[R-390] R-390/390A Tuning slug repair?

[Jordan Arndt]

Well, that was quick...

The slug wires are inserted into the adjustment screw until the end is flush 
with the very bottom of the splined opening and then soldered in place..My 
best guess is that the end of the wire is very lighly tinned, then inserted 
and soldered with heat applied to the adjustment screw...Once the wire if 
removed, you can see the opening at the bottom of the spline opening...

There does not appear to be any solder on the end of the wire that is 
threaded into the core, but there might be very small amount of epoxy or 
similar adhesive. I see some type of substance there, but not enough to tell 
what it is.

The outside diameter of the wire is ~ .0625 in., or right around 1.6 
mm...Now to find a guitar string with the right construction and materials 
and of the right diameter...!

More to follow...

agn 73...Jordan VE6ZT

----- Original Message ----- 
From: "Jordan Arndt" <Outposter30 at shaw.ca>
To: <k6fsb at arrl.net>; "Larry H" <larry41gm at gmail.com>; "Collins R-390 HF 
Receiver List" <r-390 at mailman.qth.net>
Sent: Thursday, August 26, 2021 3:57 AM
Subject: Re: [R-390] R-390/390A Tuning slug repair?


> Hi Larry, Don, Renee and the group...
>
> There appears to be a difference between how the wires are attached to the 
> slugs in the 390 and those in a 390A...
> The photo sent to me by Don WC4G shows a 390 slug which has an insert into 
> which the slug wire is "mounted" at the top end of the slug itself. I 
> don't know if those can be fully repaired if that construction is 
> implemented in all 390 Non A slugs.
>
> However, in a 390A I have been thinking of restoring, I have been able to 
> "unscrew" the broken wire leading into the slug, and on closer 
> examination, there is threading into which the slug wire appears to have 
> been "screwed" into.
>
> In fact, I was surprised at how easy it was to simply unscrew the slug 
> wire from the core itself once I found the proper technique.
>
> My next question is whether the top end of the slug wire is simply 
> soldered into the adjustment screw, or is it force fit, threaded or 
> stamped into it. I'll see if I can unsolder, or unsolder and unscrew the 
> broken wire stub from the adjustment screw because there may very well be 
> threading inside those screws similar to the threading I've found inside 
> the slug itself...
>
> Has anyone done that experiment...?
>
> More to follow I'm sure..!
>
> 73...Jordan VE6ZT