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Yaesu FL-2100B , rewinding plate choke ?

Discussion in 'Amateur Radio Amplifiers' started by KD0CAC, May 7, 2012.

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  1. KD0CAC

    KD0CAC Ham Member QRZ Page

    One of the last things to do with this amp is replace repair the plate choke / RFC choke , it is cooked on the 20m section , not total , but it maybe why it has lower output on 20m ?
    A couple questions , a test for checking the quality of this part ?
    Then any info & sources on rewinding the choke ?
    Like the details of wire and what they may be using to glue down between each winding section ?
    Thanks
     
  2. W9GB

    W9GB Ham Member QRZ Page

    John -

    Call RF Parts, to see if they have an appropriate replacement, in stock.
    Usually less than $25 USD
    http://www.rfparts.com/choke.html#hightrans

    RF Parts
    Technical Help and Customer Service
    Tech Help is NOT available through the 800 line
    (760) 744-0500
    10:00 a.m. to 4:00 p.m. PST Monday - Friday

    ===
    Carol Maher noted in 2006 that Yaesu still had that FL-2100b part, in stock?
    The part number for the RFC choke from Yaesu is: L1020655 . Cost $22 USD
    CALL Yaesu USA to ask about this part at 714-827-7600
    http://www.foxtango.org/phpBB2/viewtopic.php?t=9
     
    Last edited: May 7, 2012
  3. KD0CAC

    KD0CAC Ham Member QRZ Page

    HAL / Greg :)
    I have gotten as far as seeing the post from Carol / FoxTango [ bought the on/off power sw. from FoxTango and have part # and Yaesu phone from the link .
    But I was also looking at rolling my own , trying to buck the trend and learn building late in life , at least ham wise , lots of building in many other trades fields etc.
    A couple of questions to rolling my own would be the wire & glue holding down wire between each band segment ?
    Thanks John
     
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Usually it's just enameled copper wire and you can hold the ends and "leaders" between windings in place with nylon tie-wraps, then use a good high temperature dielectric glue to overcoat it all. I often use something that comes in little bottles with a brush from GC, called "Q-Dope." But lots of other stuff works.

    If you want to get really fancy and have the tools, you can use a Teflon form instead of ceramic and turn tiny threads into it on a lathe. That will keep the windings nice and tidy without doing anything else (except supporting the ends). I wouldn't bother taking the time to do that, but it looks cool when somebody does.
     
  5. W9GB

    W9GB Ham Member QRZ Page

    John -

    OK, Education and DIY Build over Speed
    Tom Rauch, W8JI has a nice article on building your plate choke !
    Tom includes comments on his Heathkit & Ameritron plate choke designs, pre-1979 WARC bands.
    http://www.w8ji.com/rf_plate_choke.htm

    Yes, Q-Dope (liquid polystyrene) from GC Electronics/Waldom works, I use it for my torrid winding.

    John Smith tells you how to make our own Q-Dope.
    CAUTION: Toluene is solvent (and thinner) and is flammable.
    http://www.cliftonlaboratories.com/coil_coating_compounds.htm
     
    Last edited: May 7, 2012
  6. AG6K

    AG6K QRZ Member QRZ Page

     The FL-2100B HV-RFC does not have a series resonance at 20m. When a section of a HV-RFC near the middle gets cooked, the trouble is usually a VHF series resonance. You can find the freq. of this with a dipmeter. My guess is that the resonance is c, 90MHz. The choke fix is to rewind it with modern silicone-varnish wire from an electric motor rewinding shop and then paint the winding with gloss urethane varnish to keep the wires from vibrating with modulation. The fix for the presence of intermittent VHF is to decrease the Q of the VHF suppressors. This reduces VHF amplification and that discourages VHF oscillation. It might be a good idea to also add a glitch R and glitch diodes unless you have a free supply of FL-2100B parts.
     
  7. KD0CAC

    KD0CAC Ham Member QRZ Page

    Hay thanks guys , will look over this in the next couple of days , all the sudden lots calls coming for other peoples projects , just when I was getting on a roll with getting started on my own .
    At least one of then is driving a friends uHaul , he's moving from MN. here to So. Cal. , help him get his station set up , then fly back .
    At the same time & in the oppocent direction from Dayton , oh well .
    This amp had black spots under the socket cover in back from blown resistors , but someone replaced those already .
    I've got one of the Navy grid-dip meter - PRM-10 .
    Thanks
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Where in So. Cal? We don't let new hams in here without an initiation. Where will you be?

    If you're down on the pier, drop over.
     
  9. KD0CAC

    KD0CAC Ham Member QRZ Page

    Wasn't sure where , but confirmed , he is moving San Diego , he said about a five hr. drive ?
    Is the initiation less if we both lived there before ?
    Albeit that I was mostly Sonoma Co. & he was in the Bay Area .
     
  10. WA7PRC

    WA7PRC Ham Member QRZ Page

    How torrid! ;)
     
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