The DEI transistors will never hold up to the voltage that the toshiba 2897 did.
I have seen 2879`s run at 21 volts, try that with the DEI replacement.
Hope you got deep pockets and good soldering skills
73
Jeff
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
12, 24, and 48 volts????
- Thread starter psycho
- Start date
The DEI transistors will never hold up to the voltage that the toshiba 2897 did.
I have seen 2879`s run at 21 volts, try that with the DEI replacement.
Hope you got deep pockets and good soldering skills
73
Jeff
Yup the DEI transistors are not the same transistor as the toshiba 2879. But the days of time are coming for the toshiba's. Keep what you have and don't over volt or over drive them and they will last a very long time. The DEI's don't like volts that's for sure. But keep it at 13.8-14.2 volts and again don't over drive them, and they should work. But you are right, they don't hold a candle to the old toshiba 2879.
The DEI transistors will never hold up to the voltage that the toshiba 2897 did.
I have seen 2879`s run at 21 volts, try that with the DEI replacement.
Hope you got deep pockets and good soldering skills
73
Jeff
Thanks for the clarification.
Sent from my SCH-I545 using Tapatalk
That 10% less number means a lot more than it sounds like when you consider the details. It's 10% less than the "rated" level of the real 2SC2879 just to keep the DIE part from dying while having some reliability. Now if we are talking about reducing drive by 10% compared to the Toshiba, we can expect the output to show the same 10% reduction from the 100 watt rating for 90 watts per DIE device.
The difference is extremely significant in the area of headroom. What they are not telling you is the Toshiba can be operated at 250 watts output in a circuit that is only 50% efficient and still not exceed its 250 watt continuous collector dissipation rating!!! Most transistor specifications are ABSOLUTE limits that many of us are familiar with. Exceed any one even briefly and you let the smoke out of the part.
When the Toshiba came out around 1990 it didn't take long to figure out this animal was different from the biggest Motorola or TRW parts of the day. Its specification for voltage was more like a tube in that it could be exceeded by a good deal so long as the current was controlled through the device. Controlling the current had a lot to do with proper drive levels and output matching. Handling the voltage was a matter of using the purest silicon in the transistor and plenty of it so flashover arcs were rare.
Toshiba understood the market was already flooded by Motorola with more than a dozen 12 volt bipolar devices in a similar power class. Each having slightly different specs. They wanted to dominate the high power 12 volt RF amplifier class by making a part that could replace everything else available with something better. That's why it got the highest ever current and power dissipation specs combined with the highest gain in the power class so it could be driven easily.
That changed the RF transistor market quickly. Soon, the only major equipment manufacturer using a high power Motorola RF transistor was Motorola. Kenwood, Icom, Yaesu and many others all switched to Toshiba since they also made VHF versions of this transistor. They didn't do this so they could get 250 watts per device, they did it for durability and spectral purity. Things like SWR protection and ALC were not always fast enough to save the lesser finals. Many failed in the early days of solid state 100 watt rigs.
No transistor before the Toshiba was quite the same and none after it will be since the new wave is 50 volt MOSFET devices for high power and Motorola still makes excellent 12 volt RF MOSFET's. The DIE runs reliable at 90 watts while the Toshiba makes over 200 year after year for those who ignore IMD. For those who say they won't run the DIE hard, don't forget about that needed headroom. Remember none of the junk that will use DIE transistors has SWR protection or ALC and are the most likely to self oscillate. What happens if your antenna hits a bridge when you're keyed and the SWR spikes to near infinite or the thing unexpectedly breaks into an oscillation even for a second into a real antenna?
I literally fall out on the floor every time I see a video of someone trying to convince us the DIE transistors are worth a damn rather than get on with learning the new technology and I don't mean the 11 meter power supply MOSFET's either. Don't dump your amp into an unrealistic, perfectly resistive 50 ohm dummy load while proclaiming the transistor is so good. Do what you need to do to convince manufacturers that employ engineers. Run your part at the power level you advertise it at in the simplest circuit with no protection whatsoever. Then go to your tool box, grab a screw driver and proceed to jam it right across the RF output at full power!
