Yaesu FL-2100B Input tuning problems...

Discussion in 'Amateur Radio Amplifiers' started by N8CMQ, Jan 31, 2019.

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  1. N8CMQ

    N8CMQ XML Subscriber QRZ Page

    So I am finally getting my amp powered up and I need to tune the input coils after replacing all of the original caps.

    All of the bands are OK so far, except for the 10 meter band, surprise! I wonder if it was used improperly??
    Perhaps that would explain why the band switch was very stiff when I started?
    From the looks of it, the coil has all of the windings shoved together, but even after spreading them out, it is still too low in frequency, better, but too low. So tomorrow, after a good night of sleep, I will remove one turn and see if the slug tunes it in without being all the way out.

    I am too tired to continue, and I do not work well around 2500 VDC when I am tired.
  2. N8VIL

    N8VIL Ham Member QRZ Page

    Look at the 10 meter coil. Sometimes the 10 meter tap was moved by a CB'r to work better at 11 meters. This was the case on my FL-2100B I purchaced.
  3. N8CMQ

    N8CMQ XML Subscriber QRZ Page

    Is that the output tap you mention?
    As I have not progressed to that point yet.

    I have found the 20 meter input is also showing high input SWR at the moment, 80,40, and 15 meter input SWR is less than 1.5:1, 20 meters is 3:1, and 10 meters is 1:1 at 26 MHz and rising to 3:1 as the frequency goes up.

    Once I get the input sorted out, then I will go to the output and see what is in need of massaging...
  4. N8CMQ

    N8CMQ XML Subscriber QRZ Page

    The 10 meter input problem is resolved, I ended up removing one turn and the input SWR dropped below 1.2:1 with 1.5:1 at the band edges.

    For some reason, 20 meters was over 2:1 at best, and changing the cap to ground on the tube side of the coil to 330 pF brought it down below 1.2:1.

    After all that, the amp put out a clean signal with 500 watts out.
    KD2ACO likes this.
  5. G3YRO

    G3YRO Ham Member QRZ Page

    Glad you got it sorted!

    With good valves, you should get 600 watts out of those amps (running off 220V)

    Roger G3YRO
  6. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    Love mine! So easy to tune and gives your signal some OOMPH when needed. Mine has the original Cetron tubes in it and I still get 500 out for 50 in. Never run it harder.

  7. N8CMQ

    N8CMQ XML Subscriber QRZ Page

    You mean, never run it in splatter mode?
    That takes the fun out of it! XD
    Besides, as I have no ALC circuit, I have to pay attention to the little details now.

    But, I need to upgrade my antenna now, I see problems with SWR when I run power to it.

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