Best forum for Kenwood TL-922 and 922A ?

Discussion in 'Amateur Radio Amplifiers' started by KM5L, Jan 26, 2021.

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  1. W1NJC

    W1NJC Ham Member QRZ Page

    Thanks, Roger. Yeah that's what I plan to do (well maybe 80mA and 160mA but whatever). I'm hoping for some tips on the mechanical aspects of installing the W7RY board. It uses a pass transistor for bias instead of the string of diodes approach.
  2. G3YRO

    G3YRO Ham Member QRZ Page

    Personally I prefer to use diodes, as there's less to go wrong ! (they also fit very neatly where the Zener used to go . . . and very near the SSB/CW switch, to pick up the existing wires)

    Roger G3YRO
  3. KD9IQO

    KD9IQO Ham Member QRZ Page

    (1) I replaced the filamentary lamps with LEDs. See my simplified schematic for the W7RY connections.
    (2) I found it necessary to cut the filament transformer mounting bolt. I just used a dremel and an abrasive wheel.

    Attached Files:

  4. G3YRO

    G3YRO Ham Member QRZ Page

    Well I have come to the bitter conclusion that most LEDs don't last as long as incandescent bulbs !

    This is in all sorts of equipment . . . including LED TVs . . . LED Lightbulbs . . . Cars with LED lights . . . etc etc

    Let alone I work for one of Britain's Premiership Football Clubs, looking after the Digital advertising boards all round the pitch. Every match I end up replacing about 15 panels due to blown LEDs !

    So I would certainly never replace any bulbs in my equipment with LEDs . . .

    Roger G3YRO
  5. W1NJC

    W1NJC Ham Member QRZ Page

    Low/medium intensity LEDs last quite a long time if used properly. Those OLEDs used for big screens and stuff are different. Lots of energy dissipated in those things. A regular 10-20mA or so LED will last a long time. Longer if you reduce current or PWM it. That said I like incandescent better usually, though the "warm" white LEDs are ok. I despise blue LEDs!

    Football, lol. You mean soccer?! haha
  6. G3YRO

    G3YRO Ham Member QRZ Page

    Yes but so do Incandescent bulbs ! The bulbs in my FT101E are all original bar one . . . and that had a LOT of use over the decades.

    I have only replaced ONE of the 4 tail-light bulbs in my 30 year-old car (and none of the dash or sidelight bulbs) . . .

    And in my house, about half of the ceiling bulbs are LED, and half I use 100W incandescent bulbs (I have a stash of about 50 in my loft) . . . but I am finding the LED bulbs don't last as long as the incandescent ones !

    It's called Football as you have to kick the ball with your foot . . . never understood why you call your American game Football, as they carry and throw it most of the time, hardly ever use their feet . . . it's more like a cross between Rugby and Wrestling !

    Roger G3YRO
    KD2ACO likes this.
  7. W1NJC

    W1NJC Ham Member QRZ Page

    It's true, they only kick it for punting and field goals. It's not really a "ball" either. I'm with you on incandescents. I think the problem with the LEDs is the cheap design and components. I bought some "candelabra base" ones for my bathroom fixture and all they do is flicker. A low power LED itself essentially lasts forever if not abused. For backlighting of meters, I prefer the warm glow of a filament. LEDs are fine as an indicator/standby light or a flashlight, er, torch for you Brits!

    That's why I don't want to use LEDs as this board is intended for. But since it rectifies the 8V and then grounds the resulting DC, the AC side needs to be lifted from GND. Since the lamps are grounded this is a problem. So I was going to try and run them on the DC, which should be fine.

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