Signal generator with high power output - Page 1
Forum section: electronics / testgear

author: gordy1537
author_rank: Newbie
timestamp: November 14, 2019, 11:22:41 pm
content: We would like to drive some coils with sine and square waves with ~1W to ~2W of power at frequencies going up to ~10MHz. A basic signal generator is up to the task except for the power requirement. Is there an accessory that can boost the power of a sig gen? Is there a different piece of equipment that I should be looking for? It seems like something like this should exist, but I have not had any luck in my search.

author: 0culus
author_rank: Super Contributor
timestamp: November 14, 2019, 11:48:10 pm
content: I'd just get (or build) a power amplifier with the suitable bandpass and stick it in front of an RF signal generator. The only function/signal generator I can think of off the top of my head that offers big output is the HP 3325A or B, with option 002. That gives you up to 40 Vpp, but only to 1 MHz.

author: tautech
author_rank: Super Contributor
timestamp: November 15, 2019, 12:44:27 am
content: https://siglentna.com/product/spa1010-10-watt-amplifier/

author: jonpaul
author_rank: Super Contributor
timestamp: November 15, 2019, 06:28:00 am
content: Driving an inductor can stress amplifier transistors. Air or ferrite core? Inductance ?Sine wave generation is easiest with a class C Armstrong feedback oscillator.What is the objective of your project?Jon

author: Tjuurko
author_rank: Regular Contributor
timestamp: November 15, 2019, 06:32:53 am
content: FYA20A0S DC-10MHz 20Whttps://www.ebay.com/itm/FYA20A0S-110V-Signal-Power-Amplifier-Module-For-Arbitrary-Signal-Generator-LJ-/113681647452~ $199.93http://www.aliexpress.com/item/32953196909.html~ $532.85DPA-2698 10MHz High Power Dual Channel DDS Function Signal Generator Power Amplifier DC Power Amplifier2x5W DC-10MHzhttps://www.banggood.com/DPA-2698-10MHz-High-Power-Dual-Channel-DDS-Function-Signal-Generator-Power-Amplifier-DC-Power-Amplifier-p-1441499.html~ 72.99$

author: gordy1537
author_rank: Newbie
timestamp: November 16, 2019, 11:13:07 pm
content: All excellent options! Looks like I should have been searching for a "power amplifier". Thanks to everyone for the help.

author: Datman
author_rank: Regular Contributor
timestamp: November 17, 2019, 06:57:45 pm
content: Please note that if you want a 10MHz square signal, you need a bandwidth at least 5~9 times the fundamental to have a wave similar to a square wave:https://upload.wikimedia.org/wikipedia/commons/b/bc/Fourier_series_for_square_wave.gif

author: VK5RC
author_rank: Unknown
timestamp: November 18, 2019, 09:12:21 am
content: Isn't that called an rf transmitter?RF emissions at that level are also probably regulated.

author: Someone
author_rank: Super Contributor
timestamp: November 18, 2019, 09:31:52 am
content: Quote from: VK5RC on November 18, 2019, 09:12:21 amThere are practical applications for RF up to much higher power levels, properly shielded/contained its not a transmitter.... just look at your microwave oven.

author: rvalente
author_rank: Frequent Contributor
timestamp: November 19, 2019, 12:15:51 am
content: Google feeltech amplifier.

author: excitedbox
author_rank: Regular Contributor
timestamp: November 30, 2019, 11:30:10 pm
content: I recently ordered a OPA541 amp from Elecdemo and it only cost ~22 Euros it can go up to 40V 5A continuous 10A peak. Frequency range is up to 1.6mhz according to a little note on the schematic they sent me but I can´t be sure since the text is all chinese. There are several other models with different Voltage and Amp ratings and I assume frequencies as well.The build quality is excellent but I haven´t found the time to test it yet. It makes a good impression though and I bought it after reading an article where someone was looking for a amplifier for a signal generator. (https://www.dmcinfo.com/latest-thinking/blog/id/9462/low-cost-function-generator-amplifier-diy)

author: TurboTom
author_rank: Super Contributor
timestamp: December 01, 2019, 08:39:52 am
content: A specified gain-bandwidth product of 1.6MHz for the OPA541 by far doesn't mean that a real-world amplifier utilizing it will have this bandwidth. At a voltage gain of 5, the open-loop bandwidth will be just 320kHz, and this leaves no headroom for feedback and such, which means the output signal will be highly dependent on the characteristics of the load and there will be considerable distortion and phase error.Rather consider the OPA541 as an amplifier for audio frequencies. If you want to make a faster power amp, you may want to have a look at theLT1210(unfortunately not the same power class as the OPA541...).

author: capt bullshot
author_rank: Super Contributor
timestamp: December 01, 2019, 11:06:06 am
content: This one might give you an easy to build amplifier (maybe the FYA20A0S uses this chip):https://www.analog.com/en/products/ada4870.html

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: December 01, 2019, 12:07:31 pm
content: Quote from: capt bullshot on December 01, 2019, 11:06:06 amThe LT1210 is another possible chip. It comes in a TO-220 package which would be easier to heatsink. The slew rate 900V/us matches the FYA20A0S.Link:https://www.analog.com/en/products/lt1210.html#product-overviewTake a look.Regards,Jay_Diddy_B

author: Howardlong
author_rank: Super Contributor
timestamp: December 01, 2019, 09:58:46 pm
content: Quote from: Jay_Diddy_B on December 01, 2019, 12:07:31 pmAnother option that I have used successfully is the ADA4870 eval board, it will do >35Vpp into 50 ohms with a 40V supply. I just measured the rise time with a 10MHz square wave input, 8ns on the output into a 50 ohm dummy load. (input rise time was 3.5ns). It gets a little toasty at that power, it would need a heatsink for operating at that level for extended periods.