now we are getting 65V LDMOS fets .less amps. start looking for 60V switchers . love the amp. and ldmos is class a type amp. that the bias control. the 65V is plug play. no re tuning. you are going to have a lot of fun talking on all the bands. I have tube amps. not today 90F. maybe winter!!
Alan - you could also use an external PS and an external LPF and make the amp enclosure as small as feasible and the amp enclosure would still be almost empty. That's what I do. That way I can just reuse my PS and LPF for every amp I make. But on the other hand, lots of people want a complete amp in a box, and I totally [almost] understand that too. :)
Are these devices sourced from AliExpress or somewhere similar? I am asking as I do not see NXP on these. If yes, what's your experience with these suppliers? BTW, like your neat construction technique.73's
KF8OD, Very nice amplifier. I am trying to settle on a design for a full legal limit mobile amplifier with 5 parallel boost supplies mounted close to the batteries under the hood of my 2019 F450. However it will likely end up on the other side of the the fender skirt as there is not much open space left under the hood. There should be plenty of space for the amp behind one of the back seats. I haven't settled on which LDMOS device to use, but am going to do it with a single push pull circuit. I was planning to utilize feedback in the circuit to improve linearity, but saw notes by other builders advising against it due to the possibility of causing the circuit to go into oscillation. However, I noted that you utilize feedback. Did you utilize circuit modeling to find the correct components or do it by trial and error? Ever lose any parts due to the circuit going into oscillation? Any advice would be appreciated. Thanks in advance WD0DIA
Feedback does nothing for linearity, LDMOS devices are not linear. I have never experienced oscillation. The feedback really only tames the gain on the low bands and keeps the rf input pretty uniform across 1.8-54mhz.
Very nice amp.I love these devices. I want to use the new 65 volt version of the device. I just completed a 75 amp 55-65 volt variable power supply for the project..next is the RF deck. Do you have a pcb set available for purchase? Or even a pcb layout? I am also interested in the transformer and choke parts. The pcb/engineering design kit from the mnfg is ridiculously priced. I want to use 2 devices and let it loaf. I’ve been using an 8877 for years. I had enough of tubes. Time for LDMOS Thank you.
Hey thank you so much, it is the result of two year of really hard work to make this crazy design. You too, you should have the first price !! I didn't know that this challenge was Amateur Radio oriented.
For anyone trying to figure out the efficiency and thinking Wow 40a @50v 1000w and thinking that isn't very efficient... Remember these are LDMOS Chips... they really don't start getting efficient until you get up to about 50-65% of its rating( theoretically 3900w@65v )... he's only running them at a 1/4 of what their capable (not including losses).... No, I don't advocate running anything at max but whenever he gets close to 2k that efficiency is going to come up quite a bit. Just thought I would throw that in there
@@KF8OD1 I figured you already knew about it when I posted it...I was just posting it for others that noticed the amperage vs Wattage. And then think the chip wasn't very efficient... I was just clearing that up for them... I remember when I first fired up a blf188xr and just through a few milliwatts into it I only got something like 14% efficiency... people used to silicon transistors don't understand that until they are putting appreciable power in the input into a Mosfet the efficiency is way down.... and is actually hard on the chip itself... better to lower the voltage a few volts with ldmos..
Hi Filipe, My opinion, operating ldmos devices at 50% yields better IMD. You can't dissipate the heat generated operating them at full output. Be conservative and they will last. The ratings on the datasheet are in pulse service.
MRFX1K80H is 1.8kW CW. With very good thermal management, this is obtainable... if device is run in good efficiency conditions. This device is used in laser, heaters, MRI, FM broadcast.
Hi Mike I've asked this before but do you feel a need to run your amps with LPF? If you operate on the air without a low pass filter do you notice a difference? Eric
A work of art.Congrats!
That set-up is Very Clean looking , love the surf-mont comp. and I love the ideal put to the Constuct . Great job , .73 from Pa
Beautiful work of art congratulations thank you for sharing that masterpiece with us 👍
Thank you John!
That is a work of art congratulations on a great build
Really nice project! Congratulation!
Thanks Stefan!
very nice design ! looks to be very rugged. I like the idea of operating the LDmos at 50% of the max. power.
Harry May Thanks Harry
Very nice! Good job
Gavin Smith Thanks Gavin!
Heyy Gavin !!!
now we are getting 65V LDMOS fets .less amps. start looking for 60V switchers . love the amp. and ldmos is class a type amp. that the bias control. the 65V is plug play. no re tuning. you are going to have a lot of fun talking on all the bands. I have tube amps. not today 90F. maybe winter!!
Looks good Mike, I need to go to the 16"x16" cabinet, much more room. Surprised you did the 2 1k80s, I expected the 188s.
Alan
I have a reason for building the 80h amp, I am sticking with the 188s for the complete amps for sale.
Alan - you could also use an external PS and an external LPF and make the amp enclosure as small as feasible and the amp enclosure would still be almost empty. That's what I do. That way I can just reuse my PS and LPF for every amp I make.
But on the other hand, lots of people want a complete amp in a box, and I totally [almost] understand that too.
:)
Nice !
Great job. What is the quiescent current of transistors?
