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Discussion in 'General Electronics Discussion' started by Deigh, Jul 25, 2016.

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  1. Deigh

    Deigh

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    Apr 26, 2011
    I am using a Digitech wireless N high power booster to boost the internet wi-fi signal from a public source about 150metres away. It works fairly well but I have damaged it and would like to replace it with something stronger. Can anyone suggest a reasonably priced replacement that would work better?
    Deigh
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Does your device have an external antenna connection? This is the cheapest and often most reliable method.

    How did you damage the booster?
     
  3. Deigh

    Deigh

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    Apr 26, 2011
    No external antenna connection on computer .
    wi-fi.jpg
    Aha, I was getting four bars fairly regularily, but got greedy and decided to play with setup to improve signal. Aerial was connected to a stainless steel dish by a clothes peg. Folded and drilled dish to hold aerial positively and make a tidy job of it.
    Signal went down to three bars!!!!!
    Messed with it, got clumsy and broke joint. Have repaired it with a Bondic kit but not too happy with result.
     
  4. donkey

    donkey

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    Feb 26, 2011
    I understand the problem, but I really don't know why you would take public wifi connection? do you have the owners permission?
    any way sounds like you DO have an external aerial that needs fine tuning.
     
  5. Deigh

    Deigh

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    Apr 26, 2011
    Most libraries in New Zealand have free wi-fi. You can sit in the library and use it either with you own computer or even a public one. Alternatively you can sit outside in your car or on a public bench and use it. I live in a pensioner flat within spitting distance. I do not need special permission to use it, no more than the fifty other people who live within range of it. Thanks to a stroke I have limited movement and this is cheap internet for me.
    I pay $60 per month to Spark for my mobile phone and 1gig of data, but that is not enough for regular use of medical forums so the free wi-fi is a very valuable asset.

    Fine tuning on my part was playing with a reflector behind the aerial rod, and with a bit of luck got the right setup from the word go. Trying to improve it was my undoing.
    Deigh
     
  6. Mongrel Shark

    Mongrel Shark

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    Jun 6, 2012
    Ahh the good old world of backyard beam antennas. :D

    Strainers, colanders and Pringle cans are also excellent parabolic reflectors. The pringles can has achieved legendary status in some circles.

    the wavelength of 5.4ghz wifi is 55.5555555555mm so make all your measurements multiples or divisables of 55.5mm. Or If your going for 2.4ghz wifi its 125mm.

    Also you can get proper tuned antennas on ebay. I got a 21dbi gain yagi beam for $12. Tuned for 2-6ghz complete with the right fitting... Its almost as good as the best pringles can I have seen and way better than 95% of homemade jobs. 10mbps file transfers at 20km line of sight. Overkill for what you want. A 6dbi gain unit should do the job and cost less than the parts you used to make the dish (if you had of bought them).

    Also using the bars on your computer display to meter signal strength is like using a rock to predict the weather. It might be accurate at times, but its pure coincidence. Do speed tests from a speed test website or learn to ping the router etc. Do your tuning/speed testing at 12-4am or when library/internet traffic is low.

    You know you nailed it when you have to water cool your dongle to stop it melting. I melted a sim card into my 3g dongle once (28MB/s down for 2 hours solid from an optus tower, because they gave me $3 a day unmetered access). I almost had to pay for a replacement dongle and sim. The guy in the store was sceptical at my claim that I was using it normally on facebook when it suddenly stopped and got really hot. He said he'd replace that one, but only if I tell him how fast it was really going and I'd be paying for melted dongles/sims in future.
     
  7. Deigh

    Deigh

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    Apr 26, 2011
    Mongrel Shark, thanks for that very informative reply. Unfortunately I only have the rock/weather bars to go on. Internet is notoriously weak around this area and I only want to make the best of the situation. I admire your water cooling remark but have no plans to imitate your experiment.
    I havn't had much success with Ebay, preferring to use the local TradeMe but will have another look at it following your statement.
    Deigh
     
  8. Mongrel Shark

    Mongrel Shark

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    Jun 6, 2012
    Pay special attention to antennas designated "beam" or "Yagi" This means they are highly directional. Which looks like the go for you. Also be sure they are tuned for the right freq likely 5.4ghz but maybe 2.4ghz.. Your wifi connection info on your PC will tell you which freq.

    Anything with more than 6dbi should be getting in the ballpark of your home made rig. if you get a 12 or bigger you should see significant improvement. the small 2-5dbi antennas you may see are for getting to the next room. Not strong enough for going across the road through a few walls.

    You can also use a regular omnidirectional antenna and still use the dish as a reflector to make it directional and boost the signal... Although as you are learning Trial and error with no good data is painstaking and frustrating.

    Try and at least set some control conditions so you know if changes in signal/speed are made by you or the traffic using the library network/ local telco lines...
     
  9. Deigh

    Deigh

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    Apr 26, 2011
    I'm afraid you are leaving me behind! Searched for Yagi and I found stuff too big for my small room. This is what I have at the moment Screenshot (43).png and this is what I think will do better...
    Am I right??



    Sorry about messy setup!
    Deigh
     

    Attached Files:

  10. davenn

    davenn Moderator

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    Sep 5, 2009
    probably wasn't for 2.4GHz
    I have a 16 element yagi for 2.4GHz WiFi, it's only 1 ft long

    [​IMG]

    [​IMG]


    that's from my own www page


    Dave
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Maybe Deigh lives in a very small room :)
     
    davenn likes this.
  12. Deigh

    Deigh

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    Apr 26, 2011
    Yup, My den is 3 metre by 1.8 metre. Cat swinging is banned. My main hobby is guitar and keyboards and I have to restrict myself to minor music. I only play duets, even a trio is out of the question. Large friends are discouraged from visiting at all.
    Think small when replying.
    Deigh
     
  13. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Ok. Time to be a little more serious again.

