================================================================================ TM-VCAP-SCH-005 Rev A STACK-ON MODULAR FLAT-PLATE CAPACITOR UNITS Copper Foil / Polymer Sheet Sandwich Construction ================================================================================ 1. SINGLE UNIT CONSTRUCTION ============================= EXPLODED VIEW (one CSM unit): ┌─────────────────────────────────────────────────────────────┐ │ ┌─── wire tab (solder here) ─┐ │ ← TOP FOIL LAYER │ │▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓│ ← COPPER FOIL (top) │ │░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│ ← POLYMER DIELECTRIC │ │▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓│ ← COPPER FOIL (bot) │ └─── wire tab (solder here, offset from top tab) ──────────┘ │ ═════════════════════════════════════════════════════════ │ ← PVC BACKING STRIP └─────────────────────────────────────────────────────────────┘ SIDE VIEW: ┌───────────────────────────────────────────────────────────────┐ │ ├── 5mm tab ──┤ ├── 5mm ──┤│ │ ┌─────┐────────────────────────────────────────────┐─────┐ │ │ │ TOP │▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ copper foil ▓▓▓▓▓▓▓▓▓▓▓▓│ │ │ │ │ TAB │░░░░░░░░░░░░░░░░░░░ polymer (d) ░░░░░░░░░░░░│ │ │ │ │ BOT │▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ copper foil ▓▓▓▓▓▓▓▓▓▓▓▓│ │ │ │ └─────┘════════════════════ PVC backing ═══════════└─────┘ │ │ ← W (plate width) → │ │ ←──────────────── L (plate length + tab) ──────────────────→ │ └───────────────────────────────────────────────────────────────┘ DETAIL — WIRE TABS (at left end): Top foil tab extends 5mm BEYOND the polymer sheet edge (no dielectric in tab area). Bottom foil tab extends 5mm on OPPOSITE FACE, offset 3mm down from plate edge. This ensures top and bottom tabs cannot accidentally short when stacking. ┌─ TOP TAB ─┐←3mm→┌─ BOT TAB ─┐ ─▓▓▓▓▓▓▓▓▓▓▓▓ │ │ (top foil slightly wider for tab) ───────────────────▓▓▓▓▓▓▓▓▓▓▓ (bottom foil offset) 2. STACK-ON CONNECTION METHOD ================================ PARALLEL STACKING (increases total capacitance): All units share the same two terminals. Tabs align side-by-side. MECHANICAL (velcro): ┌────────────────────────────────────────────────┐ │ ← velcro strip ──────────────────── velcro → │ Unit 3 (bottom) │ ▓▓▓▓▓▓▓▓▓░░░░░░░░░░░░░░░░░░░░░░░░░▓▓▓▓▓▓▓▓▓│ ├────────────────────────────────────────────────┤ ← contact tabs aligned │ ▓▓▓▓▓▓▓▓▓░░░░░░░░░░░░░░░░░░░░░░░░░▓▓▓▓▓▓▓▓▓│ Unit 2 (middle) ├────────────────────────────────────────────────┤ │ ▓▓▓▓▓▓▓▓▓░░░░░░░░░░░░░░░░░░░░░░░░░▓▓▓▓▓▓▓▓▓│ Unit 1 (top) └────────────────────────────────────────────────┘ │ │ T₁ (top foils, connect all) T₂ (bottom foils, connect all) SPRING CONTACT STRIP at tab edge: A 0.15mm phosphor-bronze strip crimped onto each tab edge ensures reliable low-resistance contact regardless of stack height. ┌──────┐ │ TAB ├──╮ │ │ ╰ spring strip (0.15mm PB, 3mm wide, bent into arc contact) └──────┘ RUBBER BAND METHOD (small units CSM-F, CSM-G, CSM-VHF): Wrap two rubber bands around stack in perpendicular directions. Use alligator clip or crocodile clip to grab tab stack. Works for QRP/bench use. VELCRO METHOD (medium/large units CSM-A through CSM-E): Apply self-adhesive velcro to LONG face of PVC backing. Matching velcro on adjacent units and on tuner chassis. Add/remove units in seconds; position maintained when peeled apart. 