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  • Removing resin from a 49:1 sealed transformer

    From bgonev@2:240/8001 to All on Wed Jun 18 21:01:14 2025
    Hi All,

    After I do not know how many years, I'm back here on the net :).
    So back to the primary topic:
    Recently I've purchased an 49:1 unun from a manufacturer, but I am not satisfied with the performance of it (compared with another 49:1 transformer the SWR is notably higher.
    Therefore I plan to dissassemble it completely, but the main problem is that the ferrite inside the box is sealed wit a resin. I would like to hear your opinions or experience, how to safely remove the resin without damaging/destroying the ferrite ?

    Thank you
    73 de Z32X

    --- Mystic BBS v1.12 A43 2019/03/03 (Windows/32)
    * Origin: BlackICE BBS (BlackICE.BBSindex.com:23) (2:240/8001)
  • From Scott Street@1:266/625 to bgonev on Wed Jun 18 18:15:24 2025
    Therefore I plan to dissassemble it completely, but the main problem is that the ferrite inside the box is sealed wit a resin. I would like to hear your opinions or experience, how to safely remove the resin without damaging/destroying the ferrite ?

    I would use heat from a heat gun to soften the resin and pick it out with fine tools. In my experience, their just isn't a really good way, fast way. Do a little area at a time with minimal heat to avoid cooking the resin and causing a bigger mess.

    Best of luck!

    --- Mystic BBS v1.12 A49 2024/05/29 (Linux/64)
    * Origin: <=-{ The Digital Post }-=> (1:266/625)
  • From Mortar M.@1:124/5016 to bgonev on Sun Jun 29 12:41:40 2025
    Re: Re: Removing resin from a 49:1 sealed transformer
    By: bgonev to Scott Street on Sun Jun 29 2025 16:20:09

    The way [I did it] was a [3-hour] process of [submerging] the block [in] boiling water, and chipping out parts of the resin...

    Wouldn't that damage the components inside?
    --- SBBSecho 3.28-Linux
    * Origin: End Of The Line BBS - endofthelinebbs.com (1:124/5016)
  • From bgonev@2:240/8001 to Mortar M. on Sun Jun 29 21:48:36 2025
    Well, the main aim was to salvage/save the toroid, not the windings. Also the female PL259 connector was saved..

    73 de Z32X

    --- Mystic BBS v1.12 A43 2019/03/03 (Windows/32)
    * Origin: BlackICE BBS (BlackICE.BBSindex.com:23) (2:240/8001)
  • From bgonev@2:240/8001 to Scott Street on Tue Jul 1 14:00:04 2025
    Well, not that the core is out and free, I will use today to create 4:1
    Balun. I am thinking to build 2 core Guanella version (not stacked), which in essence is a design based on two interconnected 1:1 Baluns. I've read on the net that this design is the "real" 4:1 Balun, compared to the single core design which does not provide stable balance to unbalance transformation, and that it is possible to provide the common current to the shield of the
    coaxial feed line.
    I will appreciate if someone have comparison experience based on usage on
    these 2 different designs..

    73,
    Z32X

    --- Mystic BBS v1.12 A43 2019/03/03 (Windows/32)
    * Origin: BlackICE BBS (BlackICE.BBSindex.com:23) (2:240/8001)