[K3PZN-List] Subject antennas on RV's (a.k.a. refereeing multi-band interference)

Fri Jan 29 09:21:39 EST 2016

Thanks Jim

was looking forward to your answer as well, really appreciate it.

ray

On Fri, Jan 29, 2016 at 8:48 AM, Jim Nitzberg WS3B via K3PZN-List <
k3pzn-list at mailman.qth.net> wrote:

> Dear CCARC Multi transmitter enthusiasts (and that includes RV
> transmitters),
>
> One of the most important considerations for minimizing interference
> between stations originates with the
> HF tranceiver itself.
>
> Selecting 'clean' HF transceivers goes a long way toward minimizing
> inter-station interference - even on the SAME BAND.
>
>
> Curt WB8YYY is correct, bandpass filters on each station are
> imperative....and there are different quality bandpass filters.Dunestar
> fileters are good; W3NQN design are even better (more out of band
> attenuation).
>
> We can use W3AO's famous field day setup of 20+ transmitters (where there
> are often 2 or 3 on the same band) to interpolate to a good
> multi-transmitter solution.
>
> Here are their (not so) secrets:
>
> 1.  They use antennas with a pattern.  Yagis...or dipoles.
> 2.  They line the antennas up so the "preferred direction" (due west) has
> the antenna elements sideways to each other for maximum attenuation.
> 3.  They space the antennas such that the lower in frequency you go, the
> LARGER the spacing between the same band antennas.
> 4.  They do not use off center fed antennas or antennas where the feed
> line also radiates intentionally.
> 5.  They do NOT have one antenna 'looking' into another.
>
> Rob Heath K1RH also helped pioneer an interesting field day configuration
> one year which involved a Force 12 C3S tribander, A Dunetar triplexer, and
> Dunestar bandpass filters.
>
>
> The result was (3) separate operating positions, one for 10, 15 & 20, all
> with separate feed lines, going to ONE antenna.  I believe Ray and Kerri
> may have also tried this in the past - what amazed me the most about this
> setup is the lack of any measurable interference between the 3 stations
> sharing one antenna.
>
> A multi-band dipole or vertical could also accomplish this 'trick' with an
> HF triplexer and band pass filters as well.
>
> 73,
>
> Jim   WX3B
>
>
>
> ________________________________
> From: Curt Milton via K3PZN-List <k3pzn-list at mailman.qth.net>
> To: Ray Wright <kb3vwk at gmail.com>; Carroll County Amateur Radio Club <
> k3pzn-list at mailman.qth.net>
> Cc: Curt Milton <wb8yyy at yahoo.com>
> Sent: Friday, January 29, 2016 8:28 AM
> Subject: Re: [K3PZN-List] Subject antennas on RV's
>
>
> Yes in my judgment, which by the way is mostly FD experience, that should
> work.  You will hear the second harmonic of the 40m rig if you tune there
> on 20m.  but with that modest separation you should be fine.  As I am not
> familiar with your radios, best to borrow the dunestar filters as that will
> give you so extra margin.  maybe you remember when we operated 20m SSB and
> 40m CW from the RV -- the 40m inverted V was mounted on the same mast as
> the beam.  and I remember operating without the dunestar on the 40m rig.
>
> what won't work so well is doing both rigs on the same band -- even on
> different modes.  when on the same band, there is no way to filter the
> noise created by the transmitting radio.
>
> yes do remember a ham ticket is a learning permit.  the key is to keep
> learning, and hopefully ask these questions before trying them.
>
> 73 CUL Curt
>
>
>     On Thursday, January 28, 2016 10:30 PM, Ray Wright <kb3vwk at gmail.com>
> wrote:
>
>
> so with say a dunestar filter on each 100w radio into a vertical antenna
> at front and rear of rv one on 20m and one on 40m we should be safe from
> bleedover?
>
> On Thu, Jan 28, 2016 at 9:47 PM, Curt Milton via K3PZN-List <
> k3pzn-list at mailman.qth.net> wrote:
>
> Ray/Kerri
> on two different bands you should be okay -- just separate the antennas as
> much as possible, and run a test at lower power before cranking up to 100
> watts.  if you can get a dipole for 20m up 25 feet or more it might work
> better than a vertical.  how far apart the antennas must be depends upon
> the radios some.
>
> also -- even better - borrow the club's dunestar filters -- this will give
> you a little more margin.
> 73 Curt
>
>
