SB-200 AMPLIFIER ALL PARTS BREAKDOWN

1. High Voltage Power Supply (Main Filter & Metering)

Location: Mounted on the original phenolic PCB or the replacement Harbach PM-200 board, located in the rear left corner of the chassis (viewed from front) near the power transformer. These capacitors are arranged in a series stack to handle ~2000V DC.

Ref Des	Physical Location	Original Value	Modern Equivalent Part Number	Est. Cost (Each)	Notes
C1 – C6	HV Filter Bank (6 caps in series on PCB)	125 µF, 450V Electrolytic (Axial)	Nichicon UHE2W121MHD (120µF, 450V, Radial w/adapter) or Cornell Dubilier 380LX121M450H022 (Axial). Upgrade: Nichicon UHE2W221MHD (220µF, 450V).	$8.50 – $12.00	Critical: Must replace all 6. Total capacitance is ~21µF (stock) or ~36µF (220µF mods). Polarity is critical (+ to - in series chain).
C7	HV Metering Filter (Across meter switch)	0.05 µF, 600V Paper/Plastic	WIMA FKP2D024701F00KSSD (0.047 µF, 630V Film, Axial)	$1.50	Standard value is 0.047 µF. Located near the meter switch wafer.

2. Anode (Plate) Tank & RF Output Circuit

Location: Mounted on the band switch wafer, tube socket pins, and the output tank coil assembly (center-right of chassis). These components handle high RF voltage and DC anode voltage (~2000V).

Ref Des	Physical Location	Original Value	Modern Equivalent Part Number	Est. Cost (Each)	Notes
C8	Anode Choke Bypass (Bottom of choke to chassis)	1 nF (0.001 µF), 3kV Ceramic Disc	Vishay 561R30TCC102 (1nF, 3kV) or CDR31BX102BKSR. Mod: Vishay 561R30TCC562 (5.6nF, 3kV).	$3.50 – $6.00	Key Mod: Replace with 5.6nF for 80m improvement. Located under chassis near anode choke.
C9	HV Blocking/Feedthrough (Plate to Tank)	500 pF, 5kV Doorknob	CDR32BX501BKSR or RF Parts C500-5 (500pF, 5kV Ceramic Doorknob).	$8.00 – $12.00	Large ceramic "doorknob" style. Connects plate compartment to tank coil.
C10	80m Plate Padder (Switched Fixed)	100 pF, 5kV Mica	Cornell Dubilier DM19FA101FO3 (100pF, 5kV Mica) or CDR31BX101BKSR (Must verify 5kV rating).	$6.00 – $9.00	Switched in only on 80m. Often fails; inspect closely.
C25	Plate Tuning Capacitor (Variable)	150 pF, 5kV Variable Air	Johnson 154-150-5 (150pF, 5kV Variable).	$45.00 – $65.00	Large variable capacitor on front panel shaft. Rarely needs replacement unless plates are warped.
C26	Plate Loading Capacitor (Variable Dual)	457 pF (Dual Section), 3kV Variable	Johnson 154-250-3 (250pF/section, 3kV) wired in series/parallel or Hammarlund HF-250-X.	$55.00 – $75.00	Dual-section variable. If one section shorts, the whole unit often needs replacement.
C27	80m Load Padder (Switched Fixed)	500 pF, 3kV Mica	Cornell Dubilier DM19FA501FO3 (500pF, 3kV Mica).	$6.00 – $9.00	Switched in on 80m Load circuit.

3. Input Tuned Circuit (Grid/Cathode)

Location: Mounted directly on the input band switch wafer (front left under chassis) and near the tube grid pins. Critical for matching input SWR.

