Re: New FT8 Digital Mode Easier on IRF510?


Robert Hudson
 

Hi John

Thanks for the info on the FET , I was probably a bit impatient to get it going and had not considered that aspect.    Will get some IFR510’s and replace it.  


Best Regards  Bob
On 13 Aug 2017, at 11:42 am, landrjoh@... [CHINA_QRP] <CHINA_QRP@...> wrote:

Hi Bob,


I'm surprised that the IRF540 is working as a good replacement for the original IRF510.

The IRF540 has a significantly higher input capacitance (1700 pF) compared to the IRF510 (180 pF).  From what I've read, higher MOSFET input capacitance requires higher drive levels.  Also, the IRF540 is slower to respond than a IRF510.

I wonder if the IRF540 has decreased the transmit power?

Maybe Adam can comment on this.

73,

John
AA7US

---In CHINA_QRP@..., wrote :

Hi John and all

Also my local supplier did not have the original FET but a higher current rating and seems to work well. (IFR-540)  


Bob Hudson







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