EMRFD Message Archive 9740

Message Date From Subject
9740 2014-02-14 08:09:17 Jim Miller IRF510 Successor?
I'm looking to build an amp for 630m. It doesn't need to be linear so looking at class C or E.

Browsing the IRF site shows the IRF510 to be "divested".

Any recommendations for something similar for use in a 25W or so PA?

I see some folks have used the IRF540.


jim ab3cv
9741 2014-02-14 08:14:47 William Martin Re: IRF510 Successor?
Why not use a "real" RF FET?


Bill N7EU
9742 2014-02-14 09:01:15 ashhar_farhan Re: IRF510 Successor?
Th mitsubhisi transistor series are unobtanium in many places. The IRF510s are still available manufactured by other companies. The newer substitute is STP16NF06. It was 'freshly out of stock' in the local market here, though.
- f
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9743 2014-02-14 09:06:48 Dana Myers Re: IRF510 Successor?
9744 2014-02-14 10:16:55 kb1gmx Re: IRF510 Successor?
At 500khz the RD part is expensive overkill.

Just look at the IRF parts that can be had.  Most of the power mosfets run well at up to 10mhz
and there are big ones (easily good for more than 25 watts) available.  Look at max current and 
voltage specs the input C.

With antenna efficiency typical at that frequency 1-2% with a good ground field (unless you can do 
a 475ft tower) I'd think 25W is well down the power curve.

For 1W erp I'd start at 100W class E as its easy to turn it down.

Someday soon maybe the US will get that band rather than the experimental licenses.


9745 2014-02-14 13:56:56 Jim Miller Re: IRF510 Successor?
Hi Allison

I'll look at what it would take to do 100W class E. I'd like to stay with 13.8V so that may be a limitation. I see that Jim Tonne has some class E design software. I'll give it a look.

I'll print out a few of the IRF datasheets later and do some comparisons with the 510.

I'll post back my findings.


jim ab3cv (pooped after 4hrs with snow thrower...)

9750 2014-02-15 06:43:58 nm0s_qrp Re: IRF510 Successor?
Jim, while it is true that IRF has 'divested' their commodity MOSFETs, their production has been picked up by Fairchild.  The IRF510, like the 2N2222, will be around for a long, long, time.
For a 25W amp, I'd consider going with an IRF520, which will give you a bit more ruggedness, which you'll appreciate when tuning up the antenna.

73 Dave NM0S
9755 2014-02-15 13:25:17 Jim Miller Re: IRF510 Successor?

Thanks for the input. Design margin is a good thing!

I'm now shooting for 100W Class E. The antenna and bring up will be done and "fixed" so barring antenna failures should be pretty reliable. I'm probably just going to base load my existing 160m inverted L which is 65H/65L.

I'm still in the conceptual stage although roughing out a schematic soon. I like the Ixys driver for it's simplicity and features. At ~$5 although actually more expensive than the IRF540 it looks like it saves me hassles in a one off design. Not really focused on cost at all.


jim ab3cv