[Elecraft] K2 #7379 troubleshooting

[Don Wilhelm]

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)
>>>
>>
>>
>
>
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