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- เผยแพร่เมื่อ 23 พ.ย. 2024
- Miniwhip performance is often disappointing, due to no or insufficient de=noising measures or installation faults.
Pa0nhc Miniwhip :
Technical details.
Improvements.
Important directives for all Miniwhip installations :
De-noising.
Installation.
-Comparison between a good Miniwhip and a good small active receiving loop antenna.
Excellent video that covers all the important parts practically everybody ignores when 'trying out' their own miniwhips. Done properly, and with good height, a miniwhip can outperform a standard 3-m circumference amplified loop. Maybe not on every signal, but certainly many.
As an experienced LowFer band hobbyist, it's safe to say that you covered most all of the bases. Thanks.
From the lower half of HF on down to audio frequencies the noise problems only get worse, since as you drop in frequency even tiny signals carry as if the Earth were ever more completely flat. From about 250 kHz on down it essentially is. A few mW will carry, and blanket, nearly every foot of a thousand miles. So the problem for radio reception isn't receiving a signal. It's avoiding receiving any other noise signal, because they are ALL there at the same time, from a thousand miles in every direction. The primary tool for doing this is the antenna, not the radio. You can't just buy a magic box to solve the noise problems. You MUST build a quiet antenna system for your location. If you do, you will be pleased with the results.
I bought the cheapest I could find on ebay from china and was not expecting much. After installing it on an aluminium 2.5 meter pole on a small steel rusty pole (again 2.5 m) above a metal pole barn roof, I got nothing! yes a scam!! (so I thought) A quick google on pointed out to check if you have voltage on the BNC connector leading from the power box to the antenna. I had noting, so a quick look inside showed me the polarity was wrong from the ower connector ( must have been a bad day in china that day) I re sodered and corrected the fault and now this antenna is amazing. I am hearing LW and MW (AM) stations I never head befor on a 100 meter long wire with absoulty no noise at all! I am in central France and get BBC Radio 4 30db over S9 ( i run the antenna power from a 12v DC battery)
Install it right with a good ground and this little thing is totally amazing. No scam at all!
Agreed, and the *same* thing happened to me when I bought some other Amazon mini-whip (not this version)! Came with the bias tee wired backwards! It was the "Balana" brand with so-239 connectors on antenna and bias tee box. I wonder how many other people bought one of those and it made them think every mini-whip was bad.. looks like they stopped selling that brand on Amazon for now though, at least.
They are typically great receive antennas when built and installed properly. If you listen to what the OP is saying about grounding them, using common-mode chokes and modding the ground wire on your power supply, and you will most likely be surprised at what you can hear with them!
It would be fine if people didn't instantly take to making a YT video 4 minutes after opening their miniwhip package and 'testing it out' whilst it's hanging out the window with no ground! These are excellent antennas made to look bad by people who don't think about what they're doing, or how E-field probes work.
This is the first and only time I've ever heard of mounting the mini-whip on a metal mast. I've always been told to NOT mount it to a metal mast, but rather plastic or PVC mast.
It's fine to mount on a metal mast, but with two provisos: (1) the whip must be positioned above the pole, not alongside it and (2) the metal pole must be well-grounded at its base via its own grounding point, not the mains earth or indoor pipes, for example.
Thank you dear OM. Great Advises. Best 73.
Miniwhips are fine for most applications. But careful tests on SAQ transmissions show that an amplified coax loop antenna such as the WellGood units, are substantially superior at VLF. Put into context, I get an S6 signal consistently on a loop, but a miniwhip will not detect SAQ at all. Sure, this will depend on where you live, relative to any given TX. But a loop remains the far better option.
Please start working on rx loop antenna array, steer the beams
Ok dont know it seems my original post got deleted which is strange and irritating since i had a comparison between most of my miniwhips, so i make a shorter version, i have more or less all of the active miniwhips except the giga active and mega active variants, as well as their biastees.
What i want to point out are:
* Not all BiasTees are equal (RA0SMS has the best BiasTee) not sure why yeat 202107xx version
* Grounding is not as easy as it seems, dont be shy to ferrite your ground path
* When it comes to RX CMC its easier than you think you only need to ferrite the ground path (Coax Minus path which is super easy to get very many circles around if using a thin wire)
And then my Coment was deleted! indeed TH-cam why!
As always nice and lucid explanation.
Miniwhip is an electric field probe not an antenna: the vertical antenna radiation pattern you show at 2:00 is not applicable to miniwhip.
Also that is specifically the elevation pattern of an antenna one quarter wave long, not so shorter and above a not perfect ground..
But is it an isotropic probe? Does it produce the same output for all directions of the E field?
I have an interesting extension to the concept of this antenna that will need experimental confirmation.
I have heaps of 2N5109 and 2N4416A Jfets to play with so I want to do something interesting.
My idea is to use a differential FET input stage feeding the 2N5109 using two of these capacitive probe antennas in antiphase to eliminate it's reliance upon grounding for good performance. Just a thought in case you were interested
I am a miser so far as 2N5109 is concerned.
Hello, interesting idea! Did you try it? Did you publish the result on the web?
No, I haven't tried it to date. Still a concept at this point
Wow, I have been pondering over this concept for a few days. I am sure it would be a great improvement!
There is a similar idea called "active differential antenna" (ADA) where the antenna consists of two short electric field probes connected to a differential amplifier.
Excellent explanation thank you very much.
From Mexicali BC. Mexico
Any sources that go into the idea of applying the RF input to both gates?
At first glance, I thought this might actually cause high distortion. After all, MOSFET mixers have RF and LO applied to the two gates separately and they produce mixing products at the output. So in this case the RF would mix with itself and cause harmonic, is what my naive reasoning leads me to believe. I'm sure I'm wrong but I'd like to know how it actually works out OK.
Hi where can i buy your antenna the orginal thank you
Why thin coax? I have very Good h1000 coax (10.3mm). H1000 will be good for whip?
Well done.
Greetings from Belgium , nice video. 73 👍
We need to implement lpf cutting a30mhz and high pass filter starting 1.8mhz so the the miniqhip will not be overloaded. The miniqhip itself should be shielded for better performance.
Sarma vu3zmv
Thanks for the details!
I've tried some of these worthless antennas and found they are basically a scam and won't pick up anything at all so don't waste your time or money.
Did you construct or purchased from someone?
I don't know if you are speaking about this model in particular, but if you are just speaking generally, I beg to differ.
Just about every Mini-Whip I have bought or built (4 different versions in total) has had more RX sensitivity and broad banded capability on HF than just about any other practically sized, non-loop antenna I have tried for shortwave listening, especially down in the lower shortwave frequencies.
The one mini-whip exception being some cheap Amazon version with the silver sticker on it ("Balana") which came with the power on the bias tee wired backwards, rendering it useless, until I wired it properly, then it was fine.
They can be noisy, but if you get them up high enough and properly mount/ground/choke them, they are typically great shortwave RX antennas, and I'm fairly certain this version will be one of the better ones as it does not skimp on decent parts or filtering.
I just bought 2 of his PCB kits for it, so I guess I will find out soon enough!
No, this is not true - provided you install properly and the unit is made carefully. Even the £23 version I bought from China works extremely well, even on initial indoor tests.
@@sudiptaghose5247 Purchased them.
@@scratchmoney It should be obvious to anyone that a 4" probe is not going to be able to pick up any signal below 30 Mhz!