[ARC5] Replacing the 12v tubes with 6volt types

[Geoff]

Dennis, you will find similar in other transmitting tubes where the actual 
current draw varied even in the same run.
Examples are the 6146B/S2001's in the Kenwood hybrids, the 3-500Z's in the 
TL-922 and the 3-400's in the Henry Tempo 2000. Yokagawa also used a series 
pair in the industrial amps.




----- Original Message ----- 
From: "mac" <w7qho at aol.com>
To: <WA5CAB at cs.com>
Cc: <Arc5 at mailman.qth.net>
Sent: Thursday, October 18, 2012 9:34 PM
Subject: Re: [ARC5] Replacing the 12v tubes with 6volt types


> Along the same line I checked the voltage drops across the individual
> series wired 1625 PA tubes in a stock 274N transmitter a while back
> and found a surprisingly wide variation one set of tubes to the
> next.   Worst case observed in a population of a couple dozen examples
> (mixture of NOS and other) was something around 10 volts on one tube
> and 14 volts across the filament of the other.  Worth checking out
> before running a new set for any length  of time, re-tubing, etc.
>
> Dennis D.  W7QHO
> Glendale, CA
>
> *******************
> On Oct 18, 2012, at 3:54 PM, WA5CAB at cs.com wrote (in part):
>
>> I'm surprised, considering how long this sub-thread has continued,
>> that no
>> one has mentioned the obvious.  The first criteria for s 6 volt tube
>> to
>> replace the 12A6 is that it draw the same filament current as a
>> 6SR7, which is
>> what it will be in series with.
>>
>> 6SR7     300 mA
>> 6C5       300 mA
>> 6F6       700 mA
>> 6K6       400 mA
>> 6L6       900 mA
>> 6V6       450mA
>> 6W6      1200 mA
>>
>>
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