RDVV 5 WATTS MOUTOULOS

[Imalu3055]

The probe and scale are paired (x10). If I remove the inductor and put the R of 680 the rms voltage does not reach 20mV. Could it be that the transistor is not the right one? I will reinstall the 680R resistor.

Claudio

 

[betwixt]

20mV seems far too low, the transistor shouldn't make a lot of difference to it. If you add the other inductor it will introduce other resonances in the circuit that could result in the instability you see.

The reason I asked about the probe is because at ~100MHz even a small error in probe calibration will show as a large voltage error. Have you followed the probe calibration procedure and adjusted its compensation capacitor according its instructions. Normally you use the 'scopes internal calibrator output to monitor a square wave and adjust the probe to eliminate under and overshoot.

Brian.

 

[Imalu3055]

You are absolutely right and it is so. I worked on the "L" coil adjusting it and managed to get almost 800mV RMS at the output, then I replaced the 15pF capacitors on the RDVV PCB and the RDVV started to oscillate. The output power I could not measure yet but it is less than 5W which confirms the low output of the oscillator. The transmitter works. It tunes perfect but I have to work on the oscillator output. I am honored to have received support and knowledge from all the members of the Forum. Thank you very much again. It is very important to know that there are PEOPLE on the other side of the network who are there to teach.

THANK YOU!!!

 

[vfone]

You have some issues reading your scope, as was mentioned shows 0.5V pk/pk.
The best results would be to let the 680 ohms resistor in place and add in series with it the 12uH inductor. The simulation shows a decrease in starting time of the oscillation and increase of the output level.