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SB-221 Tank Voltages and the parasitic myth

Tuning or loading an amplifier

Grid driven tetrodes

Grounded grid (cathode driven) amplifiers


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

3-500Z arcing gassy tube

572 Arcing

572B tube red ceramic glow



572B arcing and failures





Placing new 572B tubes in operation, or preconditioning 572's.



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  


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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