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refurbishing a Hygain th6dxx

Discussion in 'General Technical Questions and Answers' started by W2NK, Nov 26, 2008.

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  1. W2NK

    W2NK Ham Member QRZ Page

    I've brought an old one inside that I'd like to have ready to put up in the spring. I'd gotten it some 20 years ago and it was used at the time. With it came a SS-hardware set/clamps/plastic mounts,caps/etc.
    During this period of storage it say outside some of time, and in the garage the rest.
    So now I'm cleaning it up and getting it all sorted out. And I've some questions in general that hopefully one of you might answer.
    1. The traps-though none have any apparent damage besides the missing/deteriorated end caps, should they be pulled apart for an inspection if for no other reason than there probably may be dirt and old insect parts inside???
    2. If so, how does one pull them apart? I removed the set screw on one, but not wanting to do any damage, they seem hared to slide apart or the cover of the trap down?
    3. While looking in one of the vent holes on the trap, I can see a small section of what is probably a coil form but no wire is visible Otherwise, just put on the new end caps?

    Besides the trap question, another concern is that I'm missing the old parasitic elements but instead have 3 elements of what had been a 4 element 20 yagi (204ba?)Is there any reason not to use them in place, cut to length of course, of what had been original? The biggest change would probably be in the element diameter, being these were originally for 20 and not 10/15?

    Also, if I haven't worn out my welcome:) I seem to recall that they later made a th7 version-since I have the extra aluminum, should I be trying to add another element, and where would I get the new dimensions?

    I'd appreciate your input,
    Kathy, RN, wb2aio
  2. K9YLI

    K9YLI Ham Member QRZ Page

    after I moved from wyo i re did my th6.
    new end caps and spiders were about 40 bucks.
    when you take the end caps off you will find the spider spacers inside may have deteriorated, sun bleached, break easily.
    I think now you can get all in a kit from hy-gain /mfj.

    hard part was seperating traps on the driven element.
    the th6 used element clamps that dimple the aluminum.
    you cant pull them apart. youhave to use about a 1/2 inch drill bit and gently drill the dimple untill you are thru the outer aluminum. you will drill the inner
    tube also somewhat.
    i had some extra tubing as i ruined someof the short pieces between traps.

    be prepared to do some metal work.......................

    you should be ablel to make the parasitic element from aluminum wire
    from hardware store. number 8 or 9 wire size.

    edit re read your message.
    thought you meant the loop for the matching element...
    which parasitic elements are you missing. as some are for 10 only and some mixed for all 3 bands. directors or reflectors. ????

    make a stand off bracket if you didnt get one or its lost.

    pulling some of the tubing apart I just used a vicegrip and twisted to force up the outer tubing at the dimple.
    then just make a new piece as vicegrip and twisting pretty much makes the piece usuless.

    need to do some rat tail filing on the inside of the tube ends at the dimples.

    becarefull if you take the trap covers off. I had aluminum on one crack.
    had to pop rivet on some folded up aluminum flashing to repair it.

    and when you get to frustrated I have an almost new th7 i will sell cheeeep. part of an estate.

    and you cant convert th6 to 7 as seven has extra driven element.
    lots of tubing and 4 traps involved.
    k9yli don..
    Last edited: Nov 26, 2008
  3. W2NK

    W2NK Ham Member QRZ Page

    Hi Don, thanks for the reply.
  4. K9YLI

    K9YLI Ham Member QRZ Page

    I will try to answer the quiestions in order of something or other.

    yes the 'spiders' are the plastic 3 legged wheels inside the trap s that hold the outter sleeve in place concentric to the element.

    you can check the traps with an ohm meter.. element to element..
    trap is a coil inbetween. should be very little ohms. I did slide the trap covers off the traps,(covers are the capacitor) and double check the
    screws that connect coil wire to the element. corrosion there. loose screws.

    'stand off 'bracket i was refering to was for the matching element. my 'edit' spereated the lines a bit.
    as for a boom to mast bracket, you can get a th7 bracket which is better than the th6.
    th6 mast runs thru the middle of the boom. th7 has a side mount so antenna can be completely =assembled on the ground and then attched to side of the boom.

    all the non trapped elements can be made from aluminum tubing from hardware store, ACE home depot lowes etc.

    suspect your boom to mast clamp will be some big bucks. in the $75 region.

    and hurry up with the rebuild. you shoud know by now that all antenna work has to be done in the coldest part of january.

    email me for some more info.
  5. W2NK

    W2NK Ham Member QRZ Page

    OK, I took a closer look today and I didn't realize that they weren't solid wheels but were open spiders, as you described. Trouble is, they had so much mud/debris that I thought they were solid.... Which makes me more concerned about what must be further inside the trap.
    I did do a resistance check though, and all but one show conductivity through the trap. The bad on is on the 10/20 director and only one side. I also see the dimples you mentioned and will try and drill one out to see if I can slide the outer cover and then what's inside!
    I do need a new boom to mast bracket and will look for the one you describe or order it-do have the cast aluminum block part and at one time did have the other half but that disappeared somewhere down the line....
    Thanks for the help,
    I guess I should be thinking of taking can of compressed air to them to see what I can blow out.

  6. K9YLI

    K9YLI Ham Member QRZ Page

    email me before you order anything
    perhaps a deal you cant refuse..

    also just use the garden hose to clean out the traps.l

    also trap covers/ the capacitor sleeve should just slide off trap after taking out the sheet metal screw on each end..
  7. WD0BBR

    WD0BBR Ham Member QRZ Page


    MFJ have the trap caps in there catalog see page #75.:)
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