Troubleshoot Phillips 483x at converter stage (ech4 tube) (Techniek Radio/TV)

door Radiosterk , 19.06.2018, 19:06 (2132 dagen geleden) @ Goldline

Hi Goldline,

Thank you for your fast respond.

There is 0 volt at the top cap of ech4 tube since the grid is connected to rf tuned coil. Please see Philips 900x schematic.

Heptode is in cut-off mode or low gain ? For this question, i've already replace the existing tube with a good one, there is 150 volts at pin 8, 50 volts at pin 7, and 1 volt at pin 1.
There if a flat 452 Kc rf signal (no modulated rf signal) at pin 8 by using oscilloscope. I guest this heptode works well.

Warm Regards,

Winstony