Sine to square wave conversion at 275kHz?
I built this circuit to try and turn the sine wave output from the 0 dBm Drive output socket at 275.1kHz of my Kenwood TS-590S transceiver, into a square wave so it would drive the input of the Class D amplifier also shown in schematic form. I usually drive the amp with the CLK0 output of the Si5351A synthesiser in a QRP Labs U3S used as an exciter on LF. This works fine, but the U3S has push button set up so resetting modes is a chore. The amp divides the signal by two as if feeds the FET driver IC and the resulting output frequency is 137.550kHz.
I built the circuit in the .gif below, but as it stood the bottoms of the waveforms were rounded. I tried using the same resistor values top and bottom (3.6k) on the bases of the transistors and the wave squared up, but the shape and 50 / 50 mark space ratio is very voltage dependent (the squarer voltage supply, that is). What considerations decide the top and bottom resistor values and how should they affect the square wave produced? Any tips for this please? I am pretty new to all this at a home brew level so please keep it very simple, thanks
BTW the amp does have plenty of decoupling caps not shown in the schematic right on the IC power pins!
http://www.chriswilson.tv/squarer/input.jpg
http://www.chriswilson.tv/squarer/output.jpg
http://www.chriswilson.tv/squarer/device.jpg
http://www.chriswilson.tv/squarer/diffsqr.gif
http://www.chriswilson.tv/amp-less-surplus-controls.jpg
__________________
Mods Note:
Please upload all the images files to the forum, otherwise when we lose the links then the thread will be become useless, now all files had been downloaded and saved on the forum.
I built this circuit to try and turn the sine wave output from the 0 dBm Drive output socket at 275.1kHz of my Kenwood TS-590S transceiver, into a square wave so it would drive the input of the Class D amplifier also shown in schematic form. I usually drive the amp with the CLK0 output of the Si5351A synthesiser in a QRP Labs U3S used as an exciter on LF. This works fine, but the U3S has push button set up so resetting modes is a chore. The amp divides the signal by two as if feeds the FET driver IC and the resulting output frequency is 137.550kHz.
I built the circuit in the .gif below, but as it stood the bottoms of the waveforms were rounded. I tried using the same resistor values top and bottom (3.6k) on the bases of the transistors and the wave squared up, but the shape and 50 / 50 mark space ratio is very voltage dependent (the squarer voltage supply, that is). What considerations decide the top and bottom resistor values and how should they affect the square wave produced? Any tips for this please? I am pretty new to all this at a home brew level so please keep it very simple, thanks
http://www.chriswilson.tv/squarer/input.jpg
http://www.chriswilson.tv/squarer/output.jpg
http://www.chriswilson.tv/squarer/device.jpg
http://www.chriswilson.tv/squarer/diffsqr.gif
http://www.chriswilson.tv/amp-less-surplus-controls.jpg
__________________
Mods Note:
Please upload all the images files to the forum, otherwise when we lose the links then the thread will be become useless, now all files had been downloaded and saved on the forum.