zeno wrote:
On closer examination again, I do now see a couple of small diodes (both have
the number 205) which were hiding behind some black spaghetti pushed up against
them. This little homebrew seems to have been carefully assembled and I have no
reason to believe that the 6L6 is not the correct tube. The little rig does
work, but, as mentioned, the CW note was quite distorted and unacceptable. How
would one go about trouble shooting this problem. At this point I have limited
bench equipment , but might consider acquiring some. An oscilloscope is high on
the want list. Can you point to a part of the circuit which would result in
this very chirpy and wobbly CW tone. I would have to fire it up again to
remember how best to describe the sound of this signal.

Bill K6TAJ

The very first place to go is to check all of the chassis
grounds. If solder lugs are screwed to the chassis, loosen them and
then retighten them. If the octal tube socket has a ground ring, and metal
ears as many do, loosen its screws, and retighten them. Clean and lube the
wipers of any trimmer caps or air variable tuning caps. Clean up the pins
and socket for the crystal. Next would be any electrolytics in the circuit.
And, of course, any paper capacitors. If there are any "dogbone" resistors,
get rid of them and replace them with "modern" carbon composition resistors.

A lot of faults can be found by just listening to the note on a receiver,
and wiggling stuff around.

-Chuck Harris

Chirp can be caused by different causes.

1. The crystal may simply change frequency when first loaded. Try a
different crystal, or try the crystal in a different transmitter.

2. Feedback may be incorrect. Too much feedback can cause chirp.
Depending upon the circuit, you can change feedback by varying the
capacitance between grid and cathode.

3. Voltage stabilization. A stable voltage is less likely to chirp.
Sometimes varying the screen voltage will help make the oscillator less
likely to drift.

Draw your circuit out and match it to one in the older Radio Amateur
Handbook. Oscillator circuits are as simple as the Model T.

Colin K7FM


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zeno wrote:
On closer examination again, I do now see a couple of small diodes (both have
the number 205) which were hiding behind some black spaghetti pushed up against
them. This little homebrew seems to have been carefully assembled and I have no
reason to believe that the 6L6 is not the correct tube. The little rig does
work, but, as mentioned, the CW note was quite distorted and unacceptable. How
would one go about trouble shooting this problem. At this point I have limited
bench equipment , but might consider acquiring some. An oscilloscope is high on
the want list. Can you point to a part of the circuit which would result in
this very chirpy and wobbly CW tone. I would have to fire it up again to
remember how best to describe the sound of this signal.

Bill K6TAJ

The very first place to go is to check all of the chassis
grounds. If solder lugs are screwed to the chassis, loosen them and
then retighten them. If the octal tube socket has a ground ring, and metal
ears as many do, loosen its screws, and retighten them. Clean and lube the
wipers of any trimmer caps or air variable tuning caps. Clean up the pins
and socket for the crystal. Next would be any electrolytics in the circuit.
And, of course, any paper capacitors. If there are any "dogbone" resistors,
get rid of them and replace them with "modern" carbon composition resistors.

A lot of faults can be found by just listening to the note on a receiver,
and wiggling stuff around.

-Chuck Harris

"Roger and Ute Brown" ) writes:

Check the tube base wiring against the 6L6 and
see if everything
goes to the correct pins for such a tube. It's possible you should have a
tube which sports a rectifier (diode section) and another tube in the same
envelope). At any rate - a part by part inspection resulting in a schematic
will tell all!

I thought of that myself. While this transmitter is so simple it has
to be pretty generic, so there doesn't have to be an article about it, I
have seen "single tube" transmitters described in old magazines that
used something intended for AC/DC use, ie a power stage with a built in
rectifier that used a high filament voltage. I'm thinking 50L6, but I'm
not sure if that is right. I don't remember if there was something in an
octal package that ran off 117volts directly.

I don't think the original poster mentioned if there was a transformer, and
somehow I suspect the lack of one would be a greater indicator of this route.

Of course, selenium recitifiers may have had a brief enough life that
someone might not recognize one by sight.

Michael VE2BVW

On closer examination again, I do now see a couple of small diodes (both have
the number 205) which were hiding behind some black spaghetti pushed up against
them. This little homebrew seems to have been carefully assembled and I have no
reason to believe that the 6L6 is not the correct tube. The little rig does
work, but, as mentioned, the CW note was quite distorted and unacceptable. How
would one go about trouble shooting this problem. At this point I have limited
bench equipment , but might consider acquiring some. An oscilloscope is high on
the want list. Can you point to a part of the circuit which would result in
this very chirpy and wobbly CW tone. I would have to fire it up again to
remember how best to describe the sound of this signal.

