# Argggg WBX Front end issues **URL:** \ **Category:** GNU Radio\ **Created:** [April 13, 2012, 2:12am UTC](https://www.ruby-forum.com/t/argggg-wbx-front-end-issues/218823 "2012-04-13T02:12:44Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\ **Post date:** [April 13, 2012, 2:12am UTC](https://www.ruby-forum.com/t/argggg-wbx-front-end-issues/218823/1 "2012-04-13T02:12:44Z")
blew my second WBF front end after 1 day of wonderfull RX. I don’t know how it happend. I was using a few different types vhf and uhf omnis and yagi antennas, everything seemed to be working fine. Now it can’t hear hardly anything and the typical strong noise signal in the center freq is back. Is it possible that some of the equipment mounted on the antenna mast could be shorting it out? Or is the WBX just so sensitive that a strong signal can blow it up? I have 2 Ubiquiti bulllet2HP’s on the roof. One is clamped to the same mast as the UHF omni that was connected the to WBX. They are 24V DC over the unused pairs. Im really bummed out. Any recommendations or similar experiences ? ---
**Author:** ![dave\_k](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/9e8a1a/32.png) [@dave\_k](https://www.ruby-forum.com/u/dave_k)\ **Post date:** [April 13, 2012, 2:20am UTC](https://www.ruby-forum.com/t/argggg-wbx-front-end-issues/218823/2 "2012-04-13T02:20:17Z")
On 04/12/2012 08:11 PM, dave k wrote: > blew my second WBF front end after 1 day of wonderfull RX. I don’t know how it > happend. I was using a few different types vhf and uhf omnis and yagi antennas, > everything seemed to be working fine. Now it can’t hear hardly anything and the > typical strong noise signal in the center freq is back. Is it possible that some > of the equipment mounted on the antenna mast could be shorting it out? Or is the > WBX just so sensitive that a strong signal can blow it up? I have 2 Ubiquiti > bulllet2HP’s on the roof. One is clamped to the same mast as the UHF omni that was > connected the to WBX. They are 24V DC over the unused pairs. Im really bummed out. > Any recommendations or similar experiences ? > > * * * Unfortunately, LNAs are notoriously sensitive little princesses. The new revs of the WBX have TVS diodes between the RF connector and the LNA, which should reduce this problem, at the expense of a slightly poorer noise figure. If the local field strength of RF on your roof is high, enough can couple in to damage the LNA. In those situations a limiter might be needed, or even a stiff bandpass filter to keep stray RF fields that are out-of-band with respect to your application out of the front-end. There’s a company online, summitsource, that sells in-line gas-discharge surge arrestors for CATV/SATV use that I’ve used for protecting LNAs in the past. Taken local lightning hits and survived, for what it’s worth. The arrestors are cheap–under $4.00 apiece as I recall, and have 75-ohm connectors. About 0.3dB insertion loss. – Marcus L. Principal Investigator Shirleys Bay Radio Astronomy Consortium > **[Live Draw HK Tercepat | Result HK | HK Pools | Live HK | HK Prize Hari Ini](https://www.sbrac.org/)** > > Temukan live draw hk tercepat melalui halaman hk pools yang resmi dan dapatkan result hk prize melalui live hk secara langsung di situs kami. ---
**Author:** ![dave\_k](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/9e8a1a/32.png) [@dave\_k](https://www.ruby-forum.com/u/dave_k)\ **Post date:** [April 13, 2012, 4:05am UTC](https://www.ruby-forum.com/t/argggg-wbx-front-end-issues/218823/3 "2012-04-13T04:05:34Z")
thanks Marcus. Some of the signals i am monitoring are very strong-@860mhz approx 1/2 mile from my receive antenna. I would say from memory they were -30 or maybe -20dbm? Is this to much? My gut tells me no. Is it possible to cause damage by simply turning up the gain to high on a strong signal? I am going to remove all the WiFi stuff from the mast with my antennas. Is all i have to do is solder a new LNA to the WBXFE daughtcard? part numbers? Im with you on the sure arrestors. I do have a polyphasers impulse suppressors in line with all the feed lines coming in for lightning protection but that’s a whole different issues. ---
**Author:** ![dave\_k](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/9e8a1a/32.png) [@dave\_k](https://www.ruby-forum.com/u/dave_k)\ **Post date:** [April 13, 2012, 5:49pm UTC](https://www.ruby-forum.com/t/argggg-wbx-front-end-issues/218823/4 "2012-04-13T17:49:13Z")
A nearby lightning strike (but far from a direct hit) took out the LNA on my WBX last fall. I suspect that part of the reason was that the antenna I was using (a discone wide-band antenna mounted on the roof) is not DC grounded and thus can develop a good sized charge. An anecdote: many years ago I built a ham radio repeater system that was located on the roof of a dormitory building at school. There was a short tower on the roof and the 1/4 wave ground plane antenna was probably about 120 feet above ground. The coax cable went from the antennas down to our ham shack on the top floor of the building. At the bottom of the surplus CATV hardline cable was a PL-259 connector with a “barrel” connector to allow hooking up a flexible jumper. The dielectric between center and shield in the barrel was a clear plastic. I was working on the repeater one spring day with the antenna disconnected. Every minute or so I heard a faint “pop” sound. When I investigated, I saw blue flashes in the plastic on the barrel connector. It turned out there was storm activity in the vicinity, and the charge on the 19 inch long whip built up to a level where it arced across the 3/8 inch or so of dielectric. The storm was far enough away that we couldn’t hear the thunder inside the building. Since then, I’ve preferred to use DC-grounded antennas (or at least to have something in the system that provides a DC path)! Sadly, I didn’t follow my own advice last fall… ## John