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Author Topic: 300% Positive Peaks AM Modulation  (Read 50342 times)
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w3jn
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« Reply #25 on: April 20, 2010, 09:43:27 AM »

Anything with a separate AVC detector channel (ie most nationals, super-pros, SX-28, and R-390s).

Worst are Hallicrafters with ANLs ie SX-101, SX-100, etc - they start distorting at 60% modulation.
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W3RSW
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« Reply #26 on: April 20, 2010, 10:48:24 AM »

You all sound good on my receivers, especially the SDR, 'ceptin' fer Steve.  Grin

He always overMauldulates.
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ka3zlr
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« Reply #27 on: April 20, 2010, 11:06:17 AM »

I have a pair of Homey Tennis shoes but that don't make me a Mud Duck...lol.. Lips sealed
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W1GFH
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« Reply #28 on: April 21, 2010, 11:31:15 AM »

Did anyone mention the Radio Shack meter he was using yet? That in itself is going to cause phony measurements when combined with what he thinks the scope is showing him. It's not doing what he thinks its doing.

I found an on-air demo of his "Mauldulator" in action.

http://www.youtube.com/watch?v=TmvDVn8xnMk&feature=related

At best, it produces fair "contest" audio.  Undecided But the guy has a flair for working "maul" into his product names. Check out:

Quote
Remotomaul is a feature that lets you simply hook up a cord into your computers com port, and with the supplied software, run your radio station from any other computer on the net with a set of 10 dollar headphones.

http://www.11meteroutlaws.com/viewtopic.php?f=41&t=160
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flintstone mop
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« Reply #29 on: April 21, 2010, 02:35:26 PM »

I had an exchange of PMs from Mauldulator "motormouth". Seems like a knowledgeable person on fire about his hobby of high power CB as we are about A.M. Amateur radio. At least his CB modulation is sine waves and not overmodulated square waves. We have created a good thing with either West Coast Sound  or East Coast Sound on A.M.
Apparently extreme high power CB is very popular on the Left Coast. 5KW or more is not unheard of.
He mentioned that some of the secrets are from using computer audio recording software to "pump up" the TX audio.

Fred
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Fred KC4MOP
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« Reply #30 on: April 21, 2010, 03:32:57 PM »

What are the better boatanchor receivers to receive high positive peaks?

Carl
KM1H


I have found these evaluations useful:  http://www.w1vd.com/BAreceivertest.html

Distortion spec's relative to modulation level also bandwidth frequency response.

Rob
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ke7trp
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« Reply #31 on: April 21, 2010, 06:05:06 PM »

The guy seems pretty cool to me. I dont care if he is on CB or not.  I thought his audio was nice and clear. Its a welcome change to the flat topping distortion most Cbers run. Maybe he will ed U cate some of them into running cleaner stations.

I still dont understand how this board works. The web page is unclear.

C
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« Reply #32 on: April 22, 2010, 08:45:23 PM »

Ive been satisfied with the HRO-60, SX-28, and NC-240D so far but havent had some of the others on line when known hi level 150% positive peak stations are on. Most anything sounds OK on the BCB which I guess is limited to 125%.

Are there any SWBC stations using the high level?

Carl
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flintstone mop
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« Reply #33 on: April 22, 2010, 09:46:02 PM »

I don't know, Carl.
Most SW stations run low modulation to reduce the distortion of selective fading. I listen to a Russian station on 9660 and it has this low modulation and very bassy audio. Those Russian ballads sound really nice. You can see the carrier making some movement on the bass, but that's about it. They're probably running 250KW too.
Seems like the power houses run lower modulation and go with the huge RF into your radio.

The other side of the spectrum is WBCQ AFTER Tron adjusts the mod and EQ for the muddy bass sound, Allan Weiner RE-adjusts for the accentuated screetchy high end and baselining the carrier.

Fred
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Fred KC4MOP
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« Reply #34 on: April 23, 2010, 09:39:24 AM »

I was thinking that some of the US located bible thumpers may be pushing it much harder as they do seem to stand out with others of comparable signals.

