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K3 off frequency?

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K3 off frequency?

My K3 (with all S upgrades, ser #170) stopped working over the weekend. I noticed that on 80m, while the frequency on the rig was 3574, the frequency reported by KAT500 was 3152 (or so). No output on any other band. I then checked reception of WWV - no reception of the 10Mhz signal. I fed in a -50dBm signal at 3574KHz. No reception.

I am going to crack the case on the weekend.

The only think I can think of is that something has shaken loose as the rig was transported by car a while ago. Given the odd frequency, I am thinking that it may in the LO chain.

Any thoughts?

Raj, N2RD
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Re: K3 off frequency?

Thanks Dave. This is very helpful. I will check this for sure.

Raj

Sent from my iPhone

> On Oct 7, 2020, at 3:57 PM, David Olean <[hidden email]> wrote:
>
> Hello Raj,
>
> I had a K3 die and it was due to the 8 volt regulator going belly up. Before you do anything, check the voltages out of those regulators that are bolted to one of the side panels. Lack of 8 volts kills the synthesizer. I made a few notes when I did the repair. I have attached my notes to this message. Possibly it may be of help to you. I showed where the synthesizer frequency outputs are and what levels to expect. The K3 I fixed was also a low serial number around 375 as I recall.
>
> 73
>
> Dave K1WHS
>
>> On 10/7/2020 11:26 AM, Rajiv Dewan via Elecraft wrote:
>> My K3 (with all S upgrades, ser #170) stopped working over the weekend. I noticed that on 80m, while the frequency on the rig was 3574, the frequency reported by KAT500 was 3152 (or so). No output on any other band. I then checked reception of WWV - no reception of the 10Mhz signal. I fed in a -50dBm signal at 3574KHz. No reception.
>>
>> I am going to crack the case on the weekend.
>>
>> The only think I can think of is that something has shaken loose as the rig was transported by car a while ago. Given the odd frequency, I am thinking that it may in the LO chain.
>>
>> Any thoughts?
>>
>> Raj, N2RD
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
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> <K3 TROUBLESHOOTING NOTES.docx>

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David Olean

Re: K3 off frequency?

In reply to this post by Elecraft mailing list

Hello Elecrafters,

I had a similar problem with a K3 this past March. My brother had his K3
die and I offered to look at it for him. He claimed that he could only
hear things on part of 80 meters. All the other bands were dead on RX
and TX. When I checked it, I found similar symptoms. At one point it
started working again normally, then, with the next power cycle, it died
again. The problem was traced to the synthezizer. Board layout
diagrams are a bit sketchy for troubleshooting. I contacted Customer
Support and a wondeful tech guy gave me some pointers on where to look.

The problem, while seeming to be serious, turned out to be a simple
fix. The 8 volt three terminal regulator mounted on the side panel had
rolled over and died. When I got everything running again, I made some
notes (complete with pictures and arrows ) I tried to attach it to my
response to N2RD and the reflector, but the e mail was rejected as it
was too big. I think the notes are pretty good as it shows where to look
for voltages involved with the synthesizer, as well as LO signal levels
and frequencies, on each band for the receive and transmit paths.

Is there a simple way I can post these notes so all can see it? I did
send them to N2RD to help him figure things out. If anyone is
interested, I can send them the note. It is a WORD document and is about
3.2MB in size. The size is due to color pictures of the circuit boards
showing the test points etc.

73

Dave K1WHS

On 10/7/2020 11:26 AM, Rajiv Dewan via Elecraft wrote:

> My K3 (with all S upgrades, ser #170) stopped working over the weekend. I noticed that on 80m, while the frequency on the rig was 3574, the frequency reported by KAT500 was 3152 (or so). No output on any other band. I then checked reception of WWV - no reception of the 10Mhz signal. I fed in a -50dBm signal at 3574KHz. No reception.
>
> I am going to crack the case on the weekend.
>
> The only think I can think of is that something has shaken loose as the rig was transported by car a while ago. Given the odd frequency, I am thinking that it may in the LO chain.
>
> Any thoughts?
>
> Raj, N2RD
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]