Avoiding costly lightning damage to your radios gear

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Re: Avoiding costly lightning damage to your radios gear

K8TE
With 26 years experience in USAF communications and even more in commercial
broadcasting, I disconnect all wire inputs to my station's components when
the threat of thunderstorms arises.  If planned well, this is easy to
accomplish.  I have made significant money repairing commercial broadcast
transmitters which were installed properly but still suffered damage during
direct hits to their antennas.  That damage was very rare, but still
occurred.

I disconnect my DSL router's wall wart and phone line inputs along with
antenna, rotator control, and other cables that enter through the single
point protected/bonded/grounded panel.  That has worked every time!  If
lightning comes within ten miles, I disconnect.  If away from home, all my
valuable electronics are disconnected.  I do the same for snow storms which
with blowing wind also generate significant static electricity.

Why take the chance?  If I were to run a remote system, like my race car, I
would be ready to walk away from either in spite of taking appropriate
preventive measures and accept the loss.

73, Bill, K8TE



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Re: Avoiding costly lightning damage to your radios gear

ab2tc
In reply to this post by wayne burdick
Hi,

It's a dead short circuit for DC and low frequencies thanks to the SWR
bridge (it has a voltage transformer directly across the antenna terminals).
There seems to be different opinions on what is meant by "static". To me it
means a slowly varying DC voltage caused by static buildup in the clouds
during or before thunderstorms. The K3(S) is perfectly protected against
these. Some people include the transients that are caused by actual
lightning strikes nearby in the definition of "static". The K3(S) is not
protected against these as they have very strong high frequency content. For
these extra protection is needed as discussed several places in this thread.
I have a number of Alpha-Delta switches in my antenna system and they have
gas discharge tubes, but frankly I have no idea how effective they are.

AB2TC - Knut


wayne burdick wrote
>> On Oct 30, 2018, at 12:50 PM, Fred Jensen <

> k6dgw@

> > wrote:
>>
>> Does my K3 have a static bleed across the antenna terminal(s)?
>
> Yes.
>
> Wayne
> N6KR
> <snip>





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Re: Avoiding costly lightning damage to your radios gear

k6dgw
Hmmm ... There seem to be different flavors of static.  My reference was
to what is often called "precipitation static" [rain, snow, maybe hail] 
and which can sometimes also be caused by wind blowing sand/dust past
the antenna.  It sounds like bacon frying in the receiver.  Each drop or
snowflake acquires a minuscule charge falling or blowing which
discharges into the antenna on contact.  The typical semiconductor
devices in radio front ends these days exhibit a nearly infinite
impedance to "ground" and a tiny capacitance.  The constant little
pulses from the static charge that capacitance with essentially no
discharge path.  That's what fried the 1st 760 II and then, predictably,
the second one.

There is also the combined "static" caused by distant thunderstorms.

INT QRN: "Are you troubled by static"
QRN: "I am troubled by static"

which is different than "static" caused by corona or leakage on a high
voltage power transmission line.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

PS:  For those about to tell me "nearly infinite" is a meaningless term,
save the BW.  I know, I hold a math degree.  Just using a little
editorial license.

On 10/31/2018 3:10 PM, ab2tc wrote:

> Hi,
>
> It's a dead short circuit for DC and low frequencies thanks to the SWR
> bridge (it has a voltage transformer directly across the antenna terminals).
> There seems to be different opinions on what is meant by "static". To me it
> means a slowly varying DC voltage caused by static buildup in the clouds
> during or before thunderstorms. The K3(S) is perfectly protected against
> these. Some people include the transients that are caused by actual
> lightning strikes nearby in the definition of "static". The K3(S) is not
> protected against these as they have very strong high frequency content. For
> these extra protection is needed as discussed several places in this thread.
> I have a number of Alpha-Delta switches in my antenna system and they have
> gas discharge tubes, but frankly I have no idea how effective they are.
>
> AB2TC - Knut
>
>
> wayne burdick wrote
>>> On Oct 30, 2018, at 12:50 PM, Fred Jensen &lt;
>> k6dgw@
>> &gt; wrote:
>>> Does my K3 have a static bleed across the antenna terminal(s)?
>> Yes.
>>
>> Wayne
>> N6KR
>> <snip>
>
>
>
>
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
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>