The only problem is that I can only take listening to them maybe 30 seconds every hour Grin

Carl
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Opcom
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« Reply #35 on: April 23, 2010, 11:45:30 PM »

Here is that Wawasee modulator. It's not the same design as discussed, and I was wrong about the drive method (forgot after too many years)  but it is a classical modulation-increaser. It's kept cut off so that 4W in makes 2-3W out, but 12W in makes about 30W peak. It's amazing that 670V was put to a 6BQ5 and was reliable.

Those local religious and political stations - ugh. never was there more a collection of nuts with access to big radios. You are going to hell unless you pay! Get on the phones! (to send me, the preacher, money, even though I have been dead for years and these are just tapes). The government is using mind control! God spoke to me... The apocalypse is coming! Buy gold now! Flying Saucers! buy MREs now! {insert further alarmist current events rumors and legends here} The government is secretly doing research on the citizens! (Free tinfoil hat with every order!)

* jb_12b_om.pdf (689.8 KB - downloaded 349 times.)
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W1AEX
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« Reply #36 on: April 24, 2010, 12:58:56 PM »

Most SW stations run low modulation to reduce the distortion of selective fading.

That has been my observation too Fred. I noted one exception though while having a QSO on 7.290 MHz last Wednesday morning. There was an incredible trashy noise that sounded like splatter covering the top 50 kc of the 40 meter band. While tuning through the noise, I could hear the remnants of a female voice. When I ventured up to 7.405 MHz I came across Radio Marti and found them to be running in full guitar-amp distortion mode. I guess the engineer took the day off and someone must have cranked the audio up. Or, they might have been experiencing hardware failure of some type.

At any rate, I took a look at Radio Marti's signal with the much maligned 756 Pro III bandscope and could see artifacts exploding up and down the band, right to the limits of the bandscope (+ and - 100 kc). Quite a sight to see (and hear). At any rate, I haven't had any radios on for a couple of days so I have no clue if they corrected it. Maybe they should install a Mauldulator?
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flintstone mop
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« Reply #37 on: April 25, 2010, 09:01:26 PM »

There has been contact with the Gummint about their splatter and they claim their ancient GE 250kw transmitters are within spec. The proccessors are within guidlines for shortwave b'cast. I really hate tone-deaf engineers and someone who just goes by the book and doesn't have a clue to troubleshoot a "SYSTEM". Probably doesn't even use a 'scope
The FECES will never question their own.
Write a letter to Radio Marti. An engineer will definitly write back

Fred
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Fred KC4MOP
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« Reply #38 on: January 27, 2016, 08:54:29 PM »

In case anyone was wondering what's going on with the "mauldulator" circuit, here it is.


* image.jpg (96.55 KB, 1024x765 - viewed 1145 times.)
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KD6VXI
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Making AM GREAT Again!


« Reply #39 on: January 27, 2016, 09:47:24 PM »

John give you permission to give that out?

If not,  that's kind of wrong.

I sat on that schematic for over a year,  because he did NOT want it public domain.   He has taken measures to hide the part numbers,  etc.

I'm. all for reverse engineering for personal reasons,  use,  etc.   But taking someone's design who specifically has asked it NOT be shared,  is shitty.

--Shane
KD6VXI
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Kc2ubf
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« Reply #40 on: January 27, 2016, 11:19:59 PM »

No, but I stumbled upon it publicly posted on another forum, so I thought I would share it here.  It was already out there.  Knock off copys on ebay and all.
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KA0HCP
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« Reply #41 on: January 28, 2016, 12:43:08 PM »

Heaven forbid you publish the schematics of an illegal manufacturer and operator!  LOL
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kg7bz
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« Reply #42 on: January 28, 2016, 01:55:41 PM »

That mic input can't possible work! Running the TLO-84 op-amp open loop at DC. That schematic is missing a lot of wires.
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N1BCG
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« Reply #43 on: January 28, 2016, 06:37:50 PM »

Several things keep coming to mind each time the "positive peak" topic surfaces...

