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K2 - 20M dead

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Mike Murray-4

K2 - 20M dead

I thought I'd give a RTTY contest a try this weekend so I dove in. Found
out after switching to 15M that I had my filters wrong so had to stop, open
up the rig and reset. Everything seemed to be OK after that until I tried
transmitting on 20M - dead as a doornail! Receives on 20 just fine,
transmits OK on all other bands, but nothing on 20 in any mode. Even
occasionally shows hi current on 20 with no actual RF output.

Anyone have any idea on where I should start troubleshooting?

Mike - W0AG
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Don Wilhelm-4

Re: K2 - 20M dead

Mike,

It is highly unusual to have a transmit problem on 20 and still have
transmit on 30 meters - those two bands share both the bandpass filter
and the low pass filter.

The fact that you have HiCur messages should point the finger at the Low
Pass Filter.

Are you certain it is receiving signals that are really on 20 meters?
You might want to check the VFO frequency first - it should be 4913 kHz
higher than the frequency shown on the K2 dial. You can use the
internal counter probe in TP1 and CAL FCTR.

If this is a K2/100, remove the KPA100 and test the base K2 working into
a dummy load.

You may have to do Transmit Signal Tracing as indicated in Appendix A of
the K2 manual to find where the failure point really is.

73,
Don W3FPR

On 9/29/2013 9:46 PM, Mike Murray wrote:

> I thought I'd give a RTTY contest a try this weekend so I dove in. Found
> out after switching to 15M that I had my filters wrong so had to stop, open
> up the rig and reset. Everything seemed to be OK after that until I tried
> transmitting on 20M - dead as a doornail! Receives on 20 just fine,
> transmits OK on all other bands, but nothing on 20 in any mode. Even
> occasionally shows hi current on 20 with no actual RF output.
>
> Anyone have any idea on where I should start troubleshooting?
>
>

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Mike Murray-4

Re: K2 - 20M dead

Don,

Thanks for the quick reply and troubleshooting suggestions! I do have the
KPA100 and KAT100 installed so here's what I did:

1. Rechecked 17, 20 and 30M and only 20 was still dead on transmit.
2. Opened the K2 up, checked VFO freq and it was OK (4915). Receive also
OK on 20.
3. Removed KPA100 and KAT100. Transmit now OK on 20, so the problem must
be elsewhere.
4. Installed KPA100 and transmit still OK on 20. Aha! Problem must be in
the KAT100 somehow.
5. Reattached KAT100 and tested again. 20M now transmitting OK!

At this point I'm starting to question my sanity. All bands & modes are
back to normal, although I'm not convinced the problem won't reoccur. I
guess I'll just have to wait and see if it happens again and restart the
troubleshooting.

Thanks again for your help.

Mike - W0AG

On Mon, Sep 30, 2013 at 8:15 AM, Don Wilhelm <[hidden email]> wrote:

> Mike,
>
> It is highly unusual to have a transmit problem on 20 and still have
> transmit on 30 meters - those two bands share both the bandpass filter and
> the low pass filter.
>
> The fact that you have HiCur messages should point the finger at the Low
> Pass Filter.
>
> Are you certain it is receiving signals that are really on 20 meters? You
> might want to check the VFO frequency first - it should be 4913 kHz higher
> than the frequency shown on the K2 dial. You can use the internal counter
> probe in TP1 and CAL FCTR.
>
> If this is a K2/100, remove the KPA100 and test the base K2 working into a
> dummy load.
>
> You may have to do Transmit Signal Tracing as indicated in Appendix A of
> the K2 manual to find where the failure point really is.
>
> 73,
> Don W3FPR
>
>
> On 9/29/2013 9:46 PM, Mike Murray wrote:
>
>> I thought I'd give a RTTY contest a try this weekend so I dove in. Found
>> out after switching to 15M that I had my filters wrong so had to stop,
>> open
>> up the rig and reset. Everything seemed to be OK after that until I tried
>> transmitting on 20M - dead as a doornail! Receives on 20 just fine,
>> transmits OK on all other bands, but nothing on 20 in any mode. Even
>> occasionally shows hi current on 20 with no actual RF output.
>>
>> Anyone have any idea on where I should start troubleshooting?
>>
>>
>>
>

Don Wilhelm-4

Re: K2 - 20M dead

Mike,

Glad to hear that it is now working - but I don't like things that just
"go away"

That sounds like something got temporarily "stuck" - which usually turns
out to be an unsoldered connection.
I might also suspect a relay contact somewhere.
The relays have wiping contacts, so a few operations will typically
clean off any deposits.
I recommend just remembering this occurrence and maybe jotting down some
notes about it. If it reappears, you will have that additional info to
refresh your memory.

73,
Don W3FPR

On 9/30/2013 2:37 PM, Mike Murray wrote:

> Don,
>
> Thanks for the quick reply and troubleshooting suggestions! I do have the
> KPA100 and KAT100 installed so here's what I did:
>
> 1. Rechecked 17, 20 and 30M and only 20 was still dead on transmit.
> 2. Opened the K2 up, checked VFO freq and it was OK (4915). Receive also
> OK on 20.
> 3. Removed KPA100 and KAT100. Transmit now OK on 20, so the problem must
> be elsewhere.
> 4. Installed KPA100 and transmit still OK on 20. Aha! Problem must be in
> the KAT100 somehow.
> 5. Reattached KAT100 and tested again. 20M now transmitting OK!
>
> At this point I'm starting to question my sanity. All bands & modes are
> back to normal, although I'm not convinced the problem won't reoccur. I
> guess I'll just have to wait and see if it happens again and restart the
> troubleshooting.
>
> Thanks again for your help.
>