[K3PZN-List] Subject antennas on RV's

Thu Jan 28 22:30:13 EST 2016

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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