yesterday evening I have started some measurement about 6HV5A used like 845 driver.
The schematic was very simple: inductance on anode, Rk = 100ohm, Ck = 470uF, Rg = 75Kohm and output capacitor 2.2uF on 33 or 100Kohm load.
With medium voltage operation (about 600V) these tubes give low sperformances because distortion is high 1.1% at 25Vrms.
The good result are obtain using 980V and 100ohm on catode to keep the power nead the 30w (35w is the maximun allowed), bias about 30mA.
With these value I have got the good 1% at 120Vrms on 33Kohm load.
The freq. response is limited to 50Hz(-3db) with 20H but it will be 10Hz(-3db) using 100H 50mA Sowter 8982.
The voltage amplification is 120/0.7=155x.
audiodesign has attached this image:
Click the thumbnail to see the original image.
The schematic was very simple: inductance on anode, Rk = 100ohm, Ck = 470uF, Rg = 75Kohm and output capacitor 2.2uF on 33 or 100Kohm load.
With medium voltage operation (about 600V) these tubes give low sperformances because distortion is high 1.1% at 25Vrms.
The good result are obtain using 980V and 100ohm on catode to keep the power nead the 30w (35w is the maximun allowed), bias about 30mA.
With these value I have got the good 1% at 120Vrms on 33Kohm load.
The freq. response is limited to 50Hz(-3db) with 20H but it will be 10Hz(-3db) using 100H 50mA Sowter 8982.
The voltage amplification is 120/0.7=155x.
audiodesign has attached this image:
Click the thumbnail to see the original image.