[Elecraft] K2 - KIO2 connected under power - now it is dead

[Andreas KU7T]

Dale,

you (probably) hit the nail in the head! L1 is open.  And I can see a very
small spot on the side from burning it out.

Now, after the fact I am actually reading that it is recommended to replace
L1 because in this scenario (remoting both KAT and KPA) the current is much
larger than the 15mA it is rated for
(http://www.fidalgo.net/~wa7gxd/k2kpa100.html):

L1 is rated to power the KIO2 and perhaps an external load of 10 or 15 mA,
but not the KIO2 and the control section of the KPA100, which draws about 65
mA in my unit when idling. It could become considerably more, so replace
this choke!



----- Original Message ----- 
From: "Dale Boresz" <dmb@lightstream.net>
To: "Andreas KU7T" <ku7t@ku7t.org>
Sent: Tuesday, June 17, 2003 3:02 AM
Subject: Re: [Elecraft] K2 - KIO2 connected under power - now it is dead


> Andreas KU7T wrote:
>
> >Hi,
> >
> >I built the KIO2 and it worked rigth from the beginning, as in good
Elecraft tradition.
> >
> >Then, I tried to remote the KPA100/KAT100 and as soon as I plugged the
cable in there was a strange smell and nothing worked anymore. I am running
on battery, so I think I plugged in under power.  Well, probably not a good
thing but I did it.
> >
> >
> >
> Andreas,
>
> Check choke L1 (on the AUX Board  - the little board which plugs into
> the 10-pin control board connector) for continuity. Don't get this
> confused with choke L1 on the main KIO2 I/O board which is also 15uH.
> I'll bet that 'strange smell' was L1 burning out, and it is probably now
> 'open' conductivity-wise.
>
> L1 passes 12 volts, through via pin 8 of the rear-panel 9-pin "D-Shell"
> connector, and if it is not present, you'll find that FET Q2 on your
> KAT100 will not turn on, which in turn will not allow Q1 to conduct,
> which means that you won't have any power to your KPA100 - despite the
> fact that you still have your external 12 volts connected.
>
> -Dale / WA8SRA
>
>
>
>