Re: On the subject of fake IRF510

Richard Andrew Knack
 

I am currently building a WA2EBY 40 watt amp (see the March and April 1999 issues of QST ) that uses a PAIR of IRF-510's in a push-pull arrangement for finals. Requires 28v power, but I will be using a DC-DC boost converter for that. Needless to say, nearly the entire back of the aluminum case will be covered by a heat-sink, and the IRF's will be insulated with mica wafers from the heat-sink!

Rich
KC8MWG



On Saturday, July 15, 2017, 6:26:00 PM EDT, Andrew Krause <andrew.krause@...> wrote:


Is there an alternative in a TO-220 package? 

On Sat, Jul 15, 2017 at 6:22 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
I find this post from Allison to be informative, she definitely knows what she's doing:  
    https://groups.io/g/BITX20/ message/22597 

There are issues with the IRF510 as an RF amp.
Primary issue is poor thermal conductivity from die to TO-220 tab.
Also, the tab is connected to the drain, not the source as it would be in a good RF device,
so be careful not to short the heatsink to ground!  (Or add a $0.05 mica insulator and heatsink paste.)  
The IRF510 does work better at 24v than at 12v, giving better linearity.

But otherwise, Allison reports that the IRF510's  behavior is similar to
the 10x more expensive RF devices such as the RD16HHF1.
She continues to use the IRF510.

Jerry, KE7ER



On Sat, Jul 15, 2017 at 02:45 pm, John Backo wrote:
using a IRF MOSFET is always a case of possible pig in a poke. Some of
them will not work no matter what one does to them.




--

Andrew Krause
General Class Amateur Radio License: KM4ZJO
andrew.krause@...
(404) 732-2369



Join BITX20@groups.io to automatically receive all group messages.