[Boatanchors] Re: [Heathkit] Question on 12AU7

[Revcom]

Dan,
I am by no means an expert on this, nor an engineer, so others may
add to the comments that know a lot more.

When was doing a lot of tube type service work, we had both 12AU7s
and 5814s.  Boss said to use the 5814 for long life use, on 24hr a day
operation.  Mostly used in audio and switching, like flip-flops, and servo
amps.  Not RF applications.

According to my old GE -Essential Characterstics- book, c1963, the
5814 is listed as a "special 12AU7".  It was also listed as a 5 star product
from GE, graded for mil-spec applications and the like I guess.

Now the 5814 draws a little more on the filament, 0.175A at 12.6V while
the 12AU7 is rated at 0.15A at 12.6V.  That would mean you would not
want to mix them in especially series applications, i.e. 24V mil gear. and
if you had a lot of them it might burden the filament supply too much.

We used a lot of them in audio chains, old microwave mux gear and some
mobile applications.

5814 rated at 2.7 max plate watts, while 12AU7 at 2.75, some diff there
too.  But major difference is the output capacitance of 0.5uufd for the
5814 vs 2.0uufd for 12AU7.

So generally, they are a "direct" sub, but not really.

Rod

----- Original Message -----
From: "Dan Pividal" <dpividal at tampabay.rr.com>
To: "Revcom" <revcom at wbsnet.org>
Sent: Friday, February 01, 2008 6:04 PM
Subject: Re: [Heathkit] Question on 12AU7


> What type circuits should I avoid Rod?
> Dan/N4VET
> ----- Original Message -----
> From: "Revcom" <revcom at wbsnet.org>
> To: "Dan Pividal" <dpividal at tampabay.rr.com>; "heathkit at mailman.qth.nt"
> <heathkit at mailman.qth.net>
> Sent: Friday, February 01, 2008 6:38 PM
> Subject: Re: [Heathkit] Question on 12AU7
>
>
> > In most all circuits they will work just fine.  Probably last longer.
> > Rod
> >
> > ----- Original Message -----
> > From: "Dan Pividal" <dpividal at tampabay.rr.com>
> > To: "heathkit at mailman.qth.nt" <heathkit at mailman.qth.net>
> > Sent: Friday, February 01, 2008 10:50 AM
> > Subject: [Heathkit] Question on 12AU7
> >
> >
> >> Is the 5814A a direct substitute for a 12AU7A?
> >> I show it is when I go to some tube sub charts.
> >> I have a bunch of 5814A and would like to know.
> >> Dan/N4VET
> >>
>
>