Ref Des	Physical Location	Original Value	Modern Equivalent Part Number	Est. Cost (Each)	Notes
C29	ALC Sample Coupling	5 pF, 1kV Mica	CDR30BX5R0BKS (5pF, 1kV Mica).	$1.20	Small mica disc near ALC rectifier diode.
C30	80m Input Series	470 pF, 1kV Mica	CDR31BX471BKSR (470pF, 1kV). Mod: 910 pF for better SWR.	$1.50	On 80m switch wafer.
C31	80m Input Shunt (Filament)	(Part of L-network, often stray/structural)	N/A	N/A	Sometimes omitted or structural in L-net config.
C32	40m Input Series	310 pF, 1kV Mica	CDR31BX301BKSR (300pF, 1kV) or 330pF. Mod: 240 pF (with new choke).	$1.50	On 40m switch wafer.
C33	40m Input Shunt	510 pF, 1kV Mica	CDR31BX511BKSR (510pF, 1kV). Mod: 200 pF (swapped with C34).	$1.50	On 40m switch wafer.
C34	20m Input Series	200 pF, 1kV Mica	CDR31BX201BKSR (200pF, 1kV). Mod: 100 pF to reduce coil heat.	$1.50	On 20m switch wafer.
C35	20m Input Shunt	360 pF, 1kV Mica	CDR31BX361BKSR (360pF, 1kV). Mod: 470 pF (swapped with C34).	$1.50	On 20m switch wafer.
C36	15m Input Series	75 pF, 1kV Mica	CDR31BX750BKSR (75pF, 1kV). Mod: Replace with Johnson 142-0101-801 (Trimmer 2-10pF + fixed).	$1.50 (Cap) / $4.00 (Trimmer)	On 15m switch wafer. Often replaced with trimmer for tuning.
C37	10m Input Series	66 pF, 1kV Mica	CDR31BX680BKSR (68pF, 1kV). Mod: Replace with Trimmer.	$1.50	On 10m switch wafer (if 10m mod installed).
C38	Grid Bypass (Per Tube, Pin 1 to Ground)	200 pF, 1kV Ceramic	CDR31BX201BKSR. Critical Mod: CDR31BX102BKSR (1nF, 1kV) or 1.5nF.	$1.50	Two required. Directly on tube socket pins. Increase to 1-1.5nF for stability.
C39	10m Input Shunt	(Varies, often ~100 pF)	CDR31BX101BKSR (100pF). Mod: Trimmer.	$1.50	On 10m switch wafer.

4. Bias, Filament, Relay, and Low Voltage Circuits

Location: Scattered across the chassis: bias rectifier board (rear), filament choke (near tubes), relay assembly (front right), and meter lamp circuit.

Ref Des	Physical Location	Original Value	Modern Equivalent Part Number	Est. Cost (Each)	Notes
C12	Filament Choke Bypass	0.02 µF (20 nF), 50V+ Ceramic	Vishay K5050203Z (0.022 µF, 50V Disc).	$0.80	Mod: Relocate from choke to directly across tube grid pins for better RF ground.
C13	Bias Rectifier Filter	20 µF, 150V Electrolytic (Axial)	Nichicon UHE2E220MHD (22µF, 250V, Radial w/adapter) or Cornell Dubilier 380LX220M160A022 (Axial).	$2.50	Located on bias rectifier board.
C14	Bias Output Filter	20 µF, 150V Electrolytic (Axial)	Nichicon UHE2E220MHD (22µF, 250V).	$2.50	Located on bias rectifier board.
C15	Relay Delay/Filter	20 µF, 150V Electrolytic (Axial)	Nichicon UHE2E220MHD (22µF, 250V).	$2.50	Near relay assembly.
C16	RF Input Coupling	0.02 µF (20 nF), 600V Paper/Plastic	WIMA FKP2D022001F00KSSD (0.022 µF, 630V Film, Axial).	$1.50	Input SO-239 connector to band switch.
C17	ALC Filter	0.1 µF, 50V Electrolytic	Nichicon UHE1H100MDD (10µF, 50V) or 0.1µF Film.	$0.80	Near ALC diode. Original was likely electrolytic; film is more reliable.
C18	Meter Lamp Bypass	0.02 µF, 50V Ceramic	Vishay K5050203Z (0.022 µF, 50V).	$0.80	Across meter lamp terminals.
C19	Relay Supply Filter	2.2 µF, 250V Electrolytic (Axial)	Nichicon UHE2E2R2MHD (2.2µF, 250V Axial) or Harbach CAP-221.	$3.75	Critical for relay timing. Often leaks in old units.
C20	Relay Supply Filter (Second)	2.2 µF, 250V Electrolytic (Axial)	Nichicon UHE2E2R2MHD (2.2µF, 250V Axial).	$3.75	Parallel with C19 or separate stage depending on revision.

Total Estimated Cost for Full Capacitor Rebuild

DIY (Individual Parts): Approximately $250 – $350 depending on whether you choose standard replacements or high-end upgrades (e.g., 220µF HV caps, doorknob replacements).
Kit Approach:
- Harbach PM-200 Kit (HV Supply only): ~$125 (includes C1-C6, diodes, resistors).
- Harbach Master Kit: ~$548 (includes HV kit, fan, soft-start, input caps, grid caps, suppressors, etc.). This is often more cost-effective than sourcing every individual part.

K7ZGQ-ANTENNAS,P.F.O. Skunkworks