[Elecraft] AF/RF Knob situation - joined the club

[ajsoenke at aol.com]

After 2+ years of operation K-3 SN31 has just succumbed to a compound failure of the smaller Main control AF and RF knobs.
I thought I was pretty lucky when I first saw list notes about the knobs failing and figured maybe a bad batch, etc. The rig SN 31 was originally placed in service in late October 2007. Last week during CQWW I lost AF control, determined the knob ws slipping and took a closer look. One of the set screws was at the face of a fracture that ran across the entire half of the shaft recess. For a quick fix, I decided to swap knobs with RF control. I no sooner slipped the other knob on the AF shaft and it split lengthwise. Quick trip to the junk box and an old Heathkit all metal knob saved the day. 

Today I take a look at the list and WOW what do I see, 3 days of knobitis has hit the fan.  So, maybe the problem is not going to go away that soon. I figure if Elecraft hasn't been real responsive about the problem, they are at a loss for answers and need a few days to regroup. It does happen now and then. So, I haven't called for or requested any replacement pars right now. What I have done is take a look at some of the vast number of oscilloscopes I have piled up around my classroom. I have Leader, Heath, Phillips, Toshiba, Hitachi, Tek, ad HPs - several dozen. The only one that doesn't have a mini shaft control onit anywhere is a 60 year old DuMont. At least 75% of these scopes are over 25 years old and have had pretty rough handling in school room. Some I even brought to the classroom after 20 years use in my engineering Labs. Not one has ever had to have a knob replaced for breakage.

So what's the difference?  As far as I can tell the main difference, besides color, is the old well used knobs are made of a platic that is more compliant, and most have a metal collar inserted in them, but not all. The Heatkits from early days - up til about 1970 used metal knobs in most ham rig applications. My 54 year old Hallicrafters use plain plastic knobs - no inserts but larger shaft size. 

I have always used a very light touch when tightening the set screws, so I have no fear I overdid it.

Right now the plan here is to get the operation stabilized with the best thing I can find, then, if I like the feel and appearance, stick with it til Elecraft gets a handle on things and can supply good replacements.  Some of the Heath metal knobs are an almost perfect match and could be anodized black for a durable finish.

Al,  WA6VNN