[Amps] Harbach metering board in SB-220

[peter chadwick]

>Heath used a 5K6 resistor (R9) from the bottom end of the 3x 4M7
string to chassis. Its value is uncritical, as its function is only to prevent the
bottom end of the 3x 4M7 string from soaring to HV when the meter switch
is NOT in the "HV" position.<

Which is more than Collins did in the 30L1, although 1600 volts or so is a bit different to 2.5kV! Nevertheless, way over the ratings for a standard phenolic wafer - but they got away with it. Although Heath, in at least one of their VTVMs, used a phenolic wafer on the range switch and had a 1500 volt input rating.

73

Peter G3RZP