Featured: Heathkit SB-220 amplifiers and parts on eBay.
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The Heathkit SB-220 is a well-known vintage ham amplifier and a familiar restoration project. The basics are well established: it uses a pair of 3-500Z triodes in a grounded-grid circuit. Because these amplifiers are decades old, much of the eBay activity around them is about keeping them running, with manuals, replacement parts and restoration boards listed alongside complete amplifiers from time to time.
What turns up on eBay
A search for SB-220 listings shows how active the restoration side is. Recent results included reproduction manuals with fold-out schematics, a replacement fan motor and blade, front panel overlays, a power supply capacitor block, a rectifier and meter board, and a relay buffer for the amplifier's keying. Listings change constantly, so treat that as a snapshot rather than a catalog, and read each listing closely to see exactly what is included.
Before you power up an old SB-220
- Start with the manual. A copy of the original manual and schematic is the foundation of any restoration, and reproductions are easy to find.
- Assume the filter capacitors need attention. Electrolytic capacitors in old supplies deteriorate, and many restorers replace them, or bring the supply up slowly with a variable transformer, before applying full voltage.
- Check the tubes. Find out the history of the 3-500Z pair, and have them tested where possible.
- Protect your radio. Older amplifiers can put more voltage or current on their keying line than a modern transceiver is designed to switch, which is why keying relay buffers exist. Check your radio's keying rating before connecting it.
- Inspect the workmanship. Heathkit was known for kit-built equipment, so look closely at the quality of the original assembly and at any modifications made by later owners.
Take the high voltage seriously
A tube amplifier's plate supply is lethal, and its filter capacitors can hold a charge long after the amplifier is unplugged. Never work inside with power connected, discharge the capacitors and verify they are discharged before touching anything, and if you are not experienced with high-voltage equipment, have someone qualified do the work.
Take your time with the first power-up after a restoration. Bring the amplifier up carefully, watch its meters, and test into a dummy load before it ever sees an antenna. A careful restoration is a rewarding project; a rushed one can be dangerous and can destroy the parts you just paid for.
Buying tips
For complete amplifiers, ask for photos of the inside as well as the front panel, and ask how the seller will pack something this heavy. For parts, confirm they are listed for the SB-220 specifically, since related Heathkit amplifiers share some components but not all.
And a reminder whenever amplifiers are discussed: external linear amplifiers are not legal for use on CB radio. A restored SB-220 belongs in a licensed amateur station.
Where to get it
Browse current listings: Heathkit SB-220 amplifiers and parts on eBay.
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