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

door Radiosterk , 17.06.2018, 09:43 (2140 dagen geleden)

Good evening everyone,

I try to fix this 483x Phillips tube radio from audio stage until this converter stage, and get stuck a couple of months because of this converter stage. No reception at all from this radio.

Here are the details that i collected :
1. Using volt meter there is -8v at grid triode converter, and this oscillator signal appeared on oscilloscope.
2. If i chose band selector at bc band, frequency counter display at 900KHz - 2 MHz about.
3. If i inject 452KHz using Eico generator at top cap or grid input heptode, i could hear a loud tone from my speaker.
4. There is 150v at anode ech4 tube, and 50 volt at g2 heptode ech4 tube.
5. If i try replace the tuned coil (coil between rf and converter stage) with resistor 220k,and put the antenna at this point still no noise sound. No reception.
6. Replace the existing ech4 tube with a good one still no reception

Kindly need your help.

Beste,

Winstony