6AG7-Y used as a 6V6?

[michael silva]

Brian Carling wrote:
>
>On  4 Jul 97 at 23:10, michael silva wrote:
>
>> Jeff Herman wrote:
>> >
>> >More scouting within my Globe Scout shows a metal 6AG7-Y sitting
>> >in the 6V6 socket (xtal oscillator). Is one a replacement for the
>> >other?
>>
>> No, it's not a plug-in replacement, but in the application it's a
>> better tube.  Somebody must've rewired the socket to take the 6AG7.
>>
>> 73,
>> Mike, KK6GM
>
>I am curious why you say the 6AG7 is a "better tube" than the 6V6.
>
>If so, how come they weren't used more for speaker dirvers in
>domestic radios etc.?

Brian,

I said the 6AG7 was a better tube "in the application" (crystal
oscillator).  QST had an article in 1950(?) investigating commonly-used
tubes for crystal oscillators and the 6AG7 came out head and shoulders
above the 6V6/6L6/6F6 crowd.  I believe it's a combination of very high
gm (hence less crystal drive required) and more effective screen and
supressor grid shielding (hence better isolation of the load from the
crystal).  The ARRL handbooks consistently recommended it (and later,
other video amplifier tubes such as the 12BY7 and 6CL6 [a 6AG7 stuffed
into a mini bottle]) as the oscillator tube of choice, along with the
5763 which seems to also have both of the above characteristics.

73,
Mike, KK6GM