K2 problem: no tx output on 15 and 17m

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K2 problem: no tx output on 15 and 17m

Nick G3RWF
Any advice please?   My K2 suddenly lost tx output on 15 and 17 (actually still a tiny amount - less than a watt). Still receiving OK on those bands. I removed the 100w amp and the problem relates to the K2 barefoot. There is common circuitry on these bands - any suggestions where to start checking pl? The K2 is still working OK on all other bands.
73 Nick G3RWF
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Re: K2 problem: no tx output on 15 and 17m

vk2rq
Sounds to me like a dry joint or poor connection in the LPF for 15/17m. Check relay K11, L23 & L24, and C218-C222.

73,
Matt VK2RQ

> On 1 May 2014, at 2:18 am, "Nick Henwood" <[hidden email]> wrote:
>
> Any advice please?   My K2 suddenly lost tx output on 15 and 17 (actually still a tiny amount - less than a watt). Still receiving OK on those bands. I removed the 100w amp and the problem relates to the K2 barefoot. There is common circuitry on these bands - any suggestions where to start checking pl? The K2 is still working OK on all other bands.
> 73 Nick G3RWF
> ______________________________________________________________
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> Please help support this email list: http://www.qsl.net/donate.html
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Re: K2 problem: no tx output on 15 and 17m

Don Wilhelm-4
In reply to this post by Nick G3RWF
Nick,

My best guess is that something has happened in the 15/17 meter bandpass
filter.  You could verify that guess by doing a check of a couple points
in the Transmit Signal Tracing section of Appendix A in the manual.  
Use the RF Probe or oscilloscope with a 10X probe. You can start on page
14.  The two points of interest are the Buffer Output and the Bandpass
Filter Output.  Of course, you would set the K2 to 15 or 17 meters
rather than 40 meters as suggested in the manual.  If you have a good
amplitude signal at the Buffer Output, but little or none at the
Bandpass Filter Output, you have confirmed that the bandpass filter is
the problem.

If you are also getting HiCur messages, the most likely problem area is
the Low Pass Filter rather than the Bandpass Filter.

The first thing to check is soldering.  An unsoldered or poorly solder
connection can work fine for a long time with only mechanical contact,
but one day it develops enough oxidation to cause a problem.

73,
Don W3FPR

On 4/30/2014 12:18 PM, Nick Henwood wrote:
> Any advice please?   My K2 suddenly lost tx output on 15 and 17 (actually still a tiny amount - less than a watt). Still receiving OK on those bands. I removed the 100w amp and the problem relates to the K2 barefoot. There is common circuitry on these bands - any suggestions where to start checking pl? The K2 is still working OK on all other bands.
>

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