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6L6 substitute



 
 
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  #21  
Old December 6th 08, 03:36 PM posted to rec.radio.amateur.homebrew
ken scharf
external usenet poster
 
Posts: 182
Default 6L6 substitute

Stev eH wrote:
JIMMIE wrote:
After years of avoiding morse code I am finally getting into it. the
ideal of operating a very simple transmitter appeals to my junkbox/
trashcan construction mentality.
I am looking for a substitute for a 6L6 that has the plate brought out
the top. I was trying to build a little Glowbug transmitter but was
having all kinds of problems neutralizing the the thing. I think I
would have better luck if I can separate the grid and plate circuits
from each other. I am considering an 807 as a replacement Suggestions
would be appreciated.

Jimmie

An 807 IS a 6L6 with a top cap anode connection. Any of the TV line
output valves will also do the job if you want cheap, the 6DQ6B works
well and has an octal base (The sockets for the 807 are rare).
6146 or 2e26 etc work well but will cost you more.

Steve H

The 6BG6G / GA sweep tube is identical to the 6L6G but with a top plate cap.
  #22  
Old December 6th 08, 04:03 PM posted to rec.radio.amateur.homebrew
ken scharf
external usenet poster
 
Posts: 182
Default 6L6 substitute

Tim Wescott wrote:
On Thu, 04 Dec 2008 06:23:48 -0800, JIMMIE wrote:

After years of avoiding morse code I am finally getting into it. the
ideal of operating a very simple transmitter appeals to my junkbox/
trashcan construction mentality.
I am looking for a substitue for a 6L6 that has the plate brought out
the top. I was trying to build a little Glowbug transmitter but was
having all kinds of problems neutralizing the the thing. I think I would
have better luck if I can separate the grid and plate circuits from each
other. I am considering an 807 as a replacement Suggestions would be
appreciated.

Jimmie


Dunno if it's been mentioned yet -- 2E26. The 807 is _not_ a 6L6 in a
different envelope -- it's quit arguably the 6L6's big brother, but it's
got different ratings; it could probably be shoe-horned into a circuit
designed for the 6L6, but you'd be missing out on about 6dB of final
output power.

The 807 IS a 6L6G with a 5 pin base and the plate connected to the top.
The published ratings of the 6L6G look different than the 807 because of
their intended use. ICAS ratings for the 6L6G were never published.
Also the 807 has additional shielding and insulation over the 6L6G that
make it usable at higher frequencies and voltages than the 6L6G. Most
807's have ceramic spaces to support the plate which are lacking in the
6L6G. But make no mistake about it, the two tubes share the IDENTICAL
cathode, grids, and plate structures.

The 6BG6G tv sweep tube IS an 807 with an octal base. It has the same
ceramic plate supports, but lacks the extra rf shielding.

The 1625 is an 807 with a 12.6 volt heater and a large (same as type
'59) 7 pin base.

The type 1614 is a metal tube based on the 6L6. It is a transmitting
version, and probably has additional shielding. Otherwise its internal
structure is the same as the 6L6 metal type.

The type 1619 is sorta kinda a 6L6 with a directly heated 2.5v cathode.
Same metal bulb as the 6L6. Specs' are different due to the different
element spacing thanks to the filament cathode. This tube is often
triode connected to replace 45's and 2A3's in old radios with a socket
adapter.

As a result the of the construction differences regarding shielding, the
807 often would NOT need neutralization while 6L6G's and 6BG6G tubes
used as rf power amps do.


The 6L6GA was identical to the 6L6G except that the bulb shrunk from an
ST16 to an ST14 size. The 6L6GB was identical except for the bulb
changing again to a T14. The 6L6GC is a totally different bottle with
higher plate and screen dissipation and plate voltage ratings. The
6L6GC was said to be a plug in replacement for the older 6L6 tubes, but
RCA kept the 6L6GB around for a while anyway. In fact a bias
re-adjustment was a good idea when replacing an older 6L6 with the 'GC
version if a cathode bias resistor wasn't used.

Antique Electronics Supply has 2E26's for $6.00 each, so it's not a bad
buy -- and the 2E26 goes into an octal socket.

  #23  
Old December 6th 08, 08:56 PM posted to rec.radio.amateur.homebrew
Fred McKenzie
external usenet poster
 
Posts: 245
Default 6L6 substitute

In article
,
JIMMIE wrote:

I am considering an 807 as a replacement


Jimmie-

Just how simple will this transmitter be? My first novice transmitter
was built from an ARRL publication back in the 50s. The specification
was for a single 6V6, used as a crystal oscillator with output coupled
to the antenna.

