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1619 in SE mode
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RHersh
Sep 6, 2002, 8:51:46 PM9/6/02
to
RATs;
There was a discussion recently of the 1619 pentode. To recap, this is like a
metal 6L6 with a 2.5V 2A filament in place of a heater/cathode. I acquired a
few to experiment with and breadboarded a SE circuit for testing. I used
350VDC B+, a 500 Ohm Rk and a Magnequest FS-030 SE OPT (huge thing) wired to
present a 2K7 plate load.
The tube drew 40ma with this Rk and dissipated 13W. I loaded the OPT sec with
an 8 Ohm load and ran some tests with a sig gen. At 1V output (1/8 Watt), it
was dead flat to 20 hz, the lower limit of my generator. The effective gain in
triode mode was about 4. The 3 db down point on top was 25Khz. Not great, but
at least a half octave better than my ears. In practice, I would probably run
it at 50 ma or higher. A plate load of 4K would be better, but 2K7 works fine.
Wiring the OPT secondary for 4 Ohms and using an 8 Ohm speaker would result in
a 6K load (8 Ohm configuration is not exactly 1.4 times the ratio of the 4 Ohms
configuration). 6K would be unnecessarily high, but I'll test it anyway.
So it works in SE and shows promise for a simple amplifier. In triode mode
it should be good for a big 2 watts output. This big OPT is way overkill for
this level of power, but why not? I'll stash these parts and wait for an
inspiration to build another amp.
Right now my energy is going into the direct coupled & parafeed 801A amp. I
have finalized and tested a good PS circuit and ordered the plate chokes. Next
step is to figure out how to get all that iron onto a chassis.
Cheers
Ross Hershberger
There was a discussion recently of the 1619 pentode. To recap, this is like a
metal 6L6 with a 2.5V 2A filament in place of a heater/cathode. I acquired a
few to experiment with and breadboarded a SE circuit for testing. I used
350VDC B+, a 500 Ohm Rk and a Magnequest FS-030 SE OPT (huge thing) wired to
present a 2K7 plate load.
The tube drew 40ma with this Rk and dissipated 13W. I loaded the OPT sec with
an 8 Ohm load and ran some tests with a sig gen. At 1V output (1/8 Watt), it
was dead flat to 20 hz, the lower limit of my generator. The effective gain in
triode mode was about 4. The 3 db down point on top was 25Khz. Not great, but
at least a half octave better than my ears. In practice, I would probably run
it at 50 ma or higher. A plate load of 4K would be better, but 2K7 works fine.
Wiring the OPT secondary for 4 Ohms and using an 8 Ohm speaker would result in
a 6K load (8 Ohm configuration is not exactly 1.4 times the ratio of the 4 Ohms
configuration). 6K would be unnecessarily high, but I'll test it anyway.
So it works in SE and shows promise for a simple amplifier. In triode mode
it should be good for a big 2 watts output. This big OPT is way overkill for
this level of power, but why not? I'll stash these parts and wait for an
inspiration to build another amp.
Right now my energy is going into the direct coupled & parafeed 801A amp. I
have finalized and tested a good PS circuit and ordered the plate chokes. Next
step is to figure out how to get all that iron onto a chassis.
Cheers
Ross Hershberger
Phil
Sep 6, 2002, 11:38:45 PM9/6/02
to
Ross,
Really cool, I have wondered about these tubes in SE triode mode for a long time
(Al Marcy tried them, which is how I heard about them), but I still don't have a
test rig myself. By the way, the 1624 is *exactly* the same tube in glass, but
while
the plate dissipation of the 1619 is 15 W, the 1624 has a 25 W rating!
Phil
Ross Matheson
Sep 7, 2002, 12:09:12 AM9/7/02
to
Phil <tu...@jump.net> wrote:
[...]
: the plate dissipation of the 1619 is 15 W, the 1624 has a 25 W rating!
Ah, but see http://www.tubecad.com/december2000/page19.html
Ross M.
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