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Re: Avoiding costly lightning damage to your radios gear

Don Wilhelm
Skip,

Yes, there are various causes of static on the feedline, but static is
static.  It is a voltage charge on the feedline and it can damage equipment.
The source may be wind blowing on your antenna, rain or snow that
carries charged particles, or nearby lightning.  No matter what the
cause, it can produce a significant voltage across your feedline.  It
does not take a direct lightning hit to produce damaging voltages on
your antenna feedline.  A direct hit can cause damage to house and home
and any equipment in that home, but there are other times when the
accumulated static voltage on any feedline can cause damage to your ham
equipment.

I recall an event many years ago when I got that lesson.  I had several
antennas in the basement shack unterminated and just waiting to be
connected.  The wind was blowing and I thought nothing of it until I
picked up an open feedline and placed it near my Heathkit HW101
intending to connect it - sparks flew as the coax got close to the
chassis!  That was a warning to me - disconnect and ground all my
feedlines when not in use.  If not grounded, at least a bleed resistor
across the feedlines to discharge any built up static.

73,
Don W3FPR

On 10/31/2018 6:42 PM, Fred Jensen wrote:

> Hmmm ... There seem to be different flavors of static.  My reference was
> to what is often called "precipitation static" [rain, snow, maybe hail]
> and which can sometimes also be caused by wind blowing sand/dust past
> the antenna.  It sounds like bacon frying in the receiver.  Each drop or
> snowflake acquires a minuscule charge falling or blowing which
> discharges into the antenna on contact.  The typical semiconductor
> devices in radio front ends these days exhibit a nearly infinite
> impedance to "ground" and a tiny capacitance.  The constant little
> pulses from the static charge that capacitance with essentially no
> discharge path.  That's what fried the 1st 760 II and then, predictably,
> the second one.
>
> There is also the combined "static" caused by distant thunderstorms.
>
> INT QRN: "Are you troubled by static"
> QRN: "I am troubled by static"
>
> which is different than "static" caused by corona or leakage on a high
> voltage power transmission line.
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Re: Avoiding costly lightning damage to your radios gear

k6dgw
Yep, all true.  The somewhat insidious thing about precip static is that
it can be totally innocuous, unlike T-storms, lightning strikes, and the
like.  We hadn't even noted that it had begun snowing, fairly hard,
outside the tent, when the first rx quit.  The "frying bacon" and the
tiny little "grass" on the baseline of the panadapter should have been a
clue to "look outside" to a bunch of OF's with that much accumulated
experience ... sadly it wasn't.  OTOH, QRN from multiple distant
T-storms is just that ... annoying noise in the receiver with no danger.
Likewise with power line hash.  Of all the forms of QRN, and excluding a
lightning strike [which is hard to ignore], precip static can be the
most dangerous to equipment and go unrecognized by new folk [and a
handful of OT's].

In this age with a dearth of Elmers standing next to you, that function
seems to have migrated to email lists like this one, various fora, and
various wiki's.  I don't think they can replace W6RMK, with my latest
electronic creation [usually a TX] on his bench, explaining how the grid
of the PA rectifies some of the RF waveform and charges a capacitor that
slowly leaks off through an appropriately named "grid leak" resistor. [:-)

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 10/31/2018 4:14 PM, Don Wilhelm wrote:

> Skip,
>
> Yes, there are various causes of static on the feedline, but static is
> static.  It is a voltage charge on the feedline and it can damage
> equipment.
> The source may be wind blowing on your antenna, rain or snow that
> carries charged particles, or nearby lightning.  No matter what the
> cause, it can produce a significant voltage across your feedline.  It
> does not take a direct lightning hit to produce damaging voltages on
> your antenna feedline.  A direct hit can cause damage to house and
> home and any equipment in that home, but there are other times when
> the accumulated static voltage on any feedline can cause damage to
> your ham equipment.
>
> I recall an event many years ago when I got that lesson.  I had
> several antennas in the basement shack unterminated and just waiting
> to be connected.  The wind was blowing and I thought nothing of it
> until I picked up an open feedline and placed it near my Heathkit
> HW101 intending to connect it - sparks flew as the coax got close to
> the chassis!  That was a warning to me - disconnect and ground all my
> feedlines when not in use.  If not grounded, at least a bleed resistor
> across the feedlines to discharge any built up static.
>
> 73,
> Don W3FPR
>

