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Mike, NI2S's Ham Blog

Page 11

12-Jan-08:  Noise Blanker assembly.  An afternoon lull allowed me to dive into the noise blanker assembly.  Since I purchased my K2, there was an improvement released by Elecraft in the NB design, the parts for which I purchased from Elecraft.  Therefore, the first steps in the build were to apply the modifications:   

The remainder of the NB went together in a couple of hours.  The Elecraft Manual stresses that this PCB is going to be installed with tight clearances, so I took special care in precision soldering.  The manual recommended cutting the leads before soldering.  I found this unnecessary (as long as your solder skills are up to the challenge) except for the reverse mounted 1/4 watt resistors.

A note on how to pre-cut component leads before soldering.  After fitting the component through the PCB, I take an Exacto knife and lightly score the lead where it meets the surface of the PCB.  Then I remove the component, and find the score mark under magnification, and snip at the score.  Works every time.

 I also discovered that I am missing a capacitor from the NB kit (C12 if you really must know), so I have sent a parts request off to Elecraft this evening.   Other than the missing capacitor, the NB board is now complete.

      

A note on toroid windings.  I count the windings four times under magnification - 2 times clockwise, 2 times counter-clockwise just to be absolutely sure I have the correct number per the manual.  For tinning the leads, I have found that the best way is to very gently clamp the torrid after it's wound, and tin the leads with the toroid held this way.  Without something to hold the toroid in place while you tin the leads (using the solder blob method), the toroid moves around too much.  Care must be taken when clamping, because it is all too easy to crush the core.  All you need is just enough clamping pressure so the component does not move with solder iron contact.

Up Next - the Auto Antenna Tuner accessory kit.