In article ,
Peter Wieck wrote:
On Dec 1, 8:29*am, "Arny Krueger" wrote:
"Peter Wieck" wrote in message
a) The 300B (or any of the 300-series tubes in any case)
weren't used in Telephoney.
Actually they were. I've scrapped out enough obsolete telephone equipment to
know that they were used for output stages in drivers for long lines, and
also as voltage regulators in power supplies.
They were used in audio
recording and playback applications for moving pictures -
and again, 10%+ distortion in actual use was neither
unexpected nor unacceptable.
Ever hear of inverse feedback? The good news is that Bell labs did, and
applied it to their equipment.
Sure they did - they called it "negative feedback" and I believe they
patented the process initially. And for long-lines they may have used
the 300s for amplification - although all the literature I saw pointed
towards the 101 series for that purpose - and in one case specifically
excluded the 300 as "not suitable for the intended purpose" - and as I
dimly remember based on the high voltages required. Do you have any
specific pointers to the 300 used that way? I have always been curious
as to how *few* tubes were used in telephoney - primarily only used
for long lines and undersea cables as amplifiers and repeaters.
How few tubes were used in telephoney? I remember when I was in High School I
used to walk past a telephone central office on the way to the Barber Shop. I
think the street level was offices, but when you looked up at the second floor
windows all you could see inside was the orange glow of thousands and thousands
of tubes.
--
Regards,
John Byrns
Surf my web pages at,
http://fmamradios.com/