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

[Albert Solway]

Hi Norman and All,

May the R-390 Gods fovour  Norman and may He keep them glowing for him.

Thanks for the effort.

Al VE2TAS

Norman Ryan wrote:

> Substituting the 12AU7 with 5814A:
> The 12AU7 can be substituted in some cases with the 5814A.  Be aware
> that its filament current draw is slightly higher than for the 12AU7; i.
> e., 150 ma (12AU7) versus 175 ma (5814A).  This will pose a problem for
> the R-390 because most of the tubes filaments are wired in series off
> the 26.5 VAC.
>
> You can substitute 12AU7s where they are not wired in series with
> another type tube as long as you replace BOTH 12AU7s with 5814As.  Here
> is the list of the series filament circuits in the R-390 (non A):
>
> V202   V203   V204   V205
> 6BJ6   6C4    6C4    6C4
>
> V401   V402   V201
> 6AJ5   6AJ5   6AJ5   (Only three tubes here @ 18.9 VAC plus four chokes
> wired in series.)
>
> V501   V502   V503   V504
> 6BJ6   6BJ6   6BJ6   6BJ6
>
> V505   V506   V511
> 6BJ6   6AK6   12AU7
>
> V507   V510
> 12AU7  12AU7  <---  OK to use pairs of 5814As.
>
> RT512  V508   V701
> 3TF7   5749   5749
>
> V601   V602
> 12AU7  12AT7
>
> V603   V604   V607   V509
> 6AK6   6AK6   6BH6   6BJ6
>
> V901   V902
> 12AU7  12AU7  <---  OK to use pairs of 5814As.
>
> Each row represents a filament series circuit.  The 12AU7 in V511 should
> not be substituted with the 5814A as the latter's filament voltage will
> drop and voltage will increase across V505 (6BJ6) and V506 (6AK6).  V601
> (12AU7) should not be substituted since V602 is a 12AT7.
>
> The 12AU7s in V507 and V510 can be substituted, but use 5814As for
> BOTH.  The same applies to V901 and V902.  These are the only instances
> where the 5814A will work properly.
>
> Whew!!  This was a lot of effort to get us back on topic.  :-)
>
> 73 de Norman KG4SWM
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