ApexRadio RX antenna

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WA8ZTZ

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Had an opportunity this afternoon to check out the ApexRadio 303WA-2 vertical antenna. The antenna itself stands about 6' tall. It was mounted about 8' above ground and fed with 60' of RG-58.

Here are the results of a side by side comparison of this antenna with a plain 50' wire antenna. Testing was done mid-afternoon when signals are generally steadiest. RX was Satellit 750.

On shortwave, the Apex antenna gave far better performance than did the 50' wire. Time signal stations WWV on 10000 and 15000 and CHU on 7850 were many S-units higher on the Apex vertical.

Dropping down to the AM broadcast band, the results were similar. WLW 700 and WGN 720 both had nice signals on the Apex. WTVN 610 Columbus 5kw and WEOL Elyria 1kw both in OH both had S9+ signals on the Apex. All signals were only S1 on the wire.

Heading down to the LW NDB band my expectations were not that great. However, what a surprise awaited me. Performance on the 50' wire was dismal as expected, but logged 35 NDBs, many out as far as 300 miles, on the Apex...wow! This was mid-afternoon, not exactly the best time for NDB hunting.

This unobtrusive relatively small ApexRadio 303WA-2 antenna is a real winner. This would be an especially useful antenna for someone who lives in an antenna restricted space.
 
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ab3a

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If you don't mind my asking, please describe the 50' wire you're comparing this antenna to. I'm puzzled as to how a passive antenna so short can be so much better than a 50' piece of wire.

My best guess is that you're somehow reaping the benefit from 60' of coax on it's way up to the antenna. But I'd really like to know more.
 

WA8ZTZ

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I'm puzzled as to how a passive antenna so short can be so much better than a 50' piece of wire.
You aren't the only one... puzzles me too. Without dissecting the base section of the antenna to see what is going on inside limits me to guessing perhaps a ferrite arrangement of some sort. Would have to be very wide banded though, look at the antenna specs... 30 kHz to 30 mHz.

Anyway, the 50' wire antenna was just that. Nothing fancy, just an insulated 16awg 50' length of wire temporarily hung up about 8' and connected to the antenna input(s) of the Satellit 750 without any coax, matching device or tuner.

Your guess about the 60' coax got me thinking as to whether it was acting as an antenna so tried the ApexRadio antenna with just a 6' length of coax into my Tecsun PL600 on various SW sigs and then compared it to the 60' length of coax into the same radio, same sigs. If anything, there was a slight loss with the 60' coax.
 

WA8ZTZ

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ab3a,

Been giving this some more thought and figure that the ApexRadio antenna must have a very efficient impedance matching transformer device in order to couple the signal very effectively into the receiver. If so, it's amazing they got it so broad banded. This is just a guess on my part as there is no antenna analyzer in my shack and those of my friends only cover 160 meters at the lowest.
 

pjxii

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I just bought a used DXE NCC-1 phasing unit with plans to use it with a pair of DXE ARA3-1P active antennas when I finally have my house built. I've been fortunate to find a few acres surrounded by tomato fields in a sparsely populated rural area with absolutely no RFI. I think before I spend $300 each for the active antennas I'll try two Apex passive verticals for less than half the price of one active and see how it goes.
Man, I would love to hear from someone who has both the Apex and DXE for a comparison!
 

nanZor

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I tried the Apex 303WA-2. It is NOT an ordinary whip as you normally assume.

There is a total disconnect rf wise from the coax shield. This means that radials, should you try to use them, or incorporate the braid as a counterpoise is ineffective. This is on purpose.

It more or less emulates taking your portable receiver from inside your noisy indoor location, and walking out to the balcony or other area less noisy. They understood that for those who buy these things, they don't understand how to effectively choke/isolate an outdoor whip and are not really diy radio people who know what common-mode shield problems are with a transmission line indoors. It is basically just a fancy way of getting a small untuned whip outdoors.

So yes, getting a small whip outside surely helps! And so does the total disconnect from the common-mode of the coax running to it from indoors.

For those who don't know about common-mode issues or how to tame it, this is fantastic if 6 feet of antenna will work in your situation.

But for us, you can do the same by using 6 feet of wire, then totally isolating and choking your feedline, and then make no attempt to improve it with no radials/counterpoise either!

The Apex has it's purpose, mainly designed for easily-overloaded portables, but for most of us, it turned out to be just 6 feet of whip, totally choked from the coax shield, without any way to improve upon it. I wouldn't make it part of an extensive array.
 
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nanZor

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Your guess about the 60' cox got me thinking as to whether it was acting as an antenna so tried the ApexRadio antenna with just a 6' length of coax into my Tecsun PL600 on various SW sigs and then compared it to the 60' length of coax into the same radio, same sigs. If anything, there was a slight loss with the 60' coax.
That's it! It makes no difference, other than simple line loss, since the coax shield is not used in the normal fashion with this antenna.
 

