[VHFcontesting] Log Periodic ?

[Mark Spencer]

I've used tri plexers with my smaller LPDA on occasion (in one case I cascaded two together) to eliminate the need to switch cables.   I'm quite sure there were losses but if one is prepared to accept the gain of a typical LPDA then in my view at least the losses in the tri plexers probably are not a major issue.

I don't view this as a replacement for single band yagis.   It is fast to setup and I've made qso's in the 150 mile plus range on 144 and 222 MHz without much issue.   

It's also a handy "spare" antenna that I've had to use when single band yagis haven't been functional (the LPDA has yet to fail.)   In my experience an LPDA is considerably more effective in a typical contest than a mobile whip which would be my other alternative to a failed yagi.

Your mileage may vary (:

73

Mark S
VE7AFZ

mark at alignedsolutions.com
604 762 4099

> On Sep 13, 2017, at 3:31 PM, Jay Lubliner <ironclaw at live.com> wrote:
> 
> Hi all,
> 
> I had a Creative Design LP years ago. Realizing it's a compromise both gain wise, only 3 elements make up the log cell per say, and limited front to back isolation, I present the following discussion:
> 
> In a crowded band area or lots of high power OPS nearby, it can't handle the overload of signals because it's collecting too much signal receive wise from strong stations or nearby transmitters. You can't reduce the overload or splatter very well by turning it somewhere else for example. Also it doesn't have anymore than 6db gain. Single yagis at same boom length would have more selectivity and gain. 
> Other issue is it's not likely you have a rig with separate coax outputs for all the log could cover. 50, 144, 222, 432, 903, 1296. How do you switch bands? Coax switch? You'd need a six position or 4 positions even for lower 4 bands. Doable perhaps but one must pay attention to turn the knob every time you QSY.!!!..that gets pretty old and when you get 6 hours into contest, you forget and yell your brains into aluminum not currently resonant. You'll say, "where is that guy?...we're suppose to go to 432.1...don't hear anything!!!!
> Mine was fine for sprints or casual operating and sure one feed line is nice but adding amps and such also gets more complicated. 
> Maybe if you're very good technically you could build a relay switching box but every connection increases possible reliability and bug issues. You have enough in Rover state.
> 
> I'm sure this will stir up some chatter but just my 2 cents or 2 db's worth having used one.
> 
> Jay
> K3JAY
> 
> Sent from my iPhone
> 
>> On Sep 13, 2017, at 4:16 PM, Mark Spencer <mark at alignedsolutions.com> wrote:
>> 
>> Hi:
>> 
>> I've used the (IIRC 105 thru 1300 MHz ?) version for several years.
>> 
>> I'm happy with my purchase.   That being said it is not my primary contesting antenna and it stayed at home during the last contest as I didn't think it had enough gain to be useful at the sites I planned on visiting (plus mine didn't cover 50 MHz.)
>> 
>> I'm happy with the built quality of mine and it seems to have held up well to traveling in the bed of my 4x4 on forest roads.   In my experience it is a handy multi band antenna with some gain and directivity and I've made lots of contest contacts with mine.
>> 
>> I'd also be curious in hearing from those who have used the version that covers 50 Mhz.   I've pondered putting one up at my home qth to get a horizontal antenna with a certain amount of gain on 50 MHz and up.
>> 
>> 73
>> 
>> Mark S
>> VE7AFZ
>> mark at alignedsolutions.com
>> 604 762 4099
>> 
>>> On Sep 13, 2017, at 12:47 PM, Ed via VHFcontesting <vhfcontesting at contesting.com> wrote:
>>> 
>>> I am considering a Create LPDA for a roving station. Thinking it'll sit nicely on the roof of my fifth wheel. This would allow me to work all bands from 6m to 1.2 Ghz with a single antenna. I can also change the polarization for FM. Thoughts?  
>>> 
>>> 73,
>>> Ed NI6S
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