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The ULTIMETER wind sensor design is elegantly simple. There is not much to go wrong and it is relatively easy to check, as outlined below. If you need to contact our service department about your wind sensor operation, information from these checks will help us resolve any difficulty correctly and quickly.


If the cups are able to turn freely, they must rotate according to the velocity of the wind actually reaching them. Wind velocity at the cups may differ from that at nearby locations because of intervening trees, terrain contours, turbulence from the side walls or roof, sensor height, etc. 
Once in a great while a misguided spider or such may try to make a home in a wind sensor. This can slow down or even stop the cups entirely. On all ULTIMETER 2100, 800, and 100 stations you can easily remove the anemometer rotor and wind vane for cleaning. Simple instructions are included in your owner's manual. No tools are required. To clean out cob webs or such from older wind sensors, use a pipe cleaner without removing the rotating housings.

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We use the same temperature sensors for indoor and outdoor measurement. The sensors are so accurate and reliable that no temperature adjustments are required or provided, not even factory adjustments. If you suspect temperature readings are off a little, see whether readings some external factor may be influencing the readings. For example, if your control unit is mounted on an outside wall, the wall temperature may be affecting your indoor temperature readings. You might wish to review keyboard and temperature sensor mounting guidelines in your owners manual. If mounting location doesn't seem to answer your question, perhaps one of the simple checks below will. If you need to contact our service department about your temperature operation, information from applicable checks will help us resolve any difficulty correctly and quickly.


A temperature reading of about 150 degrees F indicates a short circuit. Unplug the temperature sensor from the junction box. The temperature display should change to -49 degrees F or all dashes, depending upon which weather station you have. If it does, the problem is definitely not in the control unit. Probably something has damaged the temperature cable - perhaps it has rubbed against a sharp object or an animal has chewed on it.


A temperature reading of - 55 degrees F or all dashes indicates an open circuit. If you own or can borrow an ohmmeter, it's easy to test the temperature sensor and its cable. The male modular plug on the end of the temperature cable has 4 gold plated contact wires. The gold plated wires are recessed slightly within the modular plug. Most test meter leads are a little too thick to make contact with the gold plated wires. A simple technique is to tape a straight pin to each meter lead and use the straight pins to contact the gold plated wires.

There should be less than 5 ohms resistance between the two terminals on the left side of the plug. There should also be less than 5 ohms between the two terminals on the right side of the plug. If the meter shows an open circuit between either of the two left terminals and either of the right terminals, something has probably damaged the temperature cable and it should be repaired or replaced. Be sure to waterproof any outdoor splice.


The indoor temperature sensor is located next to the modular phone receptacle on theright side of the instrument, far from the backlight lamps. Even so, if there is not good ventilation around the instrument, leaving the lamps on full time may increase readings slightly.


About the only way this can happen is if you're using an extension cable and there is corrosion where the extension cable connects to the temperature sensor cable. Clean or replace corroded connectors and be sure to completely waterproof the joint.


This is almost always an indication of electrical interference from a nearby source such as a powerful radio transmitter. The cure is to separate the temperature sensor cable further from the source of interference if possible. or to install an optional RFI filter. If only the highest or only the lowest reading is abnormal, the problem might be an intermittent shorted or open circuit. Because the problem is intermittent, the current reading may be ok, yet when no one is watching, the problem may occur briefly, which throws off the highest or lowest reading. An intermittent problem is most likely to be in an outside sensor or cable.

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The ULTIMETER TB rain sensor mechanism is very simple, both mechanically and electrically, so it is relatively easy to check its operation, as explained below. But first, an uncommon and baffling symptom:

If your ULTIMETER shows increasing rain readings when there is no rain or when no rain gauge is connected, the cause is almost surely a crossed wire in one of the modular receptacles, at the keyboard, junction box, or signal splitter, if used. Check the 8 and 10 conductor receptacles. If one of the gold plated wires is out of its grove and touching the adjacent wire, gently ease it back into place with a wooden toothpick or such.


To test whether a TB rain gauge is functioning, remove its cover. Note the rain reading on the display, then touching only the side of the bucket, slowly tip the see-saw mechanism to the opposite position. Wait 5 seconds, then tip it back. Again wait 5 seconds and repeat. Continue in this fashion until you have tipped the mechanism 10 times in each direction. The displayed total should have increased by 20 counts.

