[R-390] 6C4 in R-390

[Jordan Arndt]

FWIW, I was just going through the 6C4 type tubes I have, and I found one 
that is silkscreened JAN 6C4W Sylvania in green and dated 7839, but the 
etching reads 6C4WA USA.
It's the same size as, and appears to be of typical (generic) 6C4 
construction internally.

73...Jordan VE6ZT



----- Original Message ----- 
From: "Jacques Fortin" <jacques.f at videotron.ca>
To: "'Byron Tatum'" <bjtatum1 at att.net>; <r-390 at mailman.qth.net>
Sent: Monday, July 01, 2024 9:46 AM
Subject: Re: [R-390] 6C4 in R-390


> Hello Byron,
>
> I'm sorry but...
> I do not find any warning about the 6C4W in the R-390 (non-A) manuals.
> The only place I see it is in the TM11-856A (for the R-390A) on page 36.
>
> BUT the Y2K-R3a manual states:
> "(Note 10) There is a severe error in the 1956 Army R390-A manual.
> Navships 1970 manual lists the 6C4W as the tube to use.
> The “W” and “WA” postscript designations refer to mechanical ruggedization 
> specifications.
> Cross-checking of tube reference data bases confirm that the electrical 
> specifications of all types are identical.
> A “ruggedized” or “Industrial” equivalent are types 6100 and 6135 among 
> others.
> All versions will work properly. Some may be quieter or last longer.
> See Chapter 9 supplement for additional tube information."
>
> IF the concerned 6C4Ws are other than the "dwarf sized" (the overall size 
> of a 6AL5 or 6AK5) RAYTHEON branded ones, I tend to agree.
> But I really believe that the 6C4W warning in the TM11-856A is related 
> specifically to the RAYTHEON ones.
> There was many of those floating around here in Canada, sold as surplus in 
> the '70s.
> But when you plot the curves of those, they did not match the "bogey" 6C4 
> ones.
>
> For the specific case of the R-390 now and it's series strings of tubes 
> filaments:
> ONLY standard 6C4 or 6100 tubes can be used (6.3V, 150mA filament).
> The 6135 will not fit, due to it's 175mA filament rating.
>
> 73, Jacques, VE2JFE in Montreal
>
> Hello-   All of my requests for commentary were for 6C4 use in the R-390A. 
> I do recall seeing the warning in the R-390 (non-A) manual stating to not 
> use the 6C4W types. In my mind I was thinking it may have to do with 
> series-string filament concerns in the R-390. But I never investigated the 
> reason for the warning.  Thanks all,Byron W5FH 
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