The GPS engine shown is Navman Jupiter-T, part TU60-D120-041. Alas, in 2005 Navman discontinued manufacture of the Jupiter-T and my stock is exhausted. I can no longer supply the Jupiter-T.
However the standard Jupiter receivers TU30-D140-xxx and TU30-D410-xxx also have the 10 kHz output and can be used OK. It's a similar size, but the connector and pin-out is different. These receivers are often available on eBay. Before purchase, make sure that the firmware is v1.80 onwards. This is important; very early models 1995-1997 e.g. V1.16, V1.18 are not stable enough for the first few hours after power-up, and the first production (e.g. V1.03) were not even synchronised to UTC. The firmware version is printed on the label, and is also emitted at start-up in an ASCII plaintext NMEA message.
The interface PCB (part 0082-004) is available; it is 2-sided, plated-through hole, with maximum copper ground-plane, solder resist both sides and lead-free. The price at cost is GBP 17 including postage. For constructors who have difficulty obtaining the C-MAC (now RAKON) VCXO, I can supply it new from Farnell, at cost, for GBP 19.
In response to many requests, I can now supply a built and tested system similar to that shown at the top of this page for GBP 110 plus secure shipping. Note that the supplied unit will have a standard Jupiter GPS receiver, not the Jupiter-T since these are no longer available. I do not include a 12V DC 250 mA power supply, and I am unable to supply GPS antennas.
Here's the schematic (latest version of PCB); click on the diagram for full size.
PCB parts List (Part 0082-004)
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Ref Qty Description Farnell Notes
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X1 1 10 MHz C-MAC (RAKON) IQVCXO-161-B 971-2232 Or similar
U1 1 MAX233CPP 125-6273 or 938-6572
U2 1 74AC86 383-302 or 110-5997
U3,4 2 74HC390 380-787 or 119-1835
U5 1 74AC14 101-4022
L1 1 10µ Inductor 117-3864
C1,3 2 10µ 6.3v tantalum 970-8200 or 110-0451
C2 1 100µ 6.3v tantalum 970-8243 or 110-0455
C4 1 10u 35v (for 12V operation) 970-8570 or 110-0496
C5-8 4 100n 100v polyester 110-0429
R1 1 160k 1/8W MF12 934-2702
R2,3 2 22k 1/8W MF12 934-2842
R4 1 470R 1/8W MF12 934-3245
R5-8 4 200R 1/8W MF12 934-2770
Reg 1 Voltage Regulator LM7805CT 110-2157 For 12V operation
D1 1 1N4001 diode 956-4993 For 12V operation
Q1 1 BC547, BC107 etc NPN 109-7287
Terminals 2 Red Vero RS 262-2220 873-1209
16 Black Vero RS 262-2214 873-1195
DIL Socket 1 20-pin DIL socket 428-5608
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Note: Farnell Electronic Components is a world-wide supplier. But none of the parts is unusual, and will be available from your favourite dealer.
Using An External Oscillator
Here is a system using a better quality oscillator.
GPSDO using an Isotemp OCXO 134-10, often available on eBay. The ovenised oscillator has considerably better performance than a simple DIL packaged device, but at the cost of greater power consumption and increased size.
The Isotemp oscillator has an EFC range 0 to +8 Volt and the little circuit mounted on its pins is a simple DC amplifier with gain x1.6 to magnify the phase detector output from 0-5V up to 0-8V. Many people asked for this PCB, not realising that it was hand-made, masked, etched and drilled, one-at-a-time. So I had to have a batch made properly, 2-sided max copper and solder-resist (part 0083-001). This is available at cost for GBP 10 including shipping world-wide.
This OCXO has a sensitivity of 2 Hz/Volt (i.e. 3.2 Hz/Volt at the DC-amplifier input). Suitable PLL filter components are R1=160k, C1=100µF, R2,C2 not fitted.
Because the OCXO 10 MHz output is AC coupled, add pull-down 4k7 to 0V and pull-up 4k7 to +5V. These connections are to the OCXO output, and can be most easily mounted on the underside of the (green) PCB. The latest PCB (-004) has pads for these resistors.
In response to requests I supplied many of these IsoTemp-based GPSDOs built and tested. But I have no more IsoTemp oscillators.
However, if you have an IsoTemp OCXO134-10 and a suitable Jupiter GPS RX I am still able to construct it for you. A photo. The manual. Contact me by email, please.
Simple GPSDO Project - Summary of available items
Built and tested 'simple' GPSDO system:
10 MHz GPSDO based on DIL oscillator £115.00
Shipping by secure service: UK £ 10.00
EU/US/AUS etc £ 15.00
Component Parts (supplied at cost) including world-wide shipping
PCB: GPS Interface/PLL part 0082-004 £17.00
PCB: DC-Amplifier for Isotemp part 0083-001 £10.00
DIL packaged oscillator C-MAC/RAKON IQVCXO-161 £19.00
Please note that the above are the only items I can supply. Regrettably, I cannot supply separate Jupiter GPS receivers, GPS antennas, power supplies, Isotemp oscillators or kits of parts.
Last updated: 2008 Mar 30