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Discussion in 'Amateur Radio Amplifiers' started by W2PPJ, Nov 3, 2017.

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  1. W2PPJ

    W2PPJ Ham Member QRZ Page

    i broke a few wires off the alc board with big oaf fingers. i will resoder those and clip one side of 209 and report back.
  2. 9BC357

    9BC357 QRZ Member

    yes behind that small PCB is C208 and C209.
    This is the second time I seen this failure and will replace my own before this happens.

    Here is a schematic all on 1 page to make it easier.


    Attached Files:

  3. W2PPJ

    W2PPJ Ham Member QRZ Page

    i had to update my soldering gear now i have a real soldering station. i will report back asap. what is a good desoldering temp and what temp should i be running to solder. thanks for the help- Peter
  4. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    With good ol' 60/40 solder and decent RA flux, 700-740 degrees F is good depending on the tip, and the size of the connections. De-soldering with braid takes temps on the high side (750 ish) and extra flux to wet the braid so the solder flows into it.
  5. WA7PRC

    WA7PRC Ham Member QRZ Page

    63/37 SnPb solder has the lowest melting point. I prefer Kester's #245 "No Clean" flux (link) 'cuz it works and doesn't leave a mess. The only time I add flux to desolder braid is when it is dried out. I keep it in a sealed bag to make it last longer.

    Stay below 800°F (typically ≈ 700°F is OK for most SnPb alloys), and use enough "horsepower" in your solder "weapon" to get in/out fast. IMO, damage typically occurs by using not enough power, because you have to heat the connection a long time. My go-to pencil is a Weller #WES51 (50W) that does most small jobs. Most larger work is handled by my Weller #8200 gun (140/100W).
  6. W2PPJ

    W2PPJ Ham Member QRZ Page

    i clipped one side of 209 plugged in the amp went to hook my ground wire up before flipping the switch and saw a small spark at the ground.
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    Always connect ground FIRST (and disconnect LAST).

    If you're using a 2-prong power cord, you're seeing current from either C1 or C2 to ground. The schematic shows them used only w/ 100V source but, I'm sure they're used with all voltage sources:
    (click for yuuge image)
    Note that in the schematic I captured (and also redrew), I show a back-EMF diode added (in red) to RL1 coil.
  8. G3YRO

    G3YRO Ham Member QRZ Page

    So having clipped one side off, did you measure across C209 with the amp off, to check it wasn't short-circuit?

    And the same for C208?

    You are much safer doing these checks BEFORE doing anything with the amp powered up!

    Roger G3YRO
  9. W2PPJ

    W2PPJ Ham Member QRZ Page

    i found the problem- its me. i dont have a clue what im doing. i can not read a schematic and need to educate myself before taking on a project that is simple to you guys but not so much for me. i guess i got a little ahead of myself. if i had a local guy that a could pay i would trust me. there are no hams that i know of near me that do repairs i already asked around. i have had ZERO luck sending ham gear through the mail. this thing is 40 pounds i wonder how many times it will be dropped to the ground, kicked, slammed, punched, etc... im not ready to give up yet but i think that WA7PRC was right to suggest for me to take it to a pro. thanks again -peter
  10. W2PPJ

    W2PPJ Ham Member QRZ Page

    i forgot to mention i powered up the 2100b and nothing has changed since my c209 modification.

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