[ARC5] Make my Christmas better

[Brian]

Hello Ken et al,

There were many manufacturers who produced the 'coffee-grinder' Command tuning knob. 

  a.. In the better ones, there is a tight-fitting collar bearing between the tuning shaft and the screw-down outer collar. These ones have little to no backlash. 
  b.. Some do not have the collar bearing and even when the outer screw-down collar is fully tightened, there is plenty of backlash.  On some of these, I have fashioned a collar bearing and carefully fastened the whole lot back together. 
  c.. Some had the female spline loosely pinned to the tuning shaft - they have plenty of backlash. In some of these, I have driven out the original pin, fitted a tapered pin and another at right-angles to the original pin = much better.
I haven't tried this, but a temporary fix could be to jam a small piece of 0.005" shim-stock between the male and female spline parts at assembly. This approach is far less stressful than hammering a piece of 0.25" copper tubing over the male spline, where you run the risk of shattering balls in the thrust bearing. Just a thought. And if it's too tight, try thinner shim. 

Do not use a silicone-based lubricant anywhere near the tuning capacitor. It will cause havoc with the spring-finger connections to the moving parts of the tuning capacitor.

73 de Brian, VK2GCE.

On Monday, December 25, 2017 4:03 AM, you said: 
<snip>
I have several of the crank-handle type, Ronnie, in a bag somewhere in the mess here 
along with a few of those "wee knobs" which were sometimes mounted inside the covers of 
AN/ARC-5 receivers.

I really don't care for either of them since they contribute to all of the backlash which shows 
up when using them. I much prefer my own adapters made of a short section of 1/4" brass 
tubing. These show zero backlash.

At this point, I don't need any "ARC-5" bits, so unless someone else comes up with some to 
trade to you for what you've offered, as soon as I can, I'll dig them out and send you a 
couple of which ever ones you want.

So let's be clear: you are talking about those with the small black crank-handle on them (I 
think the number stamped on them is 6973, but I'm not sure), and you are NOT talking about 
the small "wee knob". Is that correct?

And I agree with you: the asking price for either one on eBay is ridiculous.

Ken W7EKB
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