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811H problem

Discussion in 'Amateur Radio Amplifiers' started by KB2E, Oct 28, 2018.

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  1. KB2E

    KB2E XML Subscriber QRZ Page

    A friends 811H has a strange problem. It works on 15 meters as designed. On other bands increasing the drive above 40 watts can cause the plate VC to arc and kick out the amp. The guy constantly forgets to chanhe bands son the amp when he changes the radio. Geeez! Any thoughtst on where to check? He should just buy a SS amp that follows the radio and an auto-tuner!
  2. AA7QQ

    AA7QQ Ham Member QRZ Page

    KD2ACO likes this.
  3. KB2E

    KB2E XML Subscriber QRZ Page

    Oh yes my wise friend and torque is king. It's a great comparison, never thought of it that way. I always try to get the point across that you can have 1500 watts into a terrible antenna and I'll do better at 100 with a 3 or 4 db gain antenna. It's just hard for some people to get that concept. "Oh but my tuner will handle 10:1!" Yeah, OK, but where's the power going? Oh well, such is life.
  4. KD2ACO

    KD2ACO Platinum Subscriber Life Member Platinum Subscriber QRZ Page

    That's a problem. His wallet will teach him a lesson. Look for scorch marks and change parts. That cap will never be the same.
  5. N7WR

    N7WR Subscriber QRZ Page

    Your friend needs to learn how to properly use a manual tune amp OR spend the money for an auto switching solid state amp. But unless his antennas are up to the task that won't solve the problem either. We all make mistakes but if he habitually changes bands without changing the band switch on the amp he needs to learn how.
  6. N5WVR

    N5WVR Ham Member QRZ Page

    I'm curious what you use for a 3 or 4 db gain antenna on 40 and 80 meters?

    This is a serious question, not an attempt to play gotcha. I'm looking into low bands antenna options myself.

    Amps are more important on the low bands because it's more difficult to get antenna gain there.
    KC9VFO likes this.
  7. KB2E

    KB2E XML Subscriber QRZ Page

    He's ordering a new cap. I can't get there until Tuesday. I'm sure there will be more parts to be ordered.
  8. KB2E

    KB2E XML Subscriber QRZ Page

    Oh please! I don't get it! But I see other changes as well. Could be a brain thing, seriously. I hope not but you never know. I'm running a THP 1.5 with the matching tuner so it all follows the radio but I still check to make sure it did before I transmit. I never forgot to change bands on my old SB-230. I just don't get it. I have said constantly, "You have to get into a routine! You have the amp on almost always so on the band change you drop out of operate FIRST and then change the amp to the band you want and then the radio. NEVER the radio first and NEVER do anything without dropping to standby!" It just doesn't sink in. Even with the setu up I have I drop to standby before I change anything and check that the system followed the radio.
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    Did he hot switch the band switch ?
  10. KB2E

    KB2E XML Subscriber QRZ Page

    Sorry just a general statement to make a point. I wish I could get that kind of gain on 40 and 80 too LOL. There's a video on youtube of a guy in Hawaii with a 80 meter yagi up 100 feet. They're putting it there with a helicopter. I wish I could remeber his call. Now there's some gain on 80!
    KD2ACO likes this.

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