Don't give me a chance to think you have a pile of videos before this one that didn't go your way and show me you're confident by holding that short on the device for a while. Once you got me convinced add some insult to injury by "bouncing" that short on and off the output so I can see how it handles transitioning between these two extremes repetitively at different phase angles. Let the sparks fly. Show me your current, volt and power meters during this abuse. Shock the RF world and do this with a single device at more than 1000 watts. Sound impossible? It was done last year and the video is all over the net with repeatable results.
One sentence sums up the reality of the DIE transistor. "If it's ANY good, why does Icom, Kenwood and Yaesu still use Motorola MOSFET's that cost $80 or more in all new equipment that would have used a 2SC2879?" Or perhaps this one is better. "If it were not for CB, DIE wouldn't sell a single transistor because it is their ONLY market".
The difference is extremely significant in the area of headroom. What they are not telling you is the Toshiba can be operated at 250 watts output in a circuit that is only 50% efficient and still not exceed its 250 watt continuous collector dissipation rating!!! Most transistor specifications are ABSOLUTE limits that many of us are familiar with. Exceed any one even briefly and you let the smoke out of the part.
When the Toshiba came out around 1990 it didn't take long to figure out this animal was different from the biggest Motorola or TRW parts of the day. Its specification for voltage was more like a tube in that it could be exceeded by a good deal so long as the current was controlled through the device. Controlling the current had a lot to do with proper drive levels and output matching. Handling the voltage was a matter of using the purest silicon in the transistor and plenty of it so flashover arcs were rare.
Toshiba understood the market was already flooded by Motorola with more than a dozen 12 volt bipolar devices in a similar power class. Each having slightly different specs. They wanted to dominate the high power 12 volt RF amplifier class by making a part that could replace everything else available with something better. That's why it got the highest ever current and power dissipation specs combined with the highest gain in the power class so it could be driven easily.
That changed the RF transistor market quickly. Soon, the only major equipment manufacturer using a high power Motorola RF transistor was Motorola. Kenwood, Icom, Yaesu and many others all switched to Toshiba since they also made VHF versions of this transistor. They didn't do this so they could get 250 watts per device, they did it for durability and spectral purity. Things like SWR protection and ALC were not always fast enough to save the lesser finals. Many failed in the early days of solid state 100 watt rigs.
No transistor before the Toshiba was quite the same and none after it will be since the new wave is 50 volt MOSFET devices for high power and Motorola still makes excellent 12 volt RF MOSFET's. The DIE runs reliable at 90 watts while the Toshiba makes over 200 year after year for those who ignore IMD. For those who say they won't run the DIE hard, don't forget about that needed headroom. Remember none of the junk that will use DIE transistors has SWR protection or ALC and are the most likely to self oscillate. What happens if your antenna hits a bridge when you're keyed and the SWR spikes to near infinite or the thing unexpectedly breaks into an oscillation even for a second into a real antenna?
I literally fall out on the floor every time I see a video of someone trying to convince us the DIE transistors are worth a damn rather than get on with learning the new technology and I don't mean the 11 meter power supply MOSFET's either. Don't dump your amp into an unrealistic, perfectly resistive 50 ohm dummy load while proclaiming the transistor is so good. Do what you need to do to convince manufacturers that employ engineers. Run your part at the power level you advertise it at in the simplest circuit with no protection whatsoever. Then go to your tool box, grab a screw driver and proceed to jam it right across the RF output at full power!
Don't give me a chance to think you have a pile of videos before this one that didn't go your way and show me you're confident by holding that short on the device for a while. Once you got me convinced add some insult to injury by "bouncing" that short on and off the output so I can see how it handles transitioning between these two extremes repetitively at different phase angles. Let the sparks fly. Show me your current, volt and power meters during this abuse. Shock the RF world and do this with a single device at more than 1000 watts. Sound impossible? It was done last year and the video is all over the net with repeatable results.
