Help with my first amplifier

Discussion in 'Amateur Radio Amplifiers' started by W5KV, Oct 14, 2018.

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  1. K2XT

    K2XT Premium Subscriber QRZ Page

    If I'm not mistaken it was something that was in the original poster's amp only, not factory supplied. So nothing to worry about.
     
  2. K2XT

    K2XT Premium Subscriber QRZ Page

    I meant to mention, and I didn't see where anyone else commented, but the marks on the parasitic resistors look like rust.
     
  3. N8FVJ

    N8FVJ Ham Member QRZ Page

    The Heathkit SB-220 is one of the best HF amplifiers ever built with a proven track record. You can buy better amps for $2K to $4K, but not more reliable IMO. The SB-220 will produce about 1200 watts PEP out on 75 meters with 100 watts drive using fresh tubes. New replacement 3-500z tubes are only $200 each vs ceramic tubes that cost $600 to $1000 each (no thanks).
    I just bought one with a Peter Dahl hypersil (C core) transformer. The transformer produces twice the HV current vs the original. This amp produces 1500 watts PEP out with 100 watts drive.
     
  4. N8FVJ

    N8FVJ Ham Member QRZ Page

    BTW- technically the SB-220 original transformer is good for 1000 watts PEP out (23lb transformer), but others have pushed it to 1200 watts PEP out on 75 meters. The AL-80B has a 26lb transformer for 1000 watts PEP out, but the SB-220 does not have to provide tube filament power like the AL-80B. Thus transformers are about equal for HV power (1000 watts PEP out). The Drake L4B has a 29lb high voltage transformer.
     
    Last edited: Nov 14, 2019

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