If your TB rain gauge appears not to be working at all or if it appears to be working intermittently, something may have damaged the rain gauge cable. If you can't find any fault in the cable, or if you have a wireless rain gauge, please contact our service department for further assistance.


If your TB rain gauge is not functioning, an electrical check can frequently help pinpoint the problem. If you own or can borrow a continuity tester or an ohmmeter, it's easy to test the rain gauge and its cable. The male modular plug on the end of the rain cable has 4 gold plated contact wires. The gold plated wires are recessed slightly within the modular plug. Most test meter leads are a little too thick to make contact with the gold plated wires. A simple technique is to tape a straight pin to each meter lead and use the straight pins to contact the gold plated wires.

Refer to the sensor pinout diagram for the TB Rain Gauge. Touch one meter lead to the Rain terminal and the other lead to the Gnd terminal. Have someone very slowly tip the rain gauge mechanism to the opposite position. As the gauge goes through the midpoint, your tester should briefly indicate electrical connection between the two leads. If it does not, either the reed switch assembly has failed, or something has probably damaged the cable, and it should be repaired or replaced. Be sure to waterproof any outdoor splice.


If there is any question about the accuracy of one of our 0.1 inch (2.5 mm) or 0.01 inch 0.25 mm) TB rain gauges, you can verify its accuracy by dripping water into it very slowly. Either size gauge should tip from one direction to the other after you have put in 7.4 cubic centimeters of water, in either of the buckets.  Most pharmacies sell an inexpensive 10 milliliter (10 cubic centimeter) liquid medicine dispenser that is ideal for this calibration check.  The calibration is changed by adjusting the stop screws upon which each bucket rests after tipping.  Raising the stop screw makes the bucket hold more rainfall before it tips; lowering the stop screw causes the bucket to tip with less rainfall received.  Adjust the screws (this means two calibrations, one for each side of the bucket) so that the bucket tips at 7.4cc of water received. 

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The ULTIMETER calculates wind chill for ambient temperatures from -50 to +50 degrees F. and for wind speeds from 0 to 125 mph. At temperatures above 50 degrees F, the indicated wind chill temperature will be the same as the current temperature, regardless of wind speed.

If the ULTIMETER temperature sensor is disconnected or if the temperature cable has been damaged, the instrument may think the outside temperature is -55 degrees F. In this case, when it registers a wind of 15 mph wind or more, it will calculate and retain a low wind chill of below -100 degrees F, which it cannot display. Instead, when you attempt to display the lowest wind chill, the ULTIMETER will flash the display rather frantically. If this happens, first be sure the temperature sensor cable is undamaged and is properly plugged in. Then press the clear key and keep it pressed for about 5 seconds, until the flashing stops. If you anticipate wind chill readings below -99 degrees F., you may wish to switch the ULTIMETER to Celsius, then convert readings back to Fahrenheit.

The ULTIMETER 2100, 800 and 100 calculate wind chill for ambient temperatures from -50 to +91.4 degrees F. and for wind speeds from 5 mph to 125 mph. Also, the ambient temperature wind chill temperature displayed for winds less than 4 mph are equal (no wind chill effect occurs).

Within the above bounds, if the temperature and wind functions are working correctly, it is almost impossible for the wind chill temperature to be wrong.

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It would be very difficult for most customers to check the accuracy of a humidity sensor. There are no readily available, easy-to-use humidity standards. Considerable care and experience are needed to obtain reliable results even from seemingly straightforward approaches, such as sling psychrometers or saturated salt solutions.

Probably the best opportunity to verify outdoor humidity readings is when there is heavy ground fog. The humidity reading then should be at or close to 100%. You could also verify the indoor sensor on such a day by temporarily setting it outside in a sheltered spot.


The humidity sensor we selected for ULTIMETER systems employs new technology that provides exceptional accuracy. We believe the sensor will also prove to be very reliable. The few problems we have seen resulted in gross errors, so there was really no doubt as to a malfunction.

If you believe there is a problem with your humidity sensor, please contact our technical support group.

