Re: Julius - How susceptable is K2 to antenna static shock?

[dw-4]

Thanks Julius,
A really great suggestion! putting them in on the other side.
Yes, well, I pulled the board last night and read the diodes with my DVM
(diode test)
They read .004 both directions.
A pretty good indicator that they were blown open.

So I replaced them with 1N914 diodes.
But the unit is still doing the same thing.
I wonder where I should look now on the board?

I also have the original (non-KPA100) cover with the built in
auto-tuner.
I wonder if I can temporarily put that on and see what the unit does.
That would tell me if the KPA100 is the true problem.

I've never had the unit running without the KPA100 on board so I'm
wondering if there is a CAL setting to tell the K2 that it is not there?

Thanks
Duane


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
--
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[Julius Fazekas n2wn]

Hi Duane,

Try checking U5, the LM358. I had one of those go the first time the radio was zapped (I put a good socket (gold plated round pin style) in for it, in case I had to change it again. Never did after the first problem.

I would not stay with the 1N914 diodes, you really should get the 1N5711s back in. See this APP Note for details: http://www.elecraft.com/Apps/RF_Det_application_note.htm

If you pull the KPA, the K2 reverts back to a QRP rig. I can't recall if you have to tell the K2 that the KPA is not there, I think it just detects that it is not installed. The manual will tell you for sure.
You won't be able to use it with a computer without the KIO2, but you would definitely be able to tell if the problem is isolated to the KPA. I would guess it is, but it all depends on what kind of hit the radio took. It's pretty robust, so I'm guessing it's just going to be a KPA fix.

You don't need to put the other top on, you can leave it open to check the radio. It might be easier with the top in place if you have the KIO2 and KBAT installed on the QRP top.

I think if you do a search through the old, pre-Nabble archives, you'll probably be able to find where Don has helped me and others with this problem in the past.

It sounds like you're going thru the process logically so far.

Hope you find it!

73,
Julius

dw-4 wrote

Thanks Julius,
A really great suggestion! putting them in on the other side.
Yes, well, I pulled the board last night and read the diodes with my DVM
(diode test)
They read .004 both directions.
A pretty good indicator that they were blown open.

So I replaced them with 1N914 diodes.
But the unit is still doing the same thing.
I wonder where I should look now on the board?

I also have the original (non-KPA100) cover with the built in
auto-tuner.
I wonder if I can temporarily put that on and see what the unit does.
That would tell me if the KPA100 is the true problem.

I've never had the unit running without the KPA100 on board so I'm
wondering if there is a CAL setting to tell the K2 that it is not there?

Thanks
Duane


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
--
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Post: mailto:[e-mail]

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