Four amps
Are these devices sourced from AliExpress or somewhere similar? I am asking as I do not see NXP on these. If yes, what's your experience with these suppliers? BTW, like your neat construction technique.73's
KF8OD, Very nice amplifier. I am trying to settle on a design for a full legal limit mobile amplifier with 5 parallel boost supplies mounted close to the batteries under the hood of my 2019 F450. However it will likely end up on the other side of the the fender skirt as there is not much open space left under the hood. There should be plenty of space for the amp behind one of the back seats. I haven't settled on which LDMOS device to use, but am going to do it with a single push pull circuit. I was planning to utilize feedback in the circuit to improve linearity, but saw notes by other builders advising against it due to the possibility of causing the circuit to go into oscillation. However, I noted that you utilize feedback. Did you utilize circuit modeling to find the correct components or do it by trial and error? Ever lose any parts due to the circuit going into oscillation? Any advice would be appreciated. Thanks in advance WD0DIA
Feedback does nothing for linearity, LDMOS devices are not linear. I have never experienced oscillation. The feedback really only tames the gain on the low bands and keeps the rf input pretty uniform across 1.8-54mhz.
Very nice amp.I love these devices. I want to use the new 65 volt version of the device. I just completed a 75 amp 55-65 volt variable power supply for the project..next is the RF deck. Do you have a pcb set available for purchase? Or even a pcb layout? I am also interested in the transformer and choke parts. The pcb/engineering design kit from the mnfg is ridiculously priced. I want to use 2 devices and let it loaf. I’ve been using an 8877 for years. I had enough of tubes. Time for LDMOS Thank you.
How can I get the PCB or finished Pallet from you directly ?
Wow really nice !!!
Thank you! Congrats on your 2nd place win in the NXP challenge. Your amplifiers are beautiful!
Hey thank you so much, it is the result of two year of really hard work to make this crazy design. You too, you should have the first price !! I didn't know that this challenge was Amateur Radio oriented.
For anyone trying to figure out the efficiency and thinking Wow 40a @50v 1000w and thinking that isn't very efficient... Remember these are LDMOS Chips... they really don't start getting efficient until you get up to about 50-65% of its rating( theoretically 3900w@65v )... he's only running them at a 1/4 of what their capable (not including losses).... No, I don't advocate running anything at max but whenever he gets close to 2k that efficiency is going to come up quite a bit. Just thought I would throw that in there
Thanks for your comment. I was much more concerned with IMD and harmonics. Don’t really care about efficiency.
@@KF8OD1 I figured you already knew about it when I posted it...I was just posting it for others that noticed the amperage vs Wattage. And then think the chip wasn't very efficient... I was just clearing that up for them... I remember when I first fired up a blf188xr and just through a few milliwatts into it I only got something like 14% efficiency... people used to silicon transistors don't understand that until they are putting appreciable power in the input into a Mosfet the efficiency is way down.... and is actually hard on the chip itself... better to lower the voltage a few volts with ldmos..
Lindo trabalho, bem limpo a montagem, 73 PY1FI
Excellent GL 73 Paul WA6PY
Hi, why only 1 kw when using 2 transistors rated for 1800w each? are you limited by the PS? nice video. 73 CT1ILT
Hi Filipe, My opinion, operating ldmos devices at 50% yields better IMD. You can't dissipate the heat generated operating them at full output. Be conservative and they will last. The ratings on the datasheet are in pulse service.
Thanks for the reply, that clears me out.
MRFX1K80H is 1.8kW CW. With very good thermal management, this is obtainable... if device is run in good efficiency conditions. This device is used in laser, heaters, MRI, FM broadcast.
How well matched do these devices need to be to have equal quiescent current with a common bias setting ?
No concern.
Wonderful design! Thank you for the video! 73! de R6FX
Hi mike
I like this . Could you build me one or sell plans and schematic to do so?
Cheers BJ
I have them for sale on my website. www.qsl.net/kf8od/swappage.html
Amazing
you have 50V 40A and 1 kW output. Does it mean the efficiency is only 50%? The datasheet promises up to 80%...
50% efficiency is all you get when covering 1.8 - 54mhz.
I think you need a lot more fans extracting hot air from the box. I think you only have one!!
Thank you for your comment. There are three fans on the heatsink that exhaust all the heat out the side of the cabinet.
Nice design! I'm a student and I'm studying HF amplifiers, could you please give me the schematic?
Go to my website, a lot of information there.
www.qsl.net/kf8od
Very nice… but Larger Fan with low speed
What psu are you using here?
Mean Well RSP-3000-48
@@KF8OD1 pricey
Do you have a diagram & parts list?
My website has a lot of construction details.
www.qsl.net/kf8od
hy there, what smps do you use in every rf pa?
Mean Well RSP-3000-48
@@KF8OD1 thanks, do you have any smps recomendedation for 1kw pa 48V and 27v Sat mosfet,?
@@endremurti Mean Well RSP-1500-48. I am sure Mean well makes a 24v supply that could be adjusted up to about 26v.
one of these days i wan tto actually run legal limit... sadly can't even put up a proper antenna where i am at.. one day.... one day...
Hi Mike I've asked this before but do you feel a need to run your amps with LPF? If you operate on the air without a low pass filter do you notice a difference? Eric
Eric Lessard Yes, you must use a LPF to comply with FCC regulations.
should be 3000
it is necessary to use water cooling. this is the best choice.