A
[email protected]
- Jan 1, 1970
- 0
Hi,
I need to drive 2 capacitive electrodes with out of phase RF (0-100
Vp-p, 10KHz - 1MHz). For this purpose i got myself one of the T&C power
amplifiers (AG1021) with a gain of 53dB upto 1MHz. I planned to use a
BALUN transformer from North hills (75 ohm: 75 ohm, 1KHz - 2MHz) to
unbalance the amplifier RF. I use a function generator as a source.
However, things are not working as i thought.
The setup is as follows: Function generator feeding the signal to the
power amplifier. The output i measure on a oscope is good 100 Vp-p for
small input signal < 1 m volt (10Khz) . As soon as i connect the output
of the amplifier to the BALUN, my reflected power to the amplifier
shoots up. And the 2 unbalanced outputs of the BALUN show merely 12
Vp-p.
I know the power amplifier is rated for 50 ohm, is there an impedance
problem. With the capacitive load at the secondary of the BALUN, the
impedance which the amplifier at the primary is surely not 50 ohms.
How can i overcome this, can i just use a BALUN with more turns on the
secondary? Say 50 ohm : 600 Ohms BALUN to step up the voltage.
I would appreciate the suggestions.
I need to drive 2 capacitive electrodes with out of phase RF (0-100
Vp-p, 10KHz - 1MHz). For this purpose i got myself one of the T&C power
amplifiers (AG1021) with a gain of 53dB upto 1MHz. I planned to use a
BALUN transformer from North hills (75 ohm: 75 ohm, 1KHz - 2MHz) to
unbalance the amplifier RF. I use a function generator as a source.
However, things are not working as i thought.
The setup is as follows: Function generator feeding the signal to the
power amplifier. The output i measure on a oscope is good 100 Vp-p for
small input signal < 1 m volt (10Khz) . As soon as i connect the output
of the amplifier to the BALUN, my reflected power to the amplifier
shoots up. And the 2 unbalanced outputs of the BALUN show merely 12
Vp-p.
I know the power amplifier is rated for 50 ohm, is there an impedance
problem. With the capacitive load at the secondary of the BALUN, the
impedance which the amplifier at the primary is surely not 50 ohms.
How can i overcome this, can i just use a BALUN with more turns on the
secondary? Say 50 ohm : 600 Ohms BALUN to step up the voltage.
I would appreciate the suggestions.