Mark,
I have had the same problem and also a hole in the 15 uH RFC. I replaced the
coil temporarily by a resistor of 10 Ohms. Elecraft uses heavier inductors
nowadays.
73 's Steef PA2A
K2 4654
K3 1184
----- Original Message -----
From: "Don Wilhelm" <[EMAIL PROTECTED]>
To: "Mark Adams, PE" <[EMAIL PROTECTED]>
Cc: <elecraft@mailman.qth.net>
Sent: Sunday, July 27, 2008 2:53 AM
Subject: Re: [Elecraft] K2 I/O Module Help Needed
Mark,
I would bet you are using an externally mounted KPA100/KAT100 combination.
That puts a load on the 12CTRL line coming out of the K2, and yes oft
times L1 on the AUX board is overloaded and goes up in smoke. It is
usually OK with the KPA100 or the KAT100 alone, but the combination of the
two overloads that tiny inductor.
You need to replace the inductor with one having a heavier current rating.
A toroid will do just fine. If you have one of those tiny cores like used
in the KSB2 RFC1 and RFC2, then just wind about 15 turns on that core.
Lacking that, use an FT37-43 core and wind about 12 turns on it (the FT-37
core is a bit large and untidy when mounted on the AUX board, but it
works). The inductance is not critical. In fact, you probably can
temporarily substitute a wire, but there may be noise coupling between
your KPA100 and KAT100 at times, so I would not recommend the wire as a
permanent fix, but it can get you going until you can get a suitable
inductor.
If you want a tool to figure the number of turns needed on a core to
produce a given inductance, I suggest you download miniRing Core
Calculator by DL5SWB - it is freeware for radio amateurs - see
www.dl5swb.de to download it.
73,
Don W3FPR
Mark Adams, PE wrote:
Hi Gang,
On FD, my K2 I/O board went south. It just stopped working when contest
time arrived Saturday. Bummer. I've just dug into the radio and found
that I have no power to U1 or Q1 on the I/O board and that L1 on the Aux2
Board is busted. Has a hole in its side to be exact. So, my junk box has
no 15uH inductors hiding anywhere. I have some inductors but no way to
measure them.
Anyone have any ideas? Is there a resistor I could sub to finish
troubleshooting? Maybe a few turns of #18 tinned wire would do the trick?
I cannot even find formulas to help me out.
Yes, I'll order a few from the big E Monday, but until then......
73,
Mark K2QO
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