Does this 1.2 KW amp from china look right?

[USXDriver]

So besides it missing a case etc does this look right? I'm not buying it or anything but am very curious to hear from someone who has some experience in amp design/building their opinion.

Sorry left out the link

Link

 

[sp5it]

Link?

 

[jrd426]

Likely this, but does not come with output transistors or heatsink.

1200W 1.8-54MHz SW Shortwave Power Amplifier Board MRFX1K80H BLF188 Power Amp | eBay

Find many great new & used options and get the best deals for 1200W 1.8-54MHz SW Shortwave Power Amplifier Board MRFX1K80H BLF188 Power Amp at the best online prices at eBay! Free shipping for many products!

www.ebay.ca

 

[999]

Likely this, but does not come with output transistors or heatsink.

1200W 1.8-54MHz SW Shortwave Power Amplifier Board MRFX1K80H BLF188 Power Amp | eBay

Find many great new & used options and get the best deals for 1200W 1.8-54MHz SW Shortwave Power Amplifier Board MRFX1K80H BLF188 Power Amp at the best online prices at eBay! Free shipping for many products!

www.ebay.ca

It looks like its designed around this mosfet.

https://www.nxp.com/docs/en/data-sheet/MRFX1K80H.pdf

 

[USXDriver]

Link?

Here is the link

 

[USXDriver]

Likely this, but does not come with output transistors or heatsink.

1200W 1.8-54MHz SW Shortwave Power Amplifier Board MRFX1K80H BLF188 Power Amp | eBay

Find many great new & used options and get the best deals for 1200W 1.8-54MHz SW Shortwave Power Amplifier Board MRFX1K80H BLF188 Power Amp at the best online prices at eBay! Free shipping for many products!

www.ebay.ca

1.2 KWT RF POWER AMPLIFIER ON 4 x SD4933 HAM RADIO HF/VHF/UHF RF power | eBay

Find many great new & used options and get the best deals for 1.2 KWT RF POWER AMPLIFIER ON 4 x SD4933 HAM RADIO HF/VHF/UHF RF power at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[999]

This is the mosfet that board is designed around.

https://www.st.com/resource/en/datasheet/sd4933.pdf

It's a 50v device with a minimum of 40v. That's where they got the 1200 watt rating from in the add.
At 40v it's rated at 300 watts per device, and at 50v it's rated at 400 watts per device.

 

[Handy Andy]

The caulk or Hot Glue mess really shows the cra(ph)manship of the enslaved workers...

You know the mounting flanges on that thing for the "pills" still need to be mounted right?

If it's rated at 1.2kW - you'll need a fire extinguisher - there are not many ferrites, nor boards that can flow out that heat efficiently in that type of package.

You're not serious are you?

Pulse mode of 50% or less on time maybe - but --- WOOF

 

[9C1Driver]

Kinda looks like an unfinished POS to me. I wouldn’t waste your money on that Chinese junk

 

[nomadradio]

Actually it needs a copper heat spreader. Aluminum has too much thermal resistance per square inch for a 300-Watt transistor that size. Copper, however, will absorb more heat per square inch. The much-larger surface of the spreader plate against the aluminum heat sink surface will carry the heat to the aluminum heat sink.

Most any RF power transistor rated over 150 Watts requires a heat spreader.

73

 

[linearone]

Another word about these MOSFET boards on eBay, while they may be an amplifier. Technically, most of them don't incorporate a complex bias scheme or any transmit receive switching. Bias on these MOSFETs is not as simple as a diode and resistor.

 

[nomadradio]

Seems to me the technical description for a "bare bones" amplifier with no relay or switching circuits is a "palett".

Still requires the antenna relay, bias switching, input attenuator (probably) and RF sensing circuit if you don't plan to key it with a patch cord like a ham linear.

Not so much a linear as a project element.

73

 

[AudioShockwav]

Still requires the antenna relay, bias switching, input attenuator (probably) ..........

You will want the input attenuator, you really don't want to overdrive those devices.
Someone will want to drive it to get mo power not understanding that they need very little drive to get the rated output.

73
Jeff

 

[jtrouter]

Actually it needs a copper heat spreader. Aluminum has too much thermal resistance per square inch for a 300-Watt transistor that size. Copper, however, will absorb more heat per square inch. The much-larger surface of the spreader plate against the aluminum heat sink surface will carry the heat to the aluminum heat sink.

Most any RF power transistor rated over 150 Watts requires a heat spreader.

73

And for those who are thinking about building one the copper board runs about
$80.00 to do it right......But they do work well.