[ARC5] 7V and 14V Tubes

[Richard Knoppow]

----- Original Message ----- 
From: "Mike Morrow" <kk5f at earthlink.net>
To: <arc5 at mailman.qth.net>
Sent: Monday, April 30, 2012 8:58 PM
Subject: Re: [ARC5] 7V and 14V Tubes


> Wayne wrote:
>
>> Actually the Loctal Tubes with 7V and 14V filaments were 
>> indeed meant for
>> 7V and 14V filament voltages...
>
> Geoff wrote:
>
>> Loktals are listed at 7 and 14V nominal in Sylvania 
>> listings and 6.3 and
>> 12.6 as acceptable. Sylvania was the developer.
>
> AFAIK, only Sylvania claimed that loctal filaments were 
> nominally rated for 7.0
> or 14.0 volts, rather than 6.3 or 12.6 volts.  That is 
> reflected in the 1951
> Sylvania tube data manual.  But sometime before the 
> publication of the 1959
> Sylvania tube data manual, Sylvania appears to have 
> abandoned this pretense.
>
> See these documents at 
> http://www.tubebooks.org/sylvania_tube_manuals_online.htm
>
> A claim that loctals used 6.3 and 12.6 volt filaments 
> seems to be the position
> that is best supported by even Sylvania's own manuals, at 
> least by 1959.
>
> Not that it ever made much difference!
>
> 73,
> Mike / KK5F


     My Sylvania manual has a pencilled date in it, 12th 
edition, 1964 but no printed date I can find.  Probably 
right because Sylvania was a division of General Telephone 
and there is a semiconductor section in the book.
     I have a tickle in my memory about Sylvania having some 
strange way of defining the voltages so that what they 
called 7V was really the same as 6.3V.  Its too vague and I 
may be confounding it with something else.
     I probably had the manuals from Tubebooks on my 1Tb HD 
that crashed, I had most of the stuff from Pete's site. 
BTW, this is an extremely valuable site but you better have 
a high speed connection to take advantage of it.  All very 
well scanned.  He has the _Radiotron_ 4th edition there 
complete and also the 3rd edition. The 3rd is much smaller 
but still interesting for earlier technology.


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