Heathkit SB-220 Amplifier: Repairs, Mods, and Upgrades

Find resources and modifications for maintaining and enhancing your Heathkit SB-220 HF linear amplifier.

David
Reviewed by • Senior RF Engineer & Technical Editor • March 2026

The Heathkit SB-220 HF amplifier remains a popular piece of gear for many amateur radio operators, even decades after its introduction. Known for its robust design and the use of two 3-500Z tubes, the SB-220 provides significant power output, making it a valuable asset for working DX and improving signal strength on crowded bands. Many hams appreciate its straightforward construction and the ability to maintain and modify the unit over its long service life.

Operators often look for resources covering common SB-220 repairs and modifications, such as replacing components or upgrading the keying circuit for modern solid-state transceivers. There are also many guides for refurbishing older units, ensuring they continue to perform reliably. Hams frequently share details on modifications to improve QSK operation for CW and digital modes, or to address specific issues like meter repair, keeping these classic amplifiers on the air for many more QSOs.

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