Technical Topics > The RF Workbench
Stretchyman 40 W TX Reliability Modifications
Charlie_Dont_Surf:
--- Quote from: Stretchyman on February 11, 2021, 0932 UTC ---
The very first ever design I made was an unashamed copy of the venerable LuLu design. Fat better than any other design to date and I must emphasise not my design. All I ever did was make a PCB to make replication a simple matter.
It uses a Xtal which I had to get made at considerable cost (£14 ea.) and managed to get quite a few units made (100 approx).
That was five years ago and all designs since 2016/17 have an AD9833 DDS.
...So as I must say again it's not my design, however there are other designs out there that are and Yes you've slagged those off as well....
--- End quote ---
Your name and email address are on the PCB silkscreen. You probably put your "STRETCHYMAN PIRATE RADIO" stickers (a ripoff of Breaking Bad) on the case too. But now you are claiming because the original design came from someone else that's it's not your fault?
I'm sorry, but you own that problem.
The rate of occurrence of this weird drifty oscillator issue is more than some sort of random, chance occurrence. You shipped "several" of these units but apparently never put them through sufficient validation and or any sort of burn-in to confirm that they stay stable over time. If you had, then you would have found this issue. Just like you would have found the famous high-voltage snap that takes out either the drain filter cap or the FET or both (and caught on fire in front of me), but you didn't, because you don't know what you are doing and can't be bothered.
Designs get shared and tweaked all the time. There's a fellow named Paul Brokaw, whose Brokaw Bandgap Cell (https://en.wikipedia.org/wiki/Brokaw_bandgap_reference) is used as a reference in nearly every IC from all manufacturers since the 1970s. There are billions of these things around the world now. By your logic, if someone makes a Brokaw Bandgap and fucks it up, then we should complain to Brokaw and not the person who fucked it up? Riiiiiiighhhhhhht.
You want all the accolades and none of the responsibility.
--- Quote from: Stretchyman on February 11, 2021, 0932 UTC ---I still suspect most 'simple' Xtal controlled designs to exhibit some form of FM that's visible on an SDR.
--- End quote ---
Cool, except that a sudden drift of 1 KHz that Chris showed is not FMing.
--- Quote from: Stretchyman on February 11, 2021, 0932 UTC ---
I look forward to seeing any design from particularly yourself or anyone else for that matter that you mass market and build 100+ units.
I doubt (know) that this will ever happen.
I look forward to your reply.
--- End quote ---
So very nice of you to invite me to play the "my balls are bigger than yours" game. Explain to me how many you've shipped has anything to do with your ability to solve problems before they are created? Apparently none. And shipping lots of defective product is the hill you've chosen to die on? And the barrier to entry for whether something is "worthy" or not is not whether it's good, it's just that you've shipped many of them, warts and all?
Also, what good would it be for me to put a schematic out when most of my problem with you is that you are absolute crap at validating and testing? You aren't going to learn those skills from a schematic.
(Shaking my head)
My professional life is in the design, validation and manufacturing and post-sale support of electronics that sells in somewhat higher orders of magnitude than what you are talking about, but please do tell me more about the the 100 you made over the course of a many years. It's amusing to me in a very haughty sort of way.
Since I have been doing this for decades, I've give you a couple of lessons for success:
1) If you don't know something, don't pull some bullshit text off the internet and use it to justify your preconceived notions. Look into yourself. Figure it out. If you don't have the answer, say, "I don't know but I'm looking into it." The smart people I know admit when they don't know something and don't make shit up.
2) Test your shit out extensively. Build 10 and put them through their paces. Leave them on for a long time. Examine design marginalities. Push and pull the design before you ever ship any product.
3) Despite your best efforts (which you have not made, see above), there will be post-sale problems with your products. Don't sweep them under the rug. Fix it or make it up to the customer.
I'll say it again: You want all the accolades and none of the responsibility. You don't know what you are doing, and don't care to know how to do things better.
As for my designs, my employment is somewhat engrossing and I'm not interested in becoming a BIG TIME PIRATE SUPPLIER MOGUL like you apparently are. I get my jollies by shipping good product that doesn't catch on fire right in front of customers.
redhat:
Boys,
Can we do with a little less hostility? There is already enough negativity on the web. If this must continue, please take it elsewhere.
Thanks,
+-RH
Stretchyman:
Yeh, he's being such a TW*T
Just ignore...
Charlie_Dont_Surf:
--- Quote from: Stretchyman on February 14, 2021, 1153 UTC ---Just ignore...
--- End quote ---
There you go. Keep your head in the sand and keep thinking that your shit don't stink. At least you are on brand.
Dare4444:
Use DDS 9850 board with Arduino and 2n7000 for very high quality professional sounding AM signal. I'll paste the code if needed. Its output is 10mW. Feed it to two parallel 2n7000 each with 1ohm source resistor and set the standing current to 15ma each with a variable pot connected to their gates. It's drain can then be connected to the final linear amplifier. No crystals or complex synthesizer needed. A simple Arduino code sets the TX frequency!!
https://ibb.co/3TMm2gb
Arduino Sketch.
#define W_CLK 13 // Pin 13 - connect to AD9850 module word load clock pin (CLK)
#define FQ_UD 8 // Pin 8 - connect to freq update pin (FQ)
#define DATA 10 // Pin 10 - connect to serial data load pin (DATA)
#define pulseHigh(pin) {digitalWrite(pin, HIGH); digitalWrite(pin, LOW); }
// transfers a byte, a bit at a time, LSB first to the 9850 via serial DATA line
void tfr_byte(byte data)
{
for (int i=0; i<8; i++, data>>=1) {
digitalWrite(DATA, data & 0x01);
pulseHigh(W_CLK); //after each bit sent, CLK is pulsed high
}
}
// frequency calc from datasheet page 8 = <sys clock> * <frequency tuning word>/2^32
void sendFrequency(double frequency) {
int32_t freq = frequency * 4294967295/125000000; // note 125 MHz clock on 9850
for (int b=0; b<4; b++, freq>>=8) {
tfr_byte(freq & 0xFF);
}
tfr_byte(0x000); // Final control byte, all 0 for 9850 chip
pulseHigh(FQ_UD); // Done! Should see output
}
void setup() {
// configure arduino data pins for output
pinMode(FQ_UD, OUTPUT);
pinMode(W_CLK, OUTPUT);
pinMode(DATA, OUTPUT);
pulseHigh(W_CLK);
pulseHigh(FQ_UD); //
}
void loop() {
sendFrequency(1e6); // Enter freq here, Right now Set to 1000,000 Hz ,1000KHz, 1MHz . Example, for 1540KHz enter 1.54e6 in the sendFrequency bracket above. I hope this is easy to understand
while(1);
}
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