question about Elecraft receivers

[KC6CNN]

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[Don Wilhelm-4]

I believe you have been hearing about the wattmeter diodes in the KPA100.
That has nothing to do with the receiver at all.  The receiver will
withstand quite an excessive surge.

The situation is that the K2/100 power control circuits depend on
measuring the transmitted power right at the antenna.  As a result, the
diodes in the wattmeter measurement circuit are quite close to the
antenna feedpoint and static surges such as caused by nearby lightning
can cause damage to those diodes.

The best solution is to remove the antenna connection when the K2 is not
in use - the best method is to use an antenna switch to connect a dummy
load to the transceiver.

Again, this has nothing to do with the receive sensitivity of the K2 or
the K3, it is only related to the ability to control the power output.  
When the wattmeter diodes are damaged, the KPA100 will go to full power
output -while displaying zero (or low) power.

I have not heard of many incidents with diode damage with the K3, but
with the K2, we hear of this problem frequently.  I do not know why the
K3 has escaped damage to the wattmeter diodes, since its power control
mechanism is similar to the K2.

If you want to be safe and protect your transceiver (no matter what the
brand or model) from surges on the antenna (from wind, rain, snow, or
nearby lightning static), then disconnect the antenna from the
transceiver when not in use.  In the best case, connect the transceiver
to a dummy load, and if you cannot manage that, at least make the
circuit between the antenna feedline and the transceiver an open circuit

73,
Don W3FPR

On 9/7/2011 10:13 PM, KC6CNN wrote:
> I have read several post about something burning out due to close by
> lightning.
> I have not heard of this many before.
> My question is because of the high sensitivity of the receivers are the
> elecraft's prone to this?
>
>
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[Guy, K2AV]

No, *ALL* electronics are sensitive to this, including the stuff in your
washers, dryers, refrigerators, air conditioners.

The amount of induced voltage from a "distant" lightning strike can
literally throw you across the room, minus your shoes.  Ask my son in law.
 It was induced voltage from a strike a quarter mile away.

Most of the prevention discussions and equipment relate to induced voltages.
 A direct strike does pretty much what it wants to regardless of what
prevention you have in.

73, Guy

On Wed, Sep 7, 2011 at 10:13 PM, KC6CNN <[hidden email]> wrote:

> I have read several post about something burning out due to close by
> lightning.
> I have not heard of this many before.
> My question is because of the high sensitivity of the receivers are the
> elecraft's prone to this?
>
>
>
> --
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> Sent from the Elecraft mailing list archive at Nabble.com.
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[k6dgw]

On 9/7/2011 7:13 PM, KC6CNN wrote:
> I have read several post about something burning out due to close by
> lightning.
> I have not heard of this many before.
> My question is because of the high sensitivity of the receivers are the
> elecraft's prone to this?

No.  You hear about Elecraft lightning damage because there are a huge
number of people on this list willing to exchange their problems,
solutions, ideas, and the like.  It happens to all electronics if the
lightning is close enough, it's just more apparent on this list.

A couple of years ago, at N6A [Alpine County in the Cal QSO Party], we
fried two [2] IC-756PRO2's with what looked and sounded like very minor
snow static.  Turned out, they had no bleed resistor on the antenna
connection and the charge just built up.  My Elecraft radios [3 of them]
all bleed the antenna connections nicely.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2011 Cal QSO Party 1-2 Oct 2011
- www.cqp.org
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[Rick Dettinger-3]

There are some exceptions like communication towers where it is known  
in advance that they will receive multiple hits over the years, and  
need to be engineered to survive.  And I can't even think about what  
it must have been like in a fire lookout tower during a storm.  I have  
seen the rods on each corner of the towers in the mountains of western  
Washington and the #4/0 copper stapled to the rock in the vicinity.  I  
understand that the lookout occupants had a special stool with glass  
legs that they sat on, feet off the floor, until the storm passed.  
Lightening is pretty much ignored in the lowlands of western  
Washington, but the Cascade Range is a different matter.  And, since  
the lookout towers were usually built on bare rock , ground is poorly  
defined.

73,
Rick Dettinger   K7MW



>
>
> A direct strike does pretty much what it wants to regardless of what
> prevention you have in.
>
> 73, Guy

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[MontyS]

Regarding induced voltages, my K3's serial port and line audio ports were damaged by induced voltages.  The receiver was fine - the antennas had been disconnected, but not the connecting cables.  I now disconnect everything, including the ground wire, during lightning storms and have had no further problem.  Florida is the lightning capital of North America, if not the world.

Monty  K2DLJ
Spring Hill, FL

On Sep 7, 2011, at 10:13 PM, KC6CNN wrote:

> I have read several post about something burning out due to close by
> lightning.

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[Mike Markowski-2]

One dry, windy winter's day (with no lightning that I was aware of, so I assume
static build up) I had such a visitor come running down my antenna to meet my
K2.  I had used the rig with no issues and then later in the day turned it on
and hit "tune" - that's when the smoke came out.  In the end it turned out that
I had to replace the watt meter diodes in both the K2 and the KPA100 as well as
a few other assorted bits & pieces in those and in my KAT100.  Gary at Elecraft
was super helpful as I worked my way through the repair.  Very small repair cost
in $ but took a few hours.

While you don't get to enjoy the wonderful smell that came with it, you can see
the immediate aftermath in photos here:

  http://udel.edu/~mm/ham/smoke/

I sure wish I had disconnected my antenna!

73,
Mike ab3ap

On 09/07/2011 11:02 PM, Don Wilhelm wrote:

> I believe you have been hearing about the wattmeter diodes in the KPA100.
> That has nothing to do with the receiver at all.  The receiver will
> withstand quite an excessive surge.
>
> The situation is that the K2/100 power control circuits depend on
> measuring the transmitted power right at the antenna.  As a result, the
> diodes in the wattmeter measurement circuit are quite close to the
> antenna feedpoint and static surges such as caused by nearby lightning
> can cause damage to those diodes.
>
> The best solution is to remove the antenna connection when the K2 is not
> in use - the best method is to use an antenna switch to connect a dummy
> load to the transceiver. [...]

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[John Harper AE5X]

I can give my own first-hand, real-world take on this. Exactly a year ago, my house took a direct hit with several shingles needing to be replaced. My one & only antenna (between roof & sky) was vaporized, as was the feedline.

We lost a lot of electronic stuff to the strike as well as some non-electronics, ie a gas line rupture.

The K3 survived even though the 12V supply was destroyed in a major and spectacular way. At the time, the antenna was not attached to the K3 but the PS was.

Further details and a photo of the feedline are here:
http://www.ae5x.com/blog/2010/09/16/lightning-strike-qrt-ekg-and-a-new-dipole/

Many told me I'd see more symptomes further down the line. They were right - 6 weeks later, my garage door opener started acting spontaneously but the K3 remains unaffected.

John AE5X
http://www.ae5x.com/blog

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[PTA_ABD]

< I have not heard of many incidents with diode damage with the K3, but
with the K2, we hear of this problem frequently.  I do not know why the
K3 has escaped damage to the wattmeter diodes, since its power control
mechanism is similar to the K2.>  from  W3FPR

Not quite. My early K3 developed the bad wattmeter diodes, even though not exposed to any obvious static buildup. I know of another local unit that had the same problem. They were replaced with a more robust set at Aptos, and working fine ever since. I'm sure more modern units have the better diodes.

I "castrate" all my stuff before threatening weather arrives: everything is disconnected, including AC. Any radio stuff has no cables attached. Outside cables have Polyphaser or static discharge devices, but I feel better doing what I do.

Paul WB2ABD
K3 #129


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