I found I could get more power with a 6L6 plugged into the same socket.
Along the way to getting more power, I found that crystal current would
increase to the point where the crystal would fracture!

If you use a 807 or 1625, I hope you will have a lower power oscillator
driving it. Something like a 6AG7 would make a nice crystal oscillator,
and should have sufficient output to drive an 807.

73,
Fred
K4DII
  #24  
Old December 6th 08, 09:41 PM posted to rec.radio.amateur.homebrew
ken scharf
external usenet poster
 
Posts: 182
Default 6L6 substitute

Fred McKenzie wrote:
In article
,
JIMMIE wrote:

I am considering an 807 as a replacement


Jimmie-

Just how simple will this transmitter be? My first novice transmitter
was built from an ARRL publication back in the 50s. The specification
was for a single 6V6, used as a crystal oscillator with output coupled
to the antenna.

I found I could get more power with a 6L6 plugged into the same socket.
Along the way to getting more power, I found that crystal current would
increase to the point where the crystal would fracture!

If you use a 807 or 1625, I hope you will have a lower power oscillator
driving it. Something like a 6AG7 would make a nice crystal oscillator,
and should have sufficient output to drive an 807.

73,
Fred
K4DII

The 6AG7 - 807 combo is a classic. E. F. Johnson sold a 50 Watt Novice
transmitter in the '50's with this tube line up (also a 5R4GY rectifier
IIRC). Other tubes that have been used as the oscillator/driver were
the 6CL6, 12BY7, 6GK6, and 5763.
  #25  
Old December 7th 08, 12:22 AM posted to rec.radio.amateur.homebrew
philo
external usenet poster
 
Posts: 18
Default 6L6 substitute


"Stev eH"
StevehkhhSDJvhvbjjxbvvbhnvbhzjdnxzvzhzdshbvnjzvnb vnvjbvbcjbvvvvnmxvzjhjzsdg
fgsfghgjsghgsljhglhdjfghfufgfhzysgfhczgugfvzlvufzv llgfzlyfyvlgbylvdfghvblyry
wrote in message
...
JIMMIE wrote:
After years of avoiding morse code I am finally getting into it. the
ideal of operating a very simple transmitter appeals to my junkbox/
trashcan construction mentality.
I am looking for a substitute for a 6L6 that has the plate brought out
the top. I was trying to build a little Glowbug transmitter but was
having all kinds of problems neutralizing the the thing. I think I
would have better luck if I can separate the grid and plate circuits
from each other. I am considering an 807 as a replacement Suggestions
would be appreciated.

Jimmie

An 807 IS a 6L6 with a top cap anode connection. Any of the TV line
output valves will also do the job if you want cheap, the 6DQ6B works
well and has an octal base (The sockets for the 807 are rare).
6146 or 2e26 etc work well but will cost you more.

Steve H



No way!

Back in the old days I've used both 6L6 and 807's and they are not the same
tube at all.

You could probably use a 6L6 to drive an 807 though

IIRC, the usual driver for an 807 was often a 6AG7 but I'd sure a 6L6 would
be fine


  #26  
Old December 7th 08, 03:06 AM posted to rec.radio.amateur.homebrew
ken scharf
external usenet poster
 
Posts: 182
Default 6L6 substitute

philo wrote:
"Stev eH"
StevehkhhSDJvhvbjjxbvvbhnvbhzjdnxzvzhzdshbvnjzvnb vnvjbvbcjbvvvvnmxvzjhjzsdg
fgsfghgjsghgsljhglhdjfghfufgfhzysgfhczgugfvzlvufzv llgfzlyfyvlgbylvdfghvblyry
wrote in message
...
JIMMIE wrote:
After years of avoiding morse code I am finally getting into it. the
ideal of operating a very simple transmitter appeals to my junkbox/
trashcan construction mentality.
I am looking for a substitute for a 6L6 that has the plate brought out
the top. I was trying to build a little Glowbug transmitter but was
having all kinds of problems neutralizing the the thing. I think I
would have better luck if I can separate the grid and plate circuits
from each other. I am considering an 807 as a replacement Suggestions
would be appreciated.

Jimmie

An 807 IS a 6L6 with a top cap anode connection. Any of the TV line
output valves will also do the job if you want cheap, the 6DQ6B works
well and has an octal base (The sockets for the 807 are rare).
6146 or 2e26 etc work well but will cost you more.

Steve H



No way!

Back in the old days I've used both 6L6 and 807's and they are not the same
tube at all.

