VB6 - Faster than Timer control?

I'm coding a program where I need really fast time control. I'm trying to send digital data throught the serial port to a radio that produces some electrical pulses. Those pulses are used to send data.

I need a way much more faster than timer control to produce the pulses of around 0.000001 seconds.
I don't know if this is possible. If not, I want to know what is the fastest time that vb can produce.