[Elecraft] K2 #7379 troubleshooting

[Brian Stevens]

Don,
Yes the K2 is completely built & I was at alignment & test part 3 when I had 
the low o/p power problem. I started the transmit
signal tracing procedure & did the receive testing to check the shared 
circuits as instructed in the manual.

I'll carry on with the transmit signal tracing & see where I get to.
Thanks
73 Brian
G0WZX
----- Original Message ----- 
From: "Don Wilhelm" <don at w3fpr.com>
To: "Brian Stevens" <brian at stevens7455.freeserve.co.uk>
Sent: Monday, November 04, 2013 1:03 PM
Subject: Re: [Elecraft] K2 #7379 troubleshooting


> Brian,
>  Do you have the K2 completely built? or have you only built it up to the 
> point where you can receive 40 meters?  I guess the point that you said 
> you had trouble adjusting the 40 meter BPF made me think the 10 MHz 
> oscillator might not work for you.
>
> If you have it completely built, then the 10 MHz crystal will work. You 
> must select the 30 meter band.
>
> However, because you have a transmit problem, you should use the transmit 
> signal tracing rather than receive - you will find the problem source more 
> easily, and the K2 itself provides the signals require for signal tracing.
>
> Again, stop at the first point where the RF is substantially lower than 
> the expected value because you have found a failure point.
>
> 73,
> Don W3FPR
>
> On 11/4/2013 5:01 AM, Brian Stevens wrote:
>> Don,
>> I've had another think & the low readings I get at LPF,BPF & T-R sw o/p's 
>> using the 10Mhz oscillator are with the VFO set so that I can hear the 
>> oscillator signal, not at 40m. Should the signal still be attenuated 
>> under these conditions?
>>
>> The low power o/p problem occurred while trying to peak the 40m BPF 
>> inductors L1/L2 with the VFO at 7.1Mhz.
>>
>> 73 Brian
>> G0WZX
>> ----- Original Message ----- From: "Don Wilhelm" <w3fpr at embarqmail.com>
>> To: "Brian Stevens" <brian at stevens7455.freeserve.co.uk>; 
>> <Elecraft at mailman.qth.net>
>> Sent: Sunday, November 03, 2013 9:15 PM
>> Subject: Re: [Elecraft] K2 #7379 troubleshooting
>>
>>
>>> Brian,
>>>
>>> If the test oscillator crystal is at 10 MHz, it *should* be very 
>>> attenuated by the 40 meter Low Pass Filter.
>>> The K2 40 meter LPF cutoff is in the range of 8.5 MHz, so it cannot be 
>>> expected to pass a 10 MHz signal.
>>>
>>> If you have a crystal in the 40 meter band, you could substitute it for 
>>> the 10 MHz crystal and try those measurements again.
>>>
>>> If you do not have such a crystal, go forward in the Troubleshooting 
>>> procedure to Transmit Signal Tracing and try those steps.  Do not skip 
>>> the oscillator checks - VFO and BFO that are in the Receiver Signal 
>>> Tracing part of the tests.
>>>
>>> One thing about the Signal Tracing steps - work in the order listed, one 
>>> point depends on the one before it being OK.
>>> Once you come to the first step where the output is significantly 
>>> (greater than 10%) lower than the Expected value, stop because you have 
>>> just found the output side of the failure point - it will be fruitless 
>>> to go on to other check points.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>>
>>>
>>> On 11/3/2013 3:53 PM, Brian Stevens wrote:
>>>> Hi,
>>>> I've hit a snag during 40m tx alignment in being unable to peak L1/L2 
>>>> to give more than about 500mW o/p with the power setting at 2W. I've 
>>>> gone through the troubleshooting procedure & all checks out ok until I 
>>>> get to the LPF,BPF & T-R switch section of the shared circuit testing.
>>>>
>>>> Using the 10Mhz crystal oscillator in the manual with 0.14V at the 
>>>> antenna i/p I get these readings:
>>>>
>>>> LPF o/p @ W1 = 0.004V (expected 0.13V)
>>>>
>>>
>>>
>>
>>
>>
>
>