Run, don't walk, to this video series by RF MAN. He is truly, THE MAN! Pete N6QW found this series, passed it to Dean KK4DAS, who alerted me. Thanks guys.
This is a six part video series on how to design an HF 50 watt RF linear amplifier using our beloved IRF-510 MOSFET. Each video is about 30 minutes long.
The author (who is this genius?) makes great use of LTSpice. I have been using this software for years, but still I learned a lot by watching these videos: AC Analysis. How to change the values of the things you are measuring. Even something as simple as drawing a wire right through a component to get leads on both sides. This is really useful stuff.
RF Man goes through the whole design of the RF amplifier. He describes how to use LTSpice to determine input and output impedances (he does this with a NanoVNA in another video). He talks about the use of negative feedback, and temperature compensation. There are swamping resistors as Q killers. This is all great, real-world stuff.
Especially useful for me was his presentation on how to do "two tone" IMD tests.
There is a lot to learn here. RF Man has a really wonderful way of explaining complex theory, and demonstrating complex tests. This series makes me want to build a MOSFET amplifier.
Look for the six parts of this series. Here is RF Man's YouTube channel:
Thank you, RF Man!
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Great timing Bill! I am working on a transmitter with the goal of 50 Watts. Have been looking at WA2EBY design but will view the videos before melting any solder.
ReplyDeleteWes W4JYK
From my experience an IRF510 pair will produce about 50 watts on 75M or 30 watts on 40M, both using a 28 VDC supply. On 20M I have been able to get 20W at 28VDC with a single IRF530. However, the best thing going is the new MRF101, a genuine RF Power MOSFET where a single device (A or B pinout versions about $30 from Mouser) will generate up to 100W with 50 VDC on all HF bands, or about 30W with 28 VDC. See Appendix 1 for the Jim Veatch WA2EUJ design: https://www.qsl.net/ve7vv/Files/100WBroadbandLF+MF+HF_RF_Amplifier-R28Jan21.pdf
ReplyDeleteIt never fails to amaze me on how long we have been using the IRF510 for HF PA's running 20+Watts?
ReplyDeleteWas the Dec 1986 QST article the first one specifically using the IRF510 and IRF523 HEXFET's for an HF PA?? I started using it on 80M CW , then 30M CW. K1ZZ suggested 40M as he liked that band. We used these for a couple of years in the field before the QST article was published. Zero failures. It was tested in the ARRL lab with a "brick on a key".
But well before that, W7ZOI designed VMOS rigs for 10M, which provided the inspiration for the IRF510 project. And as KA4KXX mentioned, operation at 28 Volts has benefits. Results in better efficiency, power gain and power output.
By 2003, EEs were making switch mode HF RF amps in class E with the 510. For example,
ReplyDeleteTelegdy A. Molnar B. Sokal N.O.: ‘Class-EM switching-mode tuned power amplifier-high efficiency with slow-switching transistor’, IEEE Trans. Microw. Theory Tech., 2003, 51, (6), pp. 1662–1676
This continues until present day. Many professional publications featured this cheap part in the industrial, scientific and medical (ISM) band all through the 2000's
Me thinks it was Mike Kossor WA2EBY in QST for March/April 1999 who really
launched this part worldwide for Hams. His wide band design remains a classic circuit.
Watch for Bootlegs !!!!!!
I just watched Part 1 of the series. Outstanding! RF Man isn't as soft-spoken as W2AEW, but he's just as clear and perhaps a bit more so.
ReplyDeleteWA2EBY did a really nice job with the broadband linear amp using the IRF510's. I met Mike at a Lucent/PRC meeting back in the day. He acknowledged the Dec '86 QST article (small world!). It was cited in several other publications from the late 80's into early 90's, as well as the K0MS article in QST, Aug 2011.
ReplyDeleteThree Hundred "Mousefet" kits were sold, 100 for each band 80/40 and 30 by W6UCM of A&A. I had several QSO's with other hams using the kit; it's a "blast" when that happens!
So, Bill, if you see a "Mousefet" in the Dollar Bin, please pick one up for me! Really!
The original version of the T41-EP transceiver by W8TEE and AC8GY used IRF510s in its 20-watt power amplifier. (It's also offered as a kit by the 4 State QRP Group.) The design showed a significant dropoff in power on the higher HF bands, mainly because the IRF510 was intended for switching power supplies running at low frequencies. Most people building the project today are using a replacement PA built with real RF MOSFETs.
ReplyDeleteI know this is the conventional belief on the IRF510. But it is important to realize that experts on RF amplifiers do not agree with this assessment. Indeed some have been able to use the IRF510 with significant power out into the VHF range. 73 Bill
DeleteMy issue with pushing IRF510 above QRP levels is getting the heat out of the device, so you would need good heatsinks to avoid failures. The RD16HHF1 and MRF101 are designed for RF and should be more reliable. Even so, putting parts to useful unintended radio purposes is a grand ham tradition.
ReplyDelete