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delta,
im up in yorkshire and have tested my i10k against my imax (without radials) same pole/coax/height, the i10k is stronger and much better performance than the imax without radials,
also tested against my sirio 827 and tested my buddies i10k against his 827 same pole/coax/height, i10k wins again and its MUCH more durable.

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the blind lead the blind but the enlightened will lead you to the sigma4

Aww thats fantastic news Bob, top stuff! I was concidering buying the GPK for the i-max but i feel like a change to be honest, ive had it 10+ years. So what do you mean by stronger, do you mean like as in rx and tx? Tell me more.. Can i also be nosey and ask how much it cost in in total as i've worked it out to be £360 inc shipping and duties, vat etc. The duty office gave me a code to have put on the package too. Is this twig worth the huge cost over the likes of imax 2000's and sirio 827's etc?

Cheers, Delta

Delta, I believe that the condition of soil affects all antennas, but in the case of the 5/8 wave this negative affect is greater with 5/8 wave antennas in particular.

I also believe there is a lot of confusion about the issue of vertical antenna gain because of the report listed below which shows the typical gains that are talked about, but in such conversations no consideration is ever made of the fact that this report was generated over an infinite conducting ground plane. This error in understanding as to what is being shown in the graph completely ingnores the realy life effect of Mother Earth on communications and under reasonable testing over real earth all of these antennas will produce very nearly the same gains.



So, the Imax antennas I have installed do not do very well here at my location. Plus I have tried many different heights trying to see if the Imax will do better, but no-way-no.

Like BM said, if your going to buy an I-10K, don't waste your money any further. As for the IMAX 2000, I just bought one, is it ten years old already? If I would have known that, I would have just bought something else. As much as I know, You cannot even compare the I-10K at all to the IMAX 2000. In other words, The I-10K is about the best you can get besides a beam or 3/4 wave maybe. Compared to the I-10K, Or one of Big Hairs antennas, The IMAX 2000 is crap. LOL! And I own one, that's the sad part.

But all is not lost, I too am going to build a 1:1 Current Balun, add a premium run of Coax, something along the lines of RG214 or so, double braid or RG-213 or even LMR-200 for that matter and I'm also going to throw down & get the GPK as well.

I guess the saying is true, "you get what you pay for" So go ahead & get the 10K & take down the IMAX. As for me, I kinda like my IMAX in spite of it's downfalls. But I'm going to make the best of it. I've also heard that Big Hair's antennas can upgrade your IMAX's coil to a bigger thicker coil & they offer a better ground plane kit than the cheap ones you see on Ebay. It's all in what you want to do. Whatever it is, do it, and do the most with it. I just may have my IMAX upgraded. Mmmmm gotta check my funds first. You know what they say, money talks but BS walks.

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"What we've got here is a failure, to communicate! Some men you just can't reach. So you get what we had here last week, which is the way he wants it! well, he gets it! I don't like my Solarcon IMAX 2000 any more than you men". (and that's no joke!).

take pie thats 6.28 times freqency times henerys and you get your ohms at that freqency that should give you a starting point.

Huh?

Let's start with PI: 3.1415926535897932384626433832795

not

6.28

Inductive reactance = 2πfl

Maybe that's where the 6.28 came from.

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If you're like everybody else,
you're about average.
73 de K7KBN

I'm sure that's where it came from, but how does that help the average person figure out the diameter and number of turns of coax to use to form an effective choke at 27Mhz?

Hmmm lots to think about then with this choke idea, and what some of you guys have suggested too. I think I’ll try the idea from the Ugly Balun site first. It says "about one foot of 5 inch size pipe is needed for a 1.8MHz to 30MHz balun. For 3.5MHz to 30MHz coverage, about 18 to 21 feet of coax is needed. This length of coax is also adequate for most applications on 1.8MHz. 18 to 21 feet should cover all of 160 through 10 meters.
The number of turns is not critical because the inductance depends more on the length of the wire (coax) than on the number of turns, which will vary depending on the diameter of the plastic pipe that is used.
NOTE: Some people build choke-baluns, without a plastic coil-form, by scramble-winding the coax into a coil and taping it together. The problem with scramble-winding is that the first and last turns of the coax may touch each other. This creates two complications. The distributed-capacitance of the balun is increased and the RF-lossy vinyl jacket of the coax is subjected to a high RF-voltage. The single-layer winding on the plastic coil-form construction method solves these problems since it divides the RF-voltage and capacitance evenly across each turn of the balun"

I will try it out and let you know how i get on.. look here BUILD AN AIR WOUND 1:1 CHOKE BALUN FOR HF - THE UGLY BALUN!
My tower is connected to the ground via 3 x7 ft steel poles that go right through a concrete base that’s one square metre. I also have grounding radials from the base of the tower to ground spikes. The antenna is connected to the 18ft centre mast that sits in the tower, I’m going to isolate it from the mast with some clear pvc that’s 3mm thick. I got it from the broken doors on a warehouse, it's used to stop the wind and rain entering the building. It's some kind of clear pvc hanging blind. I'll cut a piece to size, it's got to be better than electrical tape don't you think?. Then i'll make the choke to put under the I-10k when i get it..
It looks like you guys in the good old USA have respect for this I-10k and the few guys in England that use them too.

Thank for your help guys

delta,
"The number of turns is not critical because the inductance depends more on the length of the wire (coax) than on the number of turns, which will vary depending on the diameter of the plastic pipe that is used."...
I think you will find that this just isn't the case, the part about the length being more important than the size and number of turns in that coil. Other wise, why bother winding that feed line into a coil at all. The size/shape of that coil, length, diameter, and turns spacing also plays a part in the amount of inductance/inductive reactance produced by that coil. That inductive reactance is what gets rid of the CMC I think, since it doesn't 'radiate', which is the whole point of this.

"The problem with scramble-winding is that the first and last turns of the coax may touch each other. This creates two complications. The distributed-capacitance of the balun is increased and the RF-lossy vinyl jacket of the coax is subjected to a high RF-voltage."...
I'm sure that's probably true, but just exactly when would that decrease in distributed-capacitance and that induced RF-voltage become a problem? Before that choke does what it's supposed to do, or at some point after? (A choke isn't very efficient to start with, and while I've never encountered all circumstances of using a choke, I haven't found this sort of problem with the times I have used a choke.) That outer jacket is supposed to be RF-lossy, or an insulator. Then again, I may be misunderstanding what's meant by that.
I think it's already been said, but in case I'm mistaken, that coaxial choke is not a balun in any sense of the word. It doesn't have any of the properties that make a balun a 'balun'. It may make you happy to call your cat a dog, but until I hear it bark...
- 'Doc