Funny stuff this RFI you guys are looking at. And since I have a TIC
ring, I better try and help some in case I have the same issue arise.
So far I have not had time to use mine since its controller is back at
the factory for service.
But I may be able to detect the same stuff you gus do.
Tim and Sig, how about making a small RF Sniffer with some attenuator
resisitors to get right up to it and "sniff" around with the small loop
pickup. Perhaps you can use a small radio or a handheld spectrum
analyzer as the reciever.
The Handbook has a sniffer you could build in an hour or less. If the
fundamantal was too strong, I guess a filter could be put in the front
end of the SA or reciever to knock it down.
You may have tried this already.
Jay, WX0B
Tim Duffy wrote:
>
> Hi Ty!
>
> Thanks for your ideas. I am committed to finding the problem.
>
> I have tried all of the bonding ideas you mentioned. I think N3RS has tried
> all of them as well.
> I have disconnected the control wiring and there is still terrible harmonic
> generated noise. The
> problem seems to be exacerbated by the closeness of the two towers. In N3RS's
> case it is 127 feet
> and 40 into 20 meters. In my case it is 140 feet and 20 into 10 meters.
>
> Turning the rotor by hand also makes the same noise and harmonic issues.
>
> I think the problem may exist in the guide pulleys. They have black (contains
> carbon, which is
> conductive at radio frequencies) insulating material between the 2 sections
> of these rotating
> pulleys. 3 of them are used on each ring. The black carbon may set up a diode
> which for some
> reason bypassing with heavy wire from the boom of the antenna to the tower
> cannot fix. These
> "pulley diodes" may be the cause of the noise and the terrible harmonic
> problem in close
> proximity ring rotated antennas.
>
> That is my current hypothesis which also is where N3RS is in his testing.
>
> I will not stop working on this until it is fixed, however we are running out
> of places to look.
> These problems are always tough the first time!
>
> Any other suggestions???
>
> 73!
> Tim K3LR
>
> tgstewart@pepco.com wrote:
>
> > Have you tried bonding the ring to the motor as a test? How about the boom
> > to the ring as well?
> >
> > Another thing perhaps worth trying is to isolate both the control wiring
> > and/or control box from the rotator.
> >
> > Have you tried disengaging the motor and turning the ring by hand to see
> > what that does?
> >
> > I cant believe K3LR hasnt solved this problem! :)
> >
> > 73, Ty K3MM
> >
> >
> > "R. Sigismonti"
> > <n3rs@snip.net> To:
> > towertalk@contesting.com
> > Sent by: cc:
> > owner-towertalk@cont Subject: Re:
> > [TowerTalk] Tic Ring problem
> > esting.com
> >
> >
> > 01/22/2001 02:50 PM
> >
> >
> >
> > >The problem is not noise caused by the motor. The noise filter at
> > >the motor does a good
> > >job, except when the capacitors blow (which has only happened on my
> > >10 meter tower).
> > >
> > >N3RS verified that there is significant noise caused when the ring
> > >turns, even when turned manually (take the motor off the tower).
> >
> > Not only is the noise not caused by the motor, it is even there when
> > there is no motor action at all. We have a very aggravated case of
> > this noise problem here at N3RS. We have a 3 stack of 20M 5 element
> > yagis on TIC rings and a 3 element 40M yagi just 127 feet away. When
> > the 40M yagi is pointed at the 20M TIC rings we get a wideband noise
> > on 20M that is centered on the harmonic of the 40M signal. The 40M
> > station has all sorts of filtering and is not the cause of the noise.
> > This has also been verified by K3WU, who lives less than a mile from
> > me. He listened to both the fundamental and second harmonic of the
> > 40M signal and it is absolutely clean. The second harmonic was very
> > weak as well.
> >
> > Two weeks ago we determined that the noise is not being generated by
> > anything on the antennas themselves. This was done by shaking the
> > elements while transmitting on 40M. We also checked all RF
> > contacts/connections at the same time. We did notice a very strong
> > correlation between noise generation and gentle rocking of the TIC
> > rings. We believe that we are getting reasonably substantial
> > currents in the circuit comprised of the 20M yagi/TIC ring/tower
> > system. This is induced current from the 40M near field signal.
> > This current is flowing through a rather poorly connected and
> > weathered set of surfaces, some of which may be generating the
> > harmonics.
> >
> > Noise is also generated when we transmit on 20M and turn the rings at
> > the same time. The assumption here is that there is current induced
> > in the rings by the 20M signal itself. This noise can be heard on
> > other bands as well.
> >
> > ASAP we plan to insulate the 20M yagis from the ring assembly,
> > thereby reducing the current that is likely to flow through the
> > rotating mechanism in the ring. There are several metal-metal
> > surfaces that are not in good contact at all times in the assembly
> > and some of the galvanized surface on the rings has become quite
> > tarnished. We will post any results we get as a result of
> > introducing the insulation between the ring cradle and the 20M booms.
> >
> > 73's de Sig, N3RS
> >
> > --
> > FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> > Submissions: towertalk@contesting.com
> > Administrative requests: towertalk-REQUEST@contesting.com
> > Problems: owner-towertalk@contesting.com
> >
> > --
> > FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> > Submissions: towertalk@contesting.com
> > Administrative requests: towertalk-REQUEST@contesting.com
> > Problems: owner-towertalk@contesting.com
>
> --
> FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
--
Jay Terleski
WX0B - Array Solutions
www.arraysolutions.com
--
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
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