I think that the 4.7 pF capacitor is bogus. The capacitance between center
conductor and shield of even a few inches of coax is more than that.
But creating a quarter-wave ground "counterpoise" connected to the station
ground often helps, as mentioned in a previous message. The far end of the
wire might be hot, so don't put it where people are likely to come in
contact with it. For 20 meters, a quarter wavelength is about 16 feet.
This would be the length from whatever you consider to be your station
ground; perhaps the back of your amplifier.
Lloyd Rasmussen, Kensington, Maryland
Home: http://lras.home.sprynet.com
Work: http://www.loc.gov/nls
> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of Gale Conard
> Sent: Tuesday, February 08, 2011 12:17 AM
> To: [log in to unmask]
> Subject: Re: interesting RF problem in the shack
>
> Here is something I saved from a previous discussion about grounding. I
> haven't tried it, but several hams have testified that it has worked for
> them.
>
>
>
> Hi list:
> i think it was John who was saying that he has some grounding problems
> being on the second floor.
> I found a good method of helping to get rid of some of the floating
> ground problems.
> You use a peace of RG58 coax and put a 4.7 peaka farad seramic
> capacitor across between the ground shield and center line of the coax =
> on each end of the length you will need to go from your station to your
> ground rod or an adequet ground somewhere. Connect the center line of
> the coax to ground and the center of the other end to the radio or to
> your common station ground in the shack. This is supposed to help to
> eliminate floating ground and keep all the extra RF going to ground
> instead of coming back up your ground line.
> Regards
> Colin
> ----- Original Message -----
> From: "tom behler" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, February 07, 2011 7:57 PM
> Subject: Re: interesting RF problem in the shack
>
>
> Steve:
>
> I used this exact same set-up out in Colorado before I came back to
> Michigan, and before I installed the Windom. In fact, it's what I ran the
> Cross-country Blind ops net with last year, without a grounding system at
> all.
>
> The only thing I can think of that is different here in Michigan would be
> the Windom installation itself. But, the Windom is on a completely
> different antenna port on my Window feed through panel, and on my TenTech
> manual tuner.
>
> I will try grounding the rig-runner by connecting it to the common ground
> in
> the shack, and will also try your ferrite solution.
> Admittedly, before the Windom became unusable, I don't think I ever used
> the
> DXCC back here in Michigan on 20 meters ever since we returned. Therefore
> it's inpossible for me to tell if the problem existed before without my
> knowing it.
>
> 73 from Tom Behler: KB8TYJ
>
>
>
> ----- Original Message -----
> From: "Steve Forst" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Monday, February 07, 2011 9:33 PM
> Subject: Re: interesting RF problem in the shack
>
>
> Tom,
>
> Grounding might not be a bad idea. Also, if you have any ferrites
> around, I would try clamping a ferrite on the line from the power supply
> to the rig runner, and also the line from the rig runner to the radio.
> Maybe disconnect any other gear that is connected to the rig runner
> to try and isolate the source. Perhaps move the rig runner as far as
> possible away from the amp.
>
>
>
> Have you worked that combo of antenna/amp/band before? Did this just
> pop up out of the clear blue? If it worked fine before and now has
> problems, what has changed in the station that you can try reversing?
>
>
> And I thought I had problems...
>
> 73, Steve KW3A
>
> On 2/7/2011 8:58 PM, tom behler wrote:
> > Hi, all.
> >
> > Well, I know I'm going to get varying opinions on this one, but that's
> ok,
> > since I'm looking for a number of possible alternative causes and
> > solutions.
> >
> > As many of you know, I have gone back to using my Alpha Delta DXCC
> antenna
> > as my HF antenna, until my Windom, which took a dump on Saturday, can be
> > resurrected.
> >
> > The DXCC works great on 40 meters with both 100 wattts, and my Ameritron
> > AL811H amplifier. However, when I went to do the Cross-Country blind
> ops
> > net on 14.258 yesterday, I had an interesting experience. Things worked
> > great with 100 watts, but when I kicked the amplifier in, and tried
> > running
> > things on the usual 600 watts, I ran into problems. As soon as I keyed
> > the
> > mic, the protective circuit in my Rigrunner tripped, and everything in
> my
> > station went silent.
> >
> > I have no other indications of RFI anywhere else in the house or the
> > shack.
> > In addition, my SWR's are good with the DXCC on 20 meters (about 1.5 to
> 1)
> > without the tuner, and obviously just as good with the manual tuner. I
> > use
> > my usual procedure to tune the amp, and everything works there as well,
> > giving me forward and reflected power readings I would expect.
> >
> > Could anyone tell me what you think is going on here? Do I still have a
> > grounding issue of sorts, even though I've gotten no indication of
> > grounding
> > issues with other applications?
> >
> > Other than reducing power, is there anything anyone can suggest for me
> to
> > do
> > to try to solve this problem.
> >
> > I was thinking of grounding the Rigrunner by connecting a ground cable
> > from
> > the cover of the Rigrunner to my common station ground, but just haven't
> > gotten to it yet.
> >
> > It's just a strange problem, and only seems to occur on 20 meters with
> the
> > amp. I never had the problem at all out in Colorado, where I had no
> > station
> > grounding system at all.
> >
> > 73 from Tom Behler: KB8TYJ
> >
> 73,
>
>
>
> Gale
> [log in to unmask]
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