Thursday, April 18, 2013

Success Alignment 2 Completed at Last

After two weeks of having my PLL oscillator problems I finally cracked it and thankfully the “Alignment test part 2” is now completed. I have to give a huge thanks to Don Wilhelm from the K2 forum, without his help I would still be tearing out what little hair I have! 

As usual with these things it was something small, a resistor or to be precise a resistor network that wasn’t playing ball. After replacing various components we narrowed it down to this resistor pak and in the end I replaced the pak for two separate 10k resistors as suggested by Don and it worked. 

From removing and replacing the pak a number of times I managed to damage one of the patches off the PCB but thankfully it wasn’t required so I was extremely lucky. 

 The PLL oscillating area is the top right of the PCB, you can see in the picture below where I've replaced the resistor pak with two 10k single resistors, that finally did the trick and got it running. You can see the 6th patch is damaged but luckily is now not used.

 I must admit I was beginning to lose hope and my confidence was getting low, I really thought I wasn’t going to get the old K2 working. It’s an amazing feeling when it all comes together and you realise you are not  a solder wavering madman who mucked everything up. 

The good news is I have had a listen to 40 meters CW and the radio sounds great, the filters are really good and first impressions are that it needs a slight tweak here and there but all in all it’s a very good receiver.

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