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Dave Made Choice
- Thread starter BBB
- Start date
Another Dave Made choice appears to be available soon. Different logo, similar boxes, good stuff inside.
Pony up the $$$$.$$
I would LOVE to see that thing on a spectrum analyzer. 50 watts avg/100 peak is crazy into a 4 pill much less the 70 watt avg/150 watt peak. I wonder just how long it will take that kind of drive level and how many channels away you can be heard.
Toshiba 1446s and/or 2sc2879s. I can't fathom DM using anything else unless its the t00b stuff. I would be very, very surprised if he would spec that other chinese chit. So I see XF $355 PP vs DM $625 Toshiba.
I personally wouldn't pay much attention to the meter readings in the video either. IMO, If Dave helped in the design as mentioned, they should perform as expected within or slightly above the devices factory parameters and be tuned well. Tuning is key as I've found out over the years.
I personally wouldn't pay much attention to the meter readings in the video either. IMO, If Dave helped in the design as mentioned, they should perform as expected within or slightly above the devices factory parameters and be tuned well. Tuning is key as I've found out over the years.
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Toshiba factory specs say 100 watts pep output with a typical drive of 6 watts pep and a maximum of 10 watts pep drive per device. Already DM is running them FAAAR beyond that. Throw in class C operation and it's still a shit splatter box. Even at factory specs the IMD is only -24 dB so I cannot even imagine what it would be under DM operation conditions.
I agree to disagree. When run within specifications of the devices and tuned correctly, I have found this design of amplifier to sound good, have decent gain and be reliable.
I do agree that the The video shows crazy max operating conditions. There will always be new members in the "All Knobs To The Right Club" in any hobby that burn through what ever it is they're doing. No need to put down this solid state stuff. A lot of us have big Swan and Heathkit amps too. You would be surprised
I do agree that the The video shows crazy max operating conditions. There will always be new members in the "All Knobs To The Right Club" in any hobby that burn through what ever it is they're doing. No need to put down this solid state stuff. A lot of us have big Swan and Heathkit amps too. You would be surprised
Not putting any solidstate stuff down. In fact I have begun the transition into solidstate amps with commercial stuff being re-purposed for amateur radio use. I have a 1.2 Kw Larcan amp waiting to to be set up in a case for 6m and several MRF-151G modules waiting to be put on 2m. I LOVE the solidstate stuff. What I am putting down is the claims made about this amp. I take exception to the fact that people consider that the manufacturer of the devices (Toshiba) don't know squat about their product and that some basement amp builder has all the answers. IMD will only go DOWN when over driven and Toshiba specs them at -24 dB as a BEST CASE CONDITION. As for sounding good, that is merely subjective. I have heard operators running something sounding like absolute crap getting told they sound great. I have also know people that think that because they actually are sounding decent then they are not causing interference while the IMD products are barely 15 or 20 dB down and their RF spectrum looks like grass growing on the bottom of the spectrum analyzer screen. 1000 watts from four Toshiba 2SC2879's on 14.4 volts being driven with well over 100 watts is going to sound like crap and eat up RF spectrum. Period.
Having said that, if as you say the devices are run within manufacturers spec ( and they are not in the video) the amp can be a decent unit providing it has filtering however once people see what they think it can do the all knobs to the right mentality takes over and chaos on the band results. In the end my beef is with the outrageous claims being made as if they are normal operating conditions and NOT with normal operating conditions as outlined by Toshiba.
Having said that, if as you say the devices are run within manufacturers spec ( and they are not in the video) the amp can be a decent unit providing it has filtering however once people see what they think it can do the all knobs to the right mentality takes over and chaos on the band results. In the end my beef is with the outrageous claims being made as if they are normal operating conditions and NOT with normal operating conditions as outlined by Toshiba.
They would be good amps if they had AB biasing with proper thermal tracking, filtered output, and tuned input.
