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Thread: SWR meter - Do it yourself project

  1. #1201

  2. #1202
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    Is this a good coupler for 5.8GHz
    http://www.ebay.nl/itm/Directional-C...PAWpgcbxfsN5uA

  3. #1203
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    Quote Originally Posted by Pisces View Post
    A couple of points to consider.
    - no 2 diodes are exactly the same Vf. This has to do with the PN doping of the semiconductor diode substrate during manufacture.
    - The dual directional coupler will not be perfectly matched for coupling factor.

    Considering that your detectors are matched to within <0.1V, this difference will only cause a small error in the Vf/Vr ratio.

    I think it has been mentioned before, if you are concerned by the small sensitivity error between the detectors then you could consider a small value series resistor in the output lead of the detector with the higher V output.
    Hi, Pisces;

    I bought a -20 db 4ghz to 12.4 ghz coupler before I see -20db is not good choice on this thread. is it possible that I use higher power transmitter, like 600mw or 1w on 5.8ghz transmitter to get a good and accurate reading?

  4. #1204
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    is this thing any good for swr meter?http://www.ebay.com/itm/111199369524

  5. #1205
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    Hi, Yes you can. The recommended coupling factor 10dB is based on a 200mW Vtx and a 6dB in-line attenuator. The 10dB coupling factor is a compromise considering the max forward voltage +4V for the diode and min detector output for Vr. This determines the dynamic range for the VSWR measurement.

    If using bias and a 200mW Vtx then a coupling factor of 16db can be used. Then a 600mW Vtx and a 20dB coupling factor will work just fine.

  6. #1206
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    Hi, I've read most of this thread. I think it would be helpful for people trying to pick a coupler if a basic list could be made giving the most suited Narda and mini-circuits couplers for each of the bands.
    Andy

  7. #1207
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    Small tip for making a SWR meter:

    http://store.ivc.no/product/rf-detector
    http://store.ivc.no/product/rfd-bias

    Sorry if this has been posted earlier.

  8. #1208
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    Quote Originally Posted by bjornrailton View Post
    Small tip for making a SWR meter:

    http://store.ivc.no/product/rf-detector
    http://store.ivc.no/product/rfd-bias

    Sorry if this has been posted earlier.
    That's kinda cool. Wish they sold the coupler too, if they did I might buy one. Anyone know a source of a coupler compatible with that detector?

    -l2t
    Ken K. (learn2turn)
    AMA 221562
    KB1YMZ

  9. #1209
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    Click image for larger version. 

Name:	uwdiodes.jpg 
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ID:	73505 OK microwave experts. Will one of these "Russian crystal diodes" work and what type connection is that?

    Several listed on ebay and say will handle frequencies well over 5gig

  10. #1210
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    Quote Originally Posted by keshka View Post
    Click image for larger version. 

Name:	uwdiodes.jpg 
Views:	190 
Size:	14.9 KB 
ID:	73505 OK microwave experts. Will one of these "Russian crystal diodes" work and what type connection is that?

    Several listed on ebay and say will handle frequencies well over 5gig
    I was curious about those, came across this if anyone is curious about things like negative resistance etc.
    https://en.wikipedia.org/wiki/Oleg_Losev
    “Birds born in a cage think flying is an illness.”
    - Alejandro Jodorowsky

    Last edited by doobie; 15th August 2016 at 10:26 PM. Reason: spelt titties wrong

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