3. BAND SELECTION VISUAL GUIDE ================================ EXAMPLE: Building up for 160m → 10m capability with CSM units ┌─────────────────────────────────────────────────────────────────────┐ │ BAND │ UNITS │ C (pF) │ V_work (V) │ ├─────────┼─────────────────────────────┼──────────┼─────────────────┤ │ 160m │ 1×CSM-A2 │ 248 │ 3000 │ │ 80m │ 1×CSM-B2 │ 159 │ 3000 │ │ 40m │ 1×CSM-C2 │ 100 │ 3000 │ │ 30m │ 1×CSM-D + 1×CSM-E │ 154 │ 1500 │ │ 20m │ 1×CSM-E │ 54 │ 1500 │ │ 17m │ 1×CSM-F + 1×CSM-G │ 49 │ 1500 │ │ 15m │ 2×CSM-F │ 62 │ 1500 │ │ 12m │ 1×CSM-F + 1×CSM-G │ 49 │ 1500 │ │ 10m │ 1×CSM-G │ 18 │ 1500 │ │ VHF │ 1–3×CSM-VHF │ 10–30 │ 1500 │ └─────────┴─────────────────────────────┴──────────┴─────────────────┘ NOTE: Target C values above are STARTING POINTS. Fine-tune with inline sliding pipe cap (TM-VCAP-SCH-004) or rotary cap. 4. COMPLETE SET PHYSICAL DIMENSIONS ====================================== ALL UNITS at a glance (from TM-VCAP-CAL-006): Unit │ W×L (mm) │ Thickness │ C (pF) │ Color code ───────┼────────────┼─────────────┼──────────┼──────────────────── A2 │ 50×35 │ 1.5mm │ 248 │ ●● RED (160m) B2 │ 40×28 │ 1.5mm │ 159 │ ●● ORANGE (80m) C2 │ 32×22 │ 1.5mm │ 100 │ ●● YELLOW (40m) D │ 22×16 │ 1.2mm │ 100 │ ● GREEN (30m) E │ 16×12 │ 1.2mm │ 54 │ ● CYAN (20m) F │ 12×9 │ 1.2mm │ 31 │ ● BLUE (15m) G │ 9×7 │ 1.2mm │ 18 │ ● PURPLE (10m) VHF │ 7×5 │ 1.2mm │ 10 │ ● WHITE (VHF) Mark each unit with Dymo label or Sharpie: unit ID, C value, band(s). Store in a 4×2 grid in a pill organizer or small Pelican case. 5. HYBRID SYSTEM — STACK-ON + SLIDING PIPE ============================================ The stack-on units provide COARSE band selection (step changes in C). The sliding pipe cap provides FINE TUNING within the band. Together they cover 10 HF bands + VHF with smooth continuous tuning. CIRCUIT: Stack-on units Pipe cap Antenna T₁ ─────┤├──────────────┬─────── ||slide || ─────── to load (selected C) │ (trim C) └── RF ground (shunt path through tuner) EXAMPLE — 20m (14 MHz): 1. Install 1×CSM-E (54 pF) ← coarse 2. Start pipe cap at 0mm (0 pF) ← fine at zero 3. Tune to antenna; if SWR indicates need for more C, slide pipe in 4. SWR optimum reached at pipe x ≈ 0.5mm → C_total ≈ 54 + 9 = 63 pF 5. LOCK: remove pipe cap and replace CSM-E with CSM-E + CSM-VHF (64 pF) OR: just leave pipe cap inline and use it for fine control. 6. VOLTAGE RATING BY UNIT SIZE (100W verification) ==================================================== At 100W into 50Ω load (no mismatch): V_rms = √(P×R) = √(100×50) = 70.7 V V_peak = 70.7 × √2 = 100 V At 100W into high-Q tuner (Q=5, worst case): V_C_peak = Q × V_peak = 5 × 100 = 500 V CSM-A2 through CSM-VHF (single OHP layer, V_work=1500V): SAFE at 100W into Q≤5 tank circuit For 500W operation: use 2-layer units (V_work=3000V, allows Q up to 15) For QRP (<10W): any single-layer unit, V_peak < 50V VISUAL CHECK for HV: Inspect edge of polymer sheet at tabs: no carbonization, tracking, or discoloration. Replace dielectric sheet annually or after any suspected voltage overload. ================================================================================ END TM-VCAP-SCH-005 ================================================================================