WA8ZTZ

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I missed this thread last year. WA8ZTZ, do you still use this vertical or has it given way to your recent SWL setup?
Interesting that you should ask, just did an antenna shootout this afternoon between the Apex vertical, a homebrew box loop and a stock PAR EF-SWL connected to my Satellit 750 via a 3 way coax switch.. The loop was a disappointment as it apparently needs some kind of tuner or preamp to get it working. Otherwise, briefly summarizing... between the Apex and the PAR... the Apex had a slight edge over the PAR on LW. They both performed similarly on AM BCB. The PAR had the advantage on HF. The Apex continues to surprise me as to how well just a 6' whip performs. For someone with antenna restriction issues the Apex would be a nice choice.
 

ridgescan

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Interesting that you should ask, just did an antenna shootout this afternoon between the Apex vertical, a homebrew box loop and a stock PAR EF-SWL connected to my Satellit 750 via a 3 way coax switch.. The loop was a disappointment as it apparently needs some kind of tuner or preamp to get it working. Otherwise, briefly summarizing... between the Apex and the PAR... the Apex had a slight edge over the PAR on LW. They both performed similarly on AM BCB. The PAR had the advantage on HF. The Apex continues to surprise me as to how well just a 6' whip performs. For someone with antenna restriction issues the Apex would be a nice choice.
Cool! You have a little antenna farm like I do:D choices are cool. Glad to learn about the Apex vertical and I think others ought to take heed that this is a serious limited space RX antenna! Which means, no excuse to not get it outside:)
 

pjxii

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I tried the Apex 303WA-2. It is NOT an ordinary whip as you normally assume.

There is a total disconnect rf wise from the coax shield. This means that radials, should you try to use them, or incorporate the braid as a counterpoise is ineffective. This is on purpose.

It more or less emulates taking your portable receiver from inside your noisy indoor location, and walking out to the balcony or other area less noisy. They understood that for those who buy these things, they don't understand how to effectively choke/isolate an outdoor whip and are not really diy radio people who know what common-mode shield problems are with a transmission line indoors. It is basically just a fancy way of getting a small untuned whip outdoors.

So yes, getting a small whip outside surely helps! And so does the total disconnect from the common-mode of the coax running to it from indoors.

For those who don't know about common-mode issues or how to tame it, this is fantastic if 6 feet of antenna will work in your situation.

But for us, you can do the same by using 6 feet of wire, then totally isolating and choking your feedline, and then make no attempt to improve it with no radials/counterpoise either!

The Apex has it's purpose, mainly designed for easily-overloaded portables, but for most of us, it turned out to be just 6 feet of whip, totally choked from the coax shield, without any way to improve upon it. I wouldn't make it part of an extensive array.

This makes sense, and its obvious that most of the cost of the $300 DXE ARAV3-1P is in the preamplifier and not the 8' whip.

I do want to test out a steerable phase array but the land right now is all trees and palmettos, almost no clear areas, so it'd be diffilcult to run anything like a couple of BOGs which is why I was thinking of the Apex vertical. Maybe hang up a pair of PAR EF-SWLs (I already have one, cheap enough to get another)...
 

pjxii

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Interesting that you should ask, just did an antenna shootout this afternoon between the Apex vertical, a homebrew box loop and a stock PAR EF-SWL connected to my Satellit 750 via a 3 way coax switch.. The loop was a disappointment as it apparently needs some kind of tuner or preamp to get it working. Otherwise, briefly summarizing... between the Apex and the PAR... the Apex had a slight edge over the PAR on LW. They both performed similarly on AM BCB. The PAR had the advantage on HF. The Apex continues to surprise me as to how well just a 6' whip performs. For someone with antenna restriction issues the Apex would be a nice choice.
Wondering something...
You said earlier that the Apex was mounted 8' high (I'm assuming bottom of antenna). How high and what configuation was the PAR? Have you tried the Apex any higher?
 

prcguy

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The Apex would have a small transformer in the base, something around a 100:1 impedance ratio or maybe higher. The AOR SA7000 would be similar and I've dissected one and built a transformer that works similar.

When you use an end fed whip or wire that's really small in wavelengths, its very high impedance and can range from a few thousand ohms at HF to over 1meg ohm at VLF. Some short receive whips use an active amplifier to change the impedance and drive 50 ohm coax but you can also use a transformer. Simply connecting a 6ft whip to 50 ohm coax at something like 1MHz where the whip might be thousands of ohms would pull the signal down to nothing.

When I get back from another pending vacation I might experiment a little more with my transformer and post a parts list and diagram if it works as good as the AOR SA7000 transformer.
 

WA8ZTZ

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Wondering something...
You said earlier that the Apex was mounted 8' high (I'm assuming bottom of antenna). How high and what configuation was the PAR? Have you tried the Apex any higher?
The Apex was and still is mounted 8' above ground at its base.
The PAR is about 45' long strung between a couple of trees running NW-SE about 8-10' high.
 

majoco

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Put a 9:1 balun on the end of your wire and you will get a great improvement into the 50ohm antenna socket.
 

Fast1eddie

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Ah, the Apex. Have one and removed it from service when I divorced. It's sitting in the corner, have replaced the original hex head screws with better quality ones. Y'all have me interested in setting it back up on my apartment balcony. My Par End Fed attic installed works great, so I really have a use for it, but should be fun feeding one of my AOR's with it.

Being vertical, might help with the noise level here, but not much.

Thanks for rejuvenating my interest men.
 

majoco

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The PAR antenna is end fed at a matchbox that contains a 9:1 transformer.
....which is why I declined the PAR when I can make my own transformer and hang it on the end of a 45ft wire. The transformer is contained in a plastic pill bottle, the SO239 in the lid and shielded from the weather with another pill bottle and a 1/4" hole for the RG58. I had to buy the ferrite ring but everything else came out of the junk box.
 

WA8ZTZ

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....which is why I declined the PAR when I can make my own transformer and hang it on the end of a 45ft wire. The transformer is contained in a plastic pill bottle, the SO239 in the lid and shielded from the weather with another pill bottle and a 1/4" hole for the RG58. I had to buy the ferrite ring but everything else came out of the junk box.
What ferrite material did you use ?
 
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