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Re: Avoiding costly lightning damage to your radios gear

Gary Smith-2
In reply to this post by w5sum
Apologies if this has been suggested
already, I've got too many irons in the
fire and might have missed/forgotten if
this was earlier said; I no longer use a
wired router, all my computers are
wireless so there is no physical ethernet
connection to any computer.

I use the Netgear A6210 USB wireless Rx/Tx
dongle and it is fast, very fast. Ethernet
directly connected I get 300 Mbps download
from the cable. With the Netgear dongle, I
also get 300 Mbps. I lose nothing and
eliminate that lightning path.

As to the cable itself coming to the
house, I have replaced the cable company's
grounded F81 Barrel Connector between the
drop line and the house with a 75 ohm
grounded surge protector bought at
DXEngineering, I use them on my two HI-Z
RX arrays as well.

After taking a hit to my just out of
warranty, McIntosh tube preamp's USB this
year, (forcing me to either pay big $ in
repair or go with Toslink, I chose the
glass toslink. (For audio only, the
Toslink is excellent but with this system
Toslink only offers one way communication
from the computer to the preamp and some
home entertainment utilizes two way
communication). Fortunately, my needs
don't require this.

Those 75 ohm cable lines must be
protected, just like our communications
coax.

73,

Gary
KA1J


> very good suggestions Wayne. I work in the Communications field and
> have for 40 years. I have seen massive amounts of lightning damage,
> regardless of grounding , protection, etc etc. If you take a direct
> hit.. something is going to fry and that´s it.
>
> I unplug antennas, power cords AND Ethernet Cables to all computers in
> my ham shack. I must confess however, I have not disconnected the USB
> and RS232 lines. I sort of figure if the power cord and ethernet
> cables to my computer are disconnected, the path for the power surge
> is eliminated. BUT.. guess it would be better to be sure. And btw, yes
> my computers are all grounded very well.
>
> thanks for the heads up
>
> Ronnie W5SUM
>
>
> -----Original Message-----
> From: Wayne Burdick
> Sent: Monday, October 29, 2018 10:08 PM
> To: Elecraft Reflector
> Cc: [hidden email]
> Subject: [Elecraft] Avoiding costly lightning damage to your radios
> gear
>
> Every year, especially in summer, our techs see radios come in that
> have been damaged by lightning, despite the radio's protective
> circuitry. You can take steps to reduce your own risk.
>
> 1. Many of us remember to disconnect antennas when lightning is
> anticipated. But in our experience, the most common source of damage,
> by far, is from an attached computer. Computers themselves often fail
> due to lightning strikes. They can also act as conduits for surges to
> other gear. Just to emphasize this point: Customers often say "I
> disconnected everything but the USB cable to the computer...," which
> left the interface to their radio exposed.
>
> Note: Only in rare cases have we seen surge damage via other I/O ports
> (accessory jack, paddle/keyer jacks, PTT IN, KEY OUT, and DC). USB and
> RS232 ports are the most susceptible.
>
> 2. Some stations have an ad-hoc ground system and little or no ESD or
> surge protection. If you haven't already taken protective measures, we
> strongly recommend reading this article, which goes into some detail
> regarding how lightning finds its way in:
>
>    http://www.arrl.org/files/file/QST/This%20Month%20in%20QST/June2017
>    /Chusid-Morgan.pdf
>
> At the very least, be sure your PC and other gear share a short,
> heavy, common ground.
>
> 3. As for protecting your PC, here's a good starting point:
>
>     https://www.wikihow.com/Protect-a-PC-in-a-Thunderstorm
>
> 73,
> Wayne
> N6KR
>
>
>
>
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