    Deigh, is that N300 in working condition?

    It should be a simple matter to replace the antenna with something more directional.

    I have a small yagi that I'd strikes to requirements here, but postage to NZ would probably be ridiculous.

    Alternatively, there are antennas you can make from not much more than a connector, done bent wire and some fairly random piece of flat metal.

    The real trick is getting the short connecting cable between the N300 and the antenna (these are called "pigtails")

    In a minute (take that with a grain of salt) I will look up the various bits and pieces and reply back...
     
    Mongrel Shark likes this.
  14. Mongrel Shark

    Mongrel Shark

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    Jun 6, 2012
    What steve said. You have a good amplifier unit. You just need a better antenna for it. Ideally a directional one.


    I know you don't like ebay, but perhaps you can find similar to one of these examples at a store of your choice.

    This one looks ideal. http://www.ebay.com.au/itm/Yagi-12d...792401?hash=item2eee236411:g:ZBsAAOSwVghXFArj

    or this one if its not too big
    http://www.ebay.com.au/itm/Antenna-...182496?hash=item51cdaf82a0:g:XOYAAOSwPcVV19Hq

    This one is a bit less powerfull, but probably still better than what you have with the dish.
    http://www.ebay.com.au/itm/Alfa-7dB...549818?hash=item3ce87d173a:g:fV8AAOSwqu9VC4yM


    This one offers good power for it size http://www.ebay.com.au/itm/9dBi-9-d...275331?hash=item5d5b460a43:g:VuAAAOxykMpTIAqp


    There where a lot more to choose from... you just unscrew the antenna you have and screw one of those on via the BNC fitting.

    Or stay tuned for steves build advice. It is indeed possible to easily and cheaply make one from some wire and a BNC fitting plus a deflector or waveguide if you want directional. Provided you can handle a little maths which we can help with (steve is probably crunching it now) and cutting the wire to a precise length.
     
  15. Deigh

    Deigh

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    Apr 26, 2011
    Thanks for that info, I already have the ALFA and it is not as good as my present setup. The others seem too cheap to be really useful and the only one that looks good cannot be sent to New Zealand! To have it sent to a relative in Aussie and have it reposted here would prove inconvenient.

    Steve, Yes, the N300 is working, I repaired it with my new BONDIC device, but will have to be careful handling it.

    I badly need to make a desktop setup where I can make slight adjustments to the aerial, unfortunately I cant visualise what I need.

    Interestingly enough, in our small town there is one free Telecom wifi phonebox. It is not in line of sight for me and is probably half a kilometre away. Yet during a couple of frosty mornings last month I actually used it as my internet connection!
    Deigh
     
  16. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    I believe this is the unit you have.

    They make a range of adapters, and they seem to use the same antenna on each. So it looks like the antenna may be removable. It should be a normal threaded connector. If it can be removed, let us know what the connector inside looks like. Unfortunately there are several types of connectors and some look disturbingly similar.

    Here is a site which lists some of the types you may have. This page lists a whole lot more, but only one is interesting -- abut 3/4 of the way down the page is the SMA connector. This is slightly different to the RP-SMA in that the pin is on the male part (the RP-SMA has the pin on the female end -- which suggests that it is somewhat confused about its sexuality, but that's another discussion)

    Here is a third option, lower quality and without any measurements:

    [​IMG]

    As for the antenna, take a look at this page. This is probably the best bang for buck wifi antenna you can make from bits of scrap.

    My recommendation would be to get an N connector and mount it to the PCB (or a flat piece of metal) and build the antenna on that. Then get a short pigtail to connect the USB adapter to the N connector.

    Your only expense would be the pigtail and the N connector. The rest you should be able to beg, borrow, or steal.

    You may need to harvest a short piece of copper tube to extend the connector the appropriate amount, and then you'll also need to have a short wire from the central connector within the tube. It's also possible to just build the "bowtie" without the reflector. This is pretty trivial to do on a bulkhead N connector.
     
    Mongrel Shark likes this.
  17. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Oh, better antenna beats gain most of the time. When you say you have to handle your device "carefully", what do you mean? What did you break?
     
  18. Mongrel Shark

    Mongrel Shark

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    18
    Jun 6, 2012

    Thats pringles can/yagi territory. Like my mate that gets the library from up the mountain 20km away (with a wifi dongle in a pringles can)

    http://www.turnpoint.net/wireless/has.html
     
  19. davenn

    davenn Moderator

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    Sep 5, 2009
    the style of antenna I showed is idea for you then :)
    high gain and small size
     
  20. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Yeah, the "pringles can" style of antenna were really popular. The main issue is that they are not really suited as a feedpoint for a dish and are prone to filling up with water.

    They can also be a bit more hit and miss regarding performance.

    However neither of these are likely to be an issue for Deigh, and it's pretty easy to experiment with different tins or placement inside them.

    It's probably faster to build too.

    An interesting option is to get an SMA (or RP-SMA, or whatever the correct connector is) to N converter and mount the adapter right on the antenna. then use a long USB cable to connect everything back to the computer.

    Oh, this is a reasonable choice for a bulkhead N connector, but this is probably better. It would be even better to use a connector designed for higher frequencies, but they get really fiddly to work with.

    As for pigtails and adapters, check out eBay.
     
    davenn likes this.
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