[R-390] Floating Capacitor Cans & Other Issues

[Cecil Acuff]

30 to 50 years from now it won't matter to me no more!  The next guy can 
figure it out.  Don't know what they will be listening to then anyway....

Well the VLF chassis top side appears to have been exposed to something that 
has caused the tube bases...the part that actually bolts to the chassis and 
holds the insulated piece to corrode a bit and split/crumble.  It may have 
been rodent urine exposure or who knows what.  The chassis is not in bad 
shape it has just pretty much attacked the tube sockets.  I have a box full 
of NOS ceramic ones that I thought I'd put in.  It's going to be quite a job 
but I think it will be worth the effort.  Sad part is it don't need a recap 
below the chassis as it has all ceramic caps.  But they didn't put ceramics 
under the RF deck.....peeked in there and can see the darned Black Beauties.

Cecil.....
----- Original Message ----- 
From: "Barry Hauser" <barry at hausernet.com>
To: "Cecil Acuff" <chacuff at cableone.net>; <r-390 at mailman.qth.net>; "Jack 
Absalom" <kf4yio at charter.net>
Sent: Saturday, January 14, 2006 1:03 PM
Subject: Re: [R-390] Floating Capacitor Cans & Other Issues


>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
>>
>
>