Sure, the ground cable was acting as an antenna in the presence of an RF field.
Therefore the radio was above RF ground.
Due to the Z of the ground it only provides a DC ground.
With coax fed antennas the RF should be on the inside of the shield.
73
Bob, K4TAX
Sent from my iPhone
> On May 14, 2014, at 8:46 PM, José Félix Ballester <jfballester@gmail.com>
> wrote:
>
> All,
>
> My antenna is close to the shack and I had RFI issues with my Eagle. Tried
> many things and removing the ground connection from the equipment solved it.
> I had a ground rod with 6 gauge wire connected to everything. No ground, no
> RFI. Can someone on the know explain this to me?
>
> 73 de Pepe WP3HW
>
>
> On May 14, 2014, at 6:32 PM, Rick - DJ0IP / NJ0IP <Rick@DJ0IP.de> wrote:
>
> Carter,
>
> Most of the time this type of problem is caused by common mode current.
> I don't think the 25' away from the house is the problem.
> The problem would be an imbalance in the current on the feedline.
>
> I can't say whether or not something is wrong with your OMVI.
> Of course it is possible.
>
> However my recommendation is an RF choke on the openwire.
> YES, there is such an animal!
>
> I don't know if you can buy them ready-built in the states but you can buy
> them here.
> They are also very easy to build if you can't buy them.
> What you do is build a short thin openwire using two 18" pieces of Teflon
> insulated wire secured side by side.
> Use heat shrink tubing to secure them. They will have about 100 Ohms, but
> that doesn't matter for just 18 inches.
> Then slip a string of ferrite beads over them. Best would be #43 material.
> You can use the same ones used for RG-213.
> Use wire ties each side of the stack of toroids to prevent slippage.
> You can then place a large heat-shrink tube over the thing to make it look
> neat.
>
> Run your openwire into one end of this just before the matchbox.
> The connect the other end directly to the JV matchbox.
>
> There is a good chance that this will solve your problem, but of course I
> can't promise it.
> With just 100w, Teflon insulation may not be necessary but it should be
> something that can withstand a little bit of heat without melting.
>
> 73 - Rick, DJ0IP
> (Nr. Frankfurt am Main)
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Carter
> Sent: Wednesday, May 14, 2014 10:36 PM
> To: tentec@contesting.com
> Subject: Re: [TenTec] Eagle problem?
>
>> On 5/8/2014 6:51 PM, Stuart Rohre wrote:
>>
>> These types of problems usually indicate that there is RF leaking
>> back to any any transceiver he might try, because his antenna is too >
> close to the shack ...
>
> An interesting thought, but can we always blame the "antenna being too close
> to the shack"?
>
> I bought my Omni VI new in 1994 and have never been able to operate SSB or
> PSK31, SSTV or any other mode that required the use of the mic jack.
> (Good thing I am 99% a CW and RTTY guy. <grin> ) Anything over about 10
> (ten) watts of power seems to cause the problem, utter and complete
> distortion of the radiated signal.
>
> The shack is in the basement, the antenna is a 132' long dipole about 25
> feet high and fed with ladder (window) line to a Johnson KW Matchbox tuner.
> The length of the window line between the Matchbox and the hole in the wall
> where it exits the basement is no more than five feet. Yes, when I measure
> the RF current in each leg of the window line they are different -- to be
> expected as this is not a perfect world and the dipole is not in free space.
> The coax cable to the Centurion / Omni VI has a multiple ferrite bead balun.
>
> After years of unsuccessfully chasing around with ferrite beads and chokes,
> I was finally told [by ******] that my dipole was "too close to the house".
> Unfortunately, because of the shape of the lot, the location of trees and
> zoning/deed restrictions, the antenna HAS to be where it is.
>
> So...problem occurs at around 10 watts of output, the antenna can't be moved
> and I don't think I am the only ham in the world using a dipole close to the
> house fed with window line.
>
> This leads me to do the unthinkable and to ask about the elephant in the
> room. Rather than everyone saying the antenna "is too close to the house",
> is it possible that this particular vintage of Omni VI option 3 is just
> particularly sensitive to RF getting into the mic jack (or other ports)???
> Is this unique to my radio? Do Yaecomwoods suffer from the same issue?
>
> The reason I ask is that I am getting into PSK31, JT9 and JT65-HF (and yes,
> I realize these are "low power" modes), but I wouldn't mind going up to 20
> or 25 watts -- or SSTV at (gasp!)100 watts.
>
> I would appreciate any thoughts or suggestions. New /different radio or
> fixing this radio (how?) is OK, but a 100' tower 300' away is just not an
> option.
>
> 73,
> Carter K8VT
>
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|