TS-2000 drivers - from 2SC1972 to RD15HVF1

Discussion in 'Radio Circuits, Repair & Performance' started by CIPMAN, Mar 30, 2020.

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  1. KA9JLM

    KA9JLM Ham Member QRZ Page

    Ferrite bead.

  2. G4COE

    G4COE Ham Member QRZ Page

    Wow, that is good that.... better than nothing at all? Good work, are ya' going to let us in on the secret?


    CIPMAN QRZ Member

    HI HI, my brain didn't have that acronym stored in, thanks for the upgrade:)
    Now that you mentioned the ferrite beads, there was an undocumented 420 ohm FB from base to emitter {i.e. ground) on each of the original 2SC1972s, which I removed.

    Pardon, what secret?
  4. G4COE

    G4COE Ham Member QRZ Page

    Sorry, I meant the mods... or did you just change the transistor. Dave

    CIPMAN QRZ Member

    The mods are in the schematic I posted earlier today - https://forums.qrz.com/index.php?posts/5447830
    P.S. Basicly replace the transistor but use a separate bias network for each transistor (as opposite to the factory common network for both drivers).
  6. G4COE

    G4COE Ham Member QRZ Page

    Ah, Thanks Cipman I didn't see it. Dave

    CIPMAN QRZ Member

    No worries Dave.

    Don't have a spectrum analyzer but I remembered I have an SDR receiver:)
    This picture shows 2MHz bandwidth around 14MHz, on the bottom part of the waterfall there are only the SDR internal carriers and on the upper part there's the TS2000's 14.100MHz carrier:
    This second picture is a closeup around 14.100MHz where the 4 carriers were at 5, 25, 50, 100W from the bottom respectively: https://i.imgur.com/cJiVadk.png
    Pretty clean I'd say.
    If anyone thinks this SDR method can be of further use, I'd be happy to do more tests.

    CIPMAN QRZ Member

    I lowered the quiescent current to the lowest value the TRX could still output 90-95W on 2m, the result being 4V on the gates of the RD15HVF1s. On 20m the power is 110W.

    I ran a two tone ssb test, first with 700+1333Hz then with 850+2200Hz, each time varying the output power: 5W, 25W, 50W, 100W and checking with the SDR receiver.
    Here's the result:

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