Apex Radio 303WA-2 Antenna

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ka3jjz

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It's quite possible this would be a little too much for that radio, particularly since you're on the East Coast, where sigs tend to be stronger. Overloading is a real possibility here. Also being in Florida (the lightning capital of the US) having a potential 6 foot lightning rod on an apartment is just begging for apartment insurance issues if the antenna happens to get struck (not to mention your own insurance...).

Personally I think you'd be far and away better off by winding some very thin clear speaker wire around the perimeter of your balcony a few times (how big is the balcony?) and feeding that to a 9:1 transformer, (such as those sold by WinRadio and Palomar Engineers) with a bit of coax. Not very expensive at all (far cheaper than the Apex by a long shot) and much less likely to get nailed by a strike. It's then quite easy to change the length of the wire if you find out it's too much. And do make sure to disconnect the antenna when it's not in use...another possibility would be a small active antenna such as the North Country (link below)

Active Antenna 10kHz - 30 MHz

I'm not a big fan of actives, frankly, because they can and often do end up amplifying as much noise as signal, but when you can move the receiving element around to find a quiet spot and either the gain can be adjusted (or it's reasonably low), you have some options to consider.

Likely as not there are other possibilities - just remember during the TStorm season to be VERY careful about outdoor antennas...Mike
 
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SCPD

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I almost bought this antenna a while back. It would probably be okay for the DX-394 but the problem is that the vertical would pick up all kinds of RFI and local noise.

It's certainly a compromise antenna but it's worth a shot.

You're better off investing in an indoor loop antenna.

Mike's idea is certainly the cheaper investment however.

Just as an example:

LA5030-2 Indoor North Amer. ver. with PSU
 

haleve

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9:1 Transformer

Thanks Mike & Nick for your speedy & very informative replies, way too much RFI for any indoor antennas, Mike are these what you are referring to:

WiNRADiO WR-LWA-0130 Long Wire Adapter

Toroid cores for amateur radio

The balcony is 14' by 7', since the DX-394 has an SO239 connector should I go with the Palomar to eliminate adaptors?

Again thanks guys......Hal
 
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ka3jjz

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Adapters really aren't too much of an issue here - for HF receive any loss you might experience would be negligible. However the RFI issues you mention deserve some attention before you do anything. Obviously you can't do too much about anything your neighbor is using, but you can do some things about what you have in your apartment. You're going to need to find out what the noise is coming from - and it could be multiple things. Turning things on and off while listening to the radio's noise level would be a start. Solving this problem makes you become something of a detective...

And Nick is quite right about the vertical being something of a noise magnet (I was thinking more on the lines of safety). Yes those 2 items you have in your message are examples of what I was talking about. You have a pretty good sized balcony - particularly if it's somewhat enclosed, you could wrap your wire up and around that perimeter twice and have a decent length with which to work. A short hunk of coax from either of those 2 units to your receiver and you'd be good to go.

I forgot to mention that waterproofing the coax is critical, particularly since you live in Florida. A double wrap of good quality electrical tape at the connection point around the PL-259 (or BNC), then a bit of silicone sealant will do the job. Both can be had at places like Home Depot or Lowe's.

Mike
 
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SCPD

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Thanks Mike & Nick for your speedy & very informative replies, way too much RFI for any indoor antennas...
The Wellbrook loop will actually help to eliminate certain types of RFI. If you have RFI from digital devices indoors (that you can control) then it doesn't matter what kind of antenna you have... you need to address that first.

The Palomar device is a joke and is way over-priced. It's nothing more than a 9:1 un-un (which is what the WinRadio adapter is...)

This antenna is probably your best value -- it's very highly rated:

Par Electronics EF-SWL End Fed Dipole SWL Antenna. Par EF-SWL.

You can string up the wire around your balcony -- and it includes a proper 9:1 transformer. Just add a short length of RG-8 or better coax and you'll be fine.
 

ka3jjz

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Not a bad idea, Nick -- and it should be mentioned that you can remove the 45 foot of supplied wire and put your own on - making it easier to hide it. In certain situations I can see that black wire it comes with being very visible...like having a zebra in an art store (hi) Mike
 
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Fast1eddie

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I bought one (passive) several years back. Ah, it's ok, receives vhf low/high bands really well. HF performance was acceptable, although clearly lacking. I did not experience any noise issues with mine, guess if you are at the beach or mountains then it would fit the bill. Not using mine and should take it down.
 

