[R-390] Floating Capacitor Cans & Other Issues

[Barry Hauser]

I dunno, Cecil, that seems to be a deceptive method of stuffing the 
plug-ins.  One day, 30-50 years from now when it's time to re-do the caps 
again, some pilgrim is going to lift those things and go ... "WHOAAAAH! 
This ain't right!  I've been took!!!"

The other issue:  What could possibly cause the need to replace ALL of the 
tube sockets in that SP-600-VLF?  Not that I doubt you, but very curious. 
Severe corrosion?  Soaked with 409 and internally ionized with salt compound 
residue?  Wanna know.  (You might have posted on that before, but I don't 
remember.)

BTW -- here's a small project for the group:  It would be nice if there were 
a small standard form layout to indicate mods and when things were last 
serviced on R-390's, R-390A's, etc.  Ideally, it should go inside the radio 
somewhere -- there are a few "cubbies" -- or attached to the back panel.  It 
would be helpful when the radio is passed along -- or even before that if 
you have a few and lose track of where you left off.  That would be the 
place to indicate SS rectifiers, replacement/bypass of the selenium 
rectifier, ballast tube alternatives, tube substitutions, AGC mods, etc. 
Could be a little address book thing or a layout in Excel or Word to fill in 
on the PC and re-print each time there's a change -- or just something with 
lines to write in and indicating dates, such as "1/7/2006 -- Overhauled 
plug-in caps -- floating can method."  Be sure to write the year out in all 
four digits, so no confusion with 3006 when the time comes.

Needs some kind of holder -- maybe rolled up in an aluminum cigar tube and 
wired to the tool holders or velcro'ed on.  I've taken to putting hang-tags 
on the rack handles to keep track of things, but they're just blank and 
don't have enough room -- and the string might break -- and it doesn't look 
too pretty.

Will have to get back to you with wintertime projects -- it's half over and 
I'm way behind on 'em.  Anybody familiar with PRD-1's?

Barry


Cecil wrote:
<snipped>
>
> I refilled the engravings on my "Blue Stripper" project radio's refinished 
> front panel last night.  The panel was quite rough when I started out but 
> came out pretty nicely.  I have no plans of making this a perfect radio 
> but plan on using it as the test bed for evaluating all the mods floating 
> around to decide which ones work for me and which ones don't so I can 
> decide which ones I want to incorporate into the planned radio rebuild for 
> the listening position. (a black faced Motorola in a black CY-979A 
> cabinet)  I used a little different capacitor rebuild process than I have 
> seen after having much trouble with the drill and tap routine to attach 
> the new capacitor leads to the pins in the base of the original caps.
>
> I cut a defective octal tube base apart to salvage the pins that I 
> soldered to the new cap assemblies.  I pushed the pins into the 
> appropriate socket locations and mounted the original cans minus the bases 
> in their associated clamps and screwed the clamps back in place on the 
> audio deck.  So the cans basically float over the new cap assemblies that 
> are plugged into the octal sockets on the audio deck.  Looks completely 
> original once the module is back in the radio and I can re-enter the caps 
> at any time to make changes. I think the next one I do I will cut the 
> original cans lower around the crimp and it will look even more authentic 
> once reinstalled.
>
> Just another way of doing the cap job that will make it easier to go back 
> in.  All leads are insulated with Teflon tubing so nothing electrical 
> exposed to get against something it's not supposed to!
>
> I plan to put the panel back in place today and begin the turn up and 
> alignment.
>
> The other mods already done to this radio include replacement of the 
> selenium rectifier with a silicon bridge, 12BA6 tubes and a jumper for the 
> ballast tube,  a complete recapping of all paper caps using one of Walter 
> Wilsons kits,  a 20 turn pot for the "S" meter zero,  solid stated power 
> supply as per the military mods and an inrush current limiter for a softer 
> start.
>
> All of the various controversial stuff discussed on the list from time to 
> time....but none of the above conspire to do near the damage to the radio 
> than the government had already attempted to do by having them out in the 
> weather for an extended period.  Most of which I feel I have reversed.
>
> I expect it to be a nicely performing radio before any additional 
> performance enhancing mods are done.  The gear train sure is slick and 
> feels wonderful.  Very easy to tune both Khz and Mhz!
>
> What are some of the other group members current winter time projects.....
>
> We'd love to hear about them!
>
> My next challenge will probably be an SP-600VLF that needs caps under the 
> RF deck and every tube socket replaced.....sounds like fun don't it!  HA!
>
> Keep it FUN guys...that's why we do this!
>
> Cecil Acuff
> WB5VCE
>