How to tune a new 500 penetra

[Jackal9999]

I put it together 22 feet 4 inches and the swr is high 3.5 on 1 and 2.5 on 40 how do I adjust this thing for a decent swr this wa
S with a mfj259.

 

[Shadetree Mechanic]

Welcome to WWDX Jackal9999! You have come to the right place. Although I am not familiar with your antenna, I am sure that someone who is will stop by sooner or later.
Chris

 

[firerunner]

where do you get a 1:1 match?

 

[firerunner]

I don't know if this will help but here is some info. Looks like some differences in how to measure. I think it may be short go up past 40 and see if the swr gets better.

http://www.cbjunkies.com/threads/1614-hy-gain-spt-500-super-penetrator/page2

 

[binrat]

I think too short as well.

 

[ExitThirteen]

It should be either 22 feet, 6.5 inches, or 22 feet, 9 inches. I can't remember 100% which measurement it's supposed to be, but I think it depends on if the little "static bars" on the tip of the antenna are at 90 degrees or 45 degrees... if they are 90 degrees, should be around 22 feet, 6.5 inches. If they are at 45 degrees, it should be about 22 feet, 9 inches. Thereabouts.

~Cheers~

 

[Road Squawker]

what freq is "X = 0"...... or the lowest number?

 

[Ranch55]

I put it together 22 feet 4 inches and the swr is high 3.5 on 1 and 2.5 on 40 how do I adjust this thing for a decent swr this wa
S with a mfj259.

1) Recheck all the horizontal radial length measurements ...... 105"
2) Recheck and verify all the vertical section measurements .......

What point at the top are you measuring from ?
What point at the bottom are you measuring to ?
Did you thoroughly clean all the joints before assembly ?

Make sure that you have good coax ........

Total antenna length from top of "top hat" screw to bottom of radial bracket (not bottom of coax connector) should come in at 22' 2-1/2" to 22' 4" for a frequency of 27.205 approx.
The last Penetrator 500 that I tuned (about three months ago) ended up tuned on frequency 27.355 mhz at a total length of 22' even.
R equaled 51.8 ohms ...... X equaled -0.48 ohms .... VSWR was at 1.02 ~ 1.04

 

[JAF0]

The trouble with the new Penetrater is the top hat rods aren't bent down at a 45* angle like the early P500, they're sticking straight out it which will act as a capacity hat, electrically lengthening it past .625 wave lengths.
I junked the top hat & lengthened the radiating element to 267" and got a perfect match, with X = to less than 3 from ch1 to 40.

 

[Ranch55]

On the new model Penetrator 500, I will bend the top hat rods down at a 40 degree angle from horizontal.
This has worked well and allowed for very good tuning .......

 

[JAF0]

On the new model Penetrator 500, I will bend the top hat rods down at a 40 degree angle from horizontal.
This has worked well and allowed for very good tuning .......

So what did you find was the difference, if you tried it both ways?

I don't use the top hat rods at all. Why defeat 15" of the top of your vertical by inverting the top 9", cancelling it along with the 6" inside the downward 45 degree rods?

Just dump it and lengthen it to a full 267" vertical, centered on ch.20 for the best possible performance.