[R-390] six position rf bandswitch

[Paul H. Anderson]

On Fri, 2 Dec 2005, Norman J McSweyn wrote:

> Hi all!

> I cleaned the geartrain by seperating it from the rest of the rf deck. 
> The six position rf banswitch won't align properly(they all do work, 
> however!). I have had the deck out three times and it's still not right. 
> When tuning, sometimes you have to go below (electrical) the band and 
> come back up. The manual is pretty vague, such as: "center the contacts 
> on the switch". Not very helpful. When this deck was out, I looked 
> carefully at the switches and I do realize that if I screw this up by a 
> few degrees, it never will work right. Does anyone have a good 
> proceedure to set the switches so that this works every time, or is it 
> just an "r390a-ism" It's a bug that I'd like to shoot once and for all.

> Thoughts, questions or comments!

One thing I found is that the geneva coupler is highly sensitive to being 
securely shimmed into place.  There are some very very thin shims that go 
in to hold it in, and I _think_ they are there to reduce the side to side 
rocking that is _just_ enough to cause problems with the bandswitch 
mechanism getting too sloppy.

I had exactly your problem with several RF decks, and this was the best 
explanation I could come up with.  When I scraped around and found a shim 
that seemed hard to put in, that was about right.

I also noted that after removal, trying to put exactly the same shim into 
exactly the same spot wasn't always easy.  It may be that this calls for a 
very tight fit just to get rid of the slop.

I don't exactly know what will work for you, but I'd hold the deck so you 
can see this coupler turning and moving, and look very, very closely at it 
while turning through the bands to see if you're getting any slop there.

This problem cropped up in R-392, R-390A and R-390 radios that I have 
here.

Paul