Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: VLP SWR Meter

  1. #1
    Join Date
    Jan 2009
    Location
    Yuma, AZ
    Posts
    1,536
    Post Thanks / Like

    Default VLP SWR Meter

    Hi:
    As postulated in "SWR Meters & Antennas", I have been working on a SWR Meter to be used with low power FM transmitters.

    Even though the paper is dated April, this is not an April Fools joke. It is a viable and working SWR meter.

    There are several attachments in PDF format and the PC board layouts are entered under Library/Copper/VLP SWR Meter.

    Good luck and I hope you find this instrument useful. It is the result of many hours of construction and experimentation.

    Addition: 4-10-2012--Changed PCB file under "Library/Copper/VLP SWR Meter. Cosmetic changes only. The original is OK to use.

    Addendum: 4-27-2012--Added "VLP SWR Meter Addendum" to attached files.
    Attached Files Attached Files
    Last edited by IdunBenhad; 04-27-2012 at 03:43 PM.
    Idun



    Lotsa' Patience! (Some days you can't win, the others you lose, and forget about the rest)

    Some mornings I wake up GRUMPY and other days I let her sleep!

  2. #2
    Join Date
    Mar 2010
    Location
    Leesburg Florida
    Posts
    2,490
    Post Thanks / Like

    Default Re: VLP SWR Meter

    Very good Idun,, looks like I will have to have you make me a home etch board for me..how much will it cost...

  3. #3
    Join Date
    Aug 2008
    Location
    Columbus, OH
    Posts
    2,318
    Post Thanks / Like

    Default Re: VLP SWR Meter

    Wow.
    This is just fantastic.
    I can't wait to build this and test it.
    Most Excellent. Thanks.

  4. #4
    Join Date
    Feb 2009
    Location
    Plymouth, MN
    Posts
    8,213
    Post Thanks / Like

    Default Re: VLP SWR Meter

    What a tremendous addition to the DIYC arsenal of valuable pieces of gear! Just an AWESOME tool that can take all the ambiguity out of tuning an antenna to a radio!

    Well done, Idun!
    www.diychristmas.org

  5. #5
    Join Date
    Nov 2011
    Location
    St.Louis mo
    Posts
    1,091
    Post Thanks / Like

    Default Re: VLP SWR Meter

    Very cool! Good job on putting it together. I keep ,wanting to take my dipole in to work to sweep it on one of the Anrisu site masters that we have at work but never thought about power being to high for it. I think, I'll take this on as a project. If any one winds up making the boards, I'd take one, other wise I'll have to try it on Perfbaord.

  6. #6
    Join Date
    Jan 2009
    Location
    Yuma, AZ
    Posts
    1,536
    Post Thanks / Like

    Default Re: VLP SWR Meter

    Hi:
    imbluenote: I don't know how your antenna is constructed, but the power of the instrument you refer to should make no difference. The antenna should be capable of handling hundreds of watts if it is constructed of RG58/RG59 or similar coax.

    The power referred to in the VLP SWR Meter is the power required to run the meter itself, not to the power handling of the antenna.
    Idun



    Lotsa' Patience! (Some days you can't win, the others you lose, and forget about the rest)

    Some mornings I wake up GRUMPY and other days I let her sleep!

  7. #7
    Join Date
    Oct 2009
    Location
    Nelson (New Zealand)
    Posts
    239
    Post Thanks / Like

    Default Re: VLP SWR Meter

    Hi Idun,

    Nice bit of development work, I would expect that the "VLP SWR" meter would have some insertion loss due to the 52 Ohm resistor being permanently in series between the Transmitter and the Antenna, or am I being pedantic, or showing my age :-)

    I am running an aluminium block 50 Ohm matched stripline reflectometer on my 500mw Tx into a 50 Ohm matched antenna. My test gear tells me the antenna has around 25 Db return loss over the band of interest. Needless to say the reflected power is minimal - thankfully, but would sure show up if the antenna was damaged in any way as the metering is very much more sensitive in the reflected direction :-)

    To reduce the coverage area I run a 3.5 Db pad in series with the transmitter before the strip line, the transmitter hasn't got a "power control" on it, as these are "Illegal" in this part of the world.

