The 6L6 socket spacing on the Stromberg-Carlson 145L
TwoMuttHeads
will fit. I wonder if they anticipated 6L6G and decided they wouldn't
accommodate them or just didn't know 6L6G was on the way? Of course,
one of the 6L6 metals I have is noisy. I'll have to dig and see if
there's another out in the tube shed.
nesesu
<Chester.Copper...@Astoria.OR.edu> wrote:
> On Tue, 24 Nov 2009 18:46:20 -0800 (PST), TwoMuttHeads
> 6F6 tubes. I wanted to use 6F6G's but I can only get two in there. Dag
> nabbit!
Of course the 6F6 is a lot smaller than the 6F6G. I had not considered
that the 6L6 is also a fair bit smaller than the 6L6G since the 6L6 is
so much bigger that the 6F6/6V6 especially with the flange weld at the
bottom sticking so far out. They must have set them really close
together since all the sets that I have seen them in, in push pull,
have been far enough spaced to permit use of the 6L6G. Interesting.
Neil S.
Kenneth Scharf
later allowed fitting ST14 size tubes int T9 bulbs without over heating?
The 5881 tube will also replace the 6L6, though not at quite full
ratings, but probably will run at the power level that the 6L6M was
usually ran at.
When RCA first introduced the metal tubes it was almost like a fad.
They produced metal versions of every tube, including rectifiers where
it didn't make any sense. Vacuum rectifiers don't need shielding, the
only advantage might be size. They even made and external anode metal
rectifier tube where the twin plates were caged in a perferated metal
shell so you couldn't touch them.
Pete Bertini
"Kenneth Scharf" <wa2...@bellsouth.net> wrote in message
news:hejebh$os8$1...@news.eternal-september.org...
> > When RCA first introduced the metal tubes it was almost like a fad.
The goods news is that the metal 6L6s are cheaper than the glass versions.
> They produced metal versions of every tube, including rectifiers where it
> didn't make any sense. Vacuum rectifiers don't need shielding, the only
> advantage might be size. They even made and external anode metal
> rectifier tube where the twin plates were caged in a perferated metal
> shell so you couldn't touch them.
5Z4? IIRC, they had an extremely high failure rate, and the design was
changed in short order.. I've never seen one in 50 years!
Kenneth Scharf
RCA receiving tube manual with that in it but between the RC-12 and
RC-15 it's not there. Anybody having an RCA RC-13,or RC-14 edition tube
manual might find it there. I have a Raytheon 1938 tube manual and they
were making a replacement 5Z4 with a standard envelope by then. BTW the
only other metal rectifier tube (except for maybe a military numbered
version of the 5Z4) that I know of was the 0Z4, and it was just a metal
shell over a glass bulb, about the size of a 12SQ7 tube. The 0Z4G was a
VERY short T9 bulb with a rounded top. The inerds of the 0Z4 looked
like a large neon bulb.
Actually, there was a second metal rectifier tube I know of, the 6H6.
True, it was actually a dual diode detector, but it actually WAS used as
a full wave rectifier in VERY simple transformer operated gizmos that
only had to power one tube, such as resistance coupled preamps or phono
oscillators.
sho...@trailing-edge.com
> When RCA first introduced the metal tubes it was almost like a fad.
> They produced metal versions of every tube, including rectifiers where
> it didn't make any sense.
I would describe it as a marketing trick rather than a fad, but
certainly other manufacturers did metal tubes as well.
What's odd is that my Hallicrafters SX-110's were a model put into
production in 1959, continuing into the mid 60's, and it used (mostly)
metal octal tubes in it at a time when every other radio had begun
using miniatures. They must've found a big stash of them in some
warehouse is my best guess.
But the longest-lasting thing to have come out of the "RCA metal tube
fad", was the octal base!
Tim.
Richard Knoppow
"Kenneth Scharf" <wa2...@bellsouth.net> wrote in message
news:hejebh$os8$1...@news.eternal-september.org...
The 5881 has higher ratings than the plain 6L6 and is
essentially the same as the 6L6GC. It was designed for use
in circuits with higher screen voltages than a standard 6L6
will take such as the "ulra-linear" circuit where the
screens are fed from a tap on the output transformer
primary. This arrangement will exceed the screen dissipation
when full plate voltage is used resulting in short tube
life.
Another place I've found that a glass tube will not fit
is the converter stage for the Hallicrafters S-40 and S-40A.
The stop pin for the tuning capacitor will not clear the
somewhat larger diameter of a glass tube.
One reason for the change from semi-pear-shaped
envelopes to tubular envelopes was a change in the way the
electrode structure was supported. The narrower tubular top
of many tubes was used to support and center the top
electrode support. A different method of constucting the
support was used in the tubular envelopes.
You are quite right about metal tubes being a rage when
first released. They were supposed to have perfect
shielding, etc. That was until it was discovered that they
tended to become gassy. Evntually the seals were improved
but for a time metal tubes had a bad reputation for high
failure rates.
--
Richard Knoppow
Los Angeles
WB6KBL
dick...@ix.netcom.com
Jim Mueller
> Pete Bertini wrote:
<snip>
> BTW the
> only other metal rectifier tube (except for maybe a military numbered
> version of the 5Z4) that I know of was the 0Z4, and it was just a metal
> shell over a glass bulb, about the size of a 12SQ7 tube. The 0Z4G was a
> VERY short T9 bulb with a rounded top. The inerds of the 0Z4 looked
> like a large neon bulb.
>
>
> Actually, there was a second metal rectifier tube I know of, the 6H6.
