GrandPop the camera is powered directly from my 12.8v high power (20A) stabilised power supply
How long is the cable and its wire gauge between the power supply and the ASIAIR? And what else is connected to the end of the power cable other than the ASIAIR?
The ASIAIR can draw up to 2A at 12V. Your other devices can add more: your camera cooler can take up to 3A, some mounts could draw 5A when slewing. Each 12 watts of dew heater is another amp, etc.
Take a look at wire tables such as this one:
http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/wirega.html
With 18AWG copper (assuming it is not an "Amazon 18 AWG" from China, which is often 20 AWG, and not copper), each foot of wire has about 6.4 milliohms. And remeber the ground return also contributes to ohmic loss. So an 18 AWG good copper wire pair would be about 13 milliohms per foot. A 30 foot run would therefore be about 400 milliohms.
Now, if you are drawing just a total 5A at the telescope end, that end would see a whopping 2V drop from the power supply end. A 10A current draw would make it a 4 V drop!
A 14 AWG cable will reduce that drop by a factor of 2.5. A 12 AWG cable will drop the voltage loss by a factor of 4 compared to 18 AWG.
Remember, use only high quality copper wires.
You can place the power supply outdoors, if it is rated for outdoor usage, and under the temperature conditions that you will be using it at. That way, the lower current 110 or 230 volts AC will improve things by a factor of 10 (this is why high voltage AC system by Tesla beat out the low voltage DC sytem by Edison back in them days).
Another way is to get a 12V in, 12V out buck/boost converter at the telescope end (Amazon has plenty of them at different current capabilities). This way, the voltage drop will be "boosted" by the converter, and you can use a shorter cable between the converter and the telescope equipment. You can even use multiple buck/boost converters so that each one sources a lower current.
This is a picture of one version of my distrubution boxes outdoors at the base of the tri-pier. Notice a 15V buck/boost converter at the top righthand corner for my mount (that is what the Amazon ones typically look like):
There are plenty of solutions, you just have to come up with one that you can easily implement.
Chen