1) You only get 1500 watts PEP max. That's 375 carrier watts modulated up to but not over 100% positive. Do you really want to lower your carrier just to be wowed by what you see on a peak meter?

2) Average mod, not peaks, determine perceived volume. It's in the math, it's proven, it's inarguable. Short time peaks (nS) carry very little energy compared to increasing average modulation over longer periods.

3) +200% is a very impressive claim but it sounds like hell on the majority of receivers. It's this simple: Clip your positive peaks or it will be done for you in a distorted mess by most receivers.

4) Mod iron and bypass caps need to be rated for the dramatically higher voltages caused by cranking up the positive peaks. There's no way I'd take that chance, particularly with the mod iron.

Conclusion: What's more important? Do you like saying "200% positive peaks" on the air or do you want to sound loud *and* clean to others in the QSO? The broadcast world figured this out decades ago. Why reinvent the wheel over and over and over and over... ?


* PEPcalcs.jpg (3187.58 KB, 2668x2256 - viewed 588 times.)
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KC4VWU
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« Reply #44 on: January 28, 2016, 06:56:45 PM »

Well, it seems that it was slightly misrepresented in one of it's writeups. The author (the guy supposedly authorized to do the installs and setups) had explained that it was "essentially a transmitter", which isn't correct. It's an audio chain / modulator circuit. I suppose it would be fun to work through the schematic to calculate the parameters and possibly breadboard up to do some testing, but just not interesting enough to devote any spare time to at the moment. If the circuit is viable, maybe it could be used on lower power SS rigs like the HR-2600 for better AM response... properly adjusted of course. 
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steve_qix
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« Reply #45 on: January 31, 2016, 01:40:08 PM »

The circuit, as shown, won't work - as someone has already pointed out.  However, allowing for the reverse-engineering anomalies, or drawing errors, etc...

...what is shown in the schematic is a clipper.  D1 through D4 form a bi-directional clipper. D5, D6 and the related components form a circuit that will cause some amount of asymmetry.  The capacitor values are all missing, so trying to figure any frequency response adjustments is not possible.

Many people here on AMFone could design this or something which performs the same function, perhaps by different means, if they so desired.  Not rocket science, but definitely interesting that someone productized this and were/are successful with it!
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PA0NVD
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« Reply #46 on: January 31, 2016, 02:06:14 PM »

Lineair series modulator with sufficient headroom and run the audio first through a simple multiplier, squaring the signal. That gives something like a mauldulator signal. .
At the receiver side you can do it reverse by square rooting the signal and you are back to normal. Is there a gain like in compression technics to reduce noise?
Interesting...
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« Reply #47 on: January 31, 2016, 09:47:19 PM »

'prime minista' has a 20-30KW water cooled PA. It's OK but just looks like a bunch of more or less featureless black metal boxes in the pics I saw. OK if no one gets to see it.  Nice high power stuff but some control panel stuff would be nice.
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« Reply #48 on: February 01, 2016, 09:03:45 AM »

Also;
Quote
Looks like he massages a low level signal by reducing the carrier and keeping the original peaks. (if the pix and description are representative of the real mauldulator.  In one of the tube vids, he makes the statement that oscilloscope vertical gain has to be turned up because the carrier is now less. Then her runs it through an 811.  So much for his SS lecture on ancient tubes.  Grin

http://www.motormouthmaul.com/mmm2_003.htm

This sounds similar to what I’ve been doing with my Flex 6500. On AM, I adjust the output of the 6500 to produce 200W out of my Acom 1000. This gives me ~ 800-900W out on peaks (1:4 ratio). Next, I adjust the AM Carrier on the Flex to reduce the 200W to 100W. The peak output is still at 800-900W. My reason for doing it was to reduce the operating temperature of the ACOM, which it does by 8-10 degrees C.
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KA6BFB
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« Reply #49 on: August 26, 2016, 12:00:55 AM »

Hello All

I am the designer of the circuit you fellas are talking about in here. I see a few snarky comments that I think make the authors feel better, but for the most part, I think you have been fair. An unscrupulous person has chosen to take my design and call it his own. He claims that he "designed and developed" it and claims to be applying for a patent. I decided to do a thorough search and found this thread.

