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 Post subject: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sat 30, 2017 2:08 am 
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Joined: Jan Fri 13, 2017 5:22 pm
Posts: 10
Greetings,
I understand that this months issue of the QST magazine has a pine board AM transmitter project in it.
As I'm not a member of ARRL, I don't receive the magazine.
Has anyone here seen this article? Is it a novel circuit concept or just another copy of one of the existing layouts?


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sat 30, 2017 11:02 am 
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Joined: Nov Wed 17, 2010 11:14 pm
Posts: 84
This QST cover story is available at no cost. You do not need to be a member to read this one. Just google the title and download the pdf. Not novel but a nice approach using "Heising Modulation" 5 W on 40 meters. Authored by Bob Heil and is nicely done piece. Alan W4AMV.


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sat 30, 2017 12:28 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: North of Mpls, Minnesota
PDF is here

http://www.arrl.org/files/file/QST/This ... 8/Heil.pdf

Dave


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sat 30, 2017 1:42 pm 
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Alan and Dave, thank you.
I'll take a look at the article.
Gar


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sat 30, 2017 2:39 pm 
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Location: S. Dartmouth MA 02748-1225 USA
ggargia wrote:
Greetings,
I understand that this months issue of the QST magazine has a pine board AM transmitter project in it.
As I'm not a member of ARRL, I don't receive the magazine.
Has anyone here seen this article? Is it a novel circuit concept or just another copy of one of the existing layouts?
Novel? Yes, however, a "slat board" transmitter and power supply were developed and published in an ARRL handbook of the early 50's. There was also a miniature battery tube plug-in coil regenerative receiver too, but not slat board on a metal chassis.

If you like the concept of early homebrew Ham transmitters you might like to join the AWAGroup, a Yahoo group of mostly Hams building and using transmitters designed with tubes of 1929 and before.

https://groups.yahoo.com/neo/groups/AWAGroup

Chas

WA1JFD


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sat 30, 2017 6:42 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 9289
Location: Santa Rosa, CA
Slat board transmitters go back to the 1930s and probably a lot earlier.

http://theradioboard.com/rb/viewtopic.php?t=3580

Built at a time when TVI and EMI weren't of much concern.

Rich

Here is one done by NT9K:

Image


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sat 30, 2017 7:54 pm 
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Location: S. Dartmouth MA 02748-1225 USA
Nice!

Concerned about TVI?

Is that a problem in the digital age with CW?

Better not participate in the BK, or Cundal CW contest net week...

Have an image of slat from the 20' 30's?


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sun 31, 2017 4:24 am 
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Gotta love the improvised crystal socket!!

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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sun 31, 2017 5:17 am 
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black85vette wrote:
Gotta love the improvised crystal socket!!
Octal sockets were used in some commercial transmitters, the socket was behind a sub-panel with openings only for two crystals.


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Dec Sun 31, 2017 2:53 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Potomac, Md.
Chas wrote:
black85vette wrote:
Gotta love the improvised crystal socket!!
Octal sockets were used in some commercial transmitters, the socket was behind a sub-panel with openings only for two crystals.


Like my EFJ Ranger.

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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Jan Wed 10, 2018 4:17 am 
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Joined: Oct Tue 11, 2016 4:41 am
Posts: 115
Location: USA
ggargia wrote:
Greetings,
I understand that this months issue of the QST magazine has a pine board AM transmitter project in it.
As I'm not a member of ARRL, I don't receive the magazine.
Has anyone here seen this article? Is it a novel circuit concept or just another copy of one of the existing layouts?


Tonight I worked KK4RF on 75M who said he was using a pine-board transmitter he finished just today using the circuits Bob Heil described in the QST article. The audio sounded quite good.


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Jan Wed 10, 2018 10:16 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 1117
Location: Dallas, Texas USA
And, the original series is on Heil's website. It includes some videos as well:

https://heilsound.com/amateur-radio-pos ... d-project/


easyrider8 wrote:


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Jan Sat 13, 2018 12:59 am 
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Joined: Dec Sun 14, 2008 3:33 pm
Posts: 680
Location: Tokyo
If you haven't seen the 5W 50C5 CW transmitter, here are two links:

http://www.qsl.net/kb7tbt/manuals/Ham%2 ... esigns.pdf

http://www.qsl.net/wd4nka/TEXTS/50c5f.HTM

Looks like fun.

Rob


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Jan Sat 13, 2018 1:36 am 
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Location: Beautiful Downtown Burbank CA
I really like the neon (NE-2) warning light that lights if the 2-prong plug is reversed on a transformerless rig. I'm goin back to a project for an "update". :wink:

It should be incorporated on all transformerless homebrews.


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Jan Sat 13, 2018 3:20 am 
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Joined: Dec Sun 14, 2008 3:33 pm
Posts: 680
Location: Tokyo
What I don't like about that 50C5 circuit is the 400 ohm 20W resistor to drop the heater voltage. It's wasteful. Why not put two 50C5 tubes in parallel, wire the heaters in series? Thereby a much smaller resistor. Or use two 60FX5: no need for a dropping resistor at all then.

Or better: use them in push-pull!

Some ideas:

http://www.w7ekb.com/glowbugs/tx/transmitters.html

The killer in these simple designs is finding a suitable xtal.

Rob


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Jan Sat 13, 2018 3:29 am 
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Location: Beautiful Downtown Burbank CA
Or use DC and only drop 34V.


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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Feb Fri 09, 2018 7:15 pm 
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Joined: Oct Fri 09, 2009 9:25 pm
Posts: 258
Location: Cleveland, Ohio
I built the Bare Essentials rig many years ago and resurrected it for the Novice Rig Roundup last February. I throttled back the output to 5 watts, by lowering the screen voltage (simple increase in screen resistor value). My only upgrade is the addition of a plate current meter. The pill bottle tank coil is for 40 meters, the 80 meter coil is in the background. A British Navy key and a few FT-243's in the foreground.

I still enjoy using this rig and will again in the Novice Rig Roundup in March. The single 50C5 and the 400 ohm resistor do not exactly warm the room but both do produce some heat!

Todd
ka8gef

Attachment:
50c5 xmtr.jpg
50c5 xmtr.jpg [ 82.37 KiB | Viewed 1230 times ]

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 Post subject: Re: QST's Pine board AM transmitter with tubes
PostPosted: Feb Sun 11, 2018 3:23 pm 
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Joined: Jan Mon 28, 2013 9:35 pm
Posts: 1021
Location: Santa Rosa, CA
shinkuukan wrote:
What I don't like about that 50C5 circuit is the 400 ohm 20W resistor to drop the heater voltage. It's wasteful. Why not put two 50C5 tubes in parallel, wire the heaters in series? Thereby a much smaller resistor. Or use two 60FX5: no need for a dropping resistor at all then.

Or better: use them in push-pull!

Some ideas:

http://www.w7ekb.com/glowbugs/tx/transmitters.html

The killer in these simple designs is finding a suitable xtal.

Rob


Or use two 50C5's and a 35W4. No dropping resistor needed. This is the tube
lineup I used in a low power AM BCB transmitter design recently. One 50C5
was the xtal osc, the second was the PA.

Slat board, or breadboard layouts have been around as long as radio has.
And they are a blast to build.
Steve

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