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WH-1081 cable runs

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murray mint
Posts: 7
Joined: Thu Feb 03, 2011 7:48 am
Weather Station: WH1081
Operating System: Windows 7, Windows 10, Pi
Location: Crawley

WH-1081 cable runs

Post by murray mint » Sun Jan 03, 2016 10:29 am

Happy new year guys.

I am going to be resurecting my old WH-1081 and would like to set it up correctly, in so much as the wind speed and direction modules will be mounted on a 2 meter pole on the gable end of the roof and the rain gauge and temp/humidity sensors mounted lower on the ground.

My question is, is there a potential problem with the cable run lengths, are the limits to the runs, I'm sure there must be.

Any help would be greatly appreciated.

Murray

AllyCat
Posts: 1045
Joined: Sat Feb 26, 2011 1:58 pm
Weather Station: Fine Offset 1080/1 & 3080
Operating System: Windows XP SP3
Location: SE London

Re: WH-1081 cable runs

Post by AllyCat » Sun Jan 03, 2016 3:46 pm

Hi Murray,

It depends how old is the 1081. The hardware design (but not the model number) was changed about three years ago. Before then, the transmitter used a rather unsatisfactory Analogue-Digital Converter "shared" between the Wind Vane and External Temperature. This could cause serious temperature measurement "spikes" if there was any "crosstalk" or current-leakage (e.g. due to moisture) in the wind cable or connectors.

Later models are more tolerant, and extending the cables should not cause any issues. However, the sensor interfaces still use high impedances (to keep the battery drain low), so any leakage (e.g. due to moisture) in the cable/connectors can cause problems. Therefore, ensure that you seal all connections really well.

In "exceptional" cases (with very, very long cables), the increased cable resistance could cause a misread of certain wind directions, but these are rather problematic anyway. ;)

Cheers, Alan.

murray mint
Posts: 7
Joined: Thu Feb 03, 2011 7:48 am
Weather Station: WH1081
Operating System: Windows 7, Windows 10, Pi
Location: Crawley

Re: WH-1081 cable runs

Post by murray mint » Sun Jan 03, 2016 8:35 pm

Thanks for the info Alan. Is there anyway to identify the different models?

AllyCat
Posts: 1045
Joined: Sat Feb 26, 2011 1:58 pm
Weather Station: Fine Offset 1080/1 & 3080
Operating System: Windows XP SP3
Location: SE London

Re: WH-1081 cable runs

Post by AllyCat » Mon Jan 04, 2016 7:54 pm

Hi,

Not AFAIK from the outside, there are no "labels" or external differences. If you prise open the transmitter box (which is only glued) with a knife or (old) credit card, the "old" transmitters have a (blue) bead thermistor near to the connectors, as shown in the fourth photo here.

However, for a "non-invasive" test you could try to test if there is any interaction between the wind cable and the external temperature display: If you have a spare 4-wire "RJ11" cable (used for phones in USA, etc., but generally only broadband/modems in UK) you could plug that into the Wind socket and dip the other end into a cup of tapwater. If the temperature display changes much (within 48 seconds) then you probably have an old station.

If you don't have a cable, you might just put a drop of water onto the "wires" in the wind socket for the same test, but then try to dry them before too much gets inside the box.

Cheers, Alan.

murray mint
Posts: 7
Joined: Thu Feb 03, 2011 7:48 am
Weather Station: WH1081
Operating System: Windows 7, Windows 10, Pi
Location: Crawley

Re: WH-1081 cable runs

Post by murray mint » Mon Jan 04, 2016 9:58 pm

Thank you Alan, I will try the cable dipping exercise first.

windsurf
Posts: 4
Joined: Tue Mar 08, 2016 10:21 pm
Weather Station: WH-1081
Operating System: Mac OS
Location: Slovakia

Re: WH-1081 cable runs

Post by windsurf » Tue Mar 08, 2016 10:28 pm

On a related topic (I'm also just about to install a WH-1081) isn't it a bad idea to have the anemometer and wind direction sensor mounted so close and on the same plane horizontally?

I'm thinking that the wind turbulence crated by either one of them may affect the other resulting in inaccurate measurement of either wind speed or direction.

I'm thinking that maybe installing one of them upside down or on a separately constructed extension arm may solve the problem (if it exists in the first place) but would be interested in anyone's opinion who has real life experience with this.

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