December 2018 Diode Tester article correction

In the December 2018 edition of RadCom we published the Multi-Mode Diode Tester article by Dave Ellis, G4AJY. Unfortunately some gremlins crept into the circuit diagram, meaning that it wouldn’t work as intended if built as shown.

The main problems were the 1M resistor R4 and the labelling of switch Sw1b..

R4 was incorrectly shown as being connected between the +60V rail and the output. Its function is actually to ‘bleed off’ the 60V rail when the device is switched off, as shown in the corrected diagram below.

The circuit diagram correction also affects the wiring diagram (Figure 4 in the article); ensure you wire Sw1 in accordance with the details shown below. Please also be aware that the PCB layout in the article connects R4 to the 20V position rather than Off; this can be corrected if desired, but does not affect the function to any significant degree.

We apologise to Dave, G4AJY and anyone else who may have been affected by these errors.

Corrected circuit diagram for Diode Tester published in December 2018. Click image to embiggen.

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