New VFO knob for my KX2

In the runup to the purchase of my KX2 I read a number of comments in various places regarding the differences in the VFO between the KX2 and KX3. Most of the comments were about the difference in the feel between the two radios. There is an actual, physical difference. The main tuning encoder in the KX2 is “Mechanical, sleeve bearing” and that of the KX3 is “Optical, with ball-bearing shaft and weighted knob.” So the VFO feel is not just in your head, or your fingers, it’s actually both and based upon the fact that the mechanisms in the two radios are different.

The VFO knob may well be the primary piece of the man\machine interface of a radio. It is the knob that an Amateur Radio operator spends the most time touching\moving. It’s the one knob on a radio in which the feel is most important. In a way, Amateur Radio operators have been fiddling about with proprioception and haptic perception without likely even knowing it. The feel of this physical object and the mechanical\electrical linkage to the radio has always been very important to a radio operator and over the years manufacturers have used all manner of various mechanisms in an attempt to perform the necessary functions for the radio while providing the the right feel to the operator. In my observation the notion of this feel is often referred to as “weight.” The feel of a good VFO should not be light or loose. It should move with some reasonable effort and maintain its position when movement stops. To me it should have the feel of a weighted object moving through a reasonably viscous fluid with just the slightest amount of resistance to the imparted motion.

The VFO on my Kenwood TS-590SG has a very nice feel and even has a sliding lever beneath and just behind the VFO knob that can be used to increase the tension to suit the operator. I like mine with a little less tension and W9SIZ, who’s been twirling Collins and Hallicrafters VFO knobs all of his life, likes his with more. It actually was the very first thing that he adjusted when he took his new radio out of the box, before he even powered it up for the first time. “Tim, how do I adjust this VFO?” “Right here Uncle Paul.” Over many years his fingers and in turn his mind have developed a sense of what a VFO should feel like and the Kenwood product developers knew that the feel of this one knob is very important so they included the ability to adjust it.

There are countless examples of this on both new and old radios. For instance, I have a pair of Kenwood TS-830S transceivers. They are identical in every way except one has the highly desired Kenwood KB-1, which is solid aluminum, versus the standard plastic knob on the other. Even though the mechanical portions of the VFO are identical, the feel of the one with KB-1 is better than the one without. To this day a KB-1 is a highly sought after accessory for the TS-830S. I’ve seen them fetch upwards of $100 on eBay. All in the pursuit of improved VFO feel.

Kenwood KB-1

Aside from the actual differences in the VFO mechanism between the KX2 and the KX3 and how this affects the feel, the VFO knob on the KX2 lacks a dimple. This seems like an obvious miss on Elecraft’s part. How much more would a dimple have cost? I’m sure that we all would have happily paid the difference. So in pursuit of a dimple and some improved feel I started to search for a third-party solution. As you may be aware there is a fair cottage industry of accessories for Elecraft radios. I found some vendors that make VFO knobs for their other radios but none for the KX2. As a last resort I searched eBay and found this:

KX2 VFO tuning knob

It is solid aluminum, with straight knurling on the circumference, and as you can see, a dimple.

OEM KX2 VFO knob vs replacement

It is slightly larger than the original VFO knob (1.257 inches vs 1.112 inches) and has a reasonable heft to it. Where the original knob is just pressed onto the shaft of the VFO mechanism, the new one has a set screw (Allen wrench provided.) Installation is obviously simple. One thing of note is that since the new knob is slightly larger you may find that it might contact the display cover. Mine did. To resolve this I simply loosened the display cover screws and there was enough play in the cover to move it up slightly to clear the new VFO knob. The seller describes potential clearance issues in the posting for the item.

New VFO tuning knob

The new knob imparts a much nicer feel to the VFO and the dimple is a welcome addition. It was much less expensive than the third-party VFO knobs for other Elecraft radios and it is a very nice upgrade to my new KX2. The eBay seller was very easy to deal with and shipped the item very quickly.

 

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6 responses to “New VFO knob for my KX2

  1. Good evening, I have been using 73CNC knobs on my K3 and they are great! I have read on the Elecraft list that they may not be good for the VFO but I have never had any issues. It has been on the rig for about 5 years.
    73,
    VE3WDM
    Mike

    • Thanks for the comment Mike. Yes, I read a thread on the Elecraft list from 2010 that may be the one to which you’re referring. My guess is that it’s probably a stretch that the encoder would even notice a heavier VFO knob much less be negatively affected by it. Imagine someone’s great grandchildren using their great grandpa’s now vintage K3…”Boy I wish great grandpa hadn’t put that heavy VFO knob on his radio. I do believe that this thing has a hitch in its giddy up.” : )

      I looked at the 73CNC offerings but didn’t specifically see a KX2 knob. They make a KX3 knob but I think that the KX3 VFO knob is larger than the KX2. At least it appears to be from pictures. I don’t know anyone with a KX3 to compare. Enjoy your K3. I’m really enjoying my KX2.

      73,
      Tim
      KA9EAK

  2. Hi Tim, I have a few VK SOTA friends who own the KX3. All swear by the capabilty offered by the KX3 for portable ops. I’m looking forward to reading more on your portable operations with the KX3, parks or SOTA. I recommend using an efficient Inverted V linked dipole or perhaps a good EFHW. If your KX3 has an inbuilt ATU then the ZS6BKW antenna with 300 ohm feedline would be a smart choice. Good luck 😉 73 Andrew VK1AD

    • Thanks Andrew. I just returned home today from the first camping trip with the KX2. I really like this radio. Thanks for the antenna suggestions. I’m currently using an LNR end fed (their trail friendly 10/20/40) but some additional antenna experimenting is now in order. I think that a linked dipole is going to be first on the list.

      73,
      Tim
      KA9EAK

  3. A very well written bit of information about the importance of the main tuning knob on the KX2. I bought one and it is exactly as described. However, Elecrafter will not accept a KX2 to repair with this knob attached. Strange! Does it put extra wear on the mechanism? It is hard for me to believe that. It will accept side panels and just installing these things puts to radio at risk to the delicate ATU board and transferring finals heat sink from stock panel to panel with handle is a certain risk.

    • Thanks David. I like mine. It’s a nice improvement over the stock cheap plastic knob. I agree, it is odd that changing the side panels for the aftermarket heat sinks is OK but not a VFO knob.

      73,

      Tim
      KA9EAK

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