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Thread: Putting a switch in a antenna tuner

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  1. #1

    Default Putting a switch in a antenna tuner

    On my 75 meter dipole I have a low swr on most of the band. But when I go to the lower part of the band I need to tune it. I was thinking of putting a switch in my MFJ tuner to bypass it for the upper part of the band, and use the tuner for the lower part of it. I see in most tuners there are aluminum wires in it. Is there a reason for this?

    What I am asking is. Has any one tried this and does it work?

    Paul/ki8fr

  2. #2
    Join Date
    May 2005
    Location
    belton texas
    Posts
    731

    Default

    I don't see why it wouldn't work, most tuners have a bypass setting on the antenna switch to do just that.

    Which tuner do you have?
    73, Tom

  3. #3

    Default

    Not sure. I amnot by it. It is a small one. They called it a moble on lol

    I will have to look and see what one it is when I get home.

    Paul

  4. #4
    Join Date
    Nov 2008
    Location
    Toledo, Ohio in the United States of America
    Posts
    719

    Default

    I just sold my Vectronics antenna tuner, and, I added a bypass switch in it, which worked very well. If I still had it, I would have gladly taken pictures of the conversion that I did.
    [SIZE=1]So you run and you run to catch up with the sun but it's sinking
    Racing around to come up behind you again.
    The sun is the same in a relative way but you're older,
    Shorter of breath and one day closer to death. [/SIZE]

  5. #5

    Default

    The wires might look like aluminum, but I guarantee they are not aluminum.

    They're tinned or plated copper wires.

    For sure.

    WB2WIK/6

  6. #6

    Default

    Quote Originally Posted by WB2WIK View Post
    The wires might look like aluminum, but I guarantee they are not aluminum.

    They're tinned or plated copper wires.

    For sure.

    WB2WIK/6
    Awwwww,

    There goes my theory that at least MFJ had finally come up with an easy way to allow soldering Copper to aluminium, or even aluminum . DARN!

  7. #7
    Join Date
    Jan 2000
    Location
    Kilowatt Alley
    Posts
    9,864

    Default

    Quote Originally Posted by WA9SVD View Post
    Awwwww,

    There goes my theory that at least MFJ had finally come up with an easy way to allow soldering Copper to aluminium, or even aluminum . DARN!
    It has been mu experience that MFJ has a difficult time with soldering anything let alone something less than conventional!
    Don't most tuners have a bypass position?
    Last edited by K7MH; 11-24-2009 at 03:37 AM.
    "Oh what a tangled web we weave when first we practice to receive."
    -Otto Watt Sept. 5 1925

  8. #8

    Default Don't modify it . . .

    I'd just leave the tuner inline all the time on 75, and keep a crib sheet with the tuner settings for the low end (80 meters).

    Better yet, dump the coax, replace it with ladder line, and then you can use it anywhere with the antenna tuner.

    Coax is okay as long as the SWR is kept low. That's the advantage of ladder line -- you don't have to have a matched line for efficient power transfer. Just a good tuner.

    Gary WA7KKP

  9. #9
    Join Date
    Aug 2008
    Location
    Gloucestershire, UK
    Posts
    7

    Default

    Hi Paul,
    I'm guessing its an MFJ-971 with the nice brushed aluminium finish and cross needle meter. If so, i had one and its very annoying that it doesnt have a bypass switch, but a nice little tuner all the same. I looked at the schematic, which you can get from the MFJ site, and it looked easy enough to add a switch. I ended up selling it and getting the smaller 902 which does have a bypass, but no meter. Works fine with the built in meter on my 857 though.

    Cheers,
    James 2E0JCA

  10. #10

    Default

    I was thinking of getting a new one with a switch in it. but this is a good tuner. I got a new tuner some years back from aes. It is a acer or something like that.. It had a meter in it and it worked like crap. Was a waist of 100 bucks. I did find out what the problem was with the thing and looked like a ezy fix. Just never got to it. That is why I was thinking of just putting a switch in the MFJ. If it did not work I put it back the way it was and call it good. I got this tuner in Dayton years back for 10 bucks. Ben a excellent tuner.

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