Bill, Thank you. I'll try some of that blend.
73, Mack W4AX https://www.qrz.com/db/w4ax On Mon, Oct 27, 2025 at 12:00 PM <[email protected]> wrote: > Send R-390 mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > http://mailman.qth.net/mailman/listinfo/r-390 > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of R-390 digest..." > Today's Topics: > > 1. Re: R-391 stuck slug screws (Mack McCormick) > 2. Re: R-391 stuck slug screws (Bill Blodgett) > > > > ---------- Forwarded message ---------- > From: Mack McCormick <[email protected]> > To: R-390 Group <[email protected]> > Cc: > Bcc: > Date: Sun, 26 Oct 2025 16:59:12 -0400 > Subject: Re: [R-390] R-391 stuck slug screws > Here’s an update. Each one of the tuning shafts was sealed with some type > of sticky black substance similar in action to Loctite. The only solution I > found was to use a micro torch and heat the slug while gently turning it > until it broke free and then using a wire brush to remove the gunk. Is it > possible the depot used some sort of Locktite substance so the tuning did > not drift during vibration? In any case that tuning slugs are free now. > > 73, > > Mack > W4AX > https://www.qrz.com/db/w4ax > > > On Sun, Oct 26, 2025 at 10:33 Mack McCormick <[email protected]> wrote: > > > I'm repairing/aligning a R-391 for a friend. Every single RF deck slug > > tuning screw is solidly stuck. I think it is a galvanic response between > > the brass and steel. > > > > Does anyone have tips to free the slugs? They won't budge using a > moderate > > amount of force. I've used PB Blaster and heat to no avail. > > > > I've repaired at least one hundred 389/390/390a/391 over the years but > > this is the first one I've encountered with every slug stuck. > > > > Thanks in advance for any ideas. > > > > 73, > > > > Mack > > W4AX > > https://www.qrz.com/db/w4ax > > > > > > > ---------- Forwarded message ---------- > From: Bill Blodgett <[email protected]> > To: Mack McCormick <[email protected]> > Cc: Group R-390 <[email protected]> > Bcc: > Date: Sun, 26 Oct 2025 19:12:05 -0500 > Subject: Re: [R-390] R-391 stuck slug screws > Years ago a machinists’ magazine performed scientific comparisons of > commercial penetrants advertised to be useful in obtaining release between > “stuck” mechanical items. Included was a test of a “home remedy” of 50% > acetone and 50% automatic transmission fluid. FWIW, PB Blaster released > better than WD-40, but that’s not saying much. The hands down winner ? …. > the 50-50 mixture of acetone and transmission fluid. I’ve made this up > with synthetic auto transmission fluid, in one instance, and non-synthetic > auto transmission fluid in another. I did not perform a scientific torque > release test, but suspect that using the synthetic fluid may work the best > because it should have smaller molecules. Please note that whether you use > the synthetic or non-synthetic auto transmission fluid in the mixture, > either will separate from the acetone unless you shake it up and apply it > quickly thereafter. > > Of course, if there is actual corrosion causing the issue with the slugs, > that’s a different issue probably not solvable with a penetrant. > > Good luck & 73, > Bill > W5WHB > ++++++++++++++++ > Bill Blodgett > Arlington, Texas > > > On Oct 26, 2025, at 9:33 AM, Mack McCormick <[email protected]> wrote: > > > > I'm repairing/aligning a R-391 for a friend. Every single RF deck slug > > tuning screw is solidly stuck. I think it is a galvanic response between > > the brass and steel. > > > > Does anyone have tips to free the slugs? They won't budge using a > moderate > > amount of force. I've used PB Blaster and heat to no avail. > > > > I've repaired at least one hundred 389/390/390a/391 over the years but > this > > is the first one I've encountered with every slug stuck. > > > > Thanks in advance for any ideas. > > > > 73, > > > > Mack > > W4AX > > https://www.qrz.com/db/w4ax > > ______________________________________________________________ > > R-390 mailing list > > Home: http://mailman.qth.net/mailman/listinfo/r-390 > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:[email protected] > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > _______________________________________________ > R-390 mailing list > [email protected] > http://mailman.qth.net/mailman/listinfo/r-390 > ______________________________________________________________ R-390 mailing list Home: http://mailman.qth.net/mailman/listinfo/r-390 Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
