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Transitor operation

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Mistake on the schematic? Obviously, if you double 5MHz, you get 10MHz, which is 0.1us period, and you would have to run that through the first decade counter to get 1MHz.
 
The 1st transistor is a frequency doubler. It provides 10mhz output which is then divided by 10 in the 74ls90. No mistake on the schematic, these are positions labeled on the switch not test points.
 
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The first transistor has a collector load tuned to 10MHz and acts as a frequency doubler. So if S1a is in the '1uS' position the 74LS90 decade counter will be clocked at 10MHz and its output will be at 1MHz to give the required 1uS pulses.
The other transistors are just buffer amplifiers.
 
Ok , thanks...

What could be the max freq attainable with these components? Would 100Mhz (tuned collector) be possible if the crystal were a 50Mhz...or would it be better to just tune the Collector load to 100Mhz? Would the 5Mhz clock support 20X multiplication?
 
I'm doing something like this with a ocxo and syncing to lw radio braodcast.
 
Ok , thanks...

What could be the max freq attainable with these components? Would 100Mhz (tuned collector) be possible if the crystal were a 50Mhz...or would it be better to just tune the Collector load to 100Mhz? Would the 5Mhz clock support 20X multiplication?
For higher frequencies the multiplication starts in the osc. Crystals are operated in a 3rd, 5th, or 7th overtone with the tuned circuit determining the overtone.
For example; A 20mhz crystal in a 100mhz osc. would operate at 5th overtone.
It would also be necessary to use the high speed version of these divider ICs on the front end to operate at this frequency.
 
The circuit as shown ...doubles...the freq.. is this the 2nd overtone?
No, just a frequency doubler circuit with an output of 10Mhz.

"Overtone" refers to a mechanical vibration mode of a quartz crystal. Only 3rd, 5th, 7th, ... overtones are possible. When a chunk of quartz oscillates on one of its overtones, the frequency is not exactly three, five, seven times the fundamental oscillation frequency. The frequency stamped on a crystal can be either the fundamental, or one of the overtones (only the crystal maker can tell you which).
 
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