[Elecraft] Weighted Tuning Knobs - Any Consequence?

[Don Wilhelm]

  Ron,

Oh yes, that National knob (and gear reduction housing) was a great 
one.  I used it on several of my homebrew receivers - until the 
Eddystone 100:1 gearing slide rule dial became available - that was a 
great one too.  I still have the Eddystone on my revision of the HBR-16 
(mine was an HBR-18 with a Q multiplier at 85 kHz), and another that is 
an incomplete chassis that was once destined to become a receiver (may 
become one in time, but the probability is small).  My National NC-5 is 
unmodified, and although it sits in my attic, will never leave my hands 
due to sentimental reasons.

But those were the days of yore where you had to have a calibration 
chart to find the frequency that was represented on that National dial 
(500 dial points), and the marks on the Eddystone slide rule dial had to 
be inscribed on the dial face or deciphered from the fixed scale on the 
slide rule.

In those "days of yore", we did not care about frequency readouts to the 
nearest Hz (it was "cycles" back then), but only that one was operating 
within the band for the emission type.  Within those limits, those dials 
worked very well and were comfortable to use.

We now have accurate digital frequency readouts, and the only remaining 
discussion is how the knob "feels", "spins", "looks" and other such 
factors.  Our needs these days have changed dramatically.

I do worry about the long term durability of the encoders with quite 
heavy knobs, although I have not seen a K2 or a K3 that showed signs of 
encoder failure (yet).  I had bought a couple of those old National 
knobs and gear boxes that had a worn elliptical shaft from extensive use 
and the dial would have "hard spots" in its rotation, so they were not 
immune to problems either.

73,
Don W3FPR


On 12/22/2010 6:08 PM, Ron D'Eau Claire wrote:
> My favorite knob remains the huge tuning knob on my old National HRO5TA1 -
> about 6 inches in diameter, weighs about half a pound and was about 10 turns
> stop-to-stop.
>
> But the original question is a legitimate one. Are the simple bushings in
> the encoders up to the weight of the after-market knobs? The big national
> knob I mentioned had a huge lubricated bushing about 2 inches long
> supporting a hardened steel main shaft in a hardened sintered bronze bushing
> and, IIRC, so did the Collins rigs.
>