[VHFcontesting] Log Periodic ?

[K7XC Tim Marek]

A LPDA is a compromise antenna at best. On top of that I don't think their
made to use on a full-time Rover. That is alot of money for a compromised
solution.

The real question is are you willing to trade off convenience vs gain
during your ROVER trip.

When I was a competitive ROVER I built a heavy duty frame in the front of
the bed of either my F150 or Ranger Trucks out of 1/4 inch thick 2" wide
Aluminum Angle then mounted Heavy Duty Thick Wall Mil Surplus Aluminum Mast
on each side to hold yagis on one side and omni loops on the other. They
were always in place while driving. Use heavy duty mufler clamps with
NYLOCK nuts to make sure nothing rattles loose while on the road. Th use of
NYLOCK nuts everywhere is highly encouraged.

In the middle was a third mast on a pivot base that allowed me to install a
guyed 30ft mast with a 6M Yagi and rotor while guyed to the four corners of
the truck. Each bumper has a heavy duty eye bolt in place for just such a
purpose. This let me do a quickie mountaintop portable operation and leave
the tower trailer at home. It also allowed more antennas like a 1296 looper
on those few times I had it along.

In the cab mounted on the front of the seat I had 3 coax switches for
changing between 2, 222, and 432 loops or yagi's while driving while 6
Meters best antenna was a KB6KQ loop mounted to mast secured to one of the
rear corners of the bed  I NEVER setup additional antennas EVER as TIME is
your enemy when contesting, it finite and precious so dont waist it doing
multiple setups and tear downs.

To Me the Cost, Gain, and Pattern of a LPDA makes it a no brainer... My
answer is NO! Use real yagi antennas. One thing I always did was make my
own for pennies on the dollar out of quality materials easily obtained from
Texas Towers and shipped to your door. 10ft long booms are your goal after
all this is a ROVER and you maximize everything you can, within reason.

Another key tip to using Yagis while driving down the road, REMOVE ALL THE
REFLECTORS... This will sacrifice little gain but give you a nice lobe off
the back that is better than stacked loops and will get you contacts
quicker yet not require you stop and turn the vehicle the other direction.

Also, Never forget to have verticals for FM on every band you can as you
will drive by many people who monitor 146.52 and will QSY to 223.5, 446.0
and 1294.5 when asked to. Its all about the mults folks....

A competitive ROVER platform is more than just throwing radios in the car
for the weekend. It takes months to think through what your trying to do
with the items you have on had. Here good planning is key to avoiding
failure on the road.

Again, My personal observations from someone who has done this style of
contesting long and hard over 20+ years.

Your Mileage may vary...

73s de Tim - K7XC - DM09jh... sk


Adapt, Overcome, Succeed!


On Thu, Sep 14, 2017 at 7:15 PM, Zack Widup <w9sz.zack at gmail.com> wrote:

> The antenna testing range is done every year at Central States VHF
> Conference. Usually on Friday morning of the conference out in a hotel
> parking lot. May be changed to Saturday if it rains. Kent WA5VJB does the
> testing. Any antennas 6m thru 24 (and maybe 47) GHz are welcome. :-)
>
> 73, Zack W9SZ
>
> On Thu, Sep 14, 2017 at 12:06 PM, Bill Olson <callbill at hotmail.com> wrote:
>
> > Good idea! Sort of hard to believe that hasn't been done before.. anyone
> > have any data??
> >
> >
> > bill, K1DY
> >
> >
> > ------------------------------
> > *From:* Zack Widup <w9sz.zack at gmail.com>
> > *Sent:* Thursday, September 14, 2017 4:37 PM
> > *To:* Bill Olson; VHF Contesting Reflector
> >
> > *Subject:* Re: [VHFcontesting] Log Periodic ?
> >
> > Maybe someone can bring one to a Central States conference or another
> > conference where antenna testing is done? Kent WA5VJB has always been
> > accurate and impartial in his measurements.
> >
> > 73, Zack W9SZ
> >
> >
> > On Thu, Sep 14, 2017 at 11:13 AM, Bill Olson <callbill at hotmail.com>
> wrote:
> > > Hi all, Create claims the gain of the 50-1300MHz LPDA is 10-12dBi
> > (~8-10dBd). I don't see how those numbers could possibly be accurate
> given
> > the element taper and the boom length etc.. Reports of performance
> compared
> > to single band Yagis seem to bear that out. I'd guess the realistic gain
> is
> > more like 3-4dB over a dipole. That's like a 2 or 3 element single band
> > Yagi.. Now admittedly you'd need 2,3,4, 5 or 6 single band Yagis to do
> the
> > job since the Log Periodic does cover 6 ham bands.. If you can tolerate
> > mediocre performance (probably really poor performance on 903/1296) but
> > need the simplicity of a single antenna I guess this would be an option,
> > but I sure wouldn't go that way,. Heck, it looks like the thing costs
> $519
> > too, (from DX Engineering at any rate)!! Holy smokes! The way I see it,
> > you're paying for having broad band performance which you aren't using..
> It
> > works as well at 88MHz as it does at 144! Great for a TV antenna but who
> > needs that on the ham bands?!
> > >
> > > I GET the simplicity factor and agree that ANY antenna is better than
> no
> > antenna, and I KNOW people are using these antennas and are happy with
> > them, just saying my piece I guess..
> > >
> > >
> > > bill, K1DY in Maine
> > >
> >
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