Hot Iron’s editors are Peter Thornton, G6NGR and Frank Barnes, W4NPN. Send membership or content questions to Frank at fbw4npn@gmail.com and send technical questions to Peter at equieng@gmail.com
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| Topic of Interest | Issue |
| Amplifier: Amplifier Classes | 111 |
| Amplifier: Emitter Follower, buffer | 61, 68, 110 |
| Amplifier, Bi-directional | 107 |
| Antenna: Grounding | 111 |
| Antenna: Current Indicator Circuit, Stripline SWR Measurements, | 55, 109, 100, 118 |
| Antenna: Folded Dipoles, “Universal” HF antenna (no ground) | 107, 115 |
| Antennas for Small Spaces; mini-80 meter dipole | 34, 115 |
| Antenna: Impedance Bridge (see Google for Sevick’s(SK) and Lythall’s (SM0VPO) work also) | 100, 106, 109 |
| Antenna: Resistive Matching Bridge | 100, 109, 110 |
| Antenna: Antenna Matching Metering | 51 |
| Antenna: Measuring Antenna Current | 23, 116 |
| Antenna: Current Meter | 55, 56, 116 |
| Antenna: The Inverted VEE (also see Cebik’s work under “Antennas” on this website). | 107 |
| Antenna: Loop Counterpoises | 111 |
| Antenna: Wire tuner & counterpoise tuner, with RF Amp meter, Random Wire Tuner, ATU | 90, 100, 114 |
| Antenna: Loops & Nested Loops (85) | 85, 95, 96 |
| Antenna: Nested Dipole – all bands | 68 |
| Antenna: Matching Unit, losses, efficiency | 23, 24, 94 |
| Antenna: Antennas, Tuners & ATU’s | 101, 116 |
| Antennas: Mini-Whip, Low height, RF Current Meter, Active RF Antenna | 108, 100 |
| Antenna: Random wires, counterpoises, etc | 90 |
| Antenna: RF Power Meter, SWR | 99, 116 |
| Antenna: Switching/transfer | 103 |
| Antenna: Top Loaded (1) & (2); Top Hats | 96, 97 |
| Antenna: 80 Meter Mobile, Mobile Bobtail | 60, 114 |
| Antenna: Low VHF Antenna Ideas | 67 |
| Antenna: Doublet Antenna Ideas | 66 |
| Antenna: Changeover Relays and Relay Contact Protection | 103 |
| Antenna: Balanced to Unbalanced Transformation | 39 |
| Antenna: Toroidal Transformers and Matching | 39 |
| Antenna: QRP Dummy Load Power Meter | 3 |
| Antenna: Variable High Voltage Capacitors – Pi Network Couplers | 104 |
| Antenna: The EP Antenna | 49 |
| Antenna: UHF; using copper water pipe | 101 |
| Antenna: Masts & Guys; Corrosion, Gin-Poles | 110, 117 |
| Attenuators, 50 ohm, etc | 48 |
| Audio: High-gain Audio Amp | 85 |
| Audio: Audio Amp Chips – Information & Comparisons | 65, 116 |
| Audio: A Versatile Audio Amplifier | 20 |
| Audio: Valve Heaven | 112 |
| Audio: The Audio Cube, W4AMV | 111 |
| Audio: Audio Preamplifier | 85 |
| Audio: Tuning Headphones & Select-O-Jet | 100 |
| Audio: Humbuckers & Mixed Topics | 103, 117 |
| Audio: Microphones & AGC for mikes | 64, 79, 104 |
| Audio: Microphones & More | 73, 101, 103, 104, 117 |
| Audio: Speech Processing, Filters | 116, 118 |
| Audio: Solid State Amp Chips; LM386 | 65, 114, 116 |
| Audio: Audio Millivoltmeter | 21 |
| Audio: Adding Audio AGC to a Receiver | 88, 22 |
| Audio: Power Transformers as Audio Output Transformers | 107 |
| Batteries | 117 |
| Capacitors: Value calculations, formulas | 42 |
| Capacitors: Variable HV, using switches | 104 |
