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MikesRadioRepair Reviews Asymod iii HiFi Board
- Thread starter KD8HMO
- Start date
A persons voice is no where close to the 25khz he put into it so its not going to hog up several channels under normal use...typical youtube propaganda.
Wideband AM done properly uses less bandwidth than the typical hack job radio with d104. Doesn't piss off the neighbors as much either. The serious operator starts to care more about signal quality than watts.
A modulator circuit feeding the finals (like in the video) isn't quite the same as the "direct injected" thing people have been doing with the stock modulator in a radio. I felt that was also misleading.
I did find it interesting that these boards use 2 of the LM324 opamps. The old design used different opamps. One was an LM324. The part numbers were sanded off the MMM version too but the info is out there.
Wideband AM done properly uses less bandwidth than the typical hack job radio with d104. Doesn't piss off the neighbors as much either. The serious operator starts to care more about signal quality than watts.
A modulator circuit feeding the finals (like in the video) isn't quite the same as the "direct injected" thing people have been doing with the stock modulator in a radio. I felt that was also misleading.
I did find it interesting that these boards use 2 of the LM324 opamps. The old design used different opamps. One was an LM324. The part numbers were sanded off the MMM version too but the info is out there.
Well done video; but he could have gone into greater detail than he did.
25k wide is just too wide. He (the designer) really should have made the width adjustable - IMO. 5 or 6K wide is really enough to get the net effect.
25k wide is just too wide. He (the designer) really should have made the width adjustable - IMO. 5 or 6K wide is really enough to get the net effect.
One thing Mike mentioned, is that this asymod board is a ripoff of the MMM board.
Intellectual property rights? Can you imagine MMM applying for a patent? Not likely!
Intellectual property rights? Can you imagine MMM applying for a patent? Not likely!
I think the tx bandwidth is dependant on the input signal and is dynamic, rather than a static/fixed factor.
73
~Happy New Years!~
I remember a YouTube video from the early days where he injected a 20k tone to show the capability of the board. On a receiving radio he showed what looked like a carrier 2 channels up and down. Not sure what the newer generations of the mmm board are capable of.
Exactly. Turn down the highs on the eq. Most rack gear will not even pass frequencies as high as mike used to prove his opinion.
The first time I heard a MMM modified rig and later other direct injected rig's I thought wow, I want to sound like that!
Like so many new and or improved or diffrent time advaaced devices I wanted to run out and purchase one.
After hearing so many stations (especially on 28 AM) I kinda lost interest. I've since come to realize that
I enjoy hearing a good sounding cobra, uniden, 959 ect ect whether on AM or SSB.
I think a Kenwood, ICOM, Yaesu excetera excetera with a good Studio mic and even better a W3HIY 8 band eq or Noise Gate sounds incredible once everything is dialed in. Of course it's a little difficult to get the above-mentioned set up sounding as good as a MMM or the like on AM but it's not impossible to get them soudin close and in some cases better..
I'm truly content. That's not to say that the people who modify their radios in this way are going too far because it's what the hobby is about (for some). It's been that way since the early 20th century. Tinkering around with the equipment, finding new ways to get your signal out further, bettering one's audio building and or modifying antennas is what most will inevitably do after spending a certain amount of time in the hobby. I think if it's what one wants go for it. It's all good. Happy New Year. 73 PS. I subscribe to my YouTube channel and noticed the notification when I woke up so I check the clip out. My knowledge about anything radio related is very little but I enjoyed the clip nevertheless. I thought Mike was honest and truly believed what he was putting out there.
Like so many new and or improved or diffrent time advaaced devices I wanted to run out and purchase one.
After hearing so many stations (especially on 28 AM) I kinda lost interest. I've since come to realize that
I enjoy hearing a good sounding cobra, uniden, 959 ect ect whether on AM or SSB.
