#47

#47

Post by Phish60 » Sat, 09 Aug 1997 04:00:00



Hi!

I was wondering is a 47 is an output tube?It looks very strange. It has an
directly heated cathode. Does anyone have the RCA tube data on their
compuiter avaiable for download?

Thanks!!
Matt

 
 
 

#47

Post by John Byr » Sat, 09 Aug 1997 04:00:00



Quote:

> Hi!

> I was wondering is a 47 is an output tube?It looks very strange. It has an
> directly heated cathode. Does anyone have the RCA tube data on their
> compuiter avaiable for download?

Hi Matt,

I thought a #47 was a directly heated pilot lamp.  ;-)

Regards,

John Byrns

 
 
 

#47

Post by Phish60 » Sat, 09 Aug 1997 04:00:00


Pilot lamp? what is a pilot lamp!!? This sounds real interesing!! Whats it
do in a radio?

Thanks!
Matt

 
 
 

#47

Post by Jim Cros » Sat, 09 Aug 1997 04:00:00


Quote:

> Hi!

> I was wondering is a 47 is an output tube?It looks very strange. It has an
> directly heated cathode. Does anyone have the RCA tube data on their
> compuiter avaiable for download?

> Thanks!!
> Matt


lamp (radio dial light) is a 6V, .15A, bayonet-based light bulb.

Jim Cross - Vacuum Tubes Unlimited

 
 
 

#47

Post by Randy Gutter » Sat, 09 Aug 1997 04:00:00


Quote:

> Hi!
> I was wondering is a 47 is an output tube?It looks very strange. It has an
> directly heated cathode. Does anyone have the RCA tube data on their
> compuiter avaiable for download?

Don't have the RCA data on my computer - but I do have the GE data...
(should be roughly the same),

47 - Power Amplifier Pentode
EIA Base 5B (1 - Filament, 2 Plate, 3 Grid, 4 Screen, 5 Filament (Screen
is attached to the center of the filament/cathode))


Capacitance (pfd): In: 8.6; Out 13.0; Grid-Plate 1.2

Max Volts: Plate: 250; Screen: 250

Typical Ratings - Class A Amp:
Grid volts: -16.5;  Screen V 250; Screen Mils (zero signal) 6.0; Plate
Volts: 250
Plate ma. (zero signal):31.0; Rp Ohms: 60K; Gm umhos: 2500; Load imp.:
7000
Typical Power out (watts):2.7

HTH
--
randy guttery

Visit the Mississippi Historical Radio and Broadcasting Societies
Virtual Museum:
http://www.***tron.com/~comcents/mhr/mhrlp.html

A Tender Tale - a page dedicated to those Ships and Crews so vital to
the Silent Service:
http://www.***tron.com/~comcents/tendertale/ttp0.html

 
 
 

#47

Post by Douglas C. Dawso » Sat, 09 Aug 1997 04:00:00


The type '47 tube, first issued in 1931, was the first power pentode.
The suppressor grid is internally connected to the center of the 2.5v
filament. According to my Sylvania Technical Manual, the tube is capable
of providing 2.7 watts in Class A, single-ended operation, with 250
volts on the plate and screen, at idling currents of 31 and 6 ma for the
plate and screen respectively. The recommended cathode resistor for
self-bias operation is 450 ohms which provides a grid bias of -16.5
volts.

Because the '47 is a pentode, it requires a much smaller grid voltage
signal to be driven to full output than triode types like the '45 and
'71A which preceded it. The '47 itself was quickly superceded by
indirectly heated power pentodes like types '41 and '42.

Doug Dawson

 
 
 

#47

Post by CommQua » Sat, 09 Aug 1997 04:00:00


I think the pilot lamp is like an autopilot.

Pete

Peter Bertini  K1ZJH
Senior Technical Editor,  Communications Quarterly Magazine
"The Radio Connection,"  Popular Communications Magazine
  --  proud members of the CQ family --

 
 
 

#47

Post by Sarah Wanamake » Sat, 09 Aug 1997 04:00:00


Quote:



> > Hi!

> > I was wondering is a 47 is an output tube?It looks very strange. It has an
> > directly heated cathode. Does anyone have the RCA tube data on their
> > compuiter avaiable for download?

The 47 is a power pentode meant for use in the audio output stage.  Specs
are as follows:

        Filament:  2.5V, 1.75A
        Plate voltage:  250V max
        Grid #2:        250V max
        Grid #1:        -16.5V (-15.3V for DC filament)
        Cathode-bias resistor:  450 ohms
        Plate current:  31 ma
        Grid #2 current:  6 ma
        Plate resistance:  60K ohms
        Transconductance:  2500 umhos
        Load resistance:   7000 ohms
        Power output:       2.7 watts

HTH,
Sarah

 
 
 

#47

Post by George R. Gonzale » Sun, 10 Aug 1997 04:00:00


Nobody's mentioned yet that the type 47 tube usually came in a huge ST
style glass envelope.  Bigger than the 5U4, almost a 813-size.

That makes it especially comical to confuse it with a #47 pilot light.

(You'll run across old jokes where a type 47 tube is specified for
something miniature, like inside an active scope probe, or hearing aid)

 
 
 

#47

Post by William Bittl » Sun, 10 Aug 1997 04:00:00


Quote:

> Hi!

> I was wondering is a 47 is an output tube?It looks very strange. It has an
> directly heated cathode. Does anyone have the RCA tube data on their
> compuiter avaiable for download?

> Thanks!!
> Matt

Hi, the 47 is a direct heated pentode used in the output stage of older
radios. The most notable use of this tube was in the output stage of the
audio amp in the Philco model 90 chassis. The tube uses a 5 contact
socket and is capable of outputs as high as 2.7 watts. Filament voltage
is 2.5v at 1.75 amp. 250 volts is the max for the plate and grid 2.
pins 1 and 5 are filaments, pin 2 is the plate, pin 3 is G1 and pin 4 is
G2. Load resistance should be 7,000 ohms.
  Hope this helps
   Bill B.
 
 
 

#47

Post by Sarah Wanamake » Sun, 10 Aug 1997 04:00:00



Quote:
> Pilot lamp? what is a pilot lamp!!? This sounds real interesing!! Whats it
> do in a radio?

The pilot lamp helps steer all those stations in.  Heard of AFC? :)

Sarah

 
 
 

#47

Post by Dan Nelso » Mon, 11 Aug 1997 04:00:00


Quote:

> Hi!

> I was wondering is a 47 is an output tube?It looks very strange. It has an
> directly heated cathode. Does anyone have the RCA tube data on their
> compuiter avaiable for download?

> Thanks!!
> Matt

=====================================
Matt:

The $47 is a POWER AMPLIFIER PENTODE with 2.5V filament. It is good to
about 2.7 watts. I have the RCA data sheet and would be glad to copy and
send to you.
--
Daniel Nelson

    <:)
Beware Cause isn't Effect