[Elecraft] K2 I/O Module Help Needed

[Brian]

So does this mean that if I have a brand new KIO2 that L1 is large enough to
handle the current of the KPA 100 and KAT 100 together?  Or do I still need
to wind an inductor like recommended by Don (W3FPR) and also found on the
KK7P website to avoid "smoke" from L1.  

Thanks, 

Brian
N1WNC

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Steef PA2A
Sent: Sunday, July 27, 2008 3:54 PM
To: w3fpr at arrl.net; Mark Adams, PE
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K2 I/O Module Help Needed

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" <w3fpr at embarqmail.com>
To: "Mark Adams, PE" <k2qo at mac.com>
Cc: <elecraft at 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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