[Hi-zreceivingarraydiscussions] lightning protection

[Lee K7TJR]

   I believe we may have improved our systems ability to handle the energy from close lightning strikes. I know there are rumors out there and they are somewhat true. We have found 3 separate issues. One is that our transient diodes on the CTRL switching lines were being destroyed by induced currents. We have increased the size of those didoes and installed MOV devices across each one. So far knock on wood we have not seen any more damage to the diodes. The second item is if the system is powered and the relays in the HI-Z amps are open the FET devices and there clamping diodes can be damaged from static discharge. The only way to prevent this is to turn power off to the array during threatening storms. This has been a minimal problem. Yes, it is true we have lost a few FETs but what we have found is a third item where the Hi-Z amps were being destroyed by an induced transient on the 75 ohm output RG-6 line from the amp. We have designed some protection for this and so far we have been successful with no further damaged FETs directly attributable to this problem. We have modified all production to include these mods and have been installing them in any units that come in for service. One unfortunate individual that must live in the lightning capital of the world endured amp damage 3 times in as many weeks. Now after the mods we have heard of no more damage. Whew!
  Any one needing more information can contact us directly as we are trying to document the mod procedure now so anyone experiencing probles can take advantage of the changes. This problem from our perspective has been a very small percentage of the units in the field. Contact us if you would like us to mod the units here. We are trying to figure out an equitable way to acoomplish this at a minimum cost to both parties. Again, not everyone will need these mods. We hope to get an application note up on the web soon with the change information also. 
 Thanks to every one for the tremendous support. You never know what we might come up with next!
Lee  K7TJR