PKW Log Periodic feed rebuild

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prcguy

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We took in another abandoned child recently at the prcguy antenna orphanage, an Italian made 130MHz to 1,300MHz Log Periodic by PKW. Its very well built, except I didn't approve of the way they fed it with a huge bulky adapter with N connector. That sits at the high frequency end and its larger than the 1300MHz elements right next to it. There were also some funky VSWR blips above about 700MHz which I'm attributing to the feed thing.

1.JPG2.JPG3.JPG


So I decided to do a little surgery and eliminate the large appendage and make it more like some other well made Log Periodics I've had. I removed the odd looking assembly and replaced that with two thin brass sheets which will have a permanent soldered run of double shield, silver plated Teflon coax attached via some plastic cable clamps along the grounded side of the boom. Here is a view of the brass parts and new coax plus a female N connector mounted at the rear of the antenna on an L bracket.



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So now this newcomer with its snipped feedpoint and new silver plated coax can mingle with the other antennas here and feel comfortable that nobody will point and laugh. I'll also sleep better too.
 

JSTARS03

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I would take very good care of that for you.
Give it a nice view of the Atlantic Ocean and the beach in Sunny Florida.
 

Ubbe

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It looks like the square tube have enough room to route the coax thru it, so the tube will work as a choke and you also do not need to have that coax on the outside. I assume you are going to cover that whole solder job with rubber seal of some sort.

I wonder why some antenna solutions do not use a balun to connect a balanced antenna to an unbalanced coax.
I don't know any radioamateur, that are concerned about getting all power out from a shortwave antenna and receive as much signal as possible, would even think about connecting a coax directly to his shortwave dipole.

/Ubbe
 

prcguy

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I wanted to run the coax down the ground side tube but there are fasteners for the elements that block the path. I will only use this antenna for temporary setups so I'm not concerned with weatherproofing anything right now.

It looks like the square tube have enough room to route the coax thru it, so the tube will work as a choke and you also do not need to have that coax on the outside. I assume you are going to cover that whole solder job with rubber seal of some sort.

I wonder why some antenna solutions do not use a balun to connect a balanced antenna to an unbalanced coax.
I don't know any radioamateur, that are concerned about getting all power out from a shortwave antenna and receive as much signal as possible, would even think about connecting a coax directly to his shortwave dipole.

/Ubbe
 

RFI-EMI-GUY

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I wanted to run the coax down the ground side tube but there are fasteners for the elements that block the path. I will only use this antenna for temporary setups so I'm not concerned with weatherproofing anything right now.
How would you compare your antenna to the ones sold by Create of Japan?
 

prcguy

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I've handled a number of Create Logs both the 105 to 1300MHz and 50 to 1300MHz versions. They are mid boom mount and set up for horizontal pol and difficult to use vertical. They are also a bit lighter duty than the PKW. I also remember some plastic parts on the 50Mhz Create which break down and need replacement over time. All the elements in the PKW screw in making it easy to go portable but it is time consuming screwing in 44 elements.

I like the frequency range of the smaller Create better as it will cover the VHF air band where the PKW seems targeted more for hamsters. The Create logs are expensive and I have no idea what the PKW cost new or what shipping from the EU is. I paid $50 for this one, which seemed fair.

How would you compare your antenna to the ones sold by Create of Japan?
 

RFI-EMI-GUY

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I've handled a number of Create Logs both the 105 to 1300MHz and 50 to 1300MHz versions. They are mid boom mount and set up for horizontal pol and difficult to use vertical. They are also a bit lighter duty than the PKW. I also remember some plastic parts on the 50Mhz Create which break down and need replacement over time. All the elements in the PKW screw in making it easy to go portable but it is time consuming screwing in 44 elements.

I like the frequency range of the smaller Create better as it will cover the VHF air band where the PKW seems targeted more for hamsters. The Create logs are expensive and I have no idea what the PKW cost new or what shipping from the EU is. I paid $50 for this one, which seemed fair.
$50 sounds like theft, please where can I steal one?
 

prcguy

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Or here is another log I got off Ebay, a Racal military unit that covers 100MHz to 1GHz and folds up nice in about a minute for travel and it was basically new. I was the only bidder at $99. You guys must be a bunch of Ebay slackers, there is plenty to be had out there.

I overlaid the PKW on the Racal to see what the size differences are. I use the Racal as an illumination antenna when I set up a temporary test range for gain, etc. Not sure what I'll use the PKW for, maybe on certain camping trips when I need a multiband hamster antenna with a little gain. But I mostly fill the garage rafters with these kinds of things to make it interesting when you look up.

Racal.JPGRacal and PKW.JPG

I need to be more alert!
 

vagrant

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Got it, inside garage look up (sounds familiar). Additionally, can you put that rack of Quantar's on rollers so I can get it to the U-Haul quickly? I'll wave to the security cameras so you know it's me. Also, as I am over 50 years old, I request the customary two warning shots.
 

prcguy

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Quantar rack is on rollers. I suspect a radio person (geek) breaking into my garage would be frozen with their mouth wide open for so long they would be an easy catch. I could pick them up on my alarm system and remote camera while out for dinner and have plenty of time to finish the meal, drive home and catch them still trying to figure out what to take.

Got it, inside garage look up (sounds familiar). Additionally, can you put that rack of Quantar's on rollers so I can get it to the U-Haul quickly? I'll wave to the security cameras so you know it's me. Also, as I am over 50 years old, I request the customary two warning shots.
 
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