[Elecraft] K2 #7379 troubleshooting

[Brian Stevens]

Thanks Don, I started on the Transmit Signal Tracing & did the receieve 
signal tracing as suggested at point 5 in the preparation for transmitter 
signal tracing section. VFO & BFO frequencies checked out ok.
I'll try your suggestion of changing the crystal frequency & carry on with 
the transmit signal tracing.

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)
>>
>
>