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Please contact Peet Bros. if you believe there is a problem with your pressure readings - to date none have been reported.

Remember that if you remove all power from the instrument, it will lose the necessary calibration for your location and will display dashes instead of a pressure reading, until you enter the known sea level pressure.

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ULTIMETER keyboard/display units have proven extremely reliable, especially our newer Models 2100, 800, and 100, with their built-in static electricity protection and near "bullet proof" design. Below are a few conditions, particularly on the ULTIMETER II, that you can correct at once.

One very important note of caution: Regulated power is brought to at least one pin of almost ever receptacle in the the ULTIMETER 2100, 800, and 100 keyboard, junction box and signal splitter. Only insert the intended plug into any of these receptacles. If you intend to make up any cables of your own, be sure to follow exactly the guidance in our FAQ pages, which you can also access from our Showroom and Customer's Corner.


The microprocessor is probably "hung up", from a static electricity build up on an outdoor sensor cable. This can happen during an electrical storm but also during other conditions such as when there is a strong, dry warm wind blowing or when there is no electrical storm, but falling rain drops are electrically charged.

To fix the problem, unplug the battery and unplug the cable from the back of the keyboard/display unit, wait 5 or 10 seconds. Then reconnect the AC adapter plug. The instrument will probable now be fine. Remember to reenter time, date and your wind direction calibration number.

Peet Bros. offers a Static Electricity Discharge Unit that can help protect the keyboard from static electricity build up on the anemometer/wind vane cable. It plugs into the junction box and has a threaded ground terminal on the side.


If just the Compass Rose is flashing, this is the low battery/no battery indication. A battery check is made each midnight and also whenever you press the rain key. Press the clear key to stop the flashing temporarily and insert or replace the battery as soon as you conveniently can to protect against ac power outages.

If the whole display flashes when you try to display wind chill or lowest wind chill, the temperature sensor may be unplugged or have a damaged cable. Please refer to VERIFYING THE WIND CHILL FUNCTION.

If the whole display starts flashing periodically on its own, there may be a crossed wire in an 8 conductor receptacle on the junction box or the keyboard or on the splitter box, if used. This can cause wind signals to increment the rain total. Eventually the rain display capacity can be exceeded and the keyboard will flash to alert you.

To restore normal operation, ease the wire back into its proper groove, using a wooden toothpick or such.


The instrument will display the current readings, but it will not display the highest or lowest temperature values. This is not really a problem. What has happened is that someone started to select data to be included in the automatic scan sequence, but did not finish the process. Since highest and lowest values can not be scanned, the instrument ignores the up and down arrows until you complete the scan selection process.

To restore normal operation, press and release the scan key and all should be well again.


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The ac adapter supplied with our systems is rated at 12 volt dc output. Under no load or the rather light load of our system, these adapters will typically put out about 13v or 14 volts dc. This is not a problem; the instruments can operate directly from the output of an automobile alternator, which is about 14.6 volts.

CAUTION:  Do not use an ac adapter rated higher than 12 volt dc output. Under light load it might put out 18 to 20 volts, which could damage the instrument.

The function of the backup battery is, during brief power outages, to maintain full operation of an ULTIMETER system, while retaining calibrations, units selections and stored data. A fresh 9 volt alkaline battery should power a basic ULTIMETER 2000 for more than 24 hours and power an ULTIMETER II for more than a week. There should be almost no drain on the backup battery while external power is being supplied to the instrument. Although a backup battery is obviously very desirable, it is not required for proper operation of an ULTIMETER Weather Station.

If any aspect of your system's operation appears inconsistent with the above description, please contact our customer service department for guidance.

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The ULTIMETER II junction box only serves to interconnect cables attached to it; there are no working components inside. The ULTIMETER 2100, 800 and 100 junction boxes include devices that protect each of the outside sensors from static electricity build-up, so that excessive static electricity can be run off to earth ground.
"Keep a weather eye on Peet Bros."
USA Manufacturer of Weather Instruments,Home Weather 
Stations,Anemometers,Rain Gauges,Wind Sensors, Barometers,Humidity 
Sensors,Barometric Pressure Sensors,APRS Weather Stations,Ham Radio 
Weather Stations,and ULTIMETER Weather Sensors

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