Bill K6TAJ



Roger and Ute Brown wrote:

Bill,
It sounds like you've been around awhile and have built some stuff in the
past.
Surely you can look at the circuit and figure out what is powering the
thing. Put your
meter into that thing and start measuring voltages (from the line cord,
through the transformer and on...)
Of course, if you find "any" DC - you've got a diode someplace. Take some
paper and draw out the schematic (can't be to hard for one tube circuit).
That
will show you what you have. Check the tube base wiring against the 6L6 and
see if everything
goes to the correct pins for such a tube. It's possible you should have a
tube which sports a rectifier (diode section) and another tube in the same
envelope). At any rate - a part by part inspection resulting in a schematic
will tell all!
It's rather elementary. I'd be interested to hear what you find.
Good luck,
Roger, KL7Q

zeno wrote in message ...
I came across a cute little homebrew CW transmitter utilizing only a
single 6L6. Mostly made from radio and audio junkbox parts, it does
seem to work. I put it on the air briefly with its 40 meter Xtal and
monitored the signal on another antenna. Sounds kind of chirpy,
actually worse than chirpy. Needs some kind of work or upgrade or
correction. I did some web searching but could not actually come up
with a schematic for this rig, probably out of some old magazine or
something. I do not quite understand how it works without a power
supply rectifier. There is nothing under the hood which looks like a
diode or selenium rectifier. Anyone have a clue as to this circuit. I
am kind of new to this. How might I proceed to make this little rig
into a useable QRP unit. I think it probably makes something under 10
watts, and the cw sounds goofy, wimpy, and wobbly. It is someone's old
nice lay out failure, but it would be a fun challenge to convert it
into something useful. Anyone seen a circuit for a singl 6L6 rig?...who
knows maybe it has the wrong tube in there. Hmmmm....how to do the
detective work on this????

I have a certain nostalgia for simple one tube rigs, when I was a
novice in the early 50s as a kid I built this crazy rig with a single
117N7 that worked great with my very compromised end-fed random wire. I
have recently found the schematic for that one, but it seems kind of
crazy to build that one again, but who knows....the schematic for the
117N7 rig can be found on page 38 of "Radio For The Millions", 1945
Popular Science Publishing Co. Inc. This illustration has the chassis
plugged into the AC neutral/gound side. Another variation appears on
page 105 in "Ham Radio Projects" 1968 by Bert Simon, a circuit which
looks even more scarry since you only plug into the hot leg of the AC
outlet, and then ground the chassis to earth ground. I do not know how
I lived to tell you now that it was my first rig!

There is a one-tube rig on page 99 of "Ham Projects..." which uses a
6AV5 but that is not
the circuit I see in this unkown 6L6 rig. Let me know if you know of a
source for this single 6L6 transmitter. Nothing in either of the books
mentioned has one like this.

Other clues: it has three rf (air core) chokes, no other iron core
choke, uses two variable condensers, keys thru one of these chokes to
pin 8. Another choke goes from the antenna center pin to the chassis
ground. The 3 rf chokes used appear to be identical.

Bill / K6TAJ

"zeno" wrote in message ...
I came across a cute little homebrew CW transmitter utilizing only a
single 6L6. Mostly made from radio and audio junkbox parts, it does
seem to work. I put it on the air briefly with its 40 meter Xtal and
monitored the signal on another antenna. Sounds kind of chirpy,
actually worse than chirpy. Needs some kind of work or upgrade or
correction.
[snip]
Anyone seen a circuit for a singl 6L6 rig?...who
knows maybe it has the wrong tube in there. Hmmmm....how to do the
detective work on this????

[snip]

There is a one-tube rig on page 99 of "Ham Projects..." which uses a
6AV5 but that is not
the circuit I see in this unkown 6L6 rig. Let me know if you know of a
source for this single 6L6 transmitter. Nothing in either of the books
mentioned has one like this.

Other clues: it has three rf (air core) chokes, no other iron core
choke, uses two variable condensers, keys thru one of these chokes to
pin 8. Another choke goes from the antenna center pin to the chassis
ground. The 3 rf chokes used appear to be identical.

Bill / K6TAJ


Bill -

I seem to remember the ARRL Handbooks having a 6L6 based circuit.

Have you searched for the MEISSNER NOVICE TRANSMITTER ? I think it used a
6L6 oscillator

Have you seem the Ameco AC-1 web pages?
http://www.qsl.net/wb1gfh/ameco.html

If you solid state the rectifier, then its also one-tube !

Greg
w9gb

Anyone seen a circuit for a singl 6L6 rig?...who
knows maybe it has the wrong tube in there. Hmmmm....how to do the
detective work on this????

Zeno ...sound like the one I built in 65 from the ham section in PE mag. I
tried to get someone to answer my CQs for 2 weeks with no reply ...then I
got a guy about 5 miles away...success then I got a card from an OO in
Oregon. I was proud of that card ...showed everyone what my 6L6 would do.