Having said that, it's just class C junk to me. And I'm not even a ham guy!
~Cheers~
Having said that, it's just class C junk to me. And I'm not even a ham guy!
~Cheers~
A well built amp yes. Having the proper biasing and filtering and VSWR protection, and maybe some other stuff. Low drive, no addition of any driver, not even within the amp, like a 1x4.
Carrier output would obviously be whatever RF power is placed into the amp.
All this as well as good input/output tuning, and like I said, anything I may have left out, would be the way to go. There are other trsnsistors that can be used and aren't dangerous as everyone thinks. At 50vdc remember all you are doing is multiplying the voltage to create a need for less amperage. So 12vdc at 300a, would only be a lot less amperage at 50vdc. I truly have worked on both 24vdc and -48vdc as well as 48vdc systems. Installing power plants and batteries. Then running all power for equipment and such. Both are dangerous, but aren't anymore dangerous than a high amperage 12vdc system. I will leave that at that. Yes it would take some DC to DC conversion, but if you look around for commercial stuff like CK mentioned, it can be easy to find, and probably for cheap at the rate that many communication systems upgrade their Power Plants and Batteries truly at a remarkable rate. Anyways, me not being an amp tech, but knowing some about voltage and amperage, I would think that building a nice unit like this is totally possible and there are some builders that are already working with other things like LDMOS stuff. At any rate, don't get me wrong DM makes a nice amp, but they are more for keydowns and AM use mostly.
Unless you have the bias added and have filtering and such added, like said, they will splatter like hell with the drive that was being delivered to the amp in the video anyways. Now with a proper bias circuit with thermal tracking like stated, along with an Addendum stating to at exactly what drive level is needed to get the carrier approximately where it needs to be. At least something in wrong saying, start with .1w and slowly move carrier up to reach adequate carrier. Also pep power should be true and not some marked up "inflated" numbers at some ridiculous voltage. Most people run 12vdc systems that charge at 13.8-14.2vdc. This should be the voltage that the wattage numbers should reflect. There is much more that I could go on about that could be simply printed into an instruction manual. Haven't seen one of those yet with any 11m amps. Or maybe I just didn't get anything as such due to the fact I bought my gear used. At any rate, there are better ways to obtain clean wattage with low input drive. A simple single final radio like a uniden 980 with adjustable RF power added to it would be a great radio for this. Doesn't have much power, but is clean radio.
At any rate, yes staying within the manufacturers stated power levels would be the way to go for sure. Don't over drive the DM amp into a total splatter box and it will work on am. But without the driver and all that jazz. At least the one in the video, as I beleive this is the one we are speaking of. The new 400 correct. 4 transistor amp.
I run my TNT 600 with my uniden 980 and it truly does a great job, even on SSB I get no complaints from anyone. I have never really put more than 40-50w pep into the amp on SSB, and it's an older one with toshiba 2879's (red dot), transistors.
With that being said, I can get 750 watts out of it with about 50-60 watts of drive. And it's got heavy attenuation (padding), for a high pep input.
But heck with the 980, it does just as well, although I might loose a couple hundred watts, it's not enough to worry about. The uniden with the DK set at 4w and swinging to about 10-12 watts pep on AM using a radio shack meter, it keys up at about 80-100 watts if memory serves me right, and will swing to about 450 watts or so on the radio shack meter on SSB. Take into account that this isn't a true peak hold meter and I would say the amp is closer to 500 watts pep on SSB. Again, nothing but clean reports from locals to DX. And some critics I promise. But never was told I sounded bad one bit. Anyways. The DM amps are nice, but if I was in the market for a new amp, I would be looking into someone that is messing with LDMOS stuff. JMHO. Have a great day all.
Carrier output would obviously be whatever RF power is placed into the amp.
