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[AC9KH]

This is for all the hams that continue to push the fallacy of the EFHW8010 "all band" antenna. While such a thing is pushed ad infinitum by the commercial antenna manufacturers (excluding the reputable ones), most hams should know better. This is a demonstration that even on receive they don't work as good, and you can't talk to who you can't hear. Extreme weak signals is a good way to demonstrate this:

 

[AC9KH]

I bought a 4 core stack “commercial” version

Maybe some kind of high inductance choke you bought? Certainly not a step transformer. For a step transformer, in theory, you can stack up as many torroid cores as you want if you're trying to build some sort of loaded antenna. But it ends up being a dummy load with high copper losses in the windings.

 

[prcguy]

This is for all the hams that continue to push the fallacy of the EFHW8010 "all band" antenna. While such a thing is pushed ad infinitum by the commercial antenna manufacturers (excluding the reputable ones), most hams should know better. This is a demonstration that even on receive they don't work as good, and you can't talk to who you can't hear. Extreme weak signals is a good way to demonstrate this:

This only demonstrates someone's lack of knowledge on antennas. Why don't you just play a video of someone showing how much a Yagi sucks off the side or back compared to a 5/8 omni? That's basically the same thing. You know an 80m EFHW has gain lobes and nulls and if you compare a null point on the EFHW to a roughly 2dBd gain 5/8 the omni will be much better.

I have an 80m EFHW and a Hy-Gain Penetrator here and depending on what direction signals are coming from the EFHW can actually outperform my 5/8 on 10. The problem is I can't rotate my house with tower supports for my EFHW to aim it for maximum gain so I supplement with a 5/8 vertical on 10m. I also supplement with a 20-6m Hexbeam and most of the time the Hexbeam has a better signal on 20-10m but sometimes not and the EFHW is right in there with the Hexbeam.

I don't know what you think an EFHW has done to you to promote such hate but it doesn't deserve it. Everyone else loves them and they are a great problem solver providing good to great performance compared to most any other wire antenna. I expect next you'll be pointing out how bad they are on 2m and compare it to a 17 element 2m Yagi.

 

[AC9KH]

This only demonstrates someone's lack of knowledge on antennas. Why don't you just play a video of someone showing how much a Yagi sucks off the side or back compared to a 5/8 omni? That's basically the same thing.

Hogwash and no it's not the same thing. You know better than that and are just back to arguing for the sake of arguing. The EFHW has just as much opportunity to receive signals on one of its gain lobes as the 5/8 wave does because they are both omni-directional, and are both vertical antennas. It is an apples-to-apples comparison.

I don't have hate for the EFHW - it is a wonderful antenna on its fundamental, especially as a vertical.

I just demonstrated the difference between an antenna designed for 10m and one that's 4 wavelengths long on the same band in how efficient it is in receiving weak signals. With all your anecdotal statements about great the 80m EFHW is as a 10m antenna, prove it like I just did compared to your commercially-made omni. I can prove it without any doubt down to 30 meters. At 40 meters where the wire is a end-fed full-wave there's not much difference, although the single 40m 1/4 wave vertical still has a lower radiation takeoff angle and more gain where it counts than the full-wave wire does. On 80m the vertical wire really shines, but it's not all that great for NVIS.

I have never owned a commercially-made ham antenna in my life, so it would be an interesting comparison presented by an expert such as yourself.

 

[AK9R]

arguing for the sake of arguing

I have a suggestion: How about both of enjoy the holiday weekend and take a break from this "discussion"?

 

[Crowling]

Here

 

[Crowling]

This one. It’s NOT a choke

 

[AC9KH]

This one. It’s NOT a choke

That's interesting but it doesn't make sense. Stacking cores increases the inductance compared to a coil with the same magnetic path length and same number of turns, but on a single core. However, the flux density is the same so the saturation current is the same as that of a single core. It does not provide any benefits magnetically. It increases inductance. These things are basically voltage step-up transformers with a low voltage primary and high voltage secondary. When you double inductive reactance by stacking two cores current reduces (along with associated flux density) and I^2R heat losses increase. So there's a point of diminishing return when you stack more than two cores unless the goal is to increase inductance.

 

[Crowling]

That's interesting but it doesn't make sense. Stacking cores increases the inductance compared to a coil with the same magnetic path length and same number of turns, but on a single core. However, the flux density is the same so the saturation current is the same as that of a single core. It does not provide any benefits magnetically. It increases inductance. These things are basically voltage step-up transformers with a low voltage primary and high voltage secondary. When you double inductive reactance by stacking two cores current reduces (along with associated flux density) and I^2R heat losses increase. So there's a point of diminishing return when you stack more than two cores unless the goal is to increase inductance.

I don’t know. That’s why I asked you to build one for me the correct way. I trust your knowledge

 

[AC9KH]

I don’t know. That’s why I asked you to build one for me the correct way. I trust your knowledge

Ok, I'll wait until I get your package to see what's in it. Then I'll call you to get information on antenna length and orientation, what sort of ground do you have on it, what kind of power are you running on it, length and type of feedline, etc.. I suspect if you're running just a 100W radio that a single core using FT240-43 is all you need if your primary interest is the higher frequencies. If your primary interest is 80 and 40m, then I'd recommend a dual-core FT240-43 to get more inductance, but the higher frequencies will suffer a bit in that case and may require use of the tuner.

