Evergreen Exciter for the Special Night

Magic Eye Transmitter
Several days ago I listened to the completely empty ten meters band. There was a lot of noises, quiet CB chewing and nothing else.
Suddenly I heard a slow, quiet, but very clear telegraph code, resembling W1AW QST. I have not heard the beginning, but wrote all heard:
..Santa placed tubes on the sockets and lit it.
The soft red glow from its ones tiny heaters brightened the room.
"The glow of the valves represents how man can show his thanks for the gift of God's Son that Christmas Eve long ago.
Teach the novices to let their lamps shine before men that all may see it and glorify God.
This is what is symbolized when the red lights shine on the twilight around the world
like hundreds of bright, shining candles, each of them representing one of God's beloved radio amateurs
whose signals are sounding for all to hear."

"Yes, red glowing" said Santa, "is the first color of Christmas." He pointed to the Rudolph, Red-Nosed Reindeer.
"But the second color is green" Santa reached into his bag and pulled out Magic Eye tube and set it into the socket.
"Teach novices about Magic Eye. Green is the second color of Christmas.
The stately evergreen with its unchanging color represents the hope of eternal lif.....
At this point I lost to hear mysterious broadcast, only a few dits and dashes appeared in the noise, someone laughed quietly and that's all.
But I realized that I have to add something green to my radio. I went to my attic and found a Magic Eye tube in my junk box.

It is easy to install 6E5 on the place of oscillator tube because socket's pinout of this amazing valve is nearly the same to pinout of common 6J5 and 6C5 triodes.
So, you can replace these tubes with The Magic Eye without any soldering. But if you want to see The Legendary Green Glow, you have to apply some voltage to the Pin #6 (fluorescent screen).
It will not affect the excitation or amplification, this electrode do not cross the main electronic stream in the tube, so it is unecessary to use a regulated voltage in this circuit.
Let me demonstrate:

Magic Eye MOPA XMTR Schematic
As you can see this is my last year's SKN MOPA transmitter with some minor changes.
  1. 6C5 replaced with 6E5
  2. 6P3 (6L6) replaced with 6P7S (6BG6)
  3. adjusting capacitor C9 in exciter added
  4. amplifier's screen voltage powered by +400V through R7
  5. Magic Eye fluorescent screen is powered from the same source
  6. choke L4 in the amplifier's grid circuit (in place of 33k resistor)
I got more power, better tone, and, finally, The Magic Green Glow. Santa was right.


NW7US - Tomas said...

Very good. Thank you for sharing!

73 es Merry Christmas de NW7US

UU1CC said...

It's too late to answer "Merry Christmas!", I've missed your comment, Tom, pardon me. But it is still time to say "Happy New Year"! I hope to meet you once (in June, probably - best month for reaching seven region for me.)
Good luck!

Gregory L. Charvat said...

This is a beautiful transmitter!

You make some really nice equipment. This is how a CW transmitter ought to look.

I have never worked with magic eye tubes yet, so i am surprised at how you can use them effectively in the oscillator circuit. I will keep this trick in mind.


UU1CC said...

Glad to see you here, George.

I've never used The Magic Eyes as oscillator before, it was a very fresh (for me) idea, but, to my surprise, this circuit works just as good as it looks.
I got an audio record of my 40m CQ from Jim W1RET, but still have no idea how to attach this mp3 file here.

Anonymous said...

Thanks for publishing the circuit.
Have you the values of L1 and L4?

with kind regards and 73

Addi / DC0DW in the near of Wesel

Andy UU1CC said...

Hi Addi

I've used same values as in previously published SKN MOPA http://timelesson.blogspot.com/2009/01/straight-key-night-mopa_01.html

Frankly, this is the same transmitter with several changes such as 6BG6 (6P7S) tube in place of 6L6 (6P3) in amplifier and Magic Eye in oscillator. Coils leaved unchanged.

Ollie - W2QXR said...

Hi Andy,

I very much enjoy, and am inspired by, the wonderfully imaginative spirit that you convey in your homebrew gear, and in your photography of it and your writing about it.

I have been procrastinating the re-building of my Ollietron model A transmitter. It now has a magic eye tube as an rf output indicator. I was considering having the magic eye serve as the oscillator, as you have done.

1. What is the value of R7 (2K at 1 Watt??)
2. Is C9 variable or fixed? is it 9 pf?
3.Does the 6E5 oscillator have enough output to drive a 6L6 to its full power?

Keep up the great work. Bravo!


Andy UU1CC said...

Thank you, Ollie

Let me ask you about your Ollietron "A" transmitter, I think that it is your own design, so it should be very interesting to see one. Post a link here or drop an e-mail to ur3ijc on google mail server.

About your questions

1. R7 value (in European notation) is 2400 Ohm and at least 2 Watts. It is a screen grid ballast resistor.

2. C9 has to be adjusted properly for good note and stable oscillation, I've used a variable cap, but then replaced it with fixed one.

3. Not quite sure, it depends on crystal quality, chokes, frequency and tube rolling. I got 15 Watts on 40m and 9 Watts on 30m bands (but I'm using not 6L6 but 6BG6 tube). Anyway, it is subject to experimenting, but don't expect a QRO from this circuit.

Good luck, Ollie!
73 de UU1CC

Andy UU1CC said...

Wow! I saw this Ollietron before! It is AMAZING!

Ollietron, Inside View

W2QXR said...

Hi Andy,

Thank you for the evergreen information. I don't have a file for the Ollietron schematic, but it is basically the standard 6J5, 6L6 circuit that one sees in many handbooks. It now uses a 6L6 osc. and a KT-66 PA. The 6E5 is used as an rf output indicator. It shows the output increasing or decreasing as the transmitter is tuned. Of course the magic eye is completely unnecessary for the operation of the transmitter, yet it is important to me. I feel, as you do, that a transmitter can be much more than a device which transmits. -- It can be a delightful toy, an expression of one's personality, a work of folk-art, and a source of aesthetic satisfaction. When compared with transmitters of the 1950s, present day transceivers have no soul and no individuality. When we operate our self-made rigs, we homebrewers may again enjoy a richer experience than is available with present day ham gear. I do have a jpg file of the 6E5 rf level indicator. I can send it as an e mail attachment, if you will send me an e mail address.


Anonymous said...

Hi Andy,
Nice website! Especially enjoy the glowbug radios. The article about 1920's Soviet radio stations is interesting because we know so little about it on this side of the Atlantic. I'm gathering parts to build a glowbug myself so with some luck I will have it on air by New Years.

Cheers, Bill KB4QAA

Andy UU1CC said...

Glad to read this, Bill. Hope to meet you this Straight Key Night.

73! Andy UU1CC