Windfreak 137.5MHz-4.4GHz USB Sig Gen

[VK4GHZ]

Just wondering if anyone has played with one of these?
For US$249 (now AU$228!!!), they look interesting!

Made by Windfreak Technologies, they're a USB Powered RF Signal Generator, that works from 137.5MHz to 4.4GHz.




Some GUI screen shots from their product description...




Basic sweeping capabilities too.







More info on their website (link above)

Hmmm......

[VK4GHZ]

Windfreak have released a new product, "SynthNV".

Is has all the RF Signal Generator capabilities of their product mentioned above, as well as an on board RF power detector.
It also has an SMA connector to feed an external 10MHz reference into it.

Now we are talking!



This board lends it self to becoming a poor mans spectrum analyzer/tracking generator.

There is also a 1MHz - 4GHz RF power detector enabled by the Analog Devices ADL5513 [11] which is fed through the SMA connector at [10].

This RF detector has up to 70dB of dynamic range and can measure up to 0dBm of RF power.

Version 1 of the software will report real time power measurements but a future version will allow frequency sweeps between connector [6] and connector [10] which will give a basic ability to measure the performance of filters and other RF devices. By using an external circulator or coupler there will also be the ability to measure the return loss / VSWR of RF devices such as antennas.

Being able to sweep filters etc from 2m to 9cm would be handy.

[VK4GHZ]

FYI...
Interested in the SynthUSB, I asked about entering frequency down to the last kHz, ie; 3400.440 MHz (beacon use!) and using an external 10 MHz reference.

Yes, you can enter a frequency down to the KHz for a single frequency.
You can go even smaller (On the PLL Control tab of the software) if you know PLLs and how they work. Especially at the lower frequency ranges.
The main sacrifice is spurious performance and phase noise.

Yes, the synthesizer will do your frequency easily. You can also remove the crystal and solder on a pigtail to bring in your higher stability reference.
The ADF4350 has pretty good spec on the reference, so just about any one will work.
I think it just needs to be between .7Vpp and 3.3Vpp.
You just need to be careful with the traces when you solder and unsolder.

Cheers!
David
KD5JVC

I then enquired if the SynthUSB could be used without a tethered PC.
ie; use a PC to set the operating frequency, then disconnect the PC from the synthesizer, so the synthesizer runs stand-alone.

Hi Adam,
The SynthUSB tends to get a glitch when it is unplugged from the USB port and that sends the PLL off into la-la land even if the power connector is plugged in.
It definitely has no memory.
That's one of the reasons I made the SynthNV. Its nonvolatile memory will come back up when you plug in DC power...
No worries about writing. Ask away.
Best Regards,
David

[VK4YOI]

Hi All

Regarding the tethered PC...

Great idea, what about giving the USB Sig Gen what it needs from a PIC (or similar) into the USB port. There is a lot of development to be had with the difference in price, HHCIB?

[VK4FLR]

Adam- How are you finding this device (latest Windfreak SynthNV ) . as I am considering purchasing the same - i can see it would be extremely useful in our 2.4ghz project - no one up here has any decent test gear in this range & I can't access any test EQ at my ex work place..

Also I see there is this by Signal Hound http://www.signalhound.com/ USB 2.0 Spectrum Analyzers and Measurement Receivers USB-SA44B: 1 Hz to 4.4 GHz & this more expensive unit USB-SA124B: 100 kHz to 12.4 GHz...has anyone compared the two or played with one ?? is the latter better bang for buck or would the lesser expensive SynthNV do the job ??

Regards
Frank VK4FLR

[VK4CZ]

Adam brought his Windfreak USB Sig Gen out yesterday and we swept my 1.2 and 2.4GHz yagis.... and whilst both of the yagi's had presented 'good' SWR results when measured using commercial SWR bridges, the results of the Windfreak 'analysis' provided a very different view with both yagi's having a very flat frequency response and little if any determinable dip.

Whilst we didn't have time to play for long (my issue), the quick results seen when sweeping the 2.4GHz yagi were simply brilliant. Within a few minutes we had identified that director 5 was too short. By thickening the elements (placing a sleeve over them) we were able to quickly produce a significant and very defined dip (-22dbm from memory) close to the design freq. More playing with further directors showed that we could both move and deepen this.

Having an immediate visual display of each change shows so much more than a meter!

(Note... both yagis performed exceptionally well on the uWave Activity Day, so I'm now wondering once time is spent on the Windfreak how much better they could perform!)

I wish I'd taken a couple of pic's!

One has to go on the wish list

[VK2XSO]

Do you know what the resolution is at the higher frequencies ?
And maybe what the phase noise is like ?

[VK2JDS]

pictures would be good, also any description of how you measured the return loss as you swept the antennas.
it looks like a nice bit of gear, but what extra stuff do we need to enable such graphical displays of antenna performance
73 , Dave

[VK5KK]

Hi All,

I've had a Windfreak USB gen for a year or so. While its not a laboratory grade device, as an "off the shelf" frequency source with 1 KHz steps that goes to 4.4 Ghz its had plenty of use.

It uses an ADF4350 PLL. I've not done a qualitative phase noise measurement but it seems comparable to other ADF4350 PLL's (viz the Israeli fleabay one) when set down to odd KHz resolutions viz -75dbc @ 10 KHz. PN probably not as good as a PLL with lesser resolution (rounded frequencies) on LO duty viz 3XDK & A32 DEMI LO's (using Si4133) but thats not its intended purpose anyway.

The original TCXO is fine for sweeping (25ppm) if thats all you need. Mine settled about 25 Khz low on 2.4 Ghz but wobbled around more than acceptable for narrowband use. I have removed the onboard 10 Mhz ref and added an external Isotemp OCXO 10 Mhz ref. $25 for <100Hz stability & accuracy makes it a good "temporary" Local Oscillator for projects.

Power output is controlled by a simple look up table. Power out does vary a bit as you tune up in frequency .. viz 1 Ghz +1.8dbm, 1.75Ghz + 2.4 dbm, 2.4 Ghz +5.4dbm (it jumps up between 3db 2.2 & 2.4 Ghz), 3 Ghz +3.9dbm, 3.75 Ghz +1dbm, 4.4 Ghz -1.2dbm. As you are probably not going to sweep across more than 5-10% BW no issue.

I've installed mine in a small diecast box with feedthru's bypassing the USB feed. Still not good enough to use as a sig gen for RX testing (Still some GHz bleedthru) it does minimise direct radiation from bare PC (which you can hear for 100 metres !)

Cheers

David VK5KK