| Capacitors Electrolytic, Testing, Storage, Old ones, Reforming | 80, 100, 107, 115 |
| Capacitors: “X” and “Y” types for AC lines | 107, 108 |
| Capacitance Calculations | 108 |
| Capacitors: Polarity, Foil end | 100 |
| Capacitors: Home made HV Capacitors | 111 |
| Capacitance Multiplier, Regulator Output Smoothing; Wrap-around, Gyrater | 106, 108, 110 |
| Components: Electrolytics, ESR, etc | 79, 110 |
| Components: Op Amp Theory | 51 |
| Components: Home Made RF Chokes & Low Ohms Resistors | 112 |
| Components: Ceramic Resonators; pulling | 53, 62 |
| Components: Crystals | 100 (2 articles), 116, 117 |
| Components: Common Diodes as Varactors | 52, 53 |
| Components: LED Photo Diodes | 100 |
| Components: Digital & Analog Potentiometers | 35, 117 |
| Components: Diode Switching | 41 |
| Components: FET Biasing | 40 |
| Components: Fuses: Multiple Uses for | 100 |
| Components: HV Diodes (microwave, others) | 108 |
| Components: Inductance Calculations, Free Inductors, Much more | 78, 100, 114 |
| Components: Inductive Reactance, markings | 43 |
| Components: Transformers, 50/60 cycle, Dull Lamp Test, Calculations, etc | 100 |
| Components: Logic Chip Families, Desoldering | 22, 117 |
| Components: Pinout diagrams of transistors | 63 |
| Components: Testing Mosfets | 66 |
| Components: TOKO IF Can Freq Ranges | 13, 65 |
| Components: Toroid winding | 23, 25 |
| Components: Zener Diodes; testing | 18 |
| Components: Voltage Regulators; irregularities | 107 |
| Components: Logic Families – Characteristics | 22 |
| Components: Op Amp Configurations; Single-Rail Op Amps | 87, 100 |
| Components: Designing Series Resonant RF Tracks | 23 |
| Components: Solid State Replacements for 6AK5, EL95 & others | 78, 84, 100 |
| Components: Sourcing Low-value NPO Capacitors | 67 |
| Components: Beware of Buffers: Stopping VHF oscillations in them | 68,61 |
| Components: MOSFET Devils, Testing MOSFETs | 82, 66 |
| Components: JFETs Configured as Dual Gate MOSFETS | 91 |
| Components: More about Dual Gate MOSFETS | 48 |
| Components: MOSFET Pairs | 107 |
| Components: FET Biasing & More about FET’s | 40 & 48 |
| Components: Testing/Removing Electrolytics | 80, 100, 110 |
| Components: HV “Door Knob” Capacitor Substitutes | 104 |
| Components: Variable Capacitors and All That… | 92 |
| Components: Not all transistors with same number have same lead orientation; Replace GE Transistors with Si NPN’s | 80, 100 |
| Components: Easy Inductance Calculations | 78 |
| Components: Using DC Bias to adjust toroid inductors | 111 |
| Components: TOKO Coil Ranges | 65 |
| Components: Radio Frequency Chokes | 47 |
| Components: Testing Transistors, Ft Measurement | 75, 100 |
| Components: Calculating Needed Resistor Wattage | 53 |
| Construction Techniques | 107, 110, 119 |
| Construction Techniques, Manhattan | 107, 110 |
| Construction Techniques, Copper Connecting Straps | 111 |
| Construction: Salvaging wire, B+ wire | 110 |
| Construction: Stripping Parts & Wiring | 111 |
| Construction: Elevated pcb bus rails | 104 |
| Construction: Avoiding RF wires to front panels | 98 |