    Cheers,

    Terry
    [B]"Tory Street Lights", Nelson, NZ[/B]
    [B]2013 - "Honourable Mention"[/B] - 2013 Local Christmas Lighting Competition
    [B]2013 :-[/B] 11 x Ren 64XC's - 650 Channels, 45,000+ lights. 7,000 or so LED's this year:-)
    ----------------------------------------------
    [B]"Lucky Home" [/B]- 2012 Local Christmas Lighting Competition
    [B]2012 :-[/B] 11 x Ren 64XC's - 550 Channels, 40,000+ lights. 2,500 or so LED's for the first time :-)
    -----------------------------------------------
    [B]2011:-[/B] 7 x Ren 64XC's - 384 Channels, 30,000+ lights - all incandescents! 2 x Commercial LED Panels (72x7)!
    ------------------------------------------------
    [B]"Supreme Winner for 2010" [/B]Local Christmas Lighting Competition, 4 x Ren 64's - 256 Channels Controlled by Vixen - "Brilliant" :-)
    18,000 to 20,000 Lights - all incandescents! 2 x LedTricks Panels with "Pix C" interface's
    [B]2009:- [/B]128 Channels of "Hill 320", 4,000 Lights

  8. #8
    Join Date
    Jan 2009
    Location
    Yuma, AZ
    Posts
    1,536
    Post Thanks / Like

    Default Re: VLP SWR Meter

    Hi:
    Terry: You are right, there is insertion loss. The VLP is not intended to stay in-line, as pointed out in the writeup.

    Because this is a very simple instrument, it will not measure return loss. It is meant to help get the antenna in tune at the operators chosen frequency.

    In your case, you could leave the VLP in line and reduce your transmitter power to 1/4 of the 500 Mw. or 125 Mw. This would eliminate your 3.5 db pad, which is reducing your power to about 275 Mw. I would suspect that your range is way more than adequate with that much power.

    I haven't run a test yet, but I am curious to see what the range is with the FM02 reduced to 7.5 Mw.

    Thanks for your input.
    Idun



    Lotsa' Patience! (Some days you can't win, the others you lose, and forget about the rest)

    Some mornings I wake up GRUMPY and other days I let her sleep!

  9. #9
    Join Date
    Jan 2009
    Location
    Yuma, AZ
    Posts
    1,536
    Post Thanks / Like

    Default Re: VLP SWR Meter

    Hi:

    Return loss is a measure of how well the load and antenna are matched. The higher the return loss, the lower the SWR and the better the match.

    The VLP Meter does not directly measure return loss in db, it is only a relative indicator of the SWR and impedance matching.

    For a much better explanation of Return Loss, see this entry:

    http://www.k5rmg.org/tech/rtn-loss.html

    http://en.wikipedia.org/wiki/Return_loss

    Do a Google search for "Return Loss" for much more information.
    Idun



    Lotsa' Patience! (Some days you can't win, the others you lose, and forget about the rest)

    Some mornings I wake up GRUMPY and other days I let her sleep!

  10. #10
    Join Date
    Jan 2008
    Location
    Washington, Georgia
    Posts
    2,969
    Post Thanks / Like

    Default Re: VLP SWR Meter

    Wow, looks great Idun! Thanks for your hard work!
    DIYC Links:
    Christmas Wiki | Chat

    Ricky, Jrd

    "With great power comes great electricity bill." - Unknown Electricity Consumer
    "Your significance in life is not what you do, but how and why you do something." - Unknown Minister
    2012
    City float for Parade of Lights with:
    Fm-02 + Wall Wart Tamer
    2 Ren4Flood + DIYCFlood + Ren-W in 500 Watt enclosure
    2 Simple Renard 32
    15 SSROZ
    2 24 Channel RBW LED Ropelight Midi Trees out of artificial Christmas trees.

    Click here to show/hide my past display details ...

Page 1 of 2 12 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •