TheRadioBoard

Here is a slatboard transmitter I built and wanted to share. I spent a long time scrounging the parts for this project and pretty happy with the way it turned out. It's configured for 40m in the pictures, but an easy switch to 80m where it works a little better. The transmitter tube in the pictures is a 6L6G, but it will also work with a 6V6. The power supply is using a 5Y3G tube.











I'm a new forum member and will try to post some more of my projects. I really joined this forum to learn about DX crystal radio receivers, but I like tube gear too.

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73, Bill NT9K
http://www.nt9k.com

If you’re the smartest one in your group, your group is too small..

That's a nice-looking rig, Bill. My first Novice rig used a 6V6. How are you measuring plate current? I used a #47 (6 V @ 150 mA) bulb.

73,

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http://kr1s.kearman.com/
http://qrp.kearman.com/

Very nice work!

I especially like the "matching" slat-board power supply!

Any plans for Slat-Board ATU/AMU ?

73
kb0lxy - Eric

Thanks guys! Eric, I really didn't need an ATU as I have a 40m full wave delta loop that covers the entire CW band with a low SWR. The person I got the circuit from said he was working on a matching slatboard amplifier. He also built a matching regen receiver, but I haven't got that far yet with mine.

Jim, I"m not measuring the plate current. The simple plans didn't include any. I do have plenty of #47 bulbs and may go back and add some updates like that to it later? It was intended to be bare bones. The power supply didn't even have a fuse, but I did add one of those.

Just after I built that, a couple friends bought me a store bought slatboard transmitter and power supply kit from pasttime projects here: http://www.pastimeprojects.com/transmitterkits.html

I built the power supply, but put the transmitter kit aside for now. I've got 3 other tube transmitters in the works among my other projects and too many irons on the fire. I'll go back and finish it when the cold wx sets in!

_________________
73, Bill NT9K
http://www.nt9k.com

If you’re the smartest one in your group, your group is too small..

The idea must have been to connect a VOM or a bulb somewhere, else how can you tune it? A #47 bulb in series with the B+ line is good enough to find the dip in plate current at resonance.

73,

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http://kr1s.kearman.com/
http://qrp.kearman.com/

Hi Jim, the store bought slatboard kit I got from pasttime projects doesn't use a light bulb either. The tuning instructions for both just say to adjust to maximum output power. A friend gave me the magazine circuit that I built my home brew slatboard from. It came from CQ magazine November 2009 and basically says the same thing. I just tune it with my WM-2 meter. Here is a picture of the circuit: http://www.nt9k.com/image/slatboard9.jpg

_________________
73, Bill NT9K
http://www.nt9k.com

If you’re the smartest one in your group, your group is too small..

Hi Bill,
Nice project. That circuit reminds me of the first transmitter I built in 1965.
Mine used a 6V6 and operated on 80 meters only. I built it on a stripped
"Command Set" receiver chassis that I had. It was amazing to work half
way across the US with this little rig.

Great memories.

73, Dave
N2DS

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Please visit my website at: http://www.makearadio.com

I suppose you're using some kind of antenna tuner or a resonant antenna. A LOT of Novices got in trouble with transmitters like the Knight T-60, which used a relative-output meter instead of measuring plate current. The plate-tuning variable would tune to the second harmonic from 80 meters, putting your 3700-3750 kHz signal way outside the 40-M band. Then you got QSLs from Uncle Charlie and the Official Observers. I'll bet your transmitter will also tune to the second harmonic (and maybe the third!). Tuning for the deepest dip in plate current is the best way to ensure you're tuned to the right band. Or the peak in output power that occurs with the cap's plates closest to fully meshed.

73,

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http://kr1s.kearman.com/
http://qrp.kearman.com/

ha ha

When I was a novice, I think I qualified for WAS-OO. Even with the 80
meter dipole, sometimes I put out enough signal above 40 meters.

Dave

_________________
Please visit my website at: http://www.makearadio.com

Thanks Dave, it's nice to finally meet you! I've been studying your crystal radio website for the past couple months. I really enjoy the nostalgic stuff and why I built the slatboard and now wanting to build crystal receivers.

The original slatboard did only cover 80m, but as Jim says it can work on the 2nd harmonic with the right crystal and basket coil. However, by adding a 2nd 470pF mica cap in series in the cathode resonant circuit and using the 40m basket coil, you can use 40m crystals. The original article did recommend using only 80m crystals in the range of 3.500 to 3.520. Myself, I prefer to use the 40m mod with the 40m basket coils and regular 40m FT-243 crystals up in the old novice portion from 7.110 to 7.120mHz.

Yes Jim, I do use this transmitter with a resonant antenna. I built a 40m full wave delta loop. It's fairly flat SWR over the entire CW band and doesn't need a tuner. It also can let me swap tubes from 6V6 to 6L6. For looks, I like the old ST style G type tubes that look like old coke bottles. The real problem for me with this transmitter is the lack of a decent T/R switch, so I tend to not use it very much. I do like to drag it out for the ARRL SKN on New Years Eve. Then it's chirp isn't so looked down upon! Mostly, it was just good fun to build. So far no OO notices in the mail.

After building that slatboard, it got me into another fun bunch of projects, penning and grinding FT-243 crystals, but I'll save that for another post..

_________________
73, Bill NT9K
http://www.nt9k.com

If you’re the smartest one in your group, your group is too small..

Hi Bill,
Nice to meet you. I like your slatboard rig. Very nice. Here is the 40m one tube osc. transmitter I built as a novice in 1988 or 89. I am now in the process of upgrading it to plug in tank coils so I can also use it on 80m, and to a new wood cabinet to match a regen receiver that I built.


http://i1121.photobucket.com/albums/l51 ... G_0514.jpg

http://i1121.photobucket.com/albums/l51 ... G_0511.jpg

http://i1121.photobucket.com/albums/l51 ... G_0520.jpg

The tube is a 6146 and output is about 10w.
Randy K9ANF

Nice work Randy! Thanks for sharing it and good luck with your conversion. I've got 3 more tube transmitter projects in the works. Another slatboard, the kit version from: http://www.pastimeprojects.com/transmitterkits.html

I've scrounged all the parts to make an Ameco AC-1. well, all the parts except the chassis. I found out the chassis I bought is too short for my variable caps. The 3rd project is another simple 6L6G from October CQ magazine 2009. That one is all built on a piece of wood. I've got most of the parts for that one too, just really need to sit and melt some solder, but I prefer to take my time and lay out the parts and wiring as nice as I can.

I keep finding new projects that interrupt the others. I stumbled onto Dave's Makearadio website and now have the urge to build crystal sets. I just enjoy learning about old time electronics! It's all fun..

_________________
73, Bill NT9K
http://www.nt9k.com

If you’re the smartest one in your group, your group is too small..

Hi Bill,

A beautiful classic! It's good to see another ham venturing into the retro world of tubes!

73, Roger

Thanks Roger, I've also been admiring your 807 transmitter you posted in another thread. That is one beautiful piece of electronic artwork!

_________________
73, Bill NT9K
http://www.nt9k.com

If you’re the smartest one in your group, your group is too small..