From my experiments, the following have been confirmed for my unit, unless stated otherwise.
Confirmed pinout arrangement for my particular 5650A device:
For the FE-5650A pinout we have been using for your unit, the DB-9 connections are:
| Pin | Function |
|---|---|
| 1 | +15 V |
| 2 | 15 V ground |
| 3 | LOCK/BITE status |
| 4 | +5 V |
| 5 | 5 V ground |
| 6 | EFC — Electronic Frequency Control. UNCONFIRMED. |
| 7 | Signal ground |
| 8 | TTL serial input. UNCONFIRMED. |
| 9 | TTL serial output. UNCONFIRMED. |
Wiring up the 5650A rubidium time source at LRO:
Two regulated power supplies are required: 15V and 5V. 15V supply needs to capable of 3A, 30W.
Pins 2 and 5 (both grounds) should be connected together.
Lock/bite status indicator pin requires 4k7 pull-up resistor connected to it with other side of resistor connected to +5V power supply.
Power-up sequence for 5650A:
- Turn ON 15V power supply first.
- turn ON 5V power supply second.
Voltages seen on lock/bite status indicator vs signal ground with 4k7 pull-up resistor present:
The absolute voltages are unusual for a simple 5 V open-collector output, but the state change is highly repeatable and correlated with the rubidium unit reaching its low-power steady state.
| Condition | Pin 3 |
|---|---|
| 15 V just switched on / warming | ~3.2 V |
| Warmed up / likely locked | ~1.0 V |
| 15 V removed, 5 V still present | ~1.2 V |