For last three months I have 8 (!) R52H failed and several cards before that. Symptomes are: decrease of signal strength on both AP and client, respectively highly decrease of link quality. Method of check: if changing Antenna mode from "antenna a" to "antenna b" (pigtail on card connected to main) and signal strength not changing this implies wireless card is malfunction. I using RB433 and RB433AH. Power is supplied through the UPS. There is no thunderstorm when cards failed. Why is this happen?

Do you have any grounding for the wireless kit installation?

Check this card diversity swich with multimeter method.
http://wiki.mikrotik.com/wiki/Manual:Wi ... iagnostics

Yes, we have grounding, and we used method for diagnostic broken cards. Accordingly it the cards are broken.

That's mean your cards acquire high voltage spike (more then 50V ) on antenna central pole. In addition RB grounding use DC shorted antenna or RF surge protector to protect your cards.

But what can cause such voltage spike if there are no thunderstorm?

Your antenna working like big capacitor charge energy until it exceed DC blocking capacitor max. voltage and discharge to diversity swich what actualy is rectifier bridge. Some times I note this cases in winter at 0 humidity without any thunderstorm. There are more about divesity swich.

www.microsemi.com/micnotes/708.pdf

Use Ubquiti cards. Far less problems than with Mtik, in my experience. SR71-15 is a champ.

Thanks to all for help.

Use Ubquiti cards. Far less problems than with Mtik, in my experience. SR71-15 is a champ.

Colebert, did you ever figure out the power issue with the SR71-15?

As far as R52H's go, I don't think they are a very reliable card. I've probably purchased a dozen of them last year and all but 1 of them have failed with the exact same symptom you describe. I've not had a single failure of any other brand of card. I also have a few R5H's and I have not had any issues with them.

I was frustrated when these cards failed but what was most frustrating is that they would not stand behind the card, I had to eat the cost. It's made me leary to buy any more mikrotik cards even though the price point is excellent.

I have 2 years came down with more than 30 pieces. R52H.
Symptoms are the same.
Several helps protect - RB-5 (2) (http://tandem.ck.ua/grz.php # rb)
Malfunction due to static electricity.

Recommend some type of protection for ESD. Either through ethernet or RF side.

btw colebert, what makes SR-71 the champ? Can you be a little more specific? I'm curious.

Hi people.

Recently i had deployed a small wireless network. It's made with RB433 AP's, RB411 as clients, R52H cards, GD5W-25-NF grid antennas. In the bench, calculations show my links at 20 miles with an RSL of -68dBm. In the practice all of my links show RSL of -78dBm. That's 10dBm less than the calculated. After checking installation deploys, software configurations and hardware components i can't explain why my RX signal is 10dBm less than the expected. Searching in this forum i found many post about R52H issues with output power and received signal.

I just wanted to know is there is a way to find out if my R52H cards are working with diversity.
If someone has any other suggestion i gladly take the advice.



Best regards

If there is divesity swich or PA problem you can't make link at all for this distance. 10dB is very small value, do you add signal attenuation in pigtails in your calculation?

Hi people.

Yes, i understand this RSL is enough for the link. But you have to understand the problem, if there are tx output or sensitivity receive poblems that could limit the performance of the link. Also, i need to realize this issue because i need to get 40Km links, and with these issues by the moment i think is impossible. I place very high loss in each side of the link, very high to me is 3dBm.

any suggestions..?


Best regards