Heathkit SB-200 power supply Rebuild notes ( for 8-10 Capacitors not suggested just notes)

 PLEASE BE AWARE THAT THIS POST IS SAVED NOTES AND NOT THE BIBLE OF WHAT TO USE OR DO.

The original string used lower-rated diodes. For reliability with 220µF capacitors (and especially for Turbo mode), upgrade to 1000V+ 3A diodes. You need 10 diodes total (5 per leg of the doubler).

Quantity: 10

Part Number: 1N5408 (1000V, 3A, Axial)

Alternative: BY225 (1300V, 3A) for extra voltage headroom.

Mouser: 512-BY225 or 625-1N5408

DigiKey: 1N5408E3/54GICT-ND

2. Bleeder / Equalizing Resistors

Replace the original high-wattage wirewound resistors with modern 2W Metal Oxide or Carbon Film resistors. With 220µF caps, 82kΩ or 100kΩ provides perfect voltage balancing and safe discharge (~2 minutes) without excessive heat.

Quantity: 8 (One across each capacitor)

Resistance: 100 kΩ (Preferred for cooler operation) or 82 kΩ

Power Rating: 2 Watt (Minimum), 3 Watt (Preferred for Turbo mode)

Part Number: CFR-200JB-100K (2W, 5%) or MOX-200JB-100K (2W Metal Oxide)

Mouser: 299-100K-RC (Ohmite 2W)

DigiKey: 100KQBK-ND

3. HV Output "Glitch" Resistor (Highly Recommended)

While not originally on the doubler PCB, it is standard practice to add a surge-limiting resistor in the HV output line to protect tubes and the board during flashovers.

Quantity: 1

Resistance: 15 Ω to 47 Ω

Power Rating: 10 Watt (Wirewound or Ceramic Composition)

Part Number: OH150E (Ohmite 15Ω 10W Ceramic) or RW01015R00 (Vishay 15Ω 10W Non-Inductive)

Mouser: 290-15-RC

DigiKey: 15F10-ND

4. HV Fuse Holder & Fuse (Safety Upgrade)

Replace the original hard-wired fuse link with a panel-mount holder for serviceability.

Quantity: 1 Holder, 1 Fuse

Holder: BFN-1000 (Bussmann 10kV Fuse Holder) or equivalent ceramic HV holder.

Fuse: 2.0 Amps, 10 kV, Fast-Blow, Ceramic Body.

Part Number (Fuse): 50200 (Bussmann)

Mouser: 504-50200 (Fuse), 504-BFN-1000 (Holder)

5. RF Bypass Capacitors (Optional but Recommended)

Add these directly to the HV output point on the board to prevent RF feedback.

Quantity: 2

Value: 0.0022 µF (2200 pF)

Voltage: 3 kV to 5 kV (Ceramic Disk)

Part Number: 580-5KV222M (5kV, 2200pF)

Mouser: 580-5KV222M

DigiKey: 493-15715-ND (Similar Vishay)

Summary Shopping List

Component Value / Spec Qty Example Part Number

Rectifier Diode 1000V, 3A, Axial 10 1N5408

Bleeder Resistor 100kΩ, 2W (or 3W) 8 CFR-200JB-100K

Glitch Resistor 15Ω, 10W, Wirewound 1 OH150E

HV Fuse 2A, 10kV, Ceramic 1 Bussmann 50200

HV Fuse Holder 10kV Rating 1 Bussmann BFN-1000

RF Bypass Cap 2200pF, 3kV, Ceramic 2 580-5KV222M

Installation Note: When installing the 10 bleeder resistors (8 across caps + 2 extra if modifying the string for Turbo), ensure leads are kept short and away from high-voltage arcs. If performing the 8-capacitor Turbo mod, you will need 8 bleeder resistors total (one for each cap). The list above assumes the standard 6-cap board plus 2 added elsewhere, or a full refresh of the 6 original positions plus spares. If you are doing the 8-cap mod, simply ensure you have 8 resistors installed (one per cap).