2024-03-25

Next Generation Beacons

1 GHz VCO-PLL Clock - CVCO55CX-1000-1000 ADF4107

Overview

VCO-PLL

DDS

GPS reference

Distribution amplifiers

Service management

Sequence

PI4

Software

Emanuele, IW9GDC - "... I can really say that this hardware is actually the best ever made ..."

The OZ7IGY VCO-PLL board is heart in the Next Generation Beacons hardware but cal also be used for other clocking purposes. The VCO is locked by the PLL that is locked to a 10 MHz signal from the GPS board.. The use of GPS synchronization ensures accurate frequency. The output level is 0 dBm that can be fed directly into the DDS board or to a 1 GHz distribution amplifier if more than one DDS board needs the 1 GHz clock e.g. on a multi beacon site.

The VCO-PLL board uses an Analog Devices ADF4107 PLL that is controlled by an Atmel ATmega328 and a Crystek CVCO55CX-1000-1000 ultra low noise VCO. Alternatively a cost efficient Sirenza VCO190-992T VCO.

The VCO-PLL board also features an in-circuit serial programming (ICSP) connector for updating, configuration and service management.

The VCO-PLL board fits into a standard tinplate box or a milled alu-box.

The VCO-PLL board may also be used for other purposes where a 1 GHz clock is needed.

A 1 GHz distribution amplifier board is also available in case you want to connect more than DDS board, i.e. you want to have more than one beacon on the air.

Software

A software package is available for setting up and managing the VCO-PLL unit.

Software support is provided on the above package. From time to time new functionality is added under tight version control. The package is available with both source code and a compiled .hex file. This way specific modifications may be applied for any given application.

When cycling the power supply to the VCO-PLL it is recommended to wait at least ten seconds to ensure all capacitors are properly discharged.

Parameters

DC characteristics	Unit	Notes
Voltage	7,5 V - 15 V
Current	110 mA
Power consumption	1,5 W
RF characteristics	Unit	Notes
10 MHz lock	>-10 dBm	Datasheet for ADF4107 says -5 dBm to +5 dBm
Frequency	1 GHz
Output power	0 dBm
Second harmonic	<-30 dBc
Third harmonic	<-50 dBc
Unwanted spurious	<-70 dBc	No 10 MHz reference signal found
Phase noise	Please see plots below
Ports	Connector	Notes
Supply	2 pin Molex
10 MHz input	BNC female
RF out	SMA female
1 GHz lock	TOSLINK (optional)	A two or three pin Molex connector will also fit
ICSP	6 pin header	Standard Atmel configuration
Service	USB B, female
Mechanical	Unit	Notes
Size	54 mm x 110 mm	Fits into a standard tin plate box. Box is optional
Weight	45 g

One LED indicates when 12 V is applied and another LED indicates when the PLL is locked.

Phase noise for the high performance Crystek CVCO55CX-1000-1000. Source: Crystek datasheet.

Phase noise for the low cost Sirenza VCO190-992T. Please note that the noise performance is limited by the spectrum analyzer, HP8593E.

Frequency stability vs. time for the low cost Sirenza VCO190-992T.

Availability

The price for an assembled, tested and ready-to-use VCO-PLL unit with a Crystek CVCO55CX-1000-1000 VCO is 2125 DKK*.

The price for an assembled, tested and ready-to-use VCO-PLL unit with a Sirenza VCO190-992T VCO is 1748 DKK* (243 EUR).

Example of a milled alu-box showing RF out at the top left. In front is from left the PLL lock LED, 10 MHz input BNC, PLL lock TOSLINK opto-transmitter, USB port and 12 V LED.