It’s always great to see the R-390 mail list flicker to life again every now and then.
Seems a lot quieter these days. Les is “semi-retired”, Chuck moved on from his awesome 390A work when finding parts became tenuous, we are all older. I still have my beautiful ‘67 EAC that was thoroughly “Ripple-ized in his shop over a weekend spent together so many years back. I swapped him a really nice TV-2C for his attention. The EAC rests in a new CY-979A cabinet - and where did Mac find those years ago? Dan WB4GRA Sent from my iPhone > On Jun 27, 2024, at 7:35 PM, David Wise <[email protected]> wrote: > Discussion about two months ago: For high-Q tuned circuits, mica is still > the king, don't substitute ceramic especially Type II. > > Back when I was sorting my R390A, I warmed the IF deck with B+ applied. Next > morning a couple of the color-striped Sprague "Prokar" caps > (plastic-impregnated paper) had shorted. They had measured great for leakage > when cold. > > Dave Wise > SWL (inactive) > ________________________________ > From: [email protected] <[email protected]> on behalf > of jkharvie via R-390 <[email protected]> > Sent: Thursday, June 27, 2024 1:44 PM > To: Jim Whartenby <[email protected]>; R-390 Mailing List > <[email protected]>; Les Locklear <[email protected]> > Subject: Re: [R-390] Update on R390A, open question regarding scope and > options fir lubrication > > Hi Les,Long time no talk.... > Jim - thanks for the information. I have used WD-40 for many years. It is > an interesting blend of materials that does a good job against oils and > grease. A tooth brush is what I used on the gears. Lubrication has multiple > options. I am not familiar with the Tuffoil engine oil treatment material. > > Yes, both 10-turn mechanisms are among those that need to be lubricated, best > method I have found is to stair-step all the tabs at both ends of the range, > clean away the debris, apply a very light coating of thin oil to front and > back, work end to end to coat the tabs. > Would be interesting to have folks report back in how much torque is needed > to rotate the KC knob on their receiver, my guess within 3 sigma we are all > close. > I can say that prior to the {re}installation of the slug racks, but following > a substantial teardown and cleaning and re lubrication (all gears removed, > shafts, bushings, gears split, cleaned and teeth contact polished where > needed with 2000 silicon carbide wet dry paper on the surface plate), each > gear tooth was detailed deep clean, and used as lubrication a > multiply-alkylated cyclopentane (MAC) material, the receiver KC knob takes > very little torque to rotate. Add in the second phase of measurably reducing > electrical contact pressure by the application of NYE lubricants Inc. 760G > lube (only RF switch deck contacts completed thus far). I also applied the > 760G to t ______________________________________________________________ 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
