13 GHz Frequency Counter Prescaler

A fairly simple `divide-by-1000` circuit which was first designed by Zeljko Bozic, S52ZB, in a 2006 issue of VHF Communications Magazine. The idea of this project is to extend the range of older (and cheaper) frequency counters. You can often find 100 MHz frequency counters for as little as $20 at hamfests or eBay, and this simple circuit wi

ll extend their range up to at least 13 GHz. This version is based around a Hittite HMC363 divide-by-8 prescaler, a Fujitsu MB506 divide-by-64 prescaler, and a "divide-by-1. 953125" circuit using standard digital logic. The Hittite HMC363 front-end prescaler is good up to 13 GHz or so, and will do 15 GHz if you increase the input RF power a bit and minimize the prescaler`s exposure time. It`s possible to pick up the Hittite HMC363 evaluation board for around $100, or you may be able to receive a couple HMC363s as free samples. The evaluation board will be ideal, as it`s properly designed for high-frequency microwave work. The Fujitsu MB506 can be found in some MMDS or satellite TV downconverters, the Fujitsu MB501 can probably be substituted with a slight circuit change. Fujitsu MB501 prescalers can be found in older analog cellular phones. The rest of the circuit is just a simple ECL-to-CMOS logic converter using a Maxim MAX961 high-speed comparator, and some 74HC390 ripple-counters and 74HC02 NOR-gate logic chips wired up as a divider. The output of the Fujitsu MB506 is in Emitter-Coupled Logic (ECL), which means the signal is 1. 6 volts peak-to-peak with a DC offset of around 3 volts. The Maxim MAX961 compares this signal to a preset reference DC voltage and converts the signal into one with the normal +5/0 volts that we`re used to. The "divide-by-1. 953125" circuit is based around the fact that by using three...

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