The ideal companion for the 10:1-Vorteiler bis 500 MHz.

This Prescaler is a handy Accessories to extend the Frequency Range of almost any Counter to 17 GHz. The Use of a HMC494 (Prescaler) in alliance with a ADF4113HV (PLL Circuit) and a ATTINY45/85-20PU allows a division rate of 1000. Easy Reading assured !

The first stage is a HMC494 which divides the input signal by 8. It can handle a power range from approx. - 10 dBm up to + 10 dBm. It has an 50 Ω termination inside. No protection was foreseen in order not to disturb the input impedance.

The next stage is a PLL-IC (ADF4113HV) which is cheap and has the the ability to output the RF_IN divided by the Prescaler/Counter-value, which is set by an ATTINY45/85-20PU to 125.

The output of the pll-ic has TTL-level. It is decoupled via a 100 Ω resistor.
Left: 1GHz/1MHz, right: 17GHz/17MHz. Level was + 5 dBm.

As with any high frequency circuit, the power consumption is 'high'. The Hittite HMC494 consumes approx. 103 mA at 5 V supply. Therefore, the pcb may be equipped with a switched regulator (TSR1-2450) as well as a linear regulator (good old 7805).

Amplifiers with high gain tend to oscillate. So does the pll-circuit. If no rf signal is present at the input, an internal amplifier oscillates at about 14 MHz.

The PCB (printed circuit board) is made of FR4, 1.5 mm double sided. We know, that FR4 has an increasing attenuation above 3 GHz, that is why we kept traces as short as possible. The increasing attenuation compensates for the reduced maximum power of the first prescaler.

Other parts may be used as well. This is just a proposal.

In case you mayst need a programmeable prescaler (up to 18 GHz), you may kindly consider the remarkeable work of Dr. Thomas Baier, DG8SAQ and Andreas Zimmermann, DH7AZ : "Variabel einstellbarer Vorteiler bis 18 GHz mit ADF41020", published in Funkamateur, 12/2015, p. 1293. In case you are interested on the subject "Urheberrecht im Internet" the same edition has an interesting article by Niels Gründel.

The webmaster does not read these comments regularely. Urgent questions should be send via email. Ads or links to completely uncorrelated things will be removed.