W0YNF

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Go ahead and buy the Apex

I am contemplating getting this for my Radio Shack DX-394, anybody have one or are familiar with it's performance? It's going on a balcony as no other type of antenna is acceptable per apartment restrictions.

Apex Radio 303WA-2 Shortwave antenna. ApexRadio
I have another post in the group comparing the Par and the Apex. I have both up and run to a coax switch
so I can switch back and forth between the 2 on any freq. to see which is a better signal to listen to.
The Apex is a fine smaller profile antenna that works extremely well. It does have a built in impedance
match to make the antenna look like 50 ohms across the bands. The par is up at a height of 17-18'
sloping down slightly to 9''. The Par is far noisier during daylight from the suns Ionizing, gives a higher signal
level but more noise, and after all it really is about the S/N ratio isnt it. At night there are freqs. that are recieved better on the Apex than on the Par (believe it or not) and on maybe most signals are higher level
with the Par along with a higher noise floor. On some freqs. there is little to no difference in signals. There hasnt been any signal that I could hear on one antenna and couldnt hear on the other with the exception of 5 mhz WWV in the daytime, on the Par the signal is washed out by noise completely. Can barely hear
it on the Apex but I can pull it out. I dont know where this idea came from that vertical antennas are noisier than horizontals. I have had horizontal antennas from the 45' Par and different lengths out to 200
ft. The 200' antenna just swamped the receiver with noise and hash. The 2 quiet antennas I have had
have both been verticals, a RF Systems MTA, and now the Apex. I have everything grounded almost to
overkill, the radio, the Par, the mast that both antennas are mounted to. They are all grounded with 8'
grd. rods and no. 10 stranded copper wire. So that is not a problem. I also am not a rank beginner in radio
I am retired now and have been into radio since a teenager. Started out as a novice, worked my way
up to advanced,, then let everything lapse. Got my Tech ticket so I can talk 2-6-10 meters. Not much interest there anymore. So I'm not Sam Stupid when it comes to radios or antennas.
For apartment living the Apex would be ideal. Its not going to swamp the front end. I am familiar with that radio, while its an ok radio, that was radio shacks first attempt at a digital SW reciever and it doesnt have
a particularly "hot" front end. Its a decent performer though that goes back to the 70s -80s If I remebmber
correctly
 

SCPD

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I dont know where this idea came from that vertical antennas are noisier than horizontals.
Well, they do pick up more noise and that's just a fact. You're forgetting a couple of points. A lot of EMI is from powerline noise which can be horizontal or vertical polarized. I've recently dealt with both in this area. The powerline noise wiped out my vertical.

So my point is it depends on the source of your local noise. Case in point -- my neighbor has a pet fence which is buried in the ground. Any horizontal wire in my backyard will pick up this noise. My vertical does not.

For your situation, the vertical is better.

In an apartment complex, HF radio listening is a challenge -- period. You could have all sorts of EMI that can affect your listening.

If you're up high and on the corner of a apartment building, you might be fine with an Apex vertical. You could be equally fine with the PAR wire antenna wired around your balcony, etc.

If you were in the mountains with a battery-powered HF receiver -- either antenna would be fine and would likely receive extremely well. Heck, you could probably just throw up a random wire and make out great. It all comes down to noise mitigation and noise elimination.
 

nanZor

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I live in an extremely rf-challenged environment, and my antenna of choice is a vertical. My neighbors went bpl and put ethernet into the powerlines, rendering my homebrew hardline loop useless since I could no longer get a null.

I went vertical! BUT, I had to do my own "site survey" to find out where best to plant it. I used a portable ssb receiver, with the whip vertical, and found only 2 or 3 places on the property where the s/n ratio was clean. THATS where I put my vertical. (A top-loaded T "lazy H" vertical - thanks to N6LF....)

Critically, when using a vertical, you need a good RF ground, otherwise the coax braid becomes the radial, and allows for noise ingress or egress. An 8-foot ground rod is really only about a 2-inch or so RF contact with the soil, so really, radials - either buried, laying on top, or elevated are desired. If you lack a good RF ground, at least try to choke it with an isolator, coax coil choke, ferrite beads, etc etc. So not only is physical placement crucial, but so is choking off common-mode currents from the transmission line - even if just on receive. This also applies to loops - if you find you get odd nulls, or maybe only one deep one on one side, the loop is unbalanced, and if you have it mounted high enough, you've basically got a common-mode vertical made out of coax braid with a lollipop on the end. :)

So even though I favor homebrew, I just might try an Apex for convenience, even if the extreme broad-bandedness is at the cost of efficiency, and see how additional radials or choking might improve things. Of course, I don't just throw it outside, but find the right spot for it by doing a s/n ratio survey first.
 
