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Author Topic: A 600W BROADBAND HF AMPLIFIER USING AFFORDABLE LDMOS DEVICES  (Read 763 times)

Offline ChrisSmolinski

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The announcement of the MRF300 and MRF101 transistors by NXP in 2018 has generated quite a spark of interest in the amateur radio community and as soon as I learned about them I wanted to get some on my workbench.

This project is meant to demonstrate the capabilities of the MRF300 transistors as linear broadband devices in the 2-50MHz range and to be used by radio amateurs as a starting point for a medium-high power amplifier. This is also my entry to the NXP Homebrew RF Design Challenge 2019.

Each individual MRF300 LDMOS transistor is specified at 330W output over a 1.8-250MHz working frequency range, a maximum 28dB of gain and over 70% efficiency. The recommended supply range is 30-50Vdc. By studying the specifications, it looks like with correct broadband matching and some operational safety margin we can get close to 600W output at a voltage of around 45V across a resonably large bandwidth; the aim is to cover 1.8 to 54MHz.

https://qrpblog.com/2019/10/a-600w-broadband-hf-amplifier-using-affordable-ldmos-devices/
Chris Smolinski
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Offline redhat

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Re: A 600W BROADBAND HF AMPLIFIER USING AFFORDABLE LDMOS DEVICES
« Reply #1 on: October 29, 2019, 1742 UTC »
There is no mention of this amplifier being used for linear service, certainly not at 70% efficiency.  Tread carefully.

+-RH
« Last Edit: October 30, 2019, 0012 UTC by redhat »
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Offline CoolAM Radio

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Re: A 600W BROADBAND HF AMPLIFIER USING AFFORDABLE LDMOS DEVICES
« Reply #2 on: October 29, 2019, 1911 UTC »
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Offline OgreVorbis

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Re: A 600W BROADBAND HF AMPLIFIER USING AFFORDABLE LDMOS DEVICES
« Reply #3 on: October 31, 2019, 1037 UTC »
There is no mention of this amplifier being used for linear service, certainly not at 70% efficiency.  Tread carefully.

+-RH

Interesting you guys just mentioned this device as I just found out about it myself and I was researching it a couple days ago.

I can be used for linear amplifiers. PCS has done it for FM broadcast band: https://www.pcs-electronics.com/650w-pallet-amplifier-p-3016.html

It's a really good deal for something that can work on the VHF band.
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Offline redhat

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Re: A 600W BROADBAND HF AMPLIFIER USING AFFORDABLE LDMOS DEVICES
« Reply #4 on: October 31, 2019, 1926 UTC »
There is no mention of this amplifier being used for linear service, certainly not at 70% efficiency.  Tread carefully.

+-RH

Interesting you guys just mentioned this device as I just found out about it myself and I was researching it a couple days ago.

I can be used for linear amplifiers. PCS has done it for FM broadcast band: https://www.pcs-electronics.com/650w-pallet-amplifier-p-3016.html

It's a really good deal for something that can work on the VHF band.

Why would you use a linear amplifier for FM service?  LOTS of wasted power.

+-RH
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Offline OgreVorbis

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Re: A 600W BROADBAND HF AMPLIFIER USING AFFORDABLE LDMOS DEVICES
« Reply #5 on: November 01, 2019, 0419 UTC »

Why would you use a linear amplifier for FM service?  LOTS of wasted power.

+-RH

Don't you have to use a linear for VHF band? Confused  :o

I could see what you mean about shortwave though. Using a linear on shortwave is a waste, but on FM...

Maybe I don't know enough about the other classes of amplifiers out there for FM band.
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Offline redhat

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Re: A 600W BROADBAND HF AMPLIFIER USING AFFORDABLE LDMOS DEVICES
« Reply #6 on: November 01, 2019, 0812 UTC »
An amplifier is an amplifier, a linear amplifier is an amplifier used to amplify signals in a linear fashion.  A linear amplifier operates in some derivative of class A or AB, meaning that the active device in the amplifier is drawing current during most if not all of the cycle of the input signal. FM signals, and those in which amplitude does not carry any intelligence, can be amplified with a non-linear amplifier operating in class C, D, etc.  Modern technology has blurred the lines with class D when utilized with PWM, but for high level amplification the previous examples still hold.

https://youtu.be/c6cmkm3UPUI

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Offline Pigmeat

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Re: A 600W BROADBAND HF AMPLIFIER USING AFFORDABLE LDMOS DEVICES
« Reply #7 on: November 01, 2019, 1154 UTC »
I've known Marko from PCS for nearly 15 years. He won't rip you off or sell you crap. What you want to do with it is up to you.


Offline Radio Boogie

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Re: A 600W BROADBAND HF AMPLIFIER USING AFFORDABLE LDMOS DEVICES
« Reply #8 on: December 02, 2019, 0149 UTC »
I always wished PCS made something like their PCI card tranny, but for MW/HF operation. Just a couple watts output to drive an amp or do QRPp.
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