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DMcMahon · 27th Feb 2020, 9:28 pm

Borrowed a 1.2 Mohm resistor (R2) from my TK 5 and fitted it into the TK 819 as a temporary replacement for the open circuited R9 (1.25 Mohms).

Now get more normal voltages at the EF 86 valve, namely 33 volts at pin 5 Screen Grid (G2) and 45 volts at pin 6 (Anode) and the HT voltage at top end of R9 has dropped down from previous 200 volts to 166 volts. The HT voltage the other side of R10 which feeds R9 and R8 (anode resistor) is 199 volts.

Note - TK 819 schematic shows 100 volts at top end of R8, for various reasons I think this is incorrect/not accurate.

So the Screen Grid resistor made a substantial difference to the anode voltage (thankfully).

No obvious visual change to the EF 86 brightness.

27th Feb 2020, 9:28 pm	#207
DMcMahon Dekatron Join Date: Apr 2019 Location: Worthing, West Sussex, UK. Posts: 6,603	Re: Grundig TK 819 Any Useful Info Borrowed a 1.2 Mohm resistor (R2) from my TK 5 and fitted it into the TK 819 as a temporary replacement for the open circuited R9 (1.25 Mohms). Now get more normal voltages at the EF 86 valve, namely 33 volts at pin 5 Screen Grid (G2) and 45 volts at pin 6 (Anode) and the HT voltage at top end of R9 has dropped down from previous 200 volts to 166 volts. The HT voltage the other side of R10 which feeds R9 and R8 (anode resistor) is 199 volts. Note - TK 819 schematic shows 100 volts at top end of R8, for various reasons I think this is incorrect/not accurate. So the Screen Grid resistor made a substantial difference to the anode voltage (thankfully). No obvious visual change to the EF 86 brightness.