This is a container ship equipped with Bulkhead(Downmast) Transceiver X-band 25KW. The crew has complained that the echo received on the radar screen was very weak, a sun can be observed from near range. Most electronic parts including magnetron, modulator, receiver pcb, limiter, TR cell...etc has been replaced by technician in other port but problem still remain the same. Ship electrician has also confirmed the waveguide was good as he pump air from one end and could receive air from the other. In order to find out whether the fault was on wave guide, antenna or the electronic unit, i have done a test to prove it.
1. Removed the transceiver end top waveguide, placed a test pen with good working bulb above the center of the waveguide.
2. Transmit the radar, the RF signal will then energize the test pen bulb, the brighter the bulb is, the stronger the signal transmit out from the transceiver.
3. Reconnect the transceiver top waveguide, go to monkey Island to open the other end of the waveguide.
4. Do the same by putting a test pen across the open waveguide, if the bulb appear very weak or totally not lid at all, then the problem lies in the waveguide along the way.
5. Open part by part to check for leakage waveguide, this is not easy. One way it can be done was to pump air at one end and block the air at the other end. Create some foam with soap and apply on the waveguide run.
6. Pump air and observe bubbles from the foam. This is the same method as checking for leak Tyre
Please see some pictures taken while troubleshooting the waveguide leak problem. This fault is very tricky, anyone find it useful can try the same method without being running up and down changing parts and test the whole day not able to identified the fault.
Radar transmitted with test pen placed on top and bulb lighted up
A typical mismatch and strong reflection from the antenna.
