[Boatanchors] 6BA6 Tubes

[Richard Knoppow]

----- Original Message ----- 
From: "Mike McCarthy, W1NR" <lists at w1nr.net>
To: "Joe Walden" <w5jdy at cox.net>
Cc: <boatanchors at mailman.qth.net>
Sent: Thursday, December 15, 2011 6:29 PM
Subject: Re: [Boatanchors] 6BA6 Tubes


6BA6's can be substituted with the following:

EF93, 7543, 7496, 6BZ6§, 6AU6A, 6AU6, 6BA6WA, 6BA6W, 6CG6, 
6HR6, 6660,
5749, 6BD6

The 5749 is the same as the 6BA6W. I think I used that one 
in a Drake
restoration a while back. So, it looks like the 6AU6 is an 
acceptable
sub according to the substitution guide. Of course, all of 
these have
subtle differences that may or may not appear depending on 
the circuit.
The 6BZ6 is flagged as not being compatible in some 
circuits.

Mike, W1NR


On 12/15/2011 01:51 AM, Joe Walden wrote:
> Hello again,from Joe W. w5jdy in Norman,Ok 73069..  I am 
> in the need of four
> 6BA6 vacuum tubes for a Collins 75A3..  Not to sure why 
> but the previous
> owner put 6AU6's in the place of the 6BA6's??  I looked on 
> Ebay but didn't
> see anything like I wanted..  Would rather give the money 
> to a ham anyway..
> I would like new ones but even used tested-good would just 
> be fine..  Please
> contact me direct at:   w5jdy at cox.net     Thanks Joe
>

     6BA6 tubes can NOT be replaced with 6AU6 in most
circuits. The 6BA6 is a remote cut-off tube and the 6AU6 is
a sharp cut-off tube. Tubes controlled by AVC require the
remote cut-off property.
     The 5749, 6660, are OK, the 6BZ6 has significantly
different characterists (about double the Gm). The 6HR6 is a
semi-remote cut-off tube which will probably not be
satisfactory in the AVC stages of this receiver. I can't
find definite information on the others. Sometimes tables of
"equivalent" tubes list all of similar broad types, i.e., RF
pentodes with a given heater voltage and base with no regard
to variations. In some cases a tube may be useful with a
circuit re-design but not as a drop-in substitute for
another type.
     As a very general rule of thumb later versions of a
tube with A/B/etc suffixes can be used in place of the
earlier versions but NOT always or in all equipment.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com