Purchase Price :- $329 See links at the end for better deals.
UK pricing sucks (£298) on this so buy in the US if you shop round you should get it for around ($220)
Belt Mount Carry Case :- Extra $16 (Two Types)
Includes: Long & Short lanyards soft carry bag instruction and 2off AAA batteries.
Options :- Computer interface unit ($79)

Weather Functions :-

Wind Speed
Accuracy ±3%
Response Time 1 second
Calibration Drift <2% after 100 hours use at 7m/s

Temperature
Accuracy
Temperature ±1°C
Wind Chill ±1°C
Dew Point ±2°C
Heat Index ±3°C
Response Time approximately 1 minute for most conditions

Relative Humidity
Accuracy ±3%
Response Time approximately 1 minute for most conditions
Calibration Drift ±2% over 24 months (can be field calibrated)

Barometric Pressure
Accuracy ±3hPa (between -10°C and 60°C)
Calibration Drift ±1hPa over 12 months (can be field calibrated)

Altitude, Density Altitude
Calculated from other measurements

Display

Update 1 second
Temperature Range Normal operation from -20°C to 60°C [-4°F to 140°F]. Below
-20°C [-4°F], accurate readings may be taken by keeping the unit warmer than -20°C [-4°F] and exposing it for the minimum time necessary to take a reading (less than 1 minute).
Storage Temperature -30°C to 60°C [-22°F to 140°F].
Auto Shutdown After 15 minutes of no button presses. (This feature can be disabled.)

Physical

Battery Two AAA alkaline batteries (included). Typical life, 400 hours.
Impeller 25 mm. [1in.] diameter, sapphire bearings, light weight. User-replaceable impeller/housing assembly.
Temperature Sensor Hermetically sealed precision thermistor.
Humidity Sensor Solid state silicon capacitive sensor.
Pressure Sensor Monolithic silicon piezoresistive sensor.
Dimensions 12.7 x 4.5 x 2.8 cm. [5 x 1.8 x 1.1 in.]
Weight 102 g. [3.6 oz.]


I was waiting for a long time for the pricing on these to come down in the UK. I think I could have waited for ever! In the end I found a US dealer that was selling them at a tremendous discount that enabled me to buy the unit with spare impellers, belt carry case and the computer interface kit shipped to the UK including customs charges for over £50 less than the cost of the Kestrel 4000 unit alone in the UK.

I had seen the Kestrel 1000 unit before as a fellow RC model flying club member has one. The 1000 only shows the wind speed and takes no other measurements. I liked the 1000 unit and did consider buying one. Taking the wind speed readings is very useful for my RC model and kite flying.

The Kestrel 4000 is a far more advanced unit as you can see from the specs listed above, not only does it take the above listed readings but it also records them to the internal memory. It does this when the unit is switched off as well so that you can turn the unit on and look at the historical display of the previous readings. This is excellent for predicting changing weather conditions.

The unit is constructed from bright orange injection moulded plastic, you can also get it in black but I thought this may be a bit easy to lose. It is similar in size to a standard mobile phone (Not one of the newer ultra small versions) The unit is weather sealed (good job really) and is waterproof.

The sensors are contained in the top and rear of the unit. The wind measuring impeller runs on jewelled bearings and is fitted with a plastic flip cover to stop it from operating until required. The impeller can be replaced by the user if and when required. The Humidity and temperature sensors are located next to the impeller on the left hand side of the unit. They are protected by the casing around the sides but are exposed front and rear to allow rapid changes to be measured accurately. I would be careful not to place it on a surface or in a bag that may contain objects that would damage these. The pressure sensor is located on the back of the unit and consists of a small recessed hole.

It is powered by two AAA batteries that fit through a hatch in the base if the unit. There is a rubber gasket round this hatch to keep out the water. The batteries are rated for a typical life of 400 Hours (That about 16.5 Days of constant use). As I said before the unit still takes readings when it is switched off. This may shorten the battery life depending of the sample rate that you set for the readings. But even so 400 hours divided by a 5 second sample time every 10 minutes is still a long long time. Having not had the unit for very long I still don't know for sure how long they actually last. I will update this in a few weeks when I get to know more.

Operating the unit is reasonably simple. To turn it on press the red power button. The unit will power on and show the firmware version (Not upgradable) and the battery status for about a second then it will revert the screen that it was on the last time it was switched off.

Once the unit is powered on then the rest of the keys become useful. The up and down cursor keys will move through the various different sensor display screens for the unit see below for example screen listings. The left and right arrow keys will change the display for the current measurement to additional screens for average and trended reading depending on the selected measurement.

There are additional buttons for the screen backlight and take measurement snapshot button.

The backlight make nightime or overcast viewing a lot better. The snapshot button override the default sample time and takes an instant reading and stores it in the data log.

The data log can take 250 samples before it becomes full. When full it can stop taking readings until reset or it can be set to overwrite. The automatic sampling can be turned off altogether or pre-set to one of the following :-

Sample Time - Total Memory Time

2 Sec - 8Min 20 Sec
5 Sec - 20Min 50 Sec
10Sec - 41Min 40 Sec
20Sec - 1Hour 13 Min
30Sec - 2Hour 5Min
1Min - 4Hour 10Min
2Min - 8Hour 20Min
5Min - 20Hour 50Min
10Min - 1Day 17Hours
20Min - 3Days 11Hours
30Min - 5Days 5Hours
1Hour - 1Week 3Days
2Hour - 2Weeks 1Day
5Hour - 7Weeks 3Days
12Hour - 17Weeks 6Days

2Sec & 5Sec samples can only be used when the unit is powered on. These can be used for things like skydiving. Measure the rate of descent and show the altitude that the chute opened. Cool but I won't be trying that anytime soon :)

The system menu can be accessed by pressing the power on key again with the unit already switched on. You can the access the menus to allow the unit to be configured as you want it. You are able to set the unit to types metric or imperial of a mix of both plus units such as kts for windspeed.

The range for the graph display can also be set. This allows the unit to be tuned to the conditions it will be used in.

The Manual gives all of the instructions for the units operation. It is well worth a read through if you are thinking of getting one as it shows all of the settings and adjustments that can be made.

You can also turn off screens for measurements that you are not interested in. This is useful as it cuts down the time required to scroll round them all. You can also put your own predefined measurements on the three user screens. Other menus are also available for calibrating the unit. I have not done this as I do not require exacting measurements but for many this will be very useful. See the NK site for more info on this.

I really like the features on this unit and the ease of use. I have yet to use it in anger with my model flying but that will be tested very soon.

I also ordered the optional computer interface. This allows you to connect the unit to a PC and download all of the recorded data as a CSV file that can be used in Excel or any other spreadsheet package. This allow graphs of the conditions to be plotted. Useful for many applications. The interface also has a tripod mount so it could be set-up to take continuos readings although the interface is not of weatherproof construction and I would not want to get it wet.

Manufacturer:- www.nkhome.com

US Dealers

http://store.yahoo.com/newadv/index.html

jlbone@adelphia.net