No one has taken into consideration the Capacitance Hat when figuring overall length of antenna. if they r a 1' each that would add 2' to over all length.
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BBT Delivered Hy-Gain Penetrator 500 Today
- Thread starter Eastside
- Start date
I always thought you could add a hundred top hat radials and it would measure the same as one. So if you have 5 on top instead of 3 does it change?
The hat replaces roughly double its length in height you could add 100 as long as they are same length.
i dont know. i think thats maybe only true when its shorter than a 1/4 wave long. try measuring the height of the i10k plus the length of one foot long top hat radial and it comes out right at a 5/8. if you added two feet it would be way to long to be resonent
NB, I think MrS is right, if I understand the issue correctly. I think this only has to do with the cross sectional diameter and material size for flat type top hats. However, I'm also not sure if one wishes to replace the top of the radiator with some additional replacement length, that there is an exact 1:1 replacement ratio to be used. Although it is probably close and again based on material size...the added length may end up being a bit less that 1:1.
I also don't recall ever seeing any manufacture indicate overall radiator length included in the top hat measurements, excepting when the top hat design had some height above the tip, like a wire basket maybe.
How long does your i10k measure from the top hat screw down to the bottom of the main vertical where it meets the match? isnt the i10k top hat made with one foot long aluminum pieces? when you add the lengths together doesnt that equal 5/8 wave about 22 feet 4 inches?
NB, my top hat is made up of 2 x 20 x 1/2" flat aluminum stock. When centered it makes 2 x 10" radials that make a 20" diameter top hat. Jay says the measurement of the main radiator should be 212" and my top element is set for 27.205 mhz using his math. So my antenna should be set as follows:
45.375" as per the math Jay provides for the tip V7.
212.000" as per Jay's instructions
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257.375" from the top hat down to the bottom end of the radiator tubing. The top hat is not included in this measurement.
I figure the RF starts at the feed point so I always tend to measure from that point. In this case add 4.75" to the length above and I think that is pretty close for Jays 5/8 wave, but I'm just guessing.
For 27.205 mhz I tend to generally use 36 x .625 = 22.5, and that is what I use for my 5/8 wave models. It may be a bit long however. I think a lot has to do with the radiator diameter used in the model. So, does this mean that Jay's antenna is short, or that maybe I haven't considered the tubing diameters?
Of course I am right Marconi, you just dont put a cap hat on a antenna and think it won't effect length and you are correct it may not come down to an exact 1:1 replacement but will be close but the whole point of my post is no one took that cap hat into consideration with the new P500 they are all saying it is too short.
MrS, I'm not sure I talked about the new P500 being short in this thread, but when I did refer to the new P500 as short, I was talking about the instructions showing the radiator at 19'. I think maybe that is what others were saying as well. I called it an error and did not suggest that it was HG's setting for 10 meters. In fact, I think I suggested that 19' was likely too short for 10 meters as well.
At this point I think there are several of the new antennas around and ready to install, but thus far no reports that I can recall. The few that have talked about their new P500 being received...were suggesting they were going for 10 meters anyway. So I'm still waiting to see some numbers. I think the New P500 instructions were written to accommodate 10 meters, but I don't get the 19' indication as noted except to say the new owner has made some goofs in other antenna instructions they sell.
If you're feeling better now, maybe you could answer some questions I have asked myself on the subject of small top hats. I did some modeling that I will share. I was surprised at some of the results.
Have you modeled any 5/8 waves with a top hat, added or removed about this size?
If so, what kind of results for pattern, gain, max angle, and source match did you see...compared to a regular length antenna?
And if not, what do you think happens with the antenna in this regard?
B
BOOTY MONSTER
Guest
it's my understanding that sharp pointy things and corners can attract noise and that larger sizes and rounded corners can help with that . IF......i'm understanding that right wouldn't something with a bigger surface area and rounded edge make a better top-hat ? something like a small pot lid .. up to the size of a pizza pan ? of course dont use anything bigger than the wind-load and planing of it on the antenna can cause .
also , doesn't a larger diameter tip/top-hat slightly decrease the likely hood of a lightning strike by not focusing the charge to such a fine point of energy ?
lol , how about the wheel off a 27 inch schwin bike ??
also , doesn't a larger diameter tip/top-hat slightly decrease the likely hood of a lightning strike by not focusing the charge to such a fine point of energy ?
lol , how about the wheel off a 27 inch schwin bike ??
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My instruction manual sez the P500 is 22ft?
I see that too, on page two under the specifications. But look in your instructions on page 4, at the image of the antenna broken down into segments. My manual shows the overall length is 19' feet. That's what we're talking about when we say the antenna looks short.
ES, does your manual show to be different in this regard?
If you have a New Penetrator, have you installed and compared it yet?
If so, specifically how long is it, and at what frequency?
Give us a report when you get a chance, OK?
Page 4 in my manual shows 22ft from feed to top hat.
No I have not put my P500 up yet......need help putting up my tower.
Page 4 in my manual shows 22ft from feed to top hat.
No I have not put my P500 up yet......need help putting up my tower.
Good to know ES. I guess they fixed the error then.
Before you put your New SP500 up could you confirm for me the length and diameter for the base section overall, and the top hat radials? I've heard a guesstimate that it is 72", but that did not give us the diameter or the tapper.
As best I can tell there are 5 tapper joints, four on he radiator and 1 on each radial. Could you measure the outside diameters and lengths for those too? I could make an educated guess, but this would help me get the model to specs. This detail information is not shown on the diagram or in the parts list, unless it was added to your newer manual.
You do have one of the new styled Super Penetrators, and not a refurbished, right?
Thanks, and keep us posted.