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nanZor

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On it's way - will I have to eat my hat?

Ok, got the Apex vertical on the way. Will it be just a 50 ohm resistor with a 6-foot whip attached? Or perhaps a 9:1 balun and a 6 foot whip? Or a magic antenna that relies upon common-mode transmission line currents? I was tempted to order two so I could cut one open, but decided not to obsess over it - at least for now.

Stay tuned! :)

I'm already envisioning top-loading it like a T with 3 - 6 foot or so top loading wires, or maybe a small capacity hat. We'll see!

Forgot to mention that one of the good locations is actually indoors - fortunately near a window where 3 feet movement one side or the other renders the vertical useless. To top it off, my roof is covered in decorative metal tiles. A horizontal antenna here was useless, and the only way to get out from underneath it was to actually go vertical. Let propagation do the work, and hear plenty of amateur dx both over-the-pole, and long-path. S1-S5 maybe where other guys have armchair copy, but it can be done.

I guess I was so mad at my conditions that I took it as a challenge not to quit the hobby.
 
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nanZor

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Yep still waiting for shipment. And I hope that I didn't come across too harshly for anyone - I really don't mean to.

I'm so curious about how they are doing the broadband matching that I had to find out. :)
 

nanZor

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Ok, got the Apex Radio 303WA-2 antenna and there are some pros and cons. I won't be using it much, although I didn't expect miracles from a 6 foot whip essentially.

Very quality build, even includes some coax-seal. The mount is versatile and can be mounted in many positions.

I put a Comet Analyzer on it, and found that the swr was usually about 5:1 to 10:1, and impedances ranging from 10 to 200 ohms. No 1:1 match here. This was tested with both a 1-foot jumper and the supplied coax. Since swr at HF under such short runs isn't a huge issue - especially for rx only, I wasn't too concerned. And with these values, a fair amount of reactance along with normal resistance is indicated - something the Comet doesn't show directly, but can be seen with swr's higher than what is calculated based upon resistance alone.

Trying to improve it with radials didn't change things much at all. It appears that the matching network (whatever that is inside), totally swamps out the common mode. This is good and bad. Good to make sure that the common-mode of the coax isn't becoming part of the antenna. Bad because you can't improve performance with radials and isolating the feedline with your own choke instead. There was a minor amount of hand-capacitance detected, but nothing major, and a ferrite or two took care of that. I would still recommend some ferrites or a simple coil-wound coax choke near the feedpoint for very bad conditions. At least the noise from the common-mode cable run from your noisy room out to the balcony will be suppressed, and the antenna is hopefully outdoors and further away from local noise sources.

In effect, on HF, you have something similar, but not exactly like attaching a 6-foot radiator to the center conductor of coax, with NO radials, and choking it very heavily at the feedpoint. Longwave and medium wave with a setup like this might be another story - it is unlikely that I'll ever be able to wind or make a choke with enough choking impedance to prevent the common mode of the coax from becoming part of the antenna at these frequencies - so the Apex's lossy matching network would probably do better at that aspect.

I also tried using a T-network tuner with a bypass switch for quick A/B comparisons, and while I could tune the reactance out to get a perfect 1:1, the difference in reception was barely noticeable.

This isn't very efficient, but Apex never claimed it was. They concentrated on stating that it will cut down on intermod and crossmod by being passive. It sure does. The small whip along with the loss from the matching network help to assure this.

However, with the common mode swamped, and the impedances fairly low (even though the swr might be a tad high), the 6-foot whip is doing all the work, and you might be more able to put it into a non-noisy area. If you have a higher-quality radio than a portable, like an Icom R75, or Alinco DX-SR8 receiver for example, turn on the 10db preamp. It sounds ok under these conditions, and can recover some of the lost sensitivity of using such a short whip - but in the end that is all it is - 6 feet of radiator under the best of conditions.

I think I'll be keeping it with my bag of tricks for occasions like super high RF environments, where efficiency needs to be low, and common-mode suppression is built in, but it won' t be in daily use.
 
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E-Man

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Sorry to hear it did not work out. Thanks for taking the time to share your findings.
 
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