K3 Problem, VFO Noise While Rotating On 10 Meters

[Paul Kirley-2]

Based on the description of your rig, you have the original synthesizer(s).  The noise mod involved adding some resistors and diodes to the K3 main board at specific spots and making some firmware adjustments.

On the assumption that you have the resistors and diodes already, per your description of your K3 vintage, here are the firmware comments from the mod instructions:

**************************
IMPORTANT: You must install the resistors and diodes as described above before changing the bus
clock rate. Failure to do so will result in erratic behavior of your K3.
1. Download and install firmware revision 3.24 or later. Refer to the K3 software page for instructions.
2. IMPORTANT: Locate the CONFIG:VCO MD menu entry, and tap the 1 keypad switch until you
see SPI 2; this selects the new bus clock rate. (The default setting is SPI 1.)
*************************

I will email you the mod instructions separately so that you can see where the resistors and diodes should be (although Elecraft may have relocated them in later production).  Then you can proceed with the CONFIG setting.

73, Paul W8TM


[Elecraft] K3 Problem, VFO Noise While Rotating On 10 Meters
Randy w9zr at aol.com
Wed May 19 06:46:18 EDT 2021

When I tune the VFO knob on 10 meters I hear a scratching type noise.  This problem only occurs on 10.
There was an Elecraft mod that addressed this issue for early serial number K3's but my K3 is a later  unit with the mod built in at the factory during production. Can anyone shed some light on this issue?  I assume that this is not normal operation. 73 Randy

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Hi Paul Thanks for the reply. I have the upgraded SYN-3A synthesizer and the rig came from the factory with the resistor and diode mod installed.  The clock rate is set to SP2. I should have mentioned that info in the original post. 73 Randy In a message dated 5/19/2021 7:02:19 AM Pacific Standard Time, [hidden email] writes: 
Based on the description of your rig, you have the original synthesizer(s).  The noise mod involved adding some resistors and diodes to the K3 main board at specific spots and making some firmware adjustments. On the assumption that you have the resistors and diodes already, per your description of your K3 vintage, here are the firmware comments from the mod instructions: **************************IMPORTANT: You must install the resistors and diodes as described above before changing the busclock rate. Failure to do so will result in erratic behavior of your K3.1. Download and install firmware revision 3.24 or later. Refer to the K3 software page for instructions.2. IMPORTANT: Locate the CONFIG:VCO MD menu entry, and tap the 1 keypad switch until yousee SPI 2; this selects the new bus clock rate. (The default setting is SPI 1.)************************* I will email you the mod instructions separately so that you can see where the resistors and diodes should be (although Elecraft may have relocated them in later production).  Then you can proceed with the CONFIG setting. 73, Paul W8TM  [Elecraft] K3 Problem, VFO Noise While Rotating On 10 MetersRandy w9zr at aol.comWed May 19 06:46:18 EDT 2021 When I tune the VFO knob on 10 meters I hear a scratching type noise.  This problem only occurs on 10.There was an Elecraft mod that addressed this issue for early serial number K3's but my K3 is a later  unit with the mod built in at the factory during production. Can anyone shed some light on this issue?  I assume that this is not normal operation. 73 Randy 
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