderline junction is important - it will
>>> reduce radiation from the ladderline section and noise pick up on the coax
>>> run.
>>> 
>>> Steve G3TXQ
>>> 
>>> 
>>>> On 25/04/2015 21:11, Dick NY1E wrote:
>>>> I'm operating from a small lot in Florida winters, I have a 40M dipole up
>>>> but it doesn't quite fit my opening, it is into the branches 5 or 6 feet. I
>>>> wonder what the 51' G5RV would perform like compared to the dipole on 40,
>>>> and as a bonus I might get some other bands...   Any ideas???de Dick
>>>> NY1E/4www.ny1e.com
>>>> _______________________________________________
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