Messages

676

The RF Workbench / Re: Stretchyman “40W TX” Failure Investigation and Remediation

« on: July 03, 2021, 0053 UTC »

Please just pxss off.

Thank you for your educated, thoughtful and enlightening answer that clears up all questions that anyone on here might have about you and your cheap little fraudulent "work".

677

The RF Workbench / Re: Stretchyman “40W TX” Failure Investigation and Remediation

« on: July 02, 2021, 1708 UTC »

but hey if folk want to believe the Charlie TW*T good luck to them..

Things have improved considerably.

Str

What is there to not believe?

You, yourself, are admitting right here (and in previous posts) that you had problems with your 40W TX. You improved it by changing the power sequencing. I wrote up 36 pages in two documents detailing the issues and why they are design flaws. You even thanked me for the first report at the time. I took a different approach to improving it but that's OK; I just didn't want to change the sequencing and make it harder for people to modify.

You admitted that you have a frequency shift issue with your 10 W (I guess) crystal controlled transmitters and believe it to be the result of some specious claim that crystals oscillators axiomatically randomly drifted 1 KHz or more since the days when then they were first invented ~100 years ago, which is completely ridiculous and I explained why. I suggested that the frequency shift issue is more likely that the crystal is dissipating too much power and provided a link to technical articles suggesting the same. This was met by no counter evidence from you.

If this wasn't enough, we have the folks that chimed in here and privately to me that told me that they had the same issue with your 40W TX. The frequency shift issue is further validated every time certain stations go on the air.

Both of these issues could have been found if you had spent a modicum of time actually examining them in the prototype stage before you shipped any. It's fairly basic in the professional world to evaluate your product in the customer use case. In this case, it means actually turning the TX on and leaving it on for an hour or two and make sure that it doesn't break, it doesn't drift, the power output stays within expectations, power dissipation stays within expectations, and on and on. It's also pretty normal in this customer use case to turn the transmitter on and off each time you use it and had you done that, you no doubt would have broken a transmitter, which should have caused you to investigate. Even if that somehow did not turn up anything, when the evidence was mounting that normal customer use was breaking the the 40W TX, I showed that you were just sweeping it under the rug and blaming the user instead of actually addressing it. It was only after I wrote up my exposé that you came clean on it.

So, again, what is there to not believe?

It is perhaps no wonder that, with your behavior as it is, that Chris banned you from advertising on this forum. He didn't want to be a part of it. (Side note: I suggest that your signature and André posting the video above should also be considered advertising.)

678

General Radio Discussion / Re: Objection filed against application for DRM SWBC license

« on: April 23, 2021, 2006 UTC »

Mmmmk. So one company doing shortwave data transmission for trading  is objecting to another's proposed solution. No surprise. Business rivalry.

Unrelated but this is from Shortwave Solutions website (bold added by me):

Out of stealth mode after successfully completing a second Chicago to Europe HF link for a private client, we are excited to extend our fully proprietary solution to additional geographies and offer better wireless connections for businesses in which every millisecond matters.
 
To that end, we have already taken initial steps to construct a Chicago to Tokyo HF link and a Chicago to Mumbai HF link, which is expected to be fully operational by October 2021. Critically, these links will offer target latency of 39.0 ms for Chicago to Tokyo and target latency of 49.0 ms for Chicago to Mumbai.

Were they really trying to cloak themselves? There had to be names associated with their existing projects.

I'd like to see what frequency/power/antenna combos they propose for the Chicago to Mumbai connection.  It would seem challenging (but not impossible) to do reliably even with the low SNR requirement they have.

679

The RF Workbench / Re: GU-50 Project finished

« on: April 21, 2021, 2127 UTC »

I haven't read it all yet but thanks for the nice write up. I have had a lot of experience with tube (valve) equipment a long time ago and I love the feeling and light in a room full of warm, glowing filaments but my professional experience is strictly in transistors and I appreciate the compact efficiency of them. I probably won't go back. To each his or her own.

Just to be sure the No. 2 ‘scope probe was transferred to the input of the power amplifier and all  was  perfect  there  at  any  volume  level.  So  it  appears  that  these  amplifiers  do  not  like  to  power into the nasty reactive load of a modulation transformer, only a loudspeaker!

I have had similar experiences. I've had more problems at low frequencies where the impedance of the transformer changes the most but I guess you could have probelms at any frequency depending upon the model. It's good to do frequency sweeps and look for unexpected things.

680

North American Shortwave Pirate / Re: KDOG-Outhouse Radio 6935 USB 0001 UTC 11 Apr 2021

« on: April 11, 2021, 0104 UTC »

From WDOG over to KDOG.

S6 on the left coast (background noise is about S4 right now).

681

North American Shortwave Pirate / Re: WDOG 6925 USB 2330 UTC 10 Apr 2021

« on: April 10, 2021, 2351 UTC »

About S6 on the Northern Utah SDR with the log-periodic antenna pointed east, which is about 1 S unit above the background noise. Otherwise no copy on the left coast.

2350 - George Harrision
2351 - Baby I'm Amazed.
0001 - John Lennon

682

North American Shortwave Pirate / Re: Mix Radio International 6885 USB was 6890 USB 1537 UTC 10 Apr 2021

« on: April 10, 2021, 2236 UTC »

2230: No joy on the left coast at 2230 UTC. Because I know something is there, I think that I might hear music. (You know how that goes.) On the other hand, it is listenable on the Northern Utah SDR with the log-periodic antenna pointed east. About S7 and about 2 S units above the background noise. Very clear and distinct on the waterfall.

