[R-390] Tube List For R-390 (non A)

[Norman Ryan]

Hi, Roy,

Thanks for pointing out the discrepancy in my R-390 tube list of 20 June
2000 which I wrote for Paul Anderson (cited below).  It lacks V901
(12AU7) and V902 (12AU7) for the cal/osc module.  A pair of 5814As will
substitute OK.

Thanks also for reminding me of the 6C4 substitution issue.  Chuck
Rippel discussed this some time ago, but I forgot the details.  Have I
got it right?  6C4, 6C4WA, and 6100 = good?  6C4A = bad?

So far, my tube lists posted the other day are holding up as far as
accuracy goes.  Please pore over them and let us know any errors.  The
total should come to 33 tubes for R-390 and R-391 and 26 tubes for the
R-390A including the ballast tube in each instance.

73 de Norman KG4SWM


Roy Morgan wrote:
> From my notes file.
> Note: there may be an error in one list or the other:
> 
> TUBE LIST:
> Date: Tue, 20 Jun 2000 17:30:19 -0400 (EDT)
> From: Norman Ryan
> To: "Paul H. Anderson" <pha@pdq.com>
> cc: r-390@qth.net
> Subject: Re: [R-390] R390/391 tube complement and substitutions
> On Tue, 20 Jun 2000, Paul H. Anderson wrote:
>  >
>  > The following list is what I added up in my R-391. Does this sound right?
>  >
>  > Tube QTY
>  > 5814 6
>  > 6BJ6 6
>  > 5749 1
>  > 6AK6 3
>  > 6C4 3
>  > 6AJ5 3
>  > 6BJ6 1
>  > 12AT7 1
>  > 6BH6 1
>  > 5651 2
>  > 6082 2
>  > 26Z5W 2
>  > 3TF7 1
>  > --
>  > 32 tubes
>  >
>  > What reasonable substitutions might I make for sake of longevity and
>  > performance?
>  >
>  > From looking at the archives, I think I can use a 6100 instead of a 6C4,
>  > and maybe a 5749/6BA6W for the 6BJ6. Are these correct, and can I make
>  > other reasonable improvements, or is that a waste of time?
> 
> Hi Paul,
> Dunno if the above list is correct or not. If the R-390 is siliar to the
> R-391, tube list should be the same, right?
> Here is what I come up with in my R-390. I've read the sockets, not the
> tubes! :-)
> V201 6AJ5
> V202 6BJ6
> V203 6C4
> V204 6C4
> V205 6C4
> V401 6AJ5
> V402 6AJ5
> V501 6BJ6
> V502 6BJ6
> V503 6BJ6
> V504 6BJ6
> V505 6BJ6
> V506 6AK6
> V507 12AU7
> V508 5749
> V509 6BJ6
> V510 12AU7
> V511 12AU7
> RT512 3TF7
> V601 12AU7
> V602 12AT7
> V603 6AK6
> V604 6AK6
> V605 6082
> V606 6082
> V607 6BH6
> V608 5651
> V609 5651
> V701 5749
> V801 26Z5W
> V802 26Z5W
> Personally, I'm inclined to stick with the original types as "gotchas" can
> arise. For example, the 5814A normally substitutes for the 12AU7.
> However, since the 5814A filament current draw is higher, it doesn't work
> in all R-390 circuits since most of their filament circuits are in series.
> V601 (12AU7) and V602 (12AT7) are in series. If a 5814A is used in place
> of the 12AU7, the 12AT7 filament (wired in series) will receive higher
> voltage than that of the the 12AT7. V507 and V510, though wired in
> series, each have a 120 Ohm resistor across one half of each filament plus
> a 22 Ohm resistor in series. Confusing!
> Sometimes tubes are pinned a tad differently. If I'm not mistaken, the
> 6C4A has that or another problem, but not the 6C4WA. The 6C4WA will work
> as a replacement for the 6C4 in the R-390A, but I don't know if the
> filament current draw is an issue in the R-390.
> Bottom line is to study the tube characteristics carefully. A tube
> substitution manual can gloss over potential problems such as filament
> current draw and pinout.
> More importantly, have the depot manual and its schematics handy.
> Hope this helps.
> 73...
> Norman
> 
> - Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
> 7130 Panorama Drive, Derwood MD 20855
> Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
> roy.morgan@nist.gov --