I think a Kenwood, ICOM, Yaesu excetera excetera with a good Studio mic and even better a W3HIY 8 band eq or Noise Gate sounds incredible once everything is dialed in. Of course it's a little difficult to get the above-mentioned set up sounding as good as a MMM or the like on AM but it's not impossible to get them soudin close and in some cases better..
I'm truly content. That's not to say that the people who modify their radios in this way are going too far because it's what the hobby is about (for some). It's been that way since the early 20th century. Tinkering around with the equipment, finding new ways to get your signal out further, bettering one's audio building and or modifying antennas is what most will inevitably do after spending a certain amount of time in the hobby. I think if it's what one wants go for it. It's all good. Happy New Year. 73 PS. I subscribe to my YouTube channel and noticed the notification when I woke up so I check the clip out. My knowledge about anything radio related is very little but I enjoyed the clip nevertheless. I thought Mike was honest and truly believed what he was putting out there.
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Good video, but Mike tends to ramble a lot. If you look at the start of the sweep, this board generates a TON of harmonics. It needs to be followed by a filter with a really sharp rolloff to keep the audio within the 10Khz bandwidth of a cb channel. As a straight CB, I'll bet this thing will sound incredible with a broadcast quality mic and a studio mic preamp capable of 2v output driving it. Of course, most users could care less about bleedover, and will probably run it "balls to the wall". Even then, a filter should be used with the rolloff at 10 - 12khz, because anything over that is inaudible to the human ear (as he demonstrated) .
What I don't understand is why it's called "ASYMOD." Looking at the waveform on the scope, it looks perfectly symmetrical. However, Mike didn't modulate it anywhere near 100%, so I guess I shouldn't expect any asymmetry. Maybe there's an adjustment on the board for that, but Mike didn't show it. I guess I need to look at the ASYMOD website to see the exact capabilities of this board. All in all, looks good. Wonder what it costs ???
- 399
What I don't understand is why it's called "ASYMOD." Looking at the waveform on the scope, it looks perfectly symmetrical. However, Mike didn't modulate it anywhere near 100%, so I guess I shouldn't expect any asymmetry. Maybe there's an adjustment on the board for that, but Mike didn't show it. I guess I need to look at the ASYMOD website to see the exact capabilities of this board. All in all, looks good. Wonder what it costs ???
- 399
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I believe its $600 plus. As I mentioned I know very little about radios and the way they work but have read the description on asamoyds eBay page several times and there is an adjustment. What that adjustment is for I don't exactly know but you can tell the seller where you would like it set and they will set it at that particular setting. They offer three different radios with that board pre-installed. I think the others are in 959 and a cobra am only rig which is the cheapest of the three. The striker is the most expensive of all their pre-installed ones. I think the board itself is a little bit below $300 but don't quote me on that
It is adjustable. The width is dependent on the maximum audio frequency you feed into it. If you want 5-6khz max, limit your audio input to 5-6k and there you go.
- 399
I don't know that i would completely blame the board for the harmonics although it may intensify them.
My stryker 955 is stock and I will not use it. I ran it mobile for a few weeks and the reflected power out of the amplifiers was significantly higher than with my cobra 29. Smells like another turd export to me.
The single voltage asymod thing is pricy. The old one that required the +15v and -15v power supply goes for around 60 bucks. Figure $60 plus simple AM radio like a cobra 25, 24 volt 2 amp power supply and a small 12volt center tap transformer. Could all be had for under $150 and have a cleaner signal than an export.
The board has an asymmetry adjustment to increase positive peaks independently. You start with the asymmetry set to minimum, adjust the carrier level, adjust audio gain for desired negative modulation. At this point the waveform is symmetrical. Finally turn up the asymmetry pot for desired modulation.
Think it is limited (by what I've read/heard/watched) to the freq response of the mic and whatever outboard gear is being plugged into it. Didn't see him adjust anything except the freq feed from the sweep gen into the radio. In fact, he even pushed the envelope and put 10hz-35khz audio, and the radio still transmitted it. It needs some limiting or adjustment capacity - IMO . . .