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Home › Archive for Restorations

Category: Restorations

HMV 2007R transportable record player

By Michael Watterson Posted on 13th Aug 2020 Posted in Restorations

I was surprised to see this in the local animal welfare charity shop. I thought it looked too large to be an attaché case radio and too small to be a record player. Though it was styled like many 1950s …

HMV 2007R transportable record player Read more »

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Definitioner

Grid
An intermediate electrode between the Cathode (or Filament on a direct type) and the Anode (Plate). Types of grid include "Control" (g1) which controls the electron flow, "Screen" (g2) which is an electrostatic screen between Anode and Control grid improving RF performance, "Suppressor" (g3) which suppresses secondary emission between the Anode and Screen grid. The Control g1 is usually more negative than Cathode, Screen g2 is usually at a higher voltage than Anode and Suppressor g3 usually at Cathode voltage. Physically the grids can be helical fine wire, a mesh, rods, plates. Rods or Plates need an electron beam.
Cathode
The source of electrons in the device. if "indirect" then the cathode is tube with an internal insulated heater. A filamentary cathode is a filament heated by voltage across it which acts as the cathode.

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