[Henry] The 3K Premier Roller Inductor

Mon Dec 3 16:43:46 EST 2007

As I mentioned here a few weeks ago, I recently bought a used 3K 
Premier. I've seen several messages on various amplifier mailing lists 
discussing issues with the roller inductor. Here is what I've 
experienced so far with mine.
The amp I purchased came with the optional spinner knob on the roller 
inductor. It's a nice idea, but it doesn't work as well as I'm sure was 
intended. The roller inductor is mounted behind the front panel of the 
internal amplifier enclosure. The spinner knob turns the roller inductor 
directly, and there is also a pair of gears which drive the dial 
indicator at a much reduced rate. The problem I see is that there is no 
bearing where the shaft goes through the main front panel, leaving it 
unsupported. The spinner knob is at the end of about a 3 inch 
unsupported shaft. The result is that it wants to wobble and bind 
instead of turn smoothly when cranked with the spinner knob. Grasping 
the entire knob and rotating it, instead of using the spinner, works 
fine except that it is annoyingly slow, undoubtedly the reason the 
spinner knob was made available.
Electrically, the amp works quite well except that on 12M with the power 
supply switched to the SSB position there is the sound of an occasional 
arc when tuning the roller inductor for maximum power output. This is 
into a dummy load with 1:1 VSWR. I find this quite alarming!
I've seen discussions of using a lubricant on the roller inductor, both 
on the bearings and on the roller itself. Before I try this, I'd 
appreciate hearing from other users who have experience with these 
issues. Thanks!
73,
John, K9MM