[Elecraft] K2 VCO alignment

[Don Brown]

Hi

This usually means the VCO is not oscillating or is way off frequency. First check with the counter probe that the 12 MHz reference oscillator is working at TP3. Then check the +5 volts on pin 16 of U4 and the 8 volt supply is ok on the input of U8. If all of that is ok then check T5 after you do that check T5 again. Make sure it is wound exactly as shown in the manual and the leads are stripped properly. Check the frequency at TP1. If you have nothing there then check the VFO ALC. With the oscillator not working the voltage on the collector of Q16 should be close to 8 volts and the drain of Q17 should be close to ground. Of course look for backward diodes, transistors, wrong value parts and missed solder joints. As a last resort suspect Q18 or Q17.

Don Brown


  ----- Original Message ----- 
  From: Paul Kelly<mailto:byrddawg at sbcglobal.net> 
  To: elecraft at mailman.qth.net<mailto:elecraft at mailman.qth.net> 
  Sent: Saturday, August 28, 2004 1:36 PM
  Subject: [Elecraft] K2 VCO alignment


  I am on page 61 of the K2 manual on VCO alignment. All
  previous tests have been OK. In connecting a DMM to
  ground and R30 I get a reading of 8 volts, which is
  unacceptable. I have rewound T5, replaced C72 with a
  new cap and replaced L30. I have also verified that
  the 6 varactor diodes are of proper values. Any ideas
  out there? Thanks Paul, NN5G
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