CHAPTER 17.   OPERATION OF EQUIPMENT

SECTION 11.   WIND RETRANSMITTER

17-90.   GENERAL

There are two types of wind retransmitters used in the field. The magnetic amplifier type is powered by two mercury cells and has no provision for testing wind direction. A newer type is powered by alternating current (AC) and does have a switch for testing the wind direction indicator.

17-91.   WIND RETRANSMITTER - WEEKLY CHECK

At least once a week, the observer should check to determine that the retransmitter is within the tolerances shown below. This is done as follows:

a.  Advise each office having a wind indicator drop from the retransmitter that a test is being made.

b.  Depress the "TEST" button on the retransmitter panel.

c.  With the "TEST" button depressed, check the value on the master wind speed indicator. This value should be within 1 knot of the calibrated speed at 600 RPM.

d.  If the master indicator is not within tolerance and:

(1)  You have a magnetic amplifier type retransmitter, replace the two mercury cells, observing correct polarity. (If the meter is still out of tolerances, the electronic technician shall be notified.)

(2)  If the station has an AC powered instrument, corrective maintenance should only be done by the electronic technician.

e.  When the master meter is within tolerance, make a quick check of all other wind speed meters connected to the retransmitter. Each meter should be within 1 1/2 knots of the master meter and should show about the same differences in subsequent checks. To compare weekly checks keep a record of the readings from each meter. A sample record is shown in Figure 17-13, Wind Speed Comparison Data.

Figure 17-13. Wind Speed Comparison Data

Reading When Test Switch is Depressed
Indicator

Date

Master1

1

2

3

4

5

Remarks

1/5/86

59.8

60.1

61.0

59.8

59.8

61.2

  

1/12/86

59.7

60.0

63.2*
60.1

59.5

59.7

60.3

Indicator #2 replaced

1/19/86

59.0

59.5

60.2

59.0

59.5

59.8

  

1/26/86

58.0*

(Calibrated speed = 60.1)

Battery replaced

1/26/86

60.1

59.8

59.8

60.2

60.0

60.2

  

2/3/86

59.7

59.6

59.7

60.2

59.8

60.0

  

1 Compared with calibrated speed at 600 RPM
* Maintenance required

17-92.   WIND RETRANSMITTER - OTHER CHECKS

a.  Direction Output of Magnetic Amplifier Type Retransmitters. No special provision is made to test the direction output of battery powered retransmitters. Frequent visual checks of wind direction should be made and suspected malfunctions should be reported to the electronic technician.

b.  Direction Output of AC Type Retransmitter. To test the direction output, the observer shall set the switch on each of the four directions. To be within tolerance, the direction indicated must be within 5 degrees of the direction set on the switch. The observer shall notify the electronic technician if the wind direction is not within tolerance.

17-93. - 17-96. RESERVED