I've found that the internal tuners included in most radios these days are about useless. Some might be better than others. The one in my IC-7300 is a joke. It will tune the 75m band on my 80m EFHW, but 40m where SWR is 2:1 it won't tune. Have to use the external tuner. My transformer is wound with more inductance on the secondary for 160m where I switch the primary out and switch in a shunt with a relay. This requires an extensive ground radial system to use it on 160 as a Marconi. SWR is <1.1 on the lower end of 160 and rises to 1.6 on the upper end. The IC-7300's tuner will tune that fine, but not much else. It has pretty limited capability as an an antenna tuner.

 

[AK9R]

I've found that the internal tuners included in most radios these days are about useless. Some might be better than others. The one in my IC-7300 is a joke.

The IC-7300 manual says it will tune SWRs up to 3:1. If yours won't tune 2:1, there may be something else going on.

 

[AC9KH]

The IC-7300 manual says it will tune SWRs up to 3:1. If yours won't tune 2:1, there may be something else going on.

Yeah, the manual definitely says that, but it's a pretty well-known fact that the SWR sensing circuit on the tuner board (which is separate from the SWR sensing circuit for the meter/finals) is overly sensitive. There's even a mod you can find on the internet to solder in a resistor to make the SWR circuit less sensitive so it will actually tune. In my own playing with it, setting the tuner to E-TUN mode, it will tune just about anything. In regular mode if there's a significant reactive component in the complex impedance it will sometimes refuse to tune even at 2:1.

I suspect ICOM did this to prevent warranty claims on blown tuner boards because the components on the board are not very robust compared to an external tuner that can handle much higher voltages than than internal ICOM tuner can.

 

[Crowling]

Ok, I'll wait until I get your package to see what's in it. Then I'll call you to get information on antenna length and orientation, what sort of ground do you have on it, what kind of power are you running on it, length and type of feedline, etc.. I suspect if you're running just a 100W radio that a single core using FT240-43 is all you need if your primary interest is the higher frequencies. If your primary interest is 80 and 40m, then I'd recommend a dual-core FT240-43 to get more inductance, but the higher frequencies will suffer a bit in that case and may require use of the tuner.

I've found that the internal tuners included in most radios these days are about useless. Some might be better than others. The one in my IC-7300 is a joke. It will tune the 75m band on my 80m EFHW, but 40m where SWR is 2:1 it won't tune. Have to use the external tuner. My transformer is wound with more inductance on the secondary for 160m where I switch the primary out and switch in a shunt with a relay. This requires an extensive ground radial system to use it on 160 as a Marconi. SWR is <1.1 on the lower end of 160 and rises to 1.6 on the upper end. The IC-7300's tuner will tune that fine, but not much else. It has pretty limited capability as an an antenna tuner.

I run 1.2 KW at times and is why I wanted a 4 core 49:1. The ground scientific ground quality for my area can be found online. Think I saw that on a fcc type site some where. I use rg-8

 

[Crowling]

I use rg-8 flex at 100 feet. I use an icom ic-746 and the internal tuner works great. I use a Yaesu ft-767 as well. The antenna is 40/50 feet high at its highest as I have said before I don’t judge heights well. For a clear picture on sstv the stronger the received signal the better. I do like to use sstv.

 

[AC9KH]

I run 1.2 KW at times and is why I wanted a 4 core 49:1. The ground scientific ground quality for my area can be found online. Think I saw that on a fcc type site some where. I use rg-8

I'm afraid you're going to need different cores to run 1.2kW. You can't keep stacking up -43's to handle more power because the primary inductance goes too high to be usable above 4,000 kHz. Three stacked -43's that will handle 1.2KW on SSB is a 160/80m antenna only. And I wouldn't even use that on 160 if you're running power. The voltage will go so high on the output of the transformer that it will blow thru the windings and jump a nice blue plasma arc to anything close that's grounded. Especially if you run AM on it. That's the primary reason I don't run a EFHW on 160 and switch my antenna configuration to a 1/4 wave Marconi - much lower feedpoint impedance keeps the voltages down.

 

[Crowling]

I'm afraid you're going to need different cores to run 1.2kW. You can't keep stacking up -43's to handle more power because the primary inductance goes too high to be usable above 4,000 kHz. Three stacked -43's that will handle 1.2KW on SSB is a 160/80m antenna only. And I wouldn't even use that on 160 if you're running power. The voltage will go so high on the output of the transformer that it will blow thru the windings and jump a nice blue plasma arc to anything close that's grounded. Especially if you run AM on it. That's the primary reason I don't run a EFHW on 160 and switch my antenna configuration to a 1/4 wave Marconi - much lower feedpoint impedance keeps the voltages down.

Ok. I don’t use am anyway.

 

[Crowling]

Ok. I don’t use am anyway.

I use high power on ssb with my 1 core until it gets hot then let it cool then it’s ok

 

[AC9KH]

Ok. I don’t use am anyway.

Whether you use AM or a high duty-cycle digital mode, same difference. Even with a high-power transformer design you're limited to about 200 watts, maybe 250 max.

 

[AC9KH]

I use high power on ssb with my 1 core until it gets hot then let it cool then it’s ok

Most single core designs are good for ~200w on SSB unless you use -52 core, then about 350-400w. But a single 52 don't have enough inductance for lower frequencies so they're typically stacked 2 or 3. With three of 'em you can run 1,200w intermittent on SSB but still have to keep an eye on SWR and if it starts to get unstable it's time to quit talking and let them cool off. With amplifiers it's always better to use resonant antennas with low feedpoint impedance and forget transformers. And if you're going to use an antenna multi-band with an amp, scrap the coax, use parallel feeder and just tune it up with the shack or amp tuner.

 

[Crowling]

Ok. I don’t use am anyway.

Mr. Olson. In my hurried attempt to get the package mailed out before the weekend, I forgot to enclose a check for the return postage. I will have to send a check out usps this week. Craig