K3 Modifications Photos

Posted by Don Nesbitt on Jan 09, 2009; 2:39am
URL: http://elecraft.85.s1.nabble.com/K3-Utility-version-1-2-1-6-available-on-Elecraft-web-site-tp2131255p2131505.html

I’ve posted a few photos of the modifications that I made at the same time I installed the KDVR3.  Modifications include:

 

- External ALC Modification and Optional Pull-Up resistors for Band Outputs

 

- AF Stage Upgrade – Line Out and Speaker Amplifier (the “easy” way & using the SMD resistors)

 

- Front Panel Microphone Circuit Modification – Application Note

 

- Improving the Immunity of the Rear-Panel RS232 and Audio Connectors to RF – Application Note

 

And, a TOTALLY UNAUTHORIZED implementation of the “K3 Caution when using an external monaural speaker” post to the reflector by Wayne on December 20, 2008.  The email outlines a circuit modification which is meant to protect the audio output chip from spikes by putting a 470 ohm resistor to ground from each of the speaker outputs and suggests that a convenient place to do this would be on the audio daughter board at the single-row, right angle male connector.  You can see how I did this in the photo.  I’d advise you to WAIT until Lyle creates an actual application note and posts it!  DO THIS AT YOUR OWN RISK!  For all I know, I’ve got it wrong – but – didn’t see any smoke and it seems to work – for me!  YMMV!

 

You can see my simple photos at:  http://www.flickr.com/photos/n4hh

 

No registration is required.  Use the “Slideshow” for larger images.

 

While I really didn’t notice a “need” to do these modifications, it was convenient to do them along with the installation of the DVR.  None of these modifications (including installing the KDVR3) required the removal of the Sub-Rx and other than being a bit tedious, were simple and straight forward including using a toothpick to hold down the SMDs!  Have fun!  ‘73 es gud dxing – Don N4HH  K3/100 #83

 

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