Below is a post I did on another forum last year. Next is a reply from someone then me replying back. I later found that non-tinned copper wire will corrode with my soil type and the THHN will split. I replaced all of my wire with Paradise Robotics premium wire and all of my problems went away. ALWAYS use Lawnbott wire or Paradise Robotics wire.
Zucchetti says not to use solid core antenna wire in order to prevent RF attenuation. It is unclear if Zucchetti's comment means any stranded copper wire will suffice or to use only the wire Zucchetti provides. I used 14 ga solid THHN. This is what bamabots advised to use. If the attenuation Zucchetti is speaking of is based on stranded verses solid, the only thing I can think of is the difference in the skin effect. Audiophiles have argued this phenomenon for years (at audio frequencies). However I am no expert, but; my calculations tell me there is not much loss at 8 KHz. If someone is more knowledgeable in this field please chime in.
Skin effect is a physical phenomenon that relates to the limited penetration into a conductor of a high frequency signal according to its frequency. The less of the cable the current uses, the higher the resistance appears to be. This has specifically effect on cables that are thick and carry high frequency signals.
DC = Entire cable
1 kHz = 82.5 mils
10 kHz = 26.1 mils .66mm
100 kHz = 8.25 mils .21mm
1 MHz = .261 mils .60um
10 MHz = .0825 mils .21um
100 MHz = .0261 mils
1 GHz = .00825 mils (8 micro-inches)
AWG Circular Mil
14 4,107
15 3,257
16 2,583
I noticed Zucchetti's wire is tinned. Standard THHN solid or stranded is not. With certain types of soil the THHN copper may corrode at a higher rate.
THHN has a teflon coated insulation. Zucchetti's wire appears to be standard vinyl coated. Maybe the teflon coating becomes a dielectric and changes the capacitance of the wire to ground? I will do some experimenting with this if I can find the time. I really don't have the time to replace the wire. What type of wire are other's using? Anyone used the provided wire but has signal problems?
Steve Amelung
I would concur with this. At 8kHz (and the entire audio spectrum as far as the audiophiles are concerned) there is really no skin effect to worry about.
While stranded is typically pulled in a pro audio install, it has more to do with the ease of pulling and the fact the connectors (Speakon is typical these days) are designed for stranded. There are damping factor issues due to cable inductance to contend with in the audio frequency world, but those have nothing to do with stranded versus solid and apply only to speaker wire pairs below 200Hz, not to an inductive loop in the yard at 8kHz. Quite a mix here... Gauges of 16, 14, and 12, some solid and some stranded, some tinned and some not, some buried and some pinned above the ground. The wire has evolved a lot since the original 3200 wiring back in 2005 (zone borders have moved, sections of yard added, etc.) with each change using a different wire type (sometimes because I had it on hand). All conenctions are soldered. It should be noted that the wire has worked perfectly with 2 robots, 3 motherboards, and 3 different transmitters. This problem appeared with the 3500 upgrades, not with any changes to the wire. I highly doubt all of our wires have gone bad at the same time only among those who have the upgrades (quite a coincidence, huh?). Chasing wire issues is a dead end... they just need to make it work again like it used to.
You are correct and it looks like they have. However, there have been a LOT of problems with the 3500. My first unit was a RF mess. 2nd unit (and was a 2nd generation LB3500) worked well for the few months I had it in service. End of season came, then came this last mod. I only have 900 feet of wire, need a signal booster and have needed it with both machines. 150+ watts at 8 KHz inside a 900 foot perimeter is a lot of power.
I believe during the last mod the receivers where reprogrammed to have a higher selectivity. Then the disturbance filter was added to clean up the transmit RF. It all made sense to do this and it worked in Italy and here in the states at Kyodo. Why did it not work for us? The only difference I can think of is the wire.
Have you received your new receiver yet? Mine is working well. Or I should say like it did before the mod. There will probably be a software update that takes care of the machine taking too many breaks and acting like a fool when it touches the border.
Steve Amelung
