TS-520 choke replacement?

Discussion in '"Boat Anchor" & Classic Equipment' started by KE0EP, Aug 9, 2019.

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  1. KE0EP

    KE0EP Ham Member QRZ Page

    Powered on with heater switch up and heard a loud POP from the final cage. Traced HV to L5 which is marked as 3uH. What can I use as a replacement? Assuming it serves as a fuse for the finals, so I want to be sure the current rating is appropriate.

    Thanks es 73, Elan KE0EP

  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    It may have served as a fuse for the finals, but that is not its design purpose. It's likely something else, either a tube or one of the HV capacitors has failed for L5 to blow but it really shouldn't be viewed as a fuse as that's incidental to its real function.

    I believe that's a 6.8 uH 500mA choke. K4EAA sells a partial finals repair kit that includes that choke here: https://www.k4eaa.com/parts.htm a similar kit is available here: http://www.hybridrestore.com/parts/#fcrk

    Here's a link to the schematic and discussion of these components:https://www.k4eaa.com/final_repair.htm and more info here: http://www.hybridrestore.com/final-cage-repair/
    WQ4G likes this.
  3. KE0EP

    KE0EP Ham Member QRZ Page

    Thanks for the info. In the 520, L5 is in series with the HV rail to the final circuit.

  4. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Yes, but it's the equivalent of L1 shown in the schematics on both the sites linked above which also sits in the HV path to the finals. All the Kenwood hybrids use basically the same finals circuit though the part numbering changes between rigs and there are subtle differences like using 4 x 20 ohm resistors vs 2 x 10 ohm resistors as the cathode/meter shunts between versions of the rigs.

    The kit linked above work fine in the TS-520.
  5. KE0EP

    KE0EP Ham Member QRZ Page

    OK, I got it... thanks!

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