God Bless and Merry Christmas .... KI3R Tom Popovic Belle Vernon Pa.

"zeno" wrote in message ...
I came across a cute little homebrew CW transmitter utilizing only a
single 6L6. Mostly made from radio and audio junkbox parts, it does
seem to work. I put it on the air briefly with its 40 meter Xtal and
monitored the signal on another antenna. Sounds kind of chirpy,
actually worse than chirpy.

Bill / K6TAJ


Bill -

I just did a Google.com search for: "6L6 transmitter" and I same up with
several links and schematics. From notes, it appears several designs were
published pre-WW2 in QST.
RCA introduced the 6L6 tube in early 1936 as an audio power tube.

Are you looking at a Stancor 25-B transmitter, photo in article he
http://www.io.com/~nielw/6l6/6L6.htm

W0VLZ built the Stancor 10P, which is listed in the 1940, 5th edition of the
Stancor Hamanual
http://www.io.com/~nielw/2tube_xmtr/2tube_xmtr.htm

K4GC homebuilt 6L6
http://www.qsl.net/k4gc/6L6.html

K5DH 40 meter version built from design in "104 Ham Radio Projects for
Novice and Technician"; TAB Books, 1968
http://www.qsl.net/k5dh/6ag7_6l6.html

October 2004 issue of CQ magazine featured a 6L6 transmitter (with a
correction in the December 2004 issue under "World of Ideas")

LA6NCA Norwegian homebrew
http://www.laud.no/la6nca/homebrew/

6CL6
http://faculty.frostburg.edu/phys/la.../6cl6xmtr.html

http://www.tube.be/6l6.html

w9gb

Bill,
It sounds like you've been around awhile and have built some stuff in the
past.
Surely you can look at the circuit and figure out what is powering the
thing. Put your
meter into that thing and start measuring voltages (from the line cord,
through the transformer and on...)
Of course, if you find "any" DC - you've got a diode someplace. Take some
paper and draw out the schematic (can't be to hard for one tube circuit).
That
will show you what you have. Check the tube base wiring against the 6L6 and
see if everything
goes to the correct pins for such a tube. It's possible you should have a
tube which sports a rectifier (diode section) and another tube in the same
envelope). At any rate - a part by part inspection resulting in a schematic
will tell all!
It's rather elementary. I'd be interested to hear what you find.
Good luck,
Roger, KL7Q

zeno wrote in message ...
I came across a cute little homebrew CW transmitter utilizing only a
single 6L6. Mostly made from radio and audio junkbox parts, it does
seem to work. I put it on the air briefly with its 40 meter Xtal and
monitored the signal on another antenna. Sounds kind of chirpy,
actually worse than chirpy. Needs some kind of work or upgrade or
correction. I did some web searching but could not actually come up
with a schematic for this rig, probably out of some old magazine or
something. I do not quite understand how it works without a power
supply rectifier. There is nothing under the hood which looks like a
diode or selenium rectifier. Anyone have a clue as to this circuit. I
am kind of new to this. How might I proceed to make this little rig
into a useable QRP unit. I think it probably makes something under 10
watts, and the cw sounds goofy, wimpy, and wobbly. It is someone's old
nice lay out failure, but it would be a fun challenge to convert it
into something useful. Anyone seen a circuit for a singl 6L6 rig?...who
knows maybe it has the wrong tube in there. Hmmmm....how to do the
detective work on this????

I have a certain nostalgia for simple one tube rigs, when I was a
novice in the early 50s as a kid I built this crazy rig with a single
117N7 that worked great with my very compromised end-fed random wire. I
have recently found the schematic for that one, but it seems kind of
crazy to build that one again, but who knows....the schematic for the
117N7 rig can be found on page 38 of "Radio For The Millions", 1945
Popular Science Publishing Co. Inc. This illustration has the chassis
plugged into the AC neutral/gound side. Another variation appears on
page 105 in "Ham Radio Projects" 1968 by Bert Simon, a circuit which
looks even more scarry since you only plug into the hot leg of the AC
outlet, and then ground the chassis to earth ground. I do not know how
I lived to tell you now that it was my first rig!

There is a one-tube rig on page 99 of "Ham Projects..." which uses a
6AV5 but that is not
the circuit I see in this unkown 6L6 rig. Let me know if you know of a
source for this single 6L6 transmitter. Nothing in either of the books
mentioned has one like this.

Other clues: it has three rf (air core) chokes, no other iron core
choke, uses two variable condensers, keys thru one of these chokes to
pin 8. Another choke goes from the antenna center pin to the chassis
ground. The 3 rf chokes used appear to be identical.

Bill / K6TAJ