| Construction: Home-built Printed Circuit Boards | 83 |
| Construction: Stainless Steel Soldering, Q-Max Cutters, Tank Cutters, Hole Saws, Terminal Rails, Strange QRM? | 100 |
| Crystal Checker Using Oscilloscope & Signal Generator | 25 |
| Decibels | 49 |
| Digital: DSP | 98 |
| Diode Switching | 41 |
| Dummy Load; Misc & QRP load w/meter (3) | 3, 32, 77 |
| Ferrite Cores; identifying, uses | 79 |
| Filters: CW, Notch, etc | 14, 34, 56, 58, 106 |
| Filters: Discussion of | 43 |
| Filters: RF Bandpass, TOKO pinouts | 13 |
| Filters: Analog Switched Capacitor Filters | 111 |
| Frequency Counter – adding one | 106 |
| Freq Counter & Oscilloscope buffer | 106 |
| Frequency Counter Buffer/Amplifier | 36 |
| Freq Display, w/varicap tuning | 34 |
| Fuses | 107 |
| Grid Dip Oscillator – how it works | 31, 32, 106 |
| Grounding: of circuit boards | 99 |
| Harmonics | 82 |
| Inductance Calculations | 108 |
| Interference – LED’s and HF | 115 |
| Interstage Coupling | 20 |
| Low Pass Filter | 74 |
| Magnetic Amplifier | 100 |
| Mixers (jfet) | 107 |
| Mixers (Pullen) | 107 |
| Mosfets: Biasing (85), Testing (52) | 52, 85, 115 |
| Mosfets: High Voltage, xmtrs | 89 |
| Mosfets: Theory | 36, 48, 82, 115 |
| Morse Code; Practice; 6U8A Osc | 115 |
| NE602 usage | 72 |
| Noise Source for Impedance Bridge | 107 |
| Oscillator: VFO Construction | 118 |
| Oscillator: A novel crystal osc | 114 |
| Op Amps | 87 |
| Operating: PSK31 | 37 |
| Oscillator: Ceramic Resonators | 102 |
| Oscillator: The Synthetic Rock | 112 |
| Oscillator, Crystal: Pushing & Pulling | 108 |
| Oscillator: Resistance Stabilized | 108 |
| Oscilloscope Probes | 75 |
| Power Supply: Wall Warts | 85 |
| Power Supply: “Ideal” Pwr Supply, Notes on Grounding, the Dinky Doubler, QRP or QRO | 112 |
| Power Supply: Class “X” and “Y” Capacitors | 107 |
| Power Supply: HV, Soft-start | 101, 117, 119 |
| Power Supply: the Pink Brazilian doubler+full wave | 102 |
| Power Supply: Ideas, Protection, Smoothing | 72, 81, 115 |
| Power Supply: Some Topics; Review of 12V Supplies | 111, 117, 118 |
| Power Supply: Overvoltage & Overcurrent Protection | 86 |
| Power Supply: Protection, Crowbars, Light Bulbs – simple protection circuits | 13, 28, 69, 94 |
| Power Supply: “Silent Supplies;” Economy Pwr Supply | 100 |
| Power Supply: Transformers, Low Voltage AC for testing | 110, 115 |
| Power Supply: Regulated and B+ | 42, 106, 110 |
| Power Supply: Some Voltage Regulator Thoughts | 76, 116 |
| Power Supply: Screen grid power supplies & regulation…to extend the life of power tubes | 101 |
| Receiver: A Frequency Standard for | 66, 122 |
| Receiver: Original, and Updated Neophyte Receiver | 112 |
| Receiver: 6U8 Regenerative Receiver-All about it | 112 |
| Receiver: Hartley Regen Receivers; also A Guide to Successful Regen Receivers | 112 |
| Receiver: DC & SSB – the 4th Method? | 112 |
| Receiver: Franklin | 105 |
| Receiver: 602 as RF amp, Single Chip Receiver | 93, 115 |
| Receiver: Adding AGC | 88 |
| Receiver: Bandswitching Coils | 84 |
| Receiver: building SDR’s | 99 |
| Receiver: Fine Tuning | 92 |
