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   Home   Help Search  
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Author Topic: K1 oscilator cicuit help  (Read 2835 times)
N3IG
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Posts: 42




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« on: January 23, 2012, 03:09:58 PM »

     In the middle of building a K1 and have the receiver part of the main board built up to first alignment and can only get the dreaded E-42 message. Wrote a few e-mails to Elecraft and they told me L1 or one of the poly caps was bad, so I ordered new poly caps, pulled L1 and checked tinning of leads, re-sweat the rf board and still can not get the oscillator to run.

     If you have k1 Experience I would appreciate any ideas. My test equipment is pretty much limited to my DMM.

     Worst case scenario I will finish building the basic radio and send in for troubleshoot and alignment.

Thanks
« Last Edit: January 23, 2012, 04:03:07 PM by N3IG » Logged
AA4PB
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Posts: 14354




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« Reply #1 on: January 23, 2012, 05:55:19 PM »

Check to see that you have approx +6VDC at D (drain) of Q8.

Make sure that Q8, Q9, D3, D4, and D17 are installed correctly.

Check that RP2 is the correct value (100K) and that it is installed correctly.

Make sure you have no solder bridges or cold solder joints in the VFO or those front panel components listed in item 42 on page 3 of the manual.

If you have a receiver that will tune the 2-3MHz range run a short antenna wire near L1 while the K1 is running and tune the receiver to see if you can find the VFO signal. That will tell you if the issue is the VFO not running or the front panel circuits not working.

The signal path is Q8 (the VFO) thru Q9, thru pin 10 of P1, to the front panel, to Q1, to the MCU. The error message is an indication that the VFO signal is not making it to the MCU (U1) on the front panel.
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Bob  AA4PB
Garrisonville, VA
N3IG
Member

Posts: 42




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« Reply #2 on: January 23, 2012, 08:55:56 PM »

     Thank you. That is what I was trying to get, voltages and path etc. I will check those out after work tomorrow and see what I find. Thanks Again.
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N3IG
Member

Posts: 42




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« Reply #3 on: January 24, 2012, 02:36:42 PM »

     Getting closer, held a jumper coax from my 950 close to the k1 and found the oscillator signal at 3.025. So at least I know it is a problem in the front board. The search continues. Thanks
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N3IG
Member

Posts: 42




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« Reply #4 on: January 30, 2012, 12:31:15 AM »

     K1 is finished and working. Nice receiver.

     I do have two questions for the K1 experts though.
1. The volume is real hot, when using headphones I can barely move it and it is too loud.

2. Every minute or two I get a loud pop in the audio output. Thinking maybe cold solder joint, but where?

     Any suggestions from the K1 builders. Thanks
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AA4PB
Member

Posts: 14354




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« Reply #5 on: January 30, 2012, 05:27:17 AM »

I've build a couple of K1s and not noticed an issue with "hot" audio. I'd first try a different headset. Make sure that the AGC is working okay.

Does the "POP" still occur with the antenna disconnected? It migh be some electrical interferrence from something in the house. Of course, "hot" audio is likely to make the "POP" sound worse than normal.

Inspect solder joints with a magnifying glass. Take an insulated tool or the eraser end of a wood pencil and tap on the circuit boards in various places to see if a little vibration causes intermittent operation.

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Bob  AA4PB
Garrisonville, VA
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