[Elecraft] K2 kit building problem

[Don Wilhelm]

Gordon,

That amount of RF is about (with 800mV on the Q5 collector).

I am close to agreeing with you about a bad Q6, but do the checks I 
mentioned anyway.

If you do find out Q6 is the culprit -- if this is a kit less than 1 
year old, contact support at elecraft and ask for a replacement.
If more than 1 year old (or you were not the original purchaser), it is 
not under warranty and you will have to pay for the part - contact the 
sales office to do that (make sure you have the part number handy). 
They will need payment information.  The phone number is 831-763-4211.
The minimum parts order is $5.  Get a replacement for Q10 at the same 
time, just in case.

73,
Don W3FPR

On 3/4/2018 3:39 PM, Gordon LaPoint wrote:
> Don,
>        I have about 220mv P-P on the base of Q6.  I'm off to check all 
> the components in the base ckt of Q6, with just DC on the collector. 
> This is in Tune with the Power out set to 2W.
> 
> Thanks,
> Gordon - N1MGO
> 
> On 3/4/2018 3:10 PM, Don Wilhelm wrote:
>> Gordon,
>>
>> It is doubtful (but possible) that Q6 is bad.  Did it overheat when 
>> you powered up? - if it did, you would most likely have seen a wisp of 
>> smoke.
>>
>> How large is the signal at the base of Q6 when you have 800mV P-P on 
>> the collector of Q5?
>>
>> The base voltage on Q6 is higher than normal, it should be around 1.1 
>> volts.  I would suggest you check all components in the base circuit 
>> of Q6 first.
>>
>> 73,
>> Don W3FPR
>>
>> On 3/4/2018 2:26 PM, Gordon LaPoint wrote:
>>> I'm building a K2 kit and I have a problem.  I'm starting the 
>>> Alignment and Test, Part III on page 77-78.   I have no rf out.  I 
>>> have followed the rf through the tx chain and have a good signal at 
>>> (RF board) Q5 collector (800mv P-P) using a 400Mhz scope.  I have a 
>>> signal on Q6 base, but nothing on the collector.  The DC voltage (in 
>>> TX) at Q6 is 12.0 Collector, 1.8VDC base and 0 on emitter.  I don't 
>>> see anything wrong DC wise, is it likley that Q6 is bad?  What else 
>>> should I look for?  With the radio off the R at Q6 emitter to ground 
>>> is 1.8ohms, that looks normal, so I don't have any current flow in 
>>> Q6, it looks like.
> 
> 
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