ELECRAFT AF1 BUILDER’S ALERT #1

J1 & J3 Ring/Tip Connections

October 2, 2006

APPCLICABILITY

This Builder’s Alert applies to all AF1 kits shipped until October 2^nd, 2006.

BACKGROUND

The PC Board traces for the AF1’s audio input jack J1 and output jack J3 were wired to only the “ring” connection of the stereo tip-ring-sleeve jacks. If you are using stereo mini-phone cables this will not cause a problem, but a mono plug will not provide any audio into the AF1 as the J1 “tip” is unconnected.

Additionally, the AF1 J3 Output jack should have the tip and ring connections wired together so that stereo headphones work correctly.

CHANGES REQUIRED

If the circuit board in your kit is Revision A (shown in the lower left corner on the top of the board), make the following changes so it will work properly with an monaural plug at the input and a stereo plug at the output. (This will be corrected in future revisions of the board.)

At the pins of J1 (AF IN) on the bottom of the board, use a sharp knife to cut and remove the segment of the trace shown below. Use a short length of #24 insulated wire to make a jumper to reach between the pin on J1 shown and the small hole at the circuit via where the trace passes through to the top of the board. This change isolates the ring connection and reroutes the audio to the tip connection so a monaural plug at J1 won’t short the audio to ground.

At the pins of J3 (AF OUT) on the bottom of the board, install a jumper between the pins shown below. Use a short section of #24 insulated wire or a discarded component lead. Take care to ensure the middle connection of J3 is not shorted to ground. This ties tip and ring together so audio is present on both at the output.

If you don’t have any #24 insulated wire available, we’ll send you some at no charge upon request (simply send an email to parts@elecraft.com, and specify you need 6” of E760008 for your AF1).