You could probably use a 6L6 to drive an 807 though

IIRC, the usual driver for an 807 was often a 6AG7 but I'd sure a 6L6 would
be fine


Just for grins I got out the RCA tube handbook and compared the plate
curves for the 807 and the 6L6. Up to the limits for the 6L6, they are
IDENTICAL. The 807 curves go to higher plate voltage and current.

The 807 and the 6L6 have the SAME cathode, grid and plate structures.
The differences are in the shielding added to the 807 to reduce
grid-plate and grid-cathode capacitance, and in the plate support
spacers which are ceramic in the 807 to increase the operating voltage
rating of the tube (which is also helped by the plate top connection).
You can see the added shielding just above and below the plate supports.
The 807 is a MUCH better performer at RF than the 6L6, it usually does
NOT require neutralization and would have more power gain than the 6L6.

At Audio frequencies the two tubes will perform IDENTICALLY within their
maximum ratings.

  #27  
Old December 7th 08, 03:19 PM posted to rec.radio.amateur.homebrew
philo
external usenet poster
 
Posts: 18
Default 6L6 substitute


"ken scharf" wrote in message
...
philo wrote:
"Stev eH"

StevehkhhSDJvhvbjjxbvvbhnvbhzjdnxzvzhzdshbvnjzvnb vnvjbvbcjbvvvvnmxvzjhjzsdg

fgsfghgjsghgsljhglhdjfghfufgfhzysgfhczgugfvzlvufzv llgfzlyfyvlgbylvdfghvblyry
wrote in message
...
JIMMIE wrote:
After years of avoiding morse code I am finally getting into it. the
ideal of operating a very simple transmitter appeals to my junkbox/
trashcan construction mentality.
I am looking for a substitute for a 6L6 that has the plate brought out
the top. I was trying to build a little Glowbug transmitter but was
having all kinds of problems neutralizing the the thing. I think I
would have better luck if I can separate the grid and plate circuits
from each other. I am considering an 807 as a replacement Suggestions
would be appreciated.

Jimmie
An 807 IS a 6L6 with a top cap anode connection. Any of the TV line
output valves will also do the job if you want cheap, the 6DQ6B works
well and has an octal base (The sockets for the 807 are rare).
6146 or 2e26 etc work well but will cost you more.

Steve H



No way!

Back in the old days I've used both 6L6 and 807's and they are not the

same
tube at all.

You could probably use a 6L6 to drive an 807 though

IIRC, the usual driver for an 807 was often a 6AG7 but I'd sure a 6L6

would
be fine


Just for grins I got out the RCA tube handbook and compared the plate
curves for the 807 and the 6L6. Up to the limits for the 6L6, they are
IDENTICAL. The 807 curves go to higher plate voltage and current.

The 807 and the 6L6 have the SAME cathode, grid and plate structures.
The differences are in the shielding added to the 807 to reduce
grid-plate and grid-cathode capacitance, and in the plate support
spacers which are ceramic in the 807 to increase the operating voltage
rating of the tube (which is also helped by the plate top connection).
You can see the added shielding just above and below the plate supports.
The 807 is a MUCH better performer at RF than the 6L6, it usually does
NOT require neutralization and would have more power gain than the 6L6.

At Audio frequencies the two tubes will perform IDENTICALLY within their
maximum ratings.


Wow...thanks for the info. They are considerably closer in specs than I
realized.

Of course, you could run an 807 quite a bit past their official ratings and
never burn one out.

I recall tuning my transmitter for absolute maximum output...and that
occurred right around 50watts input.

(probably on 40 meters. I'm sure that on ten meters it would have been a lot
less)

Ran my 807 rig for years like that.

Don't really know what my 6L6 transmitter would have done...
just ran it on 40 meters at about 25 watts input...we always just considered
them to be audio tubes.


If I were going to build a tube transmitter today, I'd probably use a 6146B.


  #28  
Old December 7th 08, 05:49 PM posted to rec.radio.amateur.homebrew
ken scharf
external usenet poster
 
Posts: 182
Default 6L6 substitute

philo wrote:
"ken scharf" wrote in message
...
philo wrote:
"Stev eH"

StevehkhhSDJvhvbjjxbvvbhnvbhzjdnxzvzhzdshbvnjzvnb vnvjbvbcjbvvvvnmxvzjhjzsdg
fgsfghgjsghgsljhglhdjfghfufgfhzysgfhczgugfvzlvufzv llgfzlyfyvlgbylvdfghvblyry
wrote in message
...
JIMMIE wrote:
After years of avoiding morse code I am finally getting into it. the
ideal of operating a very simple transmitter appeals to my junkbox/
trashcan construction mentality.
I am looking for a substitute for a 6L6 that has the plate brought out
the top. I was trying to build a little Glowbug transmitter but was
having all kinds of problems neutralizing the the thing. I think I
would have better luck if I can separate the grid and plate circuits
from each other. I am considering an 807 as a replacement Suggestions
would be appreciated.

