Transformer Rewinding Service

Discussion in '"Boat Anchor" & Classic Equipment' started by W5INC, Dec 30, 2018.

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  1. K6LPM

    K6LPM Ham Member QRZ Page

    Man it always seemed to me that the winding of coils, inductance and reactance , the pearmabilty of cores ect is pure voodoo magic.
    The way someone comes up with taking "x" guage of some sort of enamaled wire and winding "#" around such type of alloy core in a particular pattern with such and such interleaves per so many windings using the skin of some peculiar exotic south Asian eel works out to be the value for whatever application or by changing the core spacing and utilizing a Teflon coated secondary wire material and rewinding it 29 turns forward during the month of Febuary only on a leap year will give you exactly so many more micro henries as to do yourself justice!

    MY HAT IS OFF AND I BOW DOWN TO THOSE OF YOU WHO MASTERED THESE BLACK ARTS AND/OR THOSE WITH ENOUGH PAITENCE AND DILIGENCE TO ACTUALLY AND ACCURATELY UNWIND AND COUNT AND UNWIND MORE SO PERFECTLY TO MAKE IT ALL GO TOGETHER AND WORK AGAIN PERFECTLY!
    Good grief! What do you do when the unthinkable occurs and you lose count??? !!!!
    Seriously! Transformer rewinding seems absolutely amazing and I totally applaud those that successfully complete it and pity the fools like me who might attempt it.
    I am pretty fearless when taking things apart, usually able to put most back together but unwind bobbins of wire ??? No thank you! Not without a Elmer present to hold me in her arms!
     
    KE9EX likes this.
  2. W5INC

    W5INC XML Subscriber QRZ Page

    I agree 100% that the Xformer environment is Voodoo magic at it's best. I have jumped into rebuilding parts such as a 4R100 Ford F350 automatic transmission in the past. A lot of parts, including very small check ball bearings are in the transmission and need to go back in the same exact way for the box to work correctly. A real PITA pulling out a transmission that wasn't rebuilt right in a 4X4 F350 7.3 diesel truck. It does give you the incentive to do it right the 1st time around.

    The Xformer rebuild is the same way, especially if you don't have the build sheet from the original manufacturer. Patience is need when taking the Xformer apart making sure you have the correct winding count when finished taking it apart. I am guessing the HV filter chokes will be a tad easier to start on as these pieces will have just 1 output voltage, instead of 3 or 4 output voltages. Shipping costs have skyrocketed here in the last 2 years and a retail shipper is getting hammered when paying the tab for shipping costs. It will make more folks wade into the Xformer rebuilding environment I am thinking, because rebuilding/shipping costs will be too far out of round for most people's AR rebuilding projects. My KWS-1 re-build project is akin to owning a boat, I reckon.
     
    K6LPM likes this.
  3. K4JOM

    K4JOM XML Subscriber QRZ Page

    do you still have a quantity of boat anchor parts, or did Mark Walker get these?
    Thanks, K4JOM.
     
  4. N8FVJ

    N8FVJ Ham Member QRZ Page

    Why rebuild? Heyboer in MI will build any transformer.
     
  5. W1VT

    W1VT Ham Member QRZ Page

    When I was a kid I rewound transformers to get custom voltages. You may want to factor in the higher AC line voltages used today. Fewer turns are needed to hit the target voltages for the secondaries, which should make it easier to get all the turns on the core. There are also rigs notorious for blowing transformers. How about redesigning the circuits to be more reliable? Getting that last 20% of power output puts a lot of stress on the parts, yet it doesn't make all that much difference when chatting on the air with other hams,

    Zak W1VT
     
    WA7PRC likes this.
  6. N8FVJ

    N8FVJ Ham Member QRZ Page

    Or redesign transformers to be more reliable. Most transformers use M19 laminations. Building a replacement using M6 laminations allow about 30% more power in same size as M19 core transformers.
     
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    When I was photoetching PCBs in the 1980s, I made one for the "RF-Proof 30-Amp Supply" (link) that was in The Radio Amateur Handbook. It used a transformer I didn't have, that seemed kinda pricey. However, I had a DOA transformer w/ enough core. It had a HV secondary that had arced thru the fish paper bobbin to the core.

    After unwinding a coupla miles of hair-thin secondary, I repaired the bobbin and rewound it with a handful of turns of 8 AWG polyimide-coated wire. Cost was $5 for the transformer. The wire was free. The PS is still in service:
    [​IMG]
    :)
     
    W1TRY likes this.

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