| Receiver: Ford DC rcvr | 99, 116 |
| Receiver: HF | 106, 119 |
| Receiver: Misc ideas re wiring & circuits | 98 |
| Receiver: Phasing DC, for sideband rejection | 79 |
| Receiver: Projects | 95, 107, 115 |
| Receiver: Projects, MOSFETS | 91, 90 |
| Receiver: Regenerative Designs/Information | 58, 60, 63, 66, 67, 77, 79, 80, 84, 87, 89, 90, 101, 107, 108, 110, 112, 115, 116, 118 |
| Receiver: TRF Receiver Designs/Info | 76, 101, 102 |
| Receiver: A very simple modular receiver | 65 |
| Receiver: Differential SA602/NE612 receiver | 101 |
| Receiver: DC Receivers | 99, 110, 112 |
| Receiver: SA602 as Receiver RF Amplifier | 93 |
| Receiver: Cascode RF Amplifier for Receiver | 102 |
| Receiver: LF Receivers using SA602 | 93 |
| Receiver: Simpleceiver DC Receiver using JFET’s as DG MOSFETs | 91 |
| Receiver: Modern alternative to the crystal set! | 91 |
| Receiver: Mixers | 117 |
| Receiver: Local Oscillator Schemes for Superhets | 107 |
| Receiver: Use Meter as Varicap Tuning Display | 33 |
| Receiver: RF amp | 92, 95 |
| Receiver: Q Multiplier | 110 |
| Receiver: Sensitivity | 41 |
| Receiver, Regen: Using TV Tubes | 107 |
| Receiver: 2 Band Mixing with NE612’s | 16 |
| Receiver, Information about AM Radios; Synchronous Detection | 58, 59, 100 |
| Receiver, Digital Signal Processing Fundamentals | 98 |
| Receiver, A Simple Introduction to Software Defined Radio (SDR) | 97 |
| Receiver, Homebrewing an SDR | 99 |
| Receiver: Updated Spontaflex Rcvr | 111 |
| Resistors: As Voltage Dividers | 54 |
| RF Chokes | 47 |
| RFI, from 3 Phase Motor Inverters (link) | Not in Issues |
| RF Stage Loose Coupler | 105 |
| RFI Febetrons & Marx Generators for RFI proofing | 111 |
| SA602 & Overtone Crystals | 47 |
| SDR: Introduction | 97 |
| Transceiver: One tube | 108 |
| Test Gear: Meter Multipliers, Grid Dipping, DC Analysis | 115, 119 |
| Test Equip: Simple 50 Ohm Test Gear | 48 |
| Test Equip: The Dim Lamp Tester | 101 |
| Test Equip: Fault-finding/Troubleshooting | 5, 71, 60, 116 |
| Test Equip: Using the Arduino + Color Display as a Panel Meter | 101 |
| Test Equip: A Megohm meter | 39 |
| Test Equip: Parasitic Oscillator Finder | 101 |
| Test Equip: Fault-finding, Cleaning Circuit Boards | 107, 116, 117 |
| Test Equipment & Low-pass filter for DVM’s | 100 |
| Test Equip: Miscellaneous, Signal Tracer/Injector, Growler | 103, 114 |
| Test Equip: Attenuators, RF amp, dummy load | 35, 39, 48 |
| Test Equip: Counter & O’scope buffer amp | 36 |
| Test Equip: Grid Dip Oscillator, Kaliatron grid dipper | 14, 31, 32, 114 |
| Test Equip: ESR Tester | 108 |
| Test Equip: Field Strength Meter, AC/RF Field Sensor | 101, 66, 118 |
| Test Equip: Grid Dip Oscillator examples | 14, 31, 32, 41 |
| Test Equip: Harmonic Marker Generator | 73 |
| Test Equip: Measuring C, L, Hi-value R | 39 |
| Test Equip: Easy way to measure Inductance | 5 |
| Test Equip: Using an Oscilloscope + Time Bases & Triggering | 15, 16, 17 |
| Test Equip: Test Leads & Probes | 12 |
| Test Equip: Test Leads: High Voltage Probes | 111 |
| Test Equip: RF Probe without diode offset voltage | 101 |
