The AA8V/W8EXI 6CL6 One-Tube Transmitter
by Greg Latta, AA8V

Other Versions of the Transmitter

Tom Green's (K7MDO) Version of the 6CL6 Transmitter

It's heartening to know that others have found these pages useful. The ultimate compliment is when I receive news that someone else has built the transmitter and has it on the air. On this page you can find pictures and information on these other versions of the transmitter.

Tom Green's (K7MDO) Version of the 6CL6 Transmitter

In November of 2011 Tom Green (K7MDO) finished building his 6CL6 transmitter and was kind enough to send me some photos. I thought it would be helpful to show how someone else put the transmitter together. If you have any questions for Tom, you can e-mail him at chknlips@msn.com

Photos of Tom Green's (K7MDO) Version of the 6CL6 Transmitter:

Front View: In his version of the transmitter, Tom used a clear plexiglass front panel. This lets you see right through to all of the parts on the top of the chassis. Tom also used a single 0D3 regulator tube rather than the two 0B2 regulator tubes that I used in my design. This places 150 volts on the screen grid, rather than 300 volts, resulting in significantly less transmitter output. However, this may improve the keying, as it will result in less crystal current. Tom's tank coil (the white coil in the middle of the photo) is from a surplus TCS-12 transmitter. It will run on 40m and 20m, but does not have enough turns to run on 80m.	Click on the image for a larger view. Click here for a super detailed view.
Bottom View: This is a bottom view of Tom's transmitter. In this view the front panel is in the top of the photo. The power supply takes up the bottom of the chassis in the photo. Connections to the power transformer are through the large circular cutout in the chassis at the lower left. To the right of that are the connections to the filter choke (small circular opening) and filter capacitors. To the right of the filter choke is the VR tube socket. Tom included a transmit/receive relay in his transmitter. This can be seen at the bottom right. The 6CL6 tube and associated components are in the upper left in the photo.	Click on the image for a larger view. Click here for a super detailed view.
Top View: In this top view of Tom's transmitter the plate tuning capacitor is on the left and the plate loading capacitor is on the right. As in other versions of the transmitter, Tom used a variable capacitor for the loading capacitor, rather than a group of switched capacitors, as in my transmitter. The variable capacitor is preferred. The power transformer is at the left in the back, and the filter choke is to its right. Both were salvaged from a 1950's URM 25D signal generator. The 0D3 regulator tube is on the right in the back, and the 6CL6 is on the left in the front, to the left of the plate tuning capacitor. The antenna connection can be seen at the right in the photo. Tom used a BNC connector for the antenna rather than an SO-239. Either will work fine. In the middle of the chassis in the front Tom has a #41 6 volt bulb connected in series with the plate transformer center tap. This gives a visual indication of the 6CL6 cathode current. However, the cathode current does not dip at resonance in this transmitter, as it does in many other transmitters. This is because of the presence of the VR tube in the circuit. In fact, the cathode current increases slightly at resonance. (The bulb gets slightly brighter at resonance.)	Click on the image for a larger view. Click here for a super detailed view.

Dave Rogers' (WB4CHK) Version of the 6CL6 Transmitter

In November of 2005 Dave Rogers (WB4CHK) finished building his 6CL6 transmitter and was kind enough to send me some photos. I thought it would be helpful to show how someone else put the transmitter together. If you have any questions for Dave, you can e-mail him at Davewb4@aol.com

Photos of Dave Rogers' (WB4CHK) Version of the 6CL6 Transmitter:

Front View: In this front view of Dave's transmitter, you can see that his front panel layout is essentially the same as the original transmitter layout. The only difference is that Dave mounted the crystal socket horizontally, whereas it is mounted vertically in the original version of the transmitter. (Note: In this photo Dave has the plate tuning and loading control labels reversed. The one marked "plate tuning" should be marked "plate loading" and vice-versa.)	Click on the image for a larger view. Click here for a super detailed view.
Rear View: This is the rear view of Dave's transmitter. The layout is similar, but not identical, to that of the original transmitter. You will notice that Dave chose to mount the power supply on a separate chassis, which gives you more room on the transmitter and makes the wiring easier. Dave also made good use of terminal strips for the power supply connections. For the tank coil, Dave used 1 1/4" PVC pipe, and it looks like it worked great.. Dave made his transmitter for 40, 30, and 20 meters, so there are fewer turns of wire and fewer taps on the coil. Another important difference is that Dave used a variable capacitor (on the right in the photo) for the loading capacitor, rather than switched, fixed, capacitors, as in the original. The variable capacitor is definitely the way to go! The large 18pf-500pf capacitor that Dave used (because that is what he had) will work fine, though it is not necessary. A smaller one would do nicely too. Any air variable capacitor with a maximum capacity of 200pf to 400pf should work fine as a loading capacitor.	Click on the image for a larger view. Click here for a super detailed view.
Power Supply: Though Dave chose to use a separate chassis for the power supply, his component layout is very similar to that of the original transmitter. Keeping to tradition, Dave used a bread loaf pan for the chassis, a practice common in the 50's and 60's. At the left rear you can see the black terminal strip that Dave used to make connections to the power supply. The terminal strip is a great idea, as it allows the power supply to be easily used to power other vintage projects.	Click on the image for a larger view. Click here for a super detailed view.

Charlie Zarek's (W9SAY) Version of the 6CL6 Transmitter

In February, 2008 I received an email from from Charlie Zarek (W9SAY) describing his version of the transmitter. Charlie mounted his transmitter in a wooden case, and designed the transmitter to run off of a generic power supply he has in his shack. If you have questions for Charlie you can e-mail him at w9say@yahoo.net

Photos of Charlie Zarek's (W9SAY) Version of the 6CL6 Transmitter:

Charlie Zarek's (W9SAY) Transmitter: In Charlie Zarek's version of the transmitter the power supply is built on a separate chassis but the voltage regulator tubes are mounted with the transmitter. Charlie used a wooden chassis for his transmitter with a black top panel. Charlie's transmitter is also a single band (40m) transmitter. This simplifies construction. RCA connectors were used for the key and antenna. The power supply connects to the transmitter via the Jones connector right behind the 6CL6.

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If you have any questions or comments, you can send E-Mail to Dr. Greg Latta at glatta@frostburg.edu