6400M/6600M Front End Protection

Thomas NE7X

Being new to SDR technology, I have been reading comments on the internet that SDR receivers are more sensitive to over-power damage, electrostatic charge on the antenna and nearby lightning surges. There are after-market devices sold by DXengineering and Cross Country Wireless which use a gas discharge tube in line with the antenna to take nearby lightning surges. Is this something I need to be concerned about with my new 6400M ?

Mark WS7M

Hi Thomas,

I cannot comment on "more sensitive" but I live in Colorado where lightning is a daily thing during the summer.

I have nothing more than a surge protector on the front end. 

My take on lightning is this:   

It manages to travel thousands of feet through air.  So having a small gap like in a relay or other device is certainly going to do almost nothing for a direct strike. 

the ultimate protection in a big storm is to completely disconnect ALL WIRES from your radio.  Everything, power, network, mics, etc.

Now on the flip side I have to send my 6500 in some day soon as I managed to **** the protection diode on my ANT 1 input.  Surprisingly it was not lightning or anything really bad.  It was a simple static build up due to a really dry day and I was swapping antennas a around.

So perhaps they are more sensitive.  It cannot hurt to protect.  That is for sure!

Bill -VA3WTB

A few weeks ago there was a good discussion about this. It was generally accepted that protection is a good investment. Many are using devices that bleed off static to ground as well as protection from near field lightning strikes.

Varistor

You should be concerned with overall lightning protection for your tower, feed lines, and station equipment. Bond all coax at the top and bottom of the tower and have ground rods at the tower and the entry point into your house. Here’s your bible: http://audiosystemsgroup.com/GroundingAndAudio.pdf

Rich McCabe

I agree,  I think most hams have a decent electrical grounds but most are not well RF grounded and even less properly bonded to other grounds.

I admit until recent years I was lacking when it comes to bonding.

David Salomon

Varistor -

Thanks for that link.  It's good information.

Tim - W4TME

While others have addressed best practices for protecting ham radio gear from lightning, I'd like to address the "more sensitive to over-power damage, electrostatic charge on the antenna and nearby lightning surges" comment.

First off, all electronic equipment, regardless if it is a superhet or a direct sampling SDR that has a connected antenna is always vulnerable to the EMP from a direct or near lightning strike; the amount of energy and fast rise times can damage a whole array of electronic components.  The only way to mitigate this threat is with proper lightning grounding techniques and good lightning arrestors.

Electrostatic discharge is handled similar to lightning mitigation, but to ensure it presents a lower risk, the lightning arrestors used for lightning mitigation should also have circuitry to bleed off DC static from the center connector of the coax.  The ICE designed lightning arrestors (now Morgan Manufacturing and sold by Array Solutions) are very good for this purpose.

There is also protection built into the FLEX-6000 themselves to mitigate EMP and static discharges with the use of sacrificial ESD diodes that are designed to **** and break the RF signal path before the sensitive components experience any damage. This protection should NEVER be your first line of defense.

Overpower damage is a different type of risk that has to be managed differently.  The FLEX-6000s can tolerate high signal levels, higher than other direct sampling SDRs. The FLEX-6000 constantly monitor the RF input signal levels and have a relay that will open if the signal level reaches the threshold point below where the ADC would experience damage. This is accompanied by an error message indicating that a signal overload condition was detected.  This condition usually happens when transmitting while receiving, which is when operating in full-duplex mode or you are using a radio with multiple SCUs (ADCs).  If you are not operating this way or there is not another transmitting antenna in your receiver's near field, you really don't have to be concerned about overload situations

It is the operator's responsibility to manage the amount of signal entering into the radio's ADC in these situations.  We have a signal level worksheet that can help you determine if your setup is going to exceed the signal level threshold. http://www.flexradio.com/downloads/flex-6000-fdx-power-calculation-worksheet-pdf/

I live in central NC and while not the lightning capital of the lower 48, we are #3 on the list.  In the 23  years I have been at my QTH, lightning has struck the house across the street twice, the house 3 doors down once and struck trees behind my house twice (one as close as 100').  My antennas and house are higher in elevation that all of the other strike points and I have never experienced any lightning-related damage other than a cordless phone. I have incorporated extensive lightning grounding at my QTH, using a halo ground around the home, all of my coax shields are grounded to a bulkhead connected to the halo ground before entering the house and I use the ICE lightning arrestors too (I have blown a few of these up as a result of the near strikes).  I have a set of coax switches that ground the center pins to the halo ground when the radio is not in use.  This grounding system based on best engineering practices and grounding antennas when not in use works and works well.  You just have to access your risk factors and decide how much lightning mitigation engineering you feel is necessary for your particular situation.

David Salomon

I live in the Atlanta area.  We get LOTS of lightning.  I had equipment blown up by a direct lightning strike once in the past (not to mention most electrical equipment throughout the house and a nice hole in the side of the house).  I had power and antennas disconnected, but missed disconnecting a single ethernet to radio connection.  Since all the shack equipment is interconnected, it all let out the magic smoke (thank you ARRL insurance).  I now use an MFJ windows passthrough connected to a ground rod bonded to the house ground.  I also use ICE lightning arrestors and, like Tim, have lost a few to nearby lightning.  It's far cheaper and much less aggravating to replace one of those than your station equipment.  Finally, when weather is expected, I now disconnect EVERYTHING: power, antennas and network connections.  The moral of the story: you can never be too safe when it comes to lightning protection.

Tim - W4TME

 It's far cheaper and much less aggravating to replace one of those than your station equipment. 

Absolutely!

KG9DW

Sounds like a great arrangement! Do you have remote control over the coax switches so that you can bring the system on line remotely?

Tim - W4TME

No.  I open the switches to operate and close them when I am done.  I don't do much remote operation, so I have not installed remotely actuated coax switches.

Ria

I never disconnect anything. We had nearby strikes and a direct strike. Not really a problem except a blown out Icom CI-V port, ONCE. EVERYTHING is bonded and towers have fields of ground rods bonded and cadwelded. I am not always at home and disconnecting 10-15 coaxes is not my idea of fun...

Rich McCabe

I am with you Ria.  I do the best I can with grounding and bonding and then roll the dice

Oddly enough the only time I have had issues was with Ethernet where it  took out 75% of everything in my house connected with Cat5.  Cameras, TVs, computer, printers, switches, etc.

Fortunately this was before I had a flex.

Being an IT guy, I see NIC failures on equipment all the time.

Don Stefanik

I dont know if this will actually help, but I have a copper stranded wire going up threw my tower to the top of the mast.

VA3KBC


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