Xtal Replacement

[Stretchyman]

My Latest offering....Altho' last time I offered something like this I sold ZERO???!!!

OK there's a great little DDS from AD the AD9833, cheap as from China on a PCB with clock etc.

I, along with a software/coding bud of mine have come up with a tunable DDS.

I'll restrict the range (full range is 0-12.5MHz) to something useful 6.2-7.2 MHz.

To tune you will have a normal 10K pot attached to an AtoD input of a processor.

Pot centre will be off, CCW will go LF and CW HF, simple eh!

Pressing a button will take it to fine tune mode (VERY FINE!) to keep all you SDR folk happy!

Then press again to store.

The pot could be front panel mounted, a preset on a PCB, perm attached or temp, whatever.

How jolly nice!

ALL my new TX's will be Gan, 40W with twiddly DDS.

OK!

 

[digitalmod]

  To be honest Streachy, 50 watts is probably enough fire. Generally were not wanting International Radio Cops calling.
I am looking at the transmitter that I posted a while back. Its NOT PWM, uses a DDS, and a fet driver and single ended FET for that final. Problem, it needs to be made PROFESSIONAL with at least VU meter and a couple of knobs to twist.
I think its fine to try in the lab for higher power, but used as a freedom radio, its tail will always be up in air.
FCC here if they want to bust:
1. look for a strong signal
2. look for some idiot always on same frequency
3. look for a predictable schedule of operations

But, current the black hole is busy devouring little American FM banders.
But.. that could change, however the 41 meter band here has just nothing there except illegals using fish radios and CB sets.
 

Also to legally market the Tx in USA, do this:
1. extend DDS to 7.325, reason AM ham window top of 40 meters to 7.3 mhz.
2. sell as a kit not as a product factory finished. Reason FCC will require type acceptance if you sell more than one.
This means make something not quite finished. Probably something easy to finished, just qualifies as a KIT

Also pro Female studio audio  connector and either a resistive attenuator, could just be cheap POT. But NO preamp! The hams want to connect a mic direct, broadcasters already have high level processed audio to input! We do nOT want distortion from non linearity or add our own attenuators. This is a pain in the ass with ham ssb transmitters. It also creates HUM
The answer may be just include a high and LOW level audio input!

[Stretchyman]

I can supply balanced in, no problem as the 'feature' is already on the latest mod amps.

The DDS will go from 0-12.5MHz so no problem with 7.3.

Yes the 'Kit thing'.

Unit wont TX until you plug in DDS module, simple as....

ANYTHING else?

 

Str.

p.s. I'm not going to fit any kind of metering as it's a right royal PITA + there's no room and I'm not sticking it in a great big box!

My stuff is compact!

ALL audio needs to be pre processed, i.e. B/W limited, level limited and compressed anyway and simply done in SoundForge, Audacity or whatever at ZERO cost.

If you want to process audio in real time, spend a silly amount of £, $, whatever on a NEVE 33609, you can use the meters on that!!

 

Oh...finally, I'm not the slightest bit interested in doing anything Legal that and the hams wont buy anything unless it costs $10,000!!

Bless 'em.

Str.

[digitalmod]

   Just thinking as a sell point, could you grab about 50 watts carrier. That number catches eyes more than 40. Also, not to push you, but there are those who always want the best. Maybe price two models, 50 watts and 100 watts. I am looking at experimenting with a conventional push pull for 40 meters at 100 watts, but no ideas on modulator. Lots of working stuff complete with cheap FETS that could do. But, although I , a grey hair engineer, its my first experiment with class E. Reading up on theory etc. Now, if you make a very high quality modulator the Yankee AM ers (hams)  will jump on it because many are using museum AM rigs such as Viking 2, DX 100 and so on.
So you get a very real market for your box.  But the sell part with hams might be more than one band, full VFO and yes, that Magic number 100 watts!

Also yes, compact is the way. Good idea. Now you may need change that logo, no offense because the hams will be putting in orders and yes FCC will stay down as long as its a kit with something the buyer must compete, even if it just plugging in a transformer. My deal rig is a compact, but fitted with meters, RF forward/Rev and audio level VU with a FRONT PANEL that could be rack mounted into a pro studio looking operation. Also make the thing able to do 50 watts, its just a better selling number.

[Josh]

Consider making a inexpensive siggen?

[JimIO]

TL494 I.C. is a good start for a series PWM. 10/$ or so on ebay.
And why class E unless you want to run on batteries? There are a few HF amp kits too If you can solder SMD.

[digitalmod]

  Ok, Streachy I understand you point of view. Wanted to say since AM pretty much went out in 1960's little effort to design a class C output with 100 watts or more and modulate it as you will.
The disadvantages, more drive power, you more than likely will pay more for real linear RF transistors.
The FETS are pretty much dirt cheap. They of course work well in class D or E mode.
Circuit considerations are different, but just slightly so. I wonder if any company ever marketed a class C transistor am trans.
I know AM transmitters unless they are from moth ball attics with tubes are damn difficult to locate for anything outside of the BC band .. I.E 1700 kHz. Medium Wave

[Stretchyman]

Where do I start...

Firstly we're way off topic.

I'm trying to put forward the idea that a modern DDS is simple and flexible and therefore there's no need for Xtals.

You can sell them all to Hams!!

I'm more interested in making it flexible without the need for a freq readout or expensive switching, just a single pot and switch so far....



