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Recent content by Spasomat

  1. S

    How to design a high directivity coupler?

    For lambda/4 microstrip couplers 25dB to 30dB directivity should be in reach with a little tuning. Waveguide measurement couplers can have e.g. 50dB directivity. They need extensive tuning by hand. Broadband couplers like in Vector-Network-Analyzers are good if they reach 15dB directivity. Does...
  2. S

    Request : USB driver for WINNT!

    To my knowledge M-Systems is the only memory stick manufacturer with an USB-driver for WINNT. Look at hxxp://www.diskonkey.com/ Have fun, Spasomat
  3. S

    Help needed for RF PCB design

    By the way: In the last microwave journal (june 03) is a longer article about test fixture basics. may be it might be worth a look.... Spasomat
  4. S

    Help needed for RF PCB design

    About the price: a microwave test fixture with 2 launchers working up to 40GHz to contact microstrip lines will cost at about 20k USD....
  5. S

    Help needed for RF PCB design

    Perhaps you can solder the VCO to small PCB pieces and then use a microwave test-fixture to connect to the transmission-lines of the PCBs. e.g. Wiltron and Connexion Rosenberger are manufacturing universal test-fixtures. Although they are not cheap, they offer reproducable measurements...
  6. S

    Why the drain negative voltage changed my bais?

    Sounds like your transistor was damaged. If FETs are used outside the specified values they sometimes don't stop working completely. They sometimes just alter their S-parameters. I would encourage you to change the FET. Regards, Spasomat
  7. S

    Help needed with Interdigital filter

    As kid-the-great said I also experienced problems in a circuit simulation of a hairpin-filter. The circuit-simulator did only cover the coupling of two coupled lines at a time. The coupling to the other coupled lines were the reason my simulation did not fit with the measured results. Finally I...
  8. S

    Question about broadband tee junction

    Hi Sviodo, which bandwith at which frequency do you want to have? What VSWR? And what dividing ratio? 1:1? Regards, Spasomat
  9. S

    Looking for people to exchange data about LABVIEW

    Hi all, I like the idea of a labview group, but could it be better or different than the source code and discussion groups on the NI web page? Regards, Spasomat
  10. S

    strange transmission line

    Hi, I've also seen the described structure in a commercial broadband amp. I don't remember the exact location but I think it was near the output and there was just one of these obscure structures in the amp. The substrate or the structure weren't coated with anything. The whole backside of the...
  11. S

    Grounding for couplers

    Hi, Bungard (w*w.bungard.com) has rivets for through hole plating. They have as well a hand operated machine for processing the rivets. Regards, Spasomat
  12. S

    LabView 6i serial problem

    Hi, serial port under different windows versions in labview isn't always easy. Have you tried the discussionforum in the NI developer zone? h**p://www.ni.com/devzone/lvzone/discussionforum.htm There are quite a few topics about serial communicaion problems. Have fun, Spasomat
  13. S

    phase-shifters from 1.5Ghz to 3Ghz

    Hi Mangas, h**p://www.spinner.de manufactures passive RF-components. I also saw there a phase shifter. Regards, Spasomat
  14. S

    What is the relation of RMS to PMPO rating?

    what is pmpo and rms Hi all, up to now I saw these PMPO-stuff only on cheap computer speakers. You know, these insane rated 200Watts PMPO devices fed by a power supply capable of delivering 10Watts :wink: For a dynamic point of view the crest factor is used, at least at serious amplifier...
  15. S

    how can i filter ac noise?

    Hi Hakan, it depends on your circuit. If you could be more specific it would be easier to help you. If the signals you are interested in are much higher than the 50Hz you could perhaps get easy rid of the hum with a simple passive 1st order highpass filter. Spasomat

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