higher output MOSFET

[k6ql]

My little Retro-40 ( a low power 40 meter transmitter/receiiver) only puts out a little over 1 watt and won't drive my HLA300 ( a solid state linear amplifier) quite hard enough. It originally used an IRF530 which I replaced with an NTE66. because the IRF530 failed and the NTE66 was available locally. Same thing. Do any of you MOSFET experts know of a "hotter" equivalent that might put out 2 or more watts when used as a 7mHz amp. in class C?

 

[BobK]

I,for one, do not know what a Retro-40 or an HLA300 is, and I am not inclined to google them in order to answer your question.

Bob

 

[duke37]

The IRF530 can switch 14A at 100V, that is over a kilowatt. You need suitable drive and power supply.

 

[k6ql]

I,for one, do not know what a Retro-40 or an HLA300 is, and I am not inclined to google them in order to answer your question.

Bob

Hi Bob,
I edited my question to explain what the devices were that I am using the MOSFET in. I appologize for not making that clear in my original post.

 

[davenn]

Hi there .....
(always good to sign your posts with your name

welcome to the forums

I agree with Duke,
The IRF530 and the 540 are still suitable devices
what is limiting the output is the drive to the device from the previous stage of the transmitter. You may be able to tweek that up a little, BUT DONT
push it too much, else you are going to loose linearity and your transmissions are going to be very dirty ie. causing splatter etc.
Your other option is to build a second IRF530 stage and drive it with the other 530 (NTE66) and end up with a good few Watts out. In that case you
may have to drop back the drive level from the driver stage

Hey good to see another ham on here there are a few of us

cheers
Dave
VK2TDN

 

[k6ql]

Thanks Dave for your reply! I am totally ignorant on these devices! I didn't even think about the driver! Sure makes sense.
The driver is a TC1412N. Maybe that is what I shoiuld be looking at and not the power mosfet.

 

[k6ql]

mosfet deiver

Would a TC1413N drive the IRF530 a little harder for a tad
more output? Would it be directly replaceable with a TC1412N?


Dave

 

[davenn]

Would a TC1413N drive the IRF530 a little harder for a tad
more output? Would it be directly replaceable with a TC1412N?

Dave

am not sure there, have never used one. Maybe some one else on here has had dealing with them and could advise


cheers
Dave

PS.... most of my activity is at the other end of the spectrum .... above 1 GHz
I do a lot of microwave gear constrruction and experimentation
see my pages at .... http://www.sydneystormcity.com/microwave.htm for some of the stuff I get up to on the ham bands

As anyone who knows me well will say... ohh, Dave yeah .. anything below a GHz is DC to him haha

 

[duke37]

I have not used mosfets at high frequencies but the problem seems to be charging and discharging the input capacitance. The input capacitance changes during the cycle.
Options
1. Use a bigger driver or more than one in parallel.
2. Use a smaller fet with lower capacitance.
3. Add some antiphase feedback (neutralisation) to cancel some of the capacitance - possibly tricky to set up.

 

[duke37]

Its me again!
I have driven mosfets with 10V, that has always seemed to be adequate at low frequencies. The driver here is supplied with 6V, is this enough to turn the fet fully on?
The TC1412N can be stand up to 16V, a few more volts should bump up the current a bit.

G3VLF