OK from the top....


40W/50W whats the difference? The design I use has a modulator which has a V ABS Max of 26V and this limits the peak voltage to the Class E stage.

Sure, if you want more power, no problem, just use more volts but not using this modulator.

Any single ended class E stage will put out 100W but would need substantially bigger ferrites and a much larger PCB.

My initial design was 10W and have managed to push the whole design to 40W and it wont go any further, simple as, OK!

Bigger box, more volts, different modulator etc etc.

Hams, hams, hams, already told you, NOT INTERESTED IN SELLING TO HAMS!

EVER...


LOGO STAYS, till I get sued....

Your 'Deal Rig'.... well good luck building that and all the metal bashing and wiring etc.

Try and build 50!

Try and build one actually, lets see it!!




'Consider making a inexpensive siggen'? WTF? I'll pass on any further comment...!!



'TL494 I.C. is a good start for a series PWM', it's 35 years old, try LTC6992, a tad more up to date bud...


Why class E, coz it's incredibly efficient, i.e. doesn't get hot and put out lots of power in a small form factor.

The HF amp kits, have you bought one? NO! They're CRAP and DONT WORK!

Pointless amplifiying anyway as you want HIGH LEVEL mod, WHY? Because it sounds great!

The ONLY AMP you will ever want is one with a BLF188XR in, end of....


OK, the steam coming out from my ears has now subsided!


I'm not trying to make a living from this and anyone who thinks they can is welcome to try.

I can assure you that you will be wasting your time.

I'm doing this purely for the love of it and sure I dont mind making a few £$ on the way but I can assure you it's a lot of effort.

The investment in components alone i.e. buying in bulk is massive, getting the metalwork, milled and engraved etc, PCB design, actually getting a design to work repeatedly, constantly trying to improve the design, the list goes on.

Everyone seems to think a 100W design will blow the market wide open, well it wont, neither will a 200W design or a 400W design.

Not enough of us left I'm afraid Chaps.

Ah well......

We can dream.....

Ahh... Feeling calmer now...


 

p.s. I do like a good Sunday morning rant, saves going to church!!

[Azimuth Coordinator]

Wow  this is an interesting discussion..  I think Stretchyman makes nice black box kit that will get you on the air for a minimum amount of dollars and is just fine for new hobbyist to get on the air with..  Now if Strechyman's  black box isn't your cup of tea or if you have a better idea then break out the copper and ferric chloride and build what you want and put it on the air.  for the $150 or so he charges it's a pretty good deal to get on the air.  If you want commercial broadcast quality then you need to build it your self as many of the OPs here have.  Now digitalmod if you want all the bell's and whistles then you could always buy a kit or two from Strechyman and improve on his design and add the features you want.

Just my 2 cents

[ChrisSmolinski]

I'm pretty sure at $150, Stretchyman is not getting rich off selling these. It must be a labor of love.

[digitalmod]

  calm yourself mate.. we are just speculating here. Now, I used to own a tube 100 watt am rig.. it was BIG, heavy had 807 modulators, a modulation transformer and pair of 6146 finals. Yes, on 80 meters it worked very well circa 1965. later as a dumb fu..k kid of 16 bought a 500 watts Tx with 810 modulators. now that busted the band.

I guess my point is we broadcasters want pro gear. It needs be reliable, not freaking be such a smoke pyre that G..od damn FCC comes into the scope sites. Now, that's the reality. I personally think a good 100 watt  DDS Class E with maybe two FETS (cheap ones) and a fancy pwm mod that could look pretty, sound like a PRO, maybe better than that. Size, is small better, but should have the correct audio and RF connectors. At 100 watts, HF a cheap PL259 female makes the grade.
I do think we do not want a government massacre day as took place 20 years ago. Do I think given sad condition of Federal Budget, plus really nobody to BITCH we are NOT likely going that way?
No, mate, but keep OUR freakin heads DOWN.
What the hell would be the point of a bust, unless something designers like you get Fucked up. And a spur ends up on a military channel.
So goal here buy good scope work bench and dummy loads watt meters and so on and start test tubing to get up to 100 watts class E. That much smoke needs be handled with care although its just a little light bulb.

So we Pirates that want to keep our art and science going have to watch the back side. If you understand.. and many of us Streach are former legal engineers in broadcasting. So, NO JUNK, look good, smell good.. be good..

[Stretchyman]

New thread needed, I have a 100W carrier generator (built in DDS), with LPF, just needs Modj, 48V at 10A. However it will need extensive testing before it leaves the lab. I have 20 PCBs to populate.

 

Str.

[JimIO]

Rants are OK and we need another thread. How about Amplifier Topologies?

LTC6992, thats a lot of stuff in a 6 pin pkg. but it won't plug in a breadboard and seems more like something used in a digital app.

I did buy one of those kits mainly for the PCB, now i'm waiting on some SMD soldering stuff so I can Xperiment.

Back to "Xtal Replacement" I have some Arduino UNO R3's and a AD9833 and AD9850 module and just got some prototype boards. Anybody here done anything like that?
I know there's stuff on Github.

[digitalmod]

 Streach, if you have the PC board for the 100 whiskey transmitter, that's a real plus. Now please say you did not plan on 20 dollar FETS because somewhere there will BE smoke..

[Stretchyman]

$20? They're GaN and work well as do SiC, but GaN better.