>     On Thursday, January 28, 2016 6:30 PM, Ray Wright <kb3vwk at gmail.com>
> wrote:
>
>
>  Thanks Curt and John
>
> The hope was to have the eagle one vertical on the ladder rack set up for
> 40m and either another vertical eagle one set up on the ground for 20m or
> maybe an inverted diapole for 20m set up as the second antenna to the
> vertical on the ladder rack?  Thoughts?
>
> ray and kerri
>
> On Thu, Jan 28, 2016 at 8:13 AM, Curt Milton via K3PZN-List <
> k3pzn-list at mailman.qth.net> wrote:
>
> > Possibly what you all are alluding to is sometimes called 'mutual
> > coupling.'  Two closely mounted antennas 'experience each other.'  There
> > are two effects -- change in the terminal impedance and distortion of the
> > antenna behavior.
> >
> > I didn't get the picture if these verticals are used on different bands
> or
> > the same one?
> >
> > The other question to ask is whether the radios will be okay with one
> > antenna transmitting and the other receiving.  I would very much worry if
> > they are used on the same band -- there is possibility for damage if they
> > are too close, and too close may not be easily to calculate at the
> > extreme.  If these are HF radios used on different bands, the band pass
> > filters in the radio contribute some rejection -- and allows coexistence.
> > Remember for example when we operated an inverted V below your tribandder
> > at field day.  We didn't have issues because they were on different bands
> > -- and it helped also to have several feet of separation.
> > I do think you can operate on different bands using verticals on an RV --
> > but best to separate them as much as possible.
> >
> > As for winter field day -- sounds like cabin fever after 2.5 feet of
> > snow.  And burning some fuel just to stay warm.  I don't know how popular
> > it is in the northern reaches, even here.  A QRP group does FYBO this
> time
> > of year, but they are based in Arizona.  I don't know, plenty of other
> > activities one can do with radios indoors this time of year.  Outdoors it
> > just might be better to be moving, maybe on some cross-country skis or
> snow
> > shoes that sitting using a radio.
> >
> > CUL 73 Curt
> >
> >
> >    On Thursday, January 28, 2016 7:19 AM, John Stephens <
> kc3fdl at gmail.com>
> > wrote:
> >
> >
> >  Kerri,
> >
> > I had the same question a a couple of months back.  So to answer the
> > question, I contacted Dr. Ed Fong who had recently given a skype
> > presentation to the CARA club on his Dual Band J-Pole Antennas.  (By the
> > way, it was VERY interesting and CCARC should do the same!).  He actually
> > has a patent on his J-Pole design.  His website is
> > http://edsantennas.weebly.com.
> >
> > His response was that it isn't the coax you need to be concerned with,
> it's
> > the antennas.  They will resonate between themselves.  In order to
> prevent
> > the antennas from resonating, 'in theory' (his words) they should be
> placed
> > at least 1 wavelength apart from each other.  For example, if you were
> > setting up 2M antennas they should be placed no closer than 2 meters
> > apart.  There are some things you can do to mount them closer, like
> offset
> > the height, but the physics and math are not trivial. Antenna for
> differing
> > bands can be placed closer together, say a couple of feet, without any
> > significant interference.
> >
> > Hope this helps.
> >
> > 73 de KC3FDL / John
> >
> >
> > --------------------------------------------------------
> > John L. Stephens // KC3FDL
> > KC3FDL at gmail.com
> > Latitude: 39.4927 Longitude: -76.8894
> > MHGL: FM19nm
> >
> > On Wed, Jan 27, 2016 at 10:50 PM, Kerri Wright <kb3vwk at gmail.com> wrote:
> >
> > > Is possible to run two vertical antennas at the same time and location
> > > with out harmful feedback on coaxial line.  If so how defeat that
> > problem?
> > > ______________________________________________________________
> > >
> > > 73 de K3PZN Westminster, MD
> > > ______________________________________________________________
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> > 73 de K3PZN Westminster, MD
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> > 73 de K3PZN Westminster, MD
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> 73 de K3PZN Westminster, MD
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