Any DDS 200 watt AM Transmitters or kits

[digitalmod]

 I am a retire engineer and yes very frustrated with the CB-Ham old man crap so now what's next? Most AM stations are exclusively using FET class E transmitters these days. I find very few designs for such as a Pirate high quality transmitter. In fact, so far I have located only FETS and DDS chips which after all, without a lab and shop equipped system including a scope, rather make making my own rubbish at this time. But perhaps somebody has designed a pirate class E AM transmitter. They are very high quality with wonderful baseband audio potential. Just, look as I have, they are no where, as scare as hen's teeth.

Jay

[Pigmeat]

I've had a 14 watt class E transmitter for nearly 20 years, and it was used when I got it. The problem is the guys who build them come and go. It's a labor of love for them, it's not like they're making a pile of money from it.

There are people who will make them to your specs, including one who has his 10 watt rigs for sale on the site, but be prepared to lay out a few bucks for the high powered ones.

I'd ask our guy on this board if he's up to building one with that kind of power. He backs up what he sells and will handhold you through getting it on the air.

[Channel Z]

Digitalmod:

If you're just looking to get on the air with a Class E AM shortwave rig, the easiest and cheapest route would be to buy one of Stretchy's Lulu transmitters.  He's running a Xmas sale on them at the moment for HFU members:

https://www.hfunderground.com/board/index.php/topic,38921.0.html

However, if you want to have some fun and learn something in the process, you should try building your own "Lulu".  Later you can move onto higher powered rigs if that's your fancy.

For starters, join the homebrewpirateradio Yahoo Group, where you will find schematics and photos of all sorts of homebrewed transmitters, plus a willing support group to answer your questions and help you build your rig.

Here are a couple of links with more info on the Lulu for you:

http://www.qsl.net/lu8eha/lab_ref2.html

https://hfunderground.com/blog/?p=72

There is a solution out there if you want to take the plunge with a higher powered Class E transmitter, pulse-width modulation and DDS/VFO in kit form, however you really should have an oscilloscope to simplify the Class E tuning procedure and some prior transmitter building experience:

http://www.shortwaveradio.co.uk/projects.htm

Welcome to the dark side!

[Stretchyman]

Cheers Chaps!

I'll wait for a PM!

Have what you want already!

4 X GaN or SiC, PCB's.

Youll have a bit of work to do but much less than building it from Scratch.

Youll need a O'scope, NO excuse, cheap enuf new these days (Siglent et al)

A very large (KW) dummy load and a high power PSU 50V min 10A, more volts is better mind around 150V max.

Str.

[redhat]

Agreed, without a scope, don't bother with class E.  It is necessary to observe the waveforms for tuning.

I'm working on something similar to W1VD's CMCD stuff (basically push-pull class E).  Right out of the box, I haven't seen anything documentation wise that fits my needs.  The AM Ham guys seem to be reluctant to put much out there.  It's 2017, why are they building RF decks to get 375 watts and need 8 fets...ludacris.  With the 2 1200V cree SiC's my testing shows good results to at least 600W carrier.  With better cooling, 1 KW seems obtainable.

Once I get something stable, I'll post the schematics and board layouts.  It's going to be a while though.  A companion stereo exciter will be included.

+-RH

[redhat]

Of course...and MW.

One of the problems I noted when building these things is getting proper drive to the PA stage.  The PA I'm working on has the necessary circuitry built in, all you need to do is provide TTL drive from an exciter  The stereo exciter will have a means to do this from a quadrature DDS source which can be disciplined to whatever you can afford (cesium fountain clock anyone, lol).  C-QUAM will be included, Kahn may be as well if I can build precise enough phase shift networks.

Not for the faint of heart, everything will be surface mount with the exception of the power components.

+-RH

[Stretchyman]

Still waiting for PM.....

 

[digitalmod]

 Yes, waiting on PM. Indeed. I have the little one for now and I like POWER, but.. that's asking for shark attacks if you are on FCC radar screen and some idiot files a jolly complaint. Such people I tire of greatly. FCC acts only on complaints!
I was think in terms of a push pull class E affair and computed a nice in range out put impedance easily matched with the very cheap (yes 125 dollars US) Hi Fi high power amps. Plenty of ways to bridge stereo output for more Juice if needed or maybe a less than perfect impedance match.
Driving the FETS in PP mode clocks 180 degree pulses from f out x 2 driver.
I have never tried to build such a beast, but it would be fun regardless.
 

[radiogaga]

Do these class d/e 10-20 watt txmitters play nice with an ab1 type linear amplifier?
rgg

[redhat]

Why bother with linears when you can have a TX that is a lot more efficient and will have lower distortion?

Did I mention lighter too?

Yes, they should play nice provided your amp provides a flat and non-reactive load.

+-RH

[digitalmod]

 To Gaga: Yes, but here it the issue, ten watts not a lot of juice. So say you had a big Grand daddy Amp.. it might not drive it without yet another intermediate.
Ten watts I think isn't going to raise much smoke, but if you be in USA know FCC sharks signals that are LOUD and come on air at predictable times. Its a shame isn't it and such a waste of tax money when we are in such debt we shall never be free.
But, Let Free Radio reign I say. 250 watts would be great, I'd love such a rig, but its a fairly big gun and makes lots of noise. Yes, enough for 20 db sn about everywhere on east coast.
But as a music producer and former engineer, I dig the idea of lets play IT

[redhat]

That's true.  My old amp needed about 100 watts PEP to get full power.

+-RH

[digitalmod]

 

 Streachyman: Sounds like you are onto the "goods". Do you have a working prototype that I could see on Utube.
I could supply a power source and yes, even a modulator if needed.
You mention a scope, and that is in the works for this new year.

Thanks

[Stretchyman]

Yes, have a 4 X GaN design finally up and running at 150-250W carrier @ 48V. I'll use 2 X 48V supplies to give 1 KW PEP.

I've ordered 2 X 10A 48V PSU's so when they come I'll wire it all up and do a vid.

Modualtor wise it's a PWM system I've been using for a while but I'll use some SiC FETs on the O/P.

I've had the RF side on a PCB since March 17 but have had 'issues' but have managed to resolve them at last and now have a stable system.

It's got an onboard DDS so easy to prog 32 X 5KHz channels, however 160KHz is somewhat wide for class E and Power and Eff% will drop without retuning and tuning caps are large, expensive and no longer manufactured! so best to stick to 16Ch and a 80KHz range.

Did I mention a 'Scope?

You simply cant do this sort of work without one, simple as...

Str.

[digitalmod]

 8)I used to work in a University EE lab, but alas, I now need rebuild my lab and construction space. Something to do in new year.
BTW mate.. the lil box is working Great. I had a tug with ordering BNC to PL 259, but its of course a no brainer.
Will look for your prototype.