One sentence sums up the reality of the DIE transistor. "If it's ANY good, why does Icom, Kenwood and Yaesu still use Motorola MOSFET's that cost $80 or more in all new equipment that would have used a 2SC2879?" Or perhaps this one is better. "If it were not for CB, DIE wouldn't sell a single transistor because it is their ONLY market".
Last edited:
And not the power supply switching kind either. REAL RF MOSFETS. They have been in commercial use for decades. CB has yet to learn about them.
I run QRP mostly but would like to find an amp to use on Dx pileups? Something like is used on channel 6, I heard a bunch of splatter a couple weeks back on 10 mtrs...went looking for it and found my hero, "Mista" on channel 6. He was about 500 miles away....keying over the lowly "Duce" who is a QRP operator I'm sure. "Mista" mainly talks to himself, pausing to make sure the lowly "Duce" still hears him and is paying attention. He also must have a deal with the electric company for commercial rates? what an amp. I googled AM channel 6 Super Bowl to see what these guys run, they don't mess around! real power.....10-30,000 watts. Some run 5000 watts in the picked up truck.....i might not want to key 5000 watts up next to my body? But "Mista" and "Duce" are fearless.
I just can't afford electric bill....and my house wire is not heavy enough......just a thought....a pileup buster with 30,000 watts just to get thru then crank down to 5000 and work QRP. Just think of the dx you could work on the first call
All on a 1/4wave vertical no beams, now that is smokin the bands ? Right??
I just can't afford electric bill....and my house wire is not heavy enough......just a thought....a pileup buster with 30,000 watts just to get thru then crank down to 5000 and work QRP. Just think of the dx you could work on the first call
All on a 1/4wave vertical no beams, now that is smokin the bands ? Right??
Pretty much anything in the BLF part number range. Most are not 12 volt devices but there are some that are.Most high power MOSFETS use 50 volts while some use 28 volts. A good 12 volt MOSFET is the DU1260T which is a 60 watt device for 2-175 MHz. Another is the DU1215S which makes a nice driver transistor at 15 watts and 2-175 MHz as well. The ERF7530 is another good one. 30 MHz, 12 volts and 75 watts output. Lots more out there. Just Google "12 volt RF MOSFET" . If you want really high power and have a 50 volt power supply on hand look at the fantastic MRF151G for 300 watts and any of the LDMOS devices from Freescale. Up to 1.2 Kw from a single device at 50 volts and these MOSFETS will work into an infinite SWR....yup dead short or open circuit practically. SWR tolerance values are typically speced at 50:1.
Here is a link to RF Parts and you can check out some data sheets there.
BLF - RF Transistors
This kinda sums up how rugged these devices are.
VSWR of 125:1 at full output, 1200 watts and no damage.
Shorted with a screwdriver, no damage.
And this is 1200 watts from one transistor.
( i like the liquid cooled copper heatsink)
https://www.youtube.com/watch?v=8ziYqjMQGEQ
Here is a 2 meter amp using a pair of Freescale MRFE6VP61K25H ldmos devices producing 2.5 KW, all home brewed.
https://www.youtube.com/watch?v=sm9midsdhMs
Real RF devices.
73
Jeff
VSWR of 125:1 at full output, 1200 watts and no damage.
Shorted with a screwdriver, no damage.
And this is 1200 watts from one transistor.
( i like the liquid cooled copper heatsink)
https://www.youtube.com/watch?v=8ziYqjMQGEQ
Here is a 2 meter amp using a pair of Freescale MRFE6VP61K25H ldmos devices producing 2.5 KW, all home brewed.
https://www.youtube.com/watch?v=sm9midsdhMs
Real RF devices.
73
Jeff
Last edited:
I was thinking of that video when I posted Jeff but it was getting too late for me to look around for it. I start my night shifts and needed my beauty sleep.
Good info guys....
So transistor amps are out.....
What are some of the tube amps to look for, that are neighborly friendly ?...
So transistor amps are out.....
What are some of the tube amps to look for, that are neighborly friendly ?...
If it was me?? SB200, SB220, AL 811 would come to mind. Personally I would stay away from the 11 metre specific amps and get a good used HF amp,but would stay away from the sweep tube jobbies.