Are these cheap Antenna Analyzer toys???

Discussion in 'General Technical Questions and Answers' started by M6LPL, Feb 13, 2018.

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  1. M6LPL

    M6LPL Ham Member QRZ Page

    G0NMY likes this.
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Made in China and I've never used one, but they don't get good reviews -- check them.

    Some reviews reported "DOA" brand new units, shipped directly from China; some reviews reported "shipped with no instructions," just a link to a website having instructions in Chinese; etc.
     
  3. VK2TIL

    VK2TIL Ham Member QRZ Page

  4. VK2TIL

    VK2TIL Ham Member QRZ Page

    Further thoughts.

    Antenna analysers are very useful but we tend to forget that there are other ways of adjusting your dipole; "old-time" methods will work just as well.

    A noise bridge is suitable and may be had cheaply, eg from ebay;

    https://www.ebay.com/sch/i.html?_fr...Xnoise+bridge.TRS0&_nkw=noise+bridge&_sacat=0

    I have a cute red Palomar one that works well; the MFJ should also be OK. The Omega (I have one of those as well) is less-useful as it only gives scalar information but it would still be OK for dipole adjustment.

    The advantage of these is that no RF source is required; just a receiver which can be the station receiver/transceiver or, as I once used, a portable SW receiver if you have one.

    Other methods use an impedance bridge or an antenna bridge; searching these terms on ebay gives some results.

    And an SWR meter is also used.

    But, for simplicity and adequate accuracy at low cost, the noise bridge is hard to beat.

    PS. The ebay link above shows postage costs to Australia; don't be intimidated by that, I see that the cute red Palomar one is post free in the US.
     
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  5. KC8VWM

    KC8VWM Moderator Volunteer Moderator QRZ Page

    I don't know about this particular model but I tried a similar cheap one and found it was fussy and difficult to "zero in" on anything.

    Reminds me of how some frequency counters work. The readings you get on the display are like a moving target and were all over the place. You're supposed to wait for the digits on the readout to stop counting, but you have to hold your nose just the right way to get any kind of useful reading. I think I ended up putting it back on the shelf and got out my SWR meter.
     
    N8EKT likes this.
  6. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    What did we ever do before portable inexpensive antenna analyzers?:eek:

    My first couple of years in ham radio, I didn't even have an SWR bridge or power meter of any kind; I was too busy making thousands of contacts on the air to be bothered.:) To "tune up," I'd dip the PA plate current of my transmitter and then adjust loading and tuning for maximum RF current in the twin lead, originally using two #47 pilot lamps coupled to the line but then found a military surplus (WW2) RF ammeter with a built in thermocouple (for $5, surplus) and used that.

    SWR? Who cares?:p
     
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  7. KP4SX

    KP4SX Subscriber QRZ Page

    I see MFJ259Bs selling close to US$100-125 and that's a fine piece of machinery to have around. I snagged an old MFJ-259 here on QRZ for $30. It was a fixer upper and looked like it had been left outside...for a long time :) The LCD module was shot and I replaced it with a 9.95 chinese frequency counter that fit quite well.
     
  8. NH7RO

    NH7RO Ham Member QRZ Page

    Quality only hurts once; save up your pounds and get a decent analyser---I suspect you'll be glad you did. While not necessary they sure make life easier!

    I'll never part with my RigExpert (unless it is to upgrade which is doubtful at this point).

    73,

    Jeff
     
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  9. KM4DYX

    KM4DYX XML Subscriber QRZ Page

    Ditto. Love my RigExpert.

    73,
    Al
     
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  10. W4KJG

    W4KJG Premium Subscriber QRZ Page

    I have been using Palomar noise bridges for longer than I can remember. I have a red one and two black ones. They go back to my broadband HF antenna design and matching system design days when I was using them by hand plotting the data on Smith Chart sheets.

    I also have several homebrew noise bridges with additional features, like expanded inductive/capacitive measurement capabilities. I can also direct measure the real resistance on it.

    A noise bridge, used in conjunction with an RTL SDR with HF upconverter, makes an inexpensive but fantastic broadband complex impedance measurement tool. By setting the noise bridge to R=50 and j=0, I can easily see relative load VSWR over a 2 MHz wide range.

    A long time ago I put together an Excel spreadsheet that takes R +/- j values from my noise bridges and provides absolute load impedance in Ohms, VSWR as a ratio, load return loss in dB, and load mismatch attenuation in dB. I have it setup so that it will graph each value vs. frequency.

    If you don't want to spend the time putting together a spread sheet, you can use one of the many on-line calculators, like this one:

    http://chemandy.com/calculators/return-loss-and-mismatch-calculator.htm

    Until I can afford a hand-held vector network analyzer that provides a Smith Chart display, I'll continue using my old technology.

    Old fashioned Ken
    W4KJG
     

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