Who posted this MRF300 amp PCB ?

[RF-Head]

@Marcel
My first proto was made with coax input and later chenged it to 2 coils but going back to the first setup becuase it was more wideband
With both versions i had some problems with input returnloss

Yes a good idea about temp compensation on the gate

Yes i let Dennis know when i have them and your welcome

[Marcel]

XXL no not really they all look very similar.

[Samedi]

NXP had a design for using the MRF300 between 87.5 - 108 MHz (broadband). That circuit uses an AFT05MS004N driver to make the whole suitable for very low input (about 10 mW to get about 300W output), but you can also leave the AFT out for higher input (about 2 - 3 watt).
I will try to attach their documentation, otherwise search for “MRF300AN WITH AFT05MS004N DRIVER 87.5-108 MHz REFERENCE CIRCUIT” on the net. It shouldn’t be very hard to find.
I made a few amps by using this design and it works fine. Make sure to use a proper heatsink and a good ventilator though, it can easily get overheated if you push it to the max…

[Marcel]

Hi Samedi,

First of all, welcome to the forum.

I know this design but read somewhere on the forum that RF-Head had major problems with it.
That is also the reason that I did not delve further into this circuit.
We would like to hear your findings and whether you have deviated from the original design.

Regards,
Marcel

[XXL]

2-3w input is way too much for this. On the datasheet it says at FM band freq's it would need around 0.8w. Also iv popped 2 of these from giving it 1.5w input. It would last about 2 weeks until finally giving up. I was scratching my head for ages wondering why such a rugged device kept blowing. That and output matching on the MRF101 board output was probably really bad for this device.

[rigmo]

npx

[Marcel]

Received the boards and scratced off the paint from 1 so I can better see how it,s put together.

The only difficult parts where do I get SMD parts?
From a standard SMD capacitor is 50V the margin is much too small with a supply voltage of about 48V.

[XXL]

Whos design is that ?

[Marcel]

EX8MLE and RF-Head.

[RF-Head]

Marcel i can send you the SMD parts needed if you want

[Marcel]

Hi Henk,

To be honest I already thought of that because you know exactly what I need and another supplier does what because he doesn't know what's going on at all.

Of course I will publish the data here if it really works as well as on the youtube video so that a replica project is certainly created that everyone can use.

Who doesn't want an RF amplifier that produces more than 300 Watts and that contains a mosfet that costs less than 40 euros.

[rigmo]

can you scan pcb i make for you gerber

[Marcel]

Hi Rigmo,

I will definitely come back to share the experiences and layout.
Due to too many projects, it is on hold for a while.

I have already emailed RF-Head that I would be happy to accept his offer after the current projects.
If you are working with this technique, then 3 lives are not enough, I now find out as a 51-year-old.

Regards,
Marcel

[rigmo]

mrf300 twix