Jimmie
An 807 IS a 6L6 with a top cap anode connection. Any of the TV line
output valves will also do the job if you want cheap, the 6DQ6B works
well and has an octal base (The sockets for the 807 are rare).
6146 or 2e26 etc work well but will cost you more.

Steve H

No way!

Back in the old days I've used both 6L6 and 807's and they are not the

same
tube at all.

You could probably use a 6L6 to drive an 807 though

IIRC, the usual driver for an 807 was often a 6AG7 but I'd sure a 6L6

would
be fine


Just for grins I got out the RCA tube handbook and compared the plate
curves for the 807 and the 6L6. Up to the limits for the 6L6, they are
IDENTICAL. The 807 curves go to higher plate voltage and current.

The 807 and the 6L6 have the SAME cathode, grid and plate structures.
The differences are in the shielding added to the 807 to reduce
grid-plate and grid-cathode capacitance, and in the plate support
spacers which are ceramic in the 807 to increase the operating voltage
rating of the tube (which is also helped by the plate top connection).
You can see the added shielding just above and below the plate supports.
The 807 is a MUCH better performer at RF than the 6L6, it usually does
NOT require neutralization and would have more power gain than the 6L6.

At Audio frequencies the two tubes will perform IDENTICALLY within their
maximum ratings.


Wow...thanks for the info. They are considerably closer in specs than I
realized.

Of course, you could run an 807 quite a bit past their official ratings and
never burn one out.

I recall tuning my transmitter for absolute maximum output...and that
occurred right around 50watts input.

(probably on 40 meters. I'm sure that on ten meters it would have been a lot
less)

Ran my 807 rig for years like that.

Don't really know what my 6L6 transmitter would have done...
just ran it on 40 meters at about 25 watts input...we always just considered
them to be audio tubes.


If I were going to build a tube transmitter today, I'd probably use a 6146B.


Well the 6L6 has changed over the years, while the 807 never did (except
for the 'W' version). Later 6L6 versions might have changed the outward
appearance of the plate in response to cost cutting and automated
assembly lines, but the internal spacing of the elements remained the
same. If you look on the QST archives (are you an ARRL member?) on line
for those old 'QSL 40' series of articles on home brew transmitters
using the 6L6G tube you can see in the pictures how the plate structure
is the same for the original 6L6G tube as the 807. And if the claims
for this tube in those home brew articles is true, the 6L6 was JUST as
rugged as the 807 in being pushed past it's ratings. Only the 6L6 would
probably arc over at the socket before the plate voltage reached what
the 807 would handle (I've heard of 807's taking over 1000 volts on the
plate just fine!).

The official ICAS ratings for the 807 allow up to 750 volts at 100ma
plate current, and there is a typical operation shown at 75 watts input,
so at 50w your transmitter wasn't even breaking a sweat yet! A pair of
807's in AB2 (SSB linear) will put out 120w PEP, just about the same as
a pair of 6146's. The 6146B officially will do about 135-140w in the
same service.

Note that ICAS ratings for the 6L6 were never published, but you can
assume that the 6L6 is identical to the 807 EXCEPT for the plate voltage
rating, which I would guess is good to 500v or so.
  #29  
Old December 7th 08, 06:09 PM posted to rec.radio.amateur.homebrew
philo
external usenet poster
 
Posts: 18
Default 6L6 substitute


"ken scharf" wrote in message
...
philo wrote:
"ken scharf" wrote in message
...
philo wrote:
"Stev eH"


StevehkhhSDJvhvbjjxbvvbhnvbhzjdnxzvzhzdshbvnjzvnb vnvjbvbcjbvvvvnmxvzjhjzsdg

fgsfghgjsghgsljhglhdjfghfufgfhzysgfhczgugfvzlvufzv llgfzlyfyvlgbylvdfghvblyry
wrote in message
...
JIMMIE wrote:
After years of avoiding morse code I am finally getting into it. the
ideal of operating a very simple transmitter appeals to my junkbox/
trashcan construction mentality.
I am looking for a substitute for a 6L6 that has the plate brought

out
the top. I was trying to build a little Glowbug transmitter but was
having all kinds of problems neutralizing the the thing. I think I
would have better luck if I can separate the grid and plate circuits
from each other. I am considering an 807 as a replacement

Suggestions
would be appreciated.

