Posted by
Don Wilhelm-4 on
Oct 06, 2010; 5:29pm
URL: http://elecraft.85.s1.nabble.com/K2-Debugging-low-transmit-power-tp5601987p5608070.html
Owen,
I tried to caution you not to get excited about RF voltage values that
were higher than the listed expected values.
That is normal for a K2 that is not detecting any output - the K2
increases the drive in an effort to obtain more output. Since you have
no output, the RF voltages on the working stages will be at the maximum
value.
The listed "expected" values are within 10% of what is to be expected
for a properly working K2 at 5 watts.
The transmit buffer has output and there is none at W6. Look at the
schematic so you can identify the components between those two points.
Basically it is the D6/D7 switch and the bandpass filter.
Is there any chance you put C6 in the wrong holes? In the set of 3
holes at the J15 location, the center hole should be empty. C6 goes in
the holes for pins 1 and 3.
73,
Don W3FPR
On 10/6/2010 11:42 AM, Owen B. Mehegan wrote:
> Hi Don -
>
> OK, I have gone through the transmit signal tracing steps and found a
> couple of anomalies. I'm referencing the specific section name and
> step number in the troubleshooting here.
>
> ALC:
> 3. Pin 2 of U8 (on the control board) shows 4.97VDC instead of the
> expected .7 - 2.5VDC. The manual tells me to check the component
> values in the RF detector, which I have. They are all correct.
>
> Transmit Mixer, Buffer, etc
> 2. Pin 4 of U10 shows .228 Vrms instead of the expected .016.
> 3. Pin 6 of U9 shows 1.148 Vrms instead of .2.
> 4. W6 shows 0.
> 5. D1 shows 0.
>
> So those seem _totally_ out of whack. These checks were done on 40m,
> which is where I'm having problems. Now what?
>
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