All this as well as good input/output tuning, and like I said, anything I may have left out, would be the way to go. There are other trsnsistors that can be used and aren't dangerous as everyone thinks. At 50vdc remember all you are doing is multiplying the voltage to create a need for less amperage. So 12vdc at 300a, would only be a lot less amperage at 50vdc. I truly have worked on both 24vdc and -48vdc as well as 48vdc systems. Installing power plants and batteries. Then running all power for equipment and such. Both are dangerous, but aren't anymore dangerous than a high amperage 12vdc system. I will leave that at that. Yes it would take some DC to DC conversion, but if you look around for commercial stuff like CK mentioned, it can be easy to find, and probably for cheap at the rate that many communication systems upgrade their Power Plants and Batteries truly at a remarkable rate. Anyways, me not being an amp tech, but knowing some about voltage and amperage, I would think that building a nice unit like this is totally possible and there are some builders that are already working with other things like LDMOS stuff. At any rate, don't get me wrong DM makes a nice amp, but they are more for keydowns and AM use mostly.
Unless you have the bias added and have filtering and such added, like said, they will splatter like hell with the drive that was being delivered to the amp in the video anyways. Now with a proper bias circuit with thermal tracking like stated, along with an Addendum stating to at exactly what drive level is needed to get the carrier approximately where it needs to be. At least something in wrong saying, start with .1w and slowly move carrier up to reach adequate carrier. Also pep power should be true and not some marked up "inflated" numbers at some ridiculous voltage. Most people run 12vdc systems that charge at 13.8-14.2vdc. This should be the voltage that the wattage numbers should reflect. There is much more that I could go on about that could be simply printed into an instruction manual. Haven't seen one of those yet with any 11m amps. Or maybe I just didn't get anything as such due to the fact I bought my gear used. At any rate, there are better ways to obtain clean wattage with low input drive. A simple single final radio like a uniden 980 with adjustable RF power added to it would be a great radio for this. Doesn't have much power, but is clean radio.
At any rate, yes staying within the manufacturers stated power levels would be the way to go for sure. Don't over drive the DM amp into a total splatter box and it will work on am. But without the driver and all that jazz. At least the one in the video, as I beleive this is the one we are speaking of. The new 400 correct. 4 transistor amp.
I run my TNT 600 with my uniden 980 and it truly does a great job, even on SSB I get no complaints from anyone. I have never really put more than 40-50w pep into the amp on SSB, and it's an older one with toshiba 2879's (red dot), transistors.
With that being said, I can get 750 watts out of it with about 50-60 watts of drive. And it's got heavy attenuation (padding), for a high pep input.
But heck with the 980, it does just as well, although I might loose a couple hundred watts, it's not enough to worry about. The uniden with the DK set at 4w and swinging to about 10-12 watts pep on AM using a radio shack meter, it keys up at about 80-100 watts if memory serves me right, and will swing to about 450 watts or so on the radio shack meter on SSB. Take into account that this isn't a true peak hold meter and I would say the amp is closer to 500 watts pep on SSB. Again, nothing but clean reports from locals to DX. And some critics I promise. But never was told I sounded bad one bit. Anyways. The DM amps are nice, but if I was in the market for a new amp, I would be looking into someone that is messing with LDMOS stuff. JMHO. Have a great day all.
If you want class AB just ask.I have a few Sidewinder boxes built that way. I'm sure Chris will build them too for a price.
Class C makes more watts, requires less parts and is very forgiving over 15 volts.
Wish Chris good luck, glad he reached out to Dave.
Class C makes more watts, requires less parts and is very forgiving over 15 volts.
Wish Chris good luck, glad he reached out to Dave.
I think everyone got used to hearing "don't ask Joe to bias it unless you want him to hang up."
interested in class AB amp, but who's Chris?
website, email address ?
thanks in advance
Howdy 131. If I'm correct you know Dave. Can you verify if this builder (Chris) is actually building these with the permission/help of Dave himself? I'm assuming it's easy to say anything without worrying about a trademark or pattin infringement lawsuit. Thanks