2340: About the same on that SDR.

0053: Signal improving as we get later in the day: S9 with peaks at S9+10 on the Northern Utah SDR. Listenable at my place near the beach, signal bouncing between S5-S7 at the moment, with my background noise being a somewhat sedate S4.

0140: Signal now decreasing as the midpoint of the path between the TX and my receiver is now likely past sunset.

683

General Radio Discussion / chinese-electronics-products-tested Blog

« on: April 10, 2021, 1725 UTC »

Passing this along:

https://chinese-electronics-products-tested.blogspot.com/

684

Equipment / Re: Looking for Linear Power Supply

« on: April 08, 2021, 2002 UTC »

I'm coming in a bit late on this but if you decide to parallel two or more power supplies, one thing to watch for/be careful of is that the output voltages of the two (or more) power supplies have to be pretty well matched when under load. (There might be an output voltage adjustment.) If the output voltages are not well matched, you will get what I call "current steering" - current from the supply at the higher voltage will source current into the supply at the lower voltage.

The amount of current will depend upon the voltage difference between the supplies and the input/output resistance of the two supplies. (This is due to Ohm's Law.) The supply that is sinking current (the one that is taking in the current) may or may not be receptive to that current that is being "forced down its throat". It depends upon how it is designed. In some cases, you may actually then see its output voltage rise to correspond with the increasing current because the regulator can't sink current (i.e., accept current) well. You may not get what you expect when this happens and if one of the supplies is sinking current, it is not helping you by supplying current to the load, your amplifier.

The usual solution to this is to put diodes in series the output of all the power supplies before the junction where they are combined. This would keep the supplies from sinking current. However, in this case, you are talking about "lots of Amperes", and you would need to find some high current diodes and/or parallel the diodes to meet the current expectations when operating normally.

So, bottom line, if you don't want to go through the whole diode thing, just keep the power supply voltages pretty well matched while under load. You will know that they are matched if you actually see the double/triple current you expect and not somewhat less current at the load.

685

SDR - Software Defined Radio / Re: KiwiSDR Camping Mode

« on: March 15, 2021, 2131 UTC »

This is ironic to me because just last Friday night I was working very late (after midnight here) in my home office and listening to the the Saturday morning AM ham nets on 3615 KHz on an SDR in the UK. I noticed that all four receivers on this SDR were occupied with people listening to the same net and I thought to myself that in some way it's a bit of a waste of resources.

686

The RF Workbench / Re: Someone had Corsair II AM TX experience?

« on: March 15, 2021, 2120 UTC »

How wrong you are...

Well, you do try to lord all over a lot of people here so...

687

The RF Workbench / Re: Stretchyman 40 W TX Reliability Modifications

« on: March 15, 2021, 2113 UTC »

Just ignore...

There you go. Keep your head in the sand and keep thinking that your shit don't stink. At least you are on brand.

688

The RF Workbench / Re: NOT A Replacement For Your Stretchy Audio Amp

« on: March 15, 2021, 2108 UTC »

My thought was that since these chips put out a PWM signal but at a voltage and drive current level that isn't going to modulate a transmitter well, simply add a follower/level-shifter after the PWM chip which will do the heavy switching and let that modulate the transmitter thought appropriate LPF filtering. As a simple feasibility check, I obtained an Adafruit PAM8302 module and put that output into the gate of a IRL510 which I had in my supply and chosen because of the low threshold voltage. It worked well enough that I am going to put together a test board with the PAM8302 driving a real FET driver and then a good FET and some filtering to drive a TX B+ input.

An update on this.

When I first looked into this, I put a follower on the PAM8302 many months ago, I spent most of my brief time looking at it (5 minutes?) more concerned with assuring that the follower was "following" than anything else. I hooked it up again recently to look at some more things and realized that I should have spent more time examining the nature of the smoosh on the oscilloscope screen that the PAM8302 puts out when I looked at it the first time.

It's advertised as Class-D, which I assume is true, but it's for sure not PWM. It looks more like Pulse Code Modulation (PCM) to me. I can't find the USB stick that has the scope image right now but from memory: the output consists of very narrow (im)pulses at something like single-digit microsecond regularity (so hundreds of Kilohertz) and the height of the pulses follows the envelope of the audio input. So it is not a constant amplitude output and not PWM. I assume that they do envelope restoration on the Class-D output (what is probably more commonly known in hobbyist circles as "drain modulation") to get it to follow the envelope of the input signal.

In any case, this changes what I was going to do with the PAM8302; a variable amplitude signal isn't going to get through a FET driver and also isn't going to take advantage of the efficiency of a switching modulator. There may be a time when I decide to make a series modulator with it (PAM8302 + follower + perhaps a level-shifter) but that time is not now so I have set that aside.

Instead, I have a PWM board in progress using the LTC6992 PWM chip and TI UCC5304 isolated FET driver and some other bits. It basically worked the first time I turned it on but there are some issues to work on before I'd be happy using it outside the lab bench.

689

SDR - Software Defined Radio / Re: KiwiSDR, SDR-14 and possible cheaper options?

« on: February 14, 2021, 0108 UTC »

Often these same users hook up a coat hanger as an antenna and also hope for the best 

Yeah, I've noticed.

690

The RF Workbench / Re: Stretchyman 40 W TX Reliability Modifications

« on: February 14, 2021, 0040 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....

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.

I still suspect most 'simple' Xtal controlled designs to exhibit some form of FM that's visible on an SDR.

Cool, except that a sudden drift of 1 KHz that Chris showed is not FMing.

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.

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.