Monday, January 11, 2010

500kHz - easy start revisited

Reaching further in my BOM, I found a 7493, which is a four-bit ripple counter having four flip-flops, so, divide by 8 is no problem.

The present easy start plan consists of an oscillator using one inverter of a 74HC240 as an oscillator with ceramic 4Mhz resonator, pulse shape the signal with a second gate. Divide the output by 8 with the 7493. This should provide a 500Hz signal.

Option 1: The resulting 500Hz signal could be fed into one inverter of the 74HC240 and into two paralleled inverters. The inverted 500Hz signal will be sent through the two further inverters. In this way, I will have made myself a little push-pull arrangement.... NPN-PNP complementary PA...

Option 2: Parallel all remaining gates and use some step-up transformation to a PA's impedance.

Experimental option: Parallel all remaining inverters and directly feed a low-ohmic aerial for QRPp experimenting.

Alternatively, one could use a 7404, here I see two inverters used for the oscillator and pulse shaping, the remaining four gates could be used in parallel.

No comments:

Post a Comment