Jimmie
An 807 IS a 6L6 with a top cap anode connection. Any of the TV line
output valves will also do the job if you want cheap, the 6DQ6B works
well and has an octal base (The sockets for the 807 are rare).
6146 or 2e26 etc work well but will cost you more.

Steve H

No way!

Back in the old days I've used both 6L6 and 807's and they are not the

same
tube at all.

You could probably use a 6L6 to drive an 807 though

IIRC, the usual driver for an 807 was often a 6AG7 but I'd sure a 6L6

would
be fine


Just for grins I got out the RCA tube handbook and compared the plate
curves for the 807 and the 6L6. Up to the limits for the 6L6, they are
IDENTICAL. The 807 curves go to higher plate voltage and current.

The 807 and the 6L6 have the SAME cathode, grid and plate structures.
The differences are in the shielding added to the 807 to reduce
grid-plate and grid-cathode capacitance, and in the plate support
spacers which are ceramic in the 807 to increase the operating voltage
rating of the tube (which is also helped by the plate top connection).
You can see the added shielding just above and below the plate

supports.
The 807 is a MUCH better performer at RF than the 6L6, it usually does
NOT require neutralization and would have more power gain than the 6L6.

At Audio frequencies the two tubes will perform IDENTICALLY within

their
maximum ratings.


Wow...thanks for the info. They are considerably closer in specs than I
realized.

Of course, you could run an 807 quite a bit past their official ratings

and
never burn one out.

I recall tuning my transmitter for absolute maximum output...and that
occurred right around 50watts input.

(probably on 40 meters. I'm sure that on ten meters it would have been a

lot
less)

Ran my 807 rig for years like that.

Don't really know what my 6L6 transmitter would have done...
just ran it on 40 meters at about 25 watts input...we always just

considered
them to be audio tubes.


If I were going to build a tube transmitter today, I'd probably use a

6146B.


Well the 6L6 has changed over the years, while the 807 never did (except
for the 'W' version). Later 6L6 versions might have changed the outward
appearance of the plate in response to cost cutting and automated
assembly lines, but the internal spacing of the elements remained the
same. If you look on the QST archives (are you an ARRL member?) on line
for those old 'QSL 40' series of articles on home brew transmitters
using the 6L6G tube you can see in the pictures how the plate structure
is the same for the original 6L6G tube as the 807. And if the claims
for this tube in those home brew articles is true, the 6L6 was JUST as
rugged as the 807 in being pushed past it's ratings. Only the 6L6 would
probably arc over at the socket before the plate voltage reached what
the 807 would handle (I've heard of 807's taking over 1000 volts on the
plate just fine!).

The official ICAS ratings for the 807 allow up to 750 volts at 100ma
plate current, and there is a typical operation shown at 75 watts input,
so at 50w your transmitter wasn't even breaking a sweat yet! A pair of
807's in AB2 (SSB linear) will put out 120w PEP, just about the same as
a pair of 6146's. The 6146B officially will do about 135-140w in the
same service.

Note that ICAS ratings for the 6L6 were never published, but you can
assume that the 6L6 is identical to the 807 EXCEPT for the plate voltage
rating, which I would guess is good to 500v or so.



Been a long time...but I am sure the plate voltage on my 807 was at least
600 volts or so.

One thing I also recall, when I had a filter cap short out on a different
set...
is seeing the rectifier tube arc over.

Of course, once the faulty cap. was replaced...the tube worked fine!



  #30  
Old December 7th 08, 07:08 PM posted to rec.radio.amateur.homebrew
msg
external usenet poster
 
Posts: 336
Default 6L6 substitute

ken scharf wrote:

snip
(I've heard of 807's taking over 1000 volts on the
plate just fine!).

The official ICAS ratings for the 807 allow up to 750 volts at 100ma
plate current, and there is a typical operation shown at 75 watts input,
so at 50w your transmitter wasn't even breaking a sweat yet! A pair of
807's in AB2 (SSB linear) will put out 120w PEP, just about the same as
a pair of 6146's. The 6146B officially will do about 135-140w in the
same service.

snip

FWIW, here is a homebrew quad 837/807 linear that does 2kw PEP with 2KV on the
plates (I have it but did not homebrew this one):

http://www.cybertheque.org/homebrew/837_linear

I took the photos some years ago using a digital camera with focus and image
burn issues; this summer I intend to reshoot these with a better camera.

Michael
 




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