Looking for a USB controllable RF sine source - Page 1
Forum section: electronics / rf-microwave

author: macona
author_rank: Regular Contributor
timestamp: April 24, 2022, 06:12:04 pm
content: I am looking for a USB based RF Sine generator for a test fixture. Frequency range between 100-250MHz and output power at about 10dbm. I dont need any Arb capabilities and looking for minimum harmonics. So far I am looking at the Signal Hound VSG25A, the only issue with that is it does not have any filtering so there can be issues with harmonics from the DAC. But I can always throw a low pass filter on it if I have to.Any other ideas? Ideally something with labview support as well since the test fixture will be based around that.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: April 25, 2022, 02:22:44 am
content: Mini-Circuits had a series of inexpensive, USB-controlled synthesizers. The one I used did cover 50...500MHz, IIRC.I did not retain documentation and/or the designation. It was in a little desktop housing.

author: DaJMasta
author_rank: Super Contributor
timestamp: April 25, 2022, 03:47:52 am
content: A lot of small form factor units seem to lack much output filtering, but what you're describing probably could be done with a standard benchtop arb - something like a Siglent may actually be more cost effective than a different brand's RF source.That said, you could look at the Holzworth HSM as well. They sort of specialize in low phase noise synthesizers, but their 1GHz source seems to be nominally -42dBc second harmonic, to +20dBm output, and USB controllable with an adapter (otherwise SPI and optionally ethernet).

author: Whales
author_rank: Super Contributor
timestamp: April 25, 2022, 03:56:50 am
content: Would an SDR be accurate enough? Transmit capable ones that is, not the RTLSDR. EgHackRFIf it's just sine then I presume the (often 8-bit) data DACs don't matter. The frequency synthesiser's specs can probably be looked up in a datasheet once you spot the part. Not sure about harmonics: presumably they're low enough to avoid spurious emissions, but I don't know how that compares to what you want.

author: LaserSteve
author_rank: Super Contributor
timestamp: April 25, 2022, 04:50:00 am
content: Pts frequency synthesizer off Ebay and buy the third party USB adapter. Input connector on the back is straightforward BCD TTL plus a voltage for RF level. I like PTS160, PTS 250 and PTS 500.Beware of the customized D3xx series for simple applications. They show up a lot especially the OEM style 330 Dual. Its still an excellent synth but unlike the standard series you may spend a lot of time making adapter cables for the rear controls.Programmed TesT Sources inc.Never owned one i didn't like. Never paid more then 250$ for one either. Yes' you may need a cheap SMA or BNC low pass. These are built like a brick outhouse. Often are made for MRI Machines.Steve

author: macona
author_rank: Regular Contributor
timestamp: April 25, 2022, 11:42:25 pm
content: I found this the other night that checks a lot of my boxes:https://windfreaktech.com/product/synthusb3-6ghz-rf-signal-generator/Anyone have experience with this company?8dBm out, which is just what I needLabView support and includes VIs to control itPretty cheap, keeps me from needing a CEAIll probably just get a 250MHz low pass from mini-circuits and stick that on there.

author: ozkarah
author_rank: Regular Contributor
timestamp: June 28, 2022, 09:40:39 pm
content: Quote from: macona on April 25, 2022, 11:42:25 pmThis is a square wave generator. You will continue to see a lot of harmonics up to 80 MHz.

author: gvz
author_rank: Contributor
timestamp: June 29, 2022, 07:05:15 pm
content: A SDR tranceiver like the HackRF or LimeMini SDR can achieve signal generation at these frequencies.Probably the output power will be less than 10 dBm (I must check specs. or test with the spectrum analyzer, if you are interested I can post LimeMini SDR results).In this case a programmable amplifier from AD could solve this problem.g.