SB-221 Tank Voltages and the parasitic myth
Tuning or loading an amplifier
Grounded grid (cathode driven) amplifiers
Preamplifiers
Receiving amplifier measurements
Vacuum Tubes
Vacuum Tube Amplifiers how the PA vacuum tube converts dc to RF
Working model for understanding how PA RF voltages are created and how amplifiers behave under various loading and drive conditions
Vacuum Tubes, arcing, vacuum tube failures, advantages and disadvantages of each type of power-grid vacuum tube, vacuum tube grid failures, vacuum tube anode failures, maximizing vacuum tube life, and quite a bit about how power grid vacuum tubes actually function
Placing new 572B tubes in operation, or preconditioning 572's.
Components
Tank Circuits two models showing tank voltages, currents, loss, and phase shift
Bandswitch Failures discusses the many common reasons for amplifier tank system switch failures
T/R relays and relay timing, including amplifier relay sequencing that will work with vacuum relays
Inductors while this deals mainly with loading coils, it is also true for amplifiers
Stability
HF Stability HF instability or instability near the operating frequency of an amplifier is by far the most damaging for of oscillation. This problem plagues amplifiers like the Collins 30L1, Dentron Clipperton L, and Yaesu FL2100.
VHF Stability Parasitics discusses causes of instability. Has spice models, pictures of resistors internal construction. Your replacement carbon composition resistor might not be a carbon composition after all!
Arcing Causes
Antenna and antenna system failures that cause power amplifier arcs
Poor or improper relay sequencing causing power amplifier arcs. This is a common problem in TL-922 Kenwood amplifiers
Improper Drive and Amplifier Tuning how incorrect drive and loading adjustments cause power amplifier arcs, especially with exciter power overshoot
Amplifier Tube Arcs causes and cures including real reasons why grid chokes fail. This is a common problem in the SB-220 SB-221, TL-922 and other amplifiers.
Improved arc protection for AL572 amplifier
Future Articles
Choke selection will describe the proper selection and construction of RF chokes
More pages soon......
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