| Test Equip: Simple RF RMS Power Meter | 99 |
| Test Equip: Multi-voltage Power Supply | 76 |
| Test Equip: Osc to test unknown coils | 56 |
| Test Equip: Oscilloscope probe, use, theory | 15, 16, 17, 75 |
| Test Equip: Peak Reading RF Voltmeter | 35, 86 |
| Test Equip: Pock-Pock RF Generator | 104, 109 |
| Test Equip: RF Power & volt Measurement | 18, 85 |
| Test Equip: Crystal Checker | 22 |
| Test Equip: SCR tester | 17 |
| Test Equip: Transistor Tester | 75, 104 |
| Test Equip: Sweep Oscillator | 105 |
| Test Equip: Noise Source | 107 |
| Test Equip: Signal Generators | 82, 87 |
| Test Equip: Simple RF Signal Generator | 87 |
| Test Equip: AF/RF Signal Tracer | 101, 102, 103 |
| Toroids | 46 |
| Transformers: About, Testing | 47, 103 |
| Transistors: Substitute, finding | 106 |
| Transistors: Testing, pin-out (varies by mfr) | 80, 107 |
| Transmitter: Wiring “Octal” sockets to take FT241, 243 & HC6-U crystals | 103 |
| Transmitter: Harry Lythall’s 5 Watt xmtr; simple AM xmtrs | 101, 114 |
| Transmitter: PCL 86 xmtr by G4VAM, and a QRPP 2m Transmitter | 112 |
| Transmitter: 2 Tube Transmitter; 1 Component Xmtr | 75, 118 |
| Transmitter: Low Band Transmitter | 87, 116 |
| Transmitter: 6CU6 or EL84, simple | 84 |
| Transmitter: Balanced Modulator, SSB | 87, 117, 118, 119 |
| Transmitter: Gate Modulation | 85 |
| Transmitter: Linear Amp | 96, 97 |
| Transmitter: MOSFET Cathode Modulator | 86 |
| Transmitter: One tube tx-rx design | 65 |
| Transmitter: Two Tube, Using odd tube types | 107 |
| Transmitter: FET RF Power Amplifiers | 9 |
| Transmitter: The Roaring Mick 6CU6 | 84 |
| Transmitter: The Mick Modulator – Cathode Modulation | 85, 86 |
| Transmitter: Output Links | 82 |
| Transmitter: Plate Supply Choke | 89 |
| Transmitter: Refurbishing a 1930’s “Plank” Xmtr | 64, 65 |
| Transmitter: Measuring RF Output Power | 86 |
| Transmitter: RF Power Measurement | 85 |
| Transmitter: Two Meters: Different Approach to 2M FM? | 111 |
| Transmitter: Two Tone Audio Oscillator for SSB Rig Tuning | 8 |
| Transmitter: Transmit/Receive changeover | 112 |
| Troubleshooting with no meter | 115 |
| Troubleshooting: Cold testing semiconductors, Resistors & Capacitors, 112 | 115, 116 |
| VFO: Misc discussion | 43, 51, 98 |
| VFO: Building and Design | 8 |
| VFO: Fine Tuning of VFO | 92 |
| VFO: Wide Range Crystal Oscillator for 80 meters | 20 |
| VFO: Mosfet example | 44, 92 |
| VFO: VFO Drift | 91 |
| VFO: VFO Ideas for Multiband CW | 77 |
| VFO: Stable VFO for 20/30/40 meters | 51 |
| VFO: Simple Fun 80 meter VFO | 44 |
| VFO: Pulling Ceramic Resonators Higher in Frequency | 44 |
| VFO: Ceramic Resonator VFO’s | 13, 15 |
| VFO: Tuning by Variable Resistor | 43, 44 |
| VFO: Wide Pull (Range) VXO | 38 |
| VFO: Pulling a Crystal Oscillator | 34, 36 |
| VFO: Harmonic VFO Possibilities | 58 |
| VFO: Using Ceramic Resonator | 13 |
| VFO: Wide Range VXO; Pullable VXO | 8, 34, 36, 38 |
| VFO: Comparisons of crystals, ceramic resonators, digital correction, DDS/Synthesizers and much general information | 98 |
| VFO: Very Stable VFO | 97 |
| VXO: About VXO’s | 97 |
| VSWR; about | 46 |