Apexradio 303wa-2 vs MLA30+ (Genuine)
My Antenna arrived, had to use world shipping, which wasnt cheap. sigh.
Anyway, it's a beautifully crafted antenna. Need to figure out where I will mount.
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Once I have it mounted, I will plug it into my Sangean ATS 909 and compare signals against the kiwi with the loop antenna.
Mounted on the garage roof
So, some really un-scientific anecdotal evidence (listening and comparing RSSI / S-Meter levels on various stations, including UTC, 20Mtr HAM, various broadcast bands, its a tight race. The MLA 30 gives a few DB more signal, however I have the gain turned up on it. The Apex whip has an inline galvanic isolation transformer on it, and the noise floor between them both is almost indistinguishable.
I'm quite amazed at the apex 303, and the fact it is a short whip totally passive.
Time to get an antenna switch.
Additionally - the mount is a roof mount kit with adjustable stays. We own a WISP, so there are plenty of these lying around, not being used any more. How fortunate for me!
I may extend the pole in the future, however for now, its working great.
There was a long thread about the Apexradio 303WA-2 some time ago on this forum.
https://forum.kiwisdr.com/index.php?p=/discussion/comment/17853
The height of the antenna above ground is likely to have a significant effect on its performance.
Generally speaking, the higher you can mount it, the better it will perform.
Can you state your KiWi URL so that I can take a listen ?
Regards,
Martin
Hi Martin,
I'll plug the antenna back in tonight - daytime around here is terrible. I have the loop plugged in currently - keen to get a switch.
http://21996.proxy.kiwisdr.com:8073/
I've plugged in the 303 :-)
Thanks for doing that.
I think the Apex is better than the loop, but in both cases you seem to be constrained by local interference.
I can hear and see noise from several switching supplies, possibly solar PV optimisers, plus what I think is a domestic Data over Mains Powerline adaptor.
The sensitivity of the Apex falls off below about 5MHz, which is what I observed with my clone, but it should still be adequate in most cases, as the noise floor naturally rises on the lower frequencies.
Have you checked your own home for sources of electrical noise ?
Regards,
Martin
I, too, noticed it has picked up more noise than the loop.
There aren't any solar panels on nearby houses so dont expect to much PV controller interference, I do use a power line adaptor in the house, however that is on a separate circuit from the garage (hobby room / study) where the kiwi is powered. The switch the kiwi is plugged into is POE, which could explain some of the noise. I might put a "dumb" switch in there to see if that cuts down some of that noise.
The Apex is in the corner of the section, which is really for convenience, however I think I will ultimately move it to a better location on a pole
I am in an urban area, with houses on all sides. What I need to do is mount it up at our Mt Kahuranaki WISP side, which has an elevation of over 600mtrs. It is a long way go if it breaks though :-)
One observation, is that the 303 and my Sangean ats909x2 play very nicely together. Whereas the 303 plugged into the kiwi there is a difference of several DB lower, where in the Sangean they are on par with each other when the loop is plugged in to the kiwi.
I think I will extend the pole somewhat over the Xmas break and see what effect that has.
OK interesting. I thought the loop was a lot noisier than the Apex ?
When I listened with the loop connected, the noise floor was about 20db higher. I think you could safely reduce the gain on the loop without degrading the Signal To Noise ratio.
My experience of PoE has generally been quite bad. The DC-DC convertors used in the actual equipment seem to be very poor in terms of radiated noise, and for that reason I try to avoid it if possible.
I suspect that quite a lot of the noise you are seeing is locally generated, so you should have various options available if you wish to try and reduce it.
Regards,
Martin
Example, a DRM signal is stronger on the kiwi with the loop than the 303 because it will decode using the loop and not the 303, whereas the 5mhz UTC signal came in better on the sangean with the 303.
Bearing in mind, the sangean has a manual RF gain control turned up full.
@G8JNJ (Martin),
What are your thoughts on these kinds of devices?
Cheers
Sean
Yeah, the loop is noisier. I'll leave the whip plugged in for a while and see what its like over all.
I’ve decided to heighten the antenna
Should be nearing 5mtrs up and over most of the neighbor’s roofs now, with the exception of the next door neighbor, they are a two story.
Regarding the DX Engineering RPA-2 pre-amplifier.
It's a good enough device, but somewhat expensive. I have used cloned copies of the RPA-1, which has a very good IMD performance, but the noise figure is not that brilliant, at around 6dB.
As your signal levels are quite low, I think one of the PGA-103 based pre-amplifiers that are available on AliEpress, such as this one, would be a good option.
https://www.aliexpress.com/item/1005005241002955.html
But you may need to add a 10dB attenuator on it's output, to bring the signal levels down to a more suitable average.
There are many other pre-amplifiers on AliExpress, that may work just as well or perhaps even better. But as most of the MMIC chips used in them only tend to be specified from about 500MHz upwards, I don't know how well they would perform on the short wave bands. From experience, the PGA-103 works well below 50MHz, and it's gradually rising input impedance, makes it suitable for use as an active antenna too.
Regards,
Martin
Ive purchased one of these
https://www.nooelec.com/store/lana-hf.html
As well as the MW notch filter - so I don't over load the kiwi if I tune into an MW station - which isn't often
Ah OK...
Personally, I wouldn't recommend that model, but let's see how it works for you, when used with your antenna.
I'm not sure what device the Noolec is using, but I guess it will be something like the Qorvo QPA4363A.
Rather than issues with MW stations, it's more likely to be issues with possible overload from any strong FM broadcast stations, or other VHF transmitters that may be around your location.
The reasons I suggested a PGA-103 based amplifier for your application are, good IMD performance, low noise figure and rising input impedance, which helps improve signals on the LF bands, especially when using a short antenna. The current consumption is a bit higher at around 100mA. Noolec may have chosen a lower power consumption device, so that it can be used with the limited current available from sdr's with built-in bias tees, many of which have a maximum current rating of around 50mA.
But experimentation is all part of the hobby, so just try it, and be sure to report back with your findings.
If you need any specific help, send me a PM.
Regards,
Martin
OK cheers Martin!
I might grab the Ali express one too as its quite cheap.
I liked the idea of the Noolec one as it covered the HF bands and was very flat across the range (and made in the US, rather than rolling the dice on Ali)
Thanks for the helpful advice - its very much appreciated.