> True, it was actually a dual diode detector, but it actually WAS used as
> a full wave rectifier in VERY simple transformer operated gizmos that
> only had to power one tube, such as resistance coupled preamps or phono
> oscillators.
Other metal rectifiers that come to mind (not including military or
industrial types) are 5T4 (cross between 5Y3 and 5U4, looks like a metal
6L6), 5W4, 6X5, 12H6 (obvious variation of 6H6), and 25Z6. I have at
least one of each of these so I know they are real.
I've never seen a "bird cage" style 5Z4 either although I have a ballast
resistor (not a tube, the resistance element is in air) that could be
mistaken for one.
--
Jim Mueller wron...@nospam.com
To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.
Michael G. Koerner
My Delco R-1117 (1936) came with a metal 5Z4 OEM. I got that set at a church
picnic auction about 30 years ago and only within the past couple of years was
I able to take a real look at it and successfully restore it to safe/reliable
operating condition (and it is a SWEET radio that punches well beyond its 6
tubes + tuning eye weight class in performance, too!). I noticed that in the
small bag of stuff in the back of the set by its chassis when I starting
working on it again in early 2008 was a Radio Shack-branded 'lifetime
guarantee' metal 5Z4. I did recall testing the tubes as part of a futile
attempt at getting the set working when I first got it. Back then I lacked
the knowledge and expertise needed to do the job right - the internet has been
a total GODSEND for these old radios. I retested the tubes when I started
working on it 'for real' in 2008 and sure enough, one of the two sides of that
OEM 5Z4 was *shorted* (the RS one tested new).
Upon receiving much learned and more experienced advice, I replaced that OEM
5Z4 with a far more reliable glass 5V4.
--
___________________________________________ ____ _______________
Regards, | |\ ____
| | | | |\
Michael G. Koerner May they | | | | | | rise again!
Appleton, Wisconsin USA | | | | | |
___________________________________________ | | | | | | _______________
Richard Knoppow
Both the 5Z3 and 5Z4 are listed in later RCA tube
manuals but are considered obsolete. The 5Z4 is the metal
tube. The 5Z3 is the 4 pin base version of the 5U4G octal
base tube and is nearly identical with it.
6H6's are occasionally used as low current rectifiers.
The miniature equivalent is the 6AL5. This tube is used for
instance, as the bias rectifier in the SP-600-JX receiver.
--
Kenneth Scharf
around 1934-36, but the problem must have been fixed before 1941 since
by then the military was using mostly metal tubes in aircraft radios.
The smaller size of the metal tubes must have been part of the reason
for that and they would NOT have used them if reliability had been an issue.
Pete Bertini
"Richard Knoppow" <dick...@ix.netcom.com> wrote in message
news:XqKdnYMmBN70jZPW...@earthlink.com...
> >
> Both the 5Z3 and 5Z4 are listed in later RCA tube manuals but are
> considered obsolete. The 5Z4 is the metal tube. The 5Z3 is the 4 pin base
> version of the 5U4G octal base tube and is nearly identical with it.
> 6H6's are occasionally used as low current rectifiers. The miniature
> equivalent is the 6AL5. This tube is used for instance, as the bias
> rectifier in the SP-600-JX receiver.
>
>
> --
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dick...@ix.netcom.com
>
There were two metal versions of the 5Z4.
The first had exposed external anodes, with high
plate voltages present external to the vacuum chamber's
eevelope. Much like a 4X150 transmitting tube.
This is the earlier, failure prone style:
http://www.tubecollector.org/5z4.htm
The user is isolated from the plate voltages by the
perforated metal shell.
The later metal versions changed the design so the plate structures
were entirely contained within the vacuum chamber.
pete k1zjh
Michael G. Koerner
> Now that's something I didn't know. IIRC metal tubes were introduced
> around 1934-36, but the problem must have been fixed before 1941 since
> by then the military was using mostly metal tubes in aircraft radios.
> The smaller size of the metal tubes must have been part of the reason
> for that and they would NOT have used them if reliability had been an
> issue.
>
>> You are quite right about metal tubes being a rage when first
>> released. They were supposed to have perfect shielding, etc. That was
>> until it was discovered that they tended to become gassy. Evntually
>> the seals were improved but for a time metal tubes had a bad
>> reputation for high failure rates.
Would the fact that they were metal instead of easily-breakable glass have
been a factor, too?
Kenneth Scharf
> Kenneth Scharf wrote:
>> Now that's something I didn't know. IIRC metal tubes were introduced
>> around 1934-36, but the problem must have been fixed before 1941 since
>> by then the military was using mostly metal tubes in aircraft radios.
>> The smaller size of the metal tubes must have been part of the reason
>> for that and they would NOT have used them if reliability had been an
>> issue.
>>
>>> You are quite right about metal tubes being a rage when first
>>> released. They were supposed to have perfect shielding, etc. That was
>>> until it was discovered that they tended to become gassy. Evntually
>>> the seals were improved but for a time metal tubes had a bad
>>> reputation for high failure rates.
>
> Would the fact that they were metal instead of easily-breakable glass
> have been a factor, too?
>
tubes as well as loktal, all of which were made of glass. Also all
power tubes (25 watts and up) were made of glass. (6L6M types max out
at about 20-25 watts). The metal octal tubes were the first truly
ruggedized tubes ever made though.
Kenneth Scharf
one rare photo. You can see the mica spacers that hold the plates in
place inside the sheild can. You couldn't sell a design like that
today, the lawyers would eat you alive. Some moron would stick a paper
clip through one of the holes and touch a plate and electrocute himself
(hopefully the metal shield is GROUNDED via pin 1 so the shock wouldn't
last very long as the paper clip would touch ground too).