First off, QIX is correct, that circuit won't work the way it is drawn, but the asymmetry part of it is correct. His analysis is also correct. The D1-D4 section was added to add a "tube sound" and the harder you hit it, the more it emulates that sound. It has no business being in this circuit. All of the audio processing and effects should be done in the rack gear or audio processing software. This was the first generation circuit, more of a proof of concept. That stage is removed from the second generation and that design also runs off a single voltage instead of three and has other enhancements that were learned from using this one.

As for the comment of this being "an illegal manufacturer and an illegal operator", this is an audio device, not an RF device. That statement would be analogous to calling a gun an illegal device. If I use it for target shooting it is perfectly legal. If somebody uses it for a murder, it is still a legal device being used in an illegal manner. This thing can be and has been attached to several amateur radios and that is the only way I use it. I have it on a Retro 75 modulating the final MOSFET output, and I am also building a power supply/modulator to provide the HV on ARC-5 T-19 tube transmitter. John himself has used it to modulate a lower stage of a yaesu FT-7 and a Kenwood TS-440. We have both been on 3870 here on the California Central Coast talking to each other on those.

The operation of the circuit is actually quite simple. It takes an audio signal and leaves everything below a set point the same level as the input (gain of 1, R13/R11), and the signal above the set point is amplified by a factor of one or greater depending on the value of R1. The diodes D5 and D6 gate the directional nature, and the high speed op amp makes up for the diode voltage drop. This approach is similar to the one in the K1JJ speculation early in this thread. In fact, the method he described is similar to one of the earlier circuits that was the foundation of this design. The problem was that we got some crossover distortion or switching noise with that approach when we tried to combine the separate halves.

We had another intermediate approach between that one and this final design that had two pots to adjust levels but it was clumsy because one of the pots affected both levels. I finally came up with the design in the D5-D6 area. It works slick. You just adjust your audio level input to the stage so that the negative peak is around 95% or so modulation on the carrier, and then adjust the asymmetry pot R1 for whatever positive peak value you desire. The output of this stage is DC shifted to adjust the DC resting voltage on the collector or drain of the RF output stage to adjust carrier level. The output impedance of the asymmetry stage is not the same in both directions because of the separate paths. It is imperative that the high impedance buffer stage be used or performance will be severely degraded. Also, 300% peaks are mentioned in this thread, which is more than possible if R1 was 20k, but that would be silly. In my own implementation of this on 80M I have a max allowable of 150% and routinely set it at 130%.

During this past week I released a drawing in Facebook of this circuit for everybody to see because I was annoyed with the person taking it for his own. I am actually grateful for somebody posting it here because that establishes at least that date that it was in the public domain. Thank you Shane for your valiant effort and concern about whether John and I would approve.

N1BCG, I have no argument against your math. Your logic and math is impeccable. You're argument might be more with all of the AM Broadcasters that continue to use it. Check out this link of a nice amateur conversation with asymmetry https://www.youtube.com/watch?v=9m1bo08YmoE&feature=share

In closing, one person in this thread remarked "since when do cb'ers care about distortion"  There are a great deal that do. John cares about his sound both there and on the amateur spectrum. I am not apologizing for anybody doing anything illegal, but I won't look down my nose at them so that I can feel superior. Some of those people are doing things at a level and caliber that is impressive no matter what frequency they are on. Of course there are many loud mouth idiots that put more signal where they don't want it with their improperly biased dirty splatter boxes that have no low pass filters on the output, but that is not everybody. For the record, I have complained about those folks too. See this link https://www.youtube.com/watch?v=q-DWG0voti0

73 Dave  KA6BFB
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