EMRFD Message Archive 3137

Message Date From Subject
3137 2009-06-03 14:33:21 timshoppa WA2EBY IRF510 MOSFET Amp
I'm looking at the March/April 1999 QST Article by WA2EBY where he shows a very simple amplifier for 160M through 10M using two IRF510's in push pull, 28 Volt power supply, to get 50W to 75W out from 1W in.

I only ever do CW, so class C is just fine by me.

Has there been any advance in state-of-the-art in cheap power MOSFET technology that I might want to consider in building my version of this?

He notes that board layout and construction details seem to be important to stability.

IRF510's seem more popular than ever in homebrew designs, so maybe there isn't really anything much better. He notes "From a thermal standpoint, the IRF510 power MOSFET is a poor choice for this RF amplifier application" then goes on to note that despite all his key-down testing he didn't get any of them to fail, and also that if they do manage to fail that the replacement is only a dollar each!

Tim N3QE
3139 2009-06-03 16:42:37 dixonglennb Re: WA2EBY IRF510 MOSFET Amp
Tim:
>
> I'm looking at the March/April 1999 QST Article by WA2EBY where he shows a very simple amplifier for 160M through 10M using two IRF510's in push pull, 28 Volt power supply, to get 50W to 75W out from 1W in.
>
> I only ever do CW, so class C is just fine by me.


That is actually a linear amplifier and can do SSB, etc.

I built it...it was lots of fun. The bank of low pass filters is particularly well-designed and I liked those so much I made it a piece of test equipment by switching the filter input to a BNC.

I used it a while, then blew it up instantly when I forgot the recommended voltage and put 36V into it. Since then, it seems to want to blow new FETs up as soon as I put them in, so I have some troubleshooting to do. My sense is that it gets pretty fragile above 24V or so.

Make sure you use exactly the same FET recommended. I think it was the one Radio Shack sells.

I think Amidon still stocks the toroid kits for the amplifier and the low pass board.

73,
Glenn AC7ZN
3140 2009-06-03 17:21:24 Sam Morgan Re: WA2EBY IRF510 MOSFET Amp
dixonglennb wrote:

> I built it...it was lots of fun. The bank of low pass filters is
> particularly well-designed and I liked those so much I made it a piece
> of test equipment by switching the filter input to a BNC.
snip
> I think Amidon still stocks the toroid kits for the amplifier and the
> low pass board.
>
just curious, would this lowpass filter board be workable for this?

--
GB & 73
KA5OAI
Sam Morgan
3142 2009-06-03 20:05:09 Allison Parent Re: WA2EBY IRF510 MOSFET Amp
3143 2009-06-03 20:22:31 Dave - WB6DHW Re: WA2EBY IRF510 MOSFET Amp
If you are an ARRL member, you should be able to download that article
from the ARRL website.
IRF510's are much more linear and produce much more power at 24V than
at 12V.

Dave - WB6DHW
<http://wb6dhw.com>

timshoppa wrote:
> I'm looking at the March/April 1999 QST Article by WA2EBY where he shows a very simple amplifier for 160M through 10M using two IRF510's in push pull, 28 Volt power supply, to get 50W to 75W out from 1W in.
>
> I only ever do CW, so class C is just fine by me.
>
> Has there been any advance in state-of-the-art in cheap power MOSFET technology that I might want to consider in building my version of this?
>
> He notes that board layout and construction details seem to be important to stability.
>
> IRF510's seem more popular than ever in homebrew designs, so maybe there isn't really anything much better. He notes "From a thermal standpoint, the IRF510 power MOSFET is a poor choice for this RF amplifier application" then goes on to note that despite all his key-down testing he didn't get any of them to fail, and also that if they do manage to fail that the replacement is only a dollar each!
>
> Tim N3QE
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>
>
3148 2009-06-04 15:12:09 Bill Noyce Re: WA2EBY IRF510 MOSFET Amp
timshoppa wrote:
> I'm looking at the March/April 1999 QST Article by WA2EBY where he shows a
> very simple amplifier for 160M through 10M using two IRF510's in push pull,
> 28 Volt power supply, to get 50W to 75W out from 1W in.

I believe this is the same amp design that appears in the "HF-Packer Amp"
http://www.hfprojectsyahoo.com/hfpackerampdiy.html
K5OOR designed a DC-DC converter to supply 24 volts to the amp, and
created a very compact layout for the converter, amp, and filter
boards. I have one, and it works great, giving about 40 watts on 160
through 20 meters (I don't recall whether it drops off after that).

-- Bill, AB1AV
3149 2009-06-05 09:54:49 timshoppa Re: WA2EBY IRF510 MOSFET Amp
3150 2009-06-05 16:49:55 Mike Collins Re: WA2EBY IRF510 MOSFET Amp
> OK, so the advice seems to be "it's a good design, nothing better in that direction has come along, build it just like the article". Will give it a shot!
>

Hi Tim,

I have built one of the WA2EBY amps. I put a pdf in the files section under Files > KF4BQ > Modification to AMP REV1.pdf with some of the modifications I have done. Mostly bias regulation for ease of input voltage changes, and somewhat different LPF filter band arrangement/design.

AMP has OK IMD performance at the higher power levels. Best with 28-32V. I use the WB6DHW power supply to step up the voltage to 32V.

The IMD performance suffers a bit at the lower power levels. I also built up another amp (with a spare set of Far Circuits PCBs) using a pair of RD16HHF1 FETs. Much better IMD performance but less output power. A single ended RD16HHF1 class A amp was also built and compared to the others. Some of the results can be found in the Softrock group under my call (KF4BQ).

In summary, you can't go wrong. Get some PCBs or buy one of the amps from HFPROJECTS. For CW only probably pretty hard to beat the dual IRF510's with high voltage...

I still have the orig set of IRF510's in my amp and it has been through some hard testing :))

73, Mike Collins KF4BQ