How susceptable is K2 to antenna static shock?

[dw-4]

Hi all,
I left the K2 antenna plugged in today and went to work.
We did get a fast moving torrential downpour with some lightning
activity in the area where I work which is about 20 miles north of the
shack.
So I'm not sure if there was any lightning in the area of the shack.

Anyway, I used the K2 last night and then shut it down.
Turned it on when I got home from work and it receives with no problem
but shows Hi Cur now in TUNE mode, on all bands.
Its been raining all day long, and I have a doublet with 450 ladder and
a SGC external antenna tuner mounted on a tree.
I will check the tuner box as soon as I can but so far the K2 is a no go
on xmit.
Also, the supply voltage really starts to sag when I set the power pot
up above 6 watts on tune.
I have the KPA100 on board.
I wish now I had a 100watt dummy load.
The power supply is a brand new 7AMP switcher so I'm not suspecting it
as the first thing on the list.

Has anyone seen the K2 act like this before?

Thanks
Duane
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[Mark Bayern]

> Has anyone seen the K2 act like this before?

Yes.  In my case D16 and D17 of the KPA100 had failed. These are the
diodes in the swr/power monitor. When the K2 controller doesn't get a
power reading it just keeps on trying. Eventually you reach the
current limit.

On a slightly different topic, are you planning on using that 7amp
supply to power the K2 at 100 watts? If the K2 was 100% efficient 7
amps at 12volts gets 84watts, not 100.

Mark
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[Geoffrey Mackenzie-Kennedy]

> Has anyone seen the K2 act like this before?

Yes some years ago, after a falling pine brought down the antenna in use
while the K2/100 was transmitting (CW).  Diodes D12 and D14 in the KPA100's
T-R switch both failed into a shorted condition, and one of the diodes in
the K2's T-R switch failed as well. I was very lucky that the KPA100's
transistors did not blow. My K2/100 now shares a protective shutdown system.

I suggest that you do not use the transmitter until you have checked out the
T-R switches in the KPA100 and the K2.

73,
Geoff
GM4ESD

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[Julius Fazekas n2wn]

Duane,

Have run into the same thing as others have mentioned. Should you need to replace the two diodes in question, you may want to consider mounting them on the opposite side of the board. I found they were easier to replace, should you have to do it again.

The best thing to eliminate this problem is to disconnect the antenna when the radio is not in use. Some go as far as disconnecting any power or computer lines as well.

A good antenna switch, like the Alpha Deltas or separate surge suppressors with other antenna switches will help. The same devices could be used on both antenna positions on the KAT100 too.

Too, any power sources (power supply, logging computer connected to the mains) should also have surge suppression to help protect "back door" hits. I'm partial to Tripp-Lite products.

Hope you've found the problem and have it fixed.

Cheers,
Julius

dw-4 wrote

Hi all,
I left the K2 antenna plugged in today and went to work.
We did get a fast moving torrential downpour with some lightning
activity in the area where I work which is about 20 miles north of the
shack.
So I'm not sure if there was any lightning in the area of the shack.

Anyway, I used the K2 last night and then shut it down.
Turned it on when I got home from work and it receives with no problem
but shows Hi Cur now in TUNE mode, on all bands.
Its been raining all day long, and I have a doublet with 450 ladder and
a SGC external antenna tuner mounted on a tree.
I will check the tuner box as soon as I can but so far the K2 is a no go
on xmit.
Also, the supply voltage really starts to sag when I set the power pot
up above 6 watts on tune.
I have the KPA100 on board.
I wish now I had a 100watt dummy load.
The power supply is a brand new 7AMP switcher so I'm not suspecting it
as the first thing on the list.

Has anyone seen the K2 act like this before?

Thanks
Duane
--
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[Bill Coleman-2]

On Jul 1, 2009, at 8:31 AM, Geoffrey Mackenzie-Kennedy wrote:

> Yes some years ago, after a falling pine brought down the antenna in  
> use
> while the K2/100 was transmitting (CW).  Diodes D12 and D14 in the  
> KPA100's
> T-R switch both failed into a shorted condition, and one of the  
> diodes in
> the K2's T-R switch failed as well. I was very lucky that the KPA100's
> transistors did not blow. My K2/100 now shares a protective shutdown  
> system.

A couple of years ago, when trying to use the K2 as a receiver with a  
homebrew transmitter for Straight Key Night, I accidentally  
transmitted about 12 or so watts directly into the front end of the  
K2/100 for over 30 seconds. The K2/100 isn't apparently any worse for  
wear.

So, it would take a considerable discharge to cause a problem of this  
type.

Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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[Geoffrey Mackenzie-Kennedy]

Hi Bill,

Yes I agree that it would take a considerable discharge to cause a problem
of this type, however this incident took place during a severe gale, without
any lightning in the area, during a CQ WW. It is a moot question whether the
wind plus rain resulted in the tree becoming charged after it was uprooted
and still falling.. The receiver was unharmed, but most if not all of the
KAT100's LEDs came on.

This was one occasion when catenary "fused" counterweights proved their
worth, allowing the 15m Lazy H to come down under the tree suffering minor
damage.

73,
Geoff
GM4ESD


On Thursday, July 02, 2009 5:22 at AM, Bill Coleman wrote:

 > On Jul 1, 2009, at 8:31 AM, Geoffrey Mackenzie-Kennedy wrote:

>
>> Yes some years ago, after a falling pine brought down the antenna in  use
>> while the K2/100 was transmitting (CW).  Diodes D12 and D14 in the
>> KPA100's
>> T-R switch both failed into a shorted condition, and one of the  diodes
>> in
>> the K2's T-R switch failed as well. I was very lucky that the KPA100's
>> transistors did not blow. My K2/100 now shares a protective shutdown
>> system.
>
> A couple of years ago, when trying to use the K2 as a receiver with a
> homebrew transmitter for Straight Key Night, I accidentally  transmitted
> about 12 or so watts directly into the front end of the  K2/100 for over
> 30 seconds. The K2/100 isn't apparently any worse for  wear.
>
> So, it would take a considerable discharge to cause a problem of this
> type.

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