Cheap 3GHz source. - Page 1
Forum section: electronics / testgear

author: McBryce
author_rank: Super Contributor
timestamp: February 07, 2018, 11:26:19 am
content: Hi,I'm looking to do a quick test on some frequency counters that go up to around 3 to 4 GHz, I don't need GHz for anything else I do, so an expensive frequency generator would be wasted money. It needs to be relatively accurate (I'm not calibrating, just testing the function) and cheap. What are my best options?McBryce.

author: awallin
author_rank: Frequent Contributor
timestamp: February 07, 2018, 11:43:59 am
content: from digikey an ADF4350 eval-board (EVAL-ADF4350EB1Z-ND) is about 130 euros - is that cheap?take a 10 MHz or so reference for the ADF4350 from the back of your standard HF signal generator?

author: McBryce
author_rank: Super Contributor
timestamp: February 07, 2018, 12:51:14 pm
content: Quote from: awallin on February 07, 2018, 11:43:59 amI was thinking more €10 Chinese PCB level. It also needs to be relatively portable.McBryce.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 07, 2018, 02:40:51 pm
content: https://www.ebay.com.my/itm/New-140MHz-4-4GHz-with-Sweep-Function-RF-Signal-Generator/263273012630?hash=item3d4c4b5d96:g:cNUAAOSwySlZ6pm~if you are thinking one day you'll need SA, for a little bit addition of a cost ishttps://www.ebay.com.my/itm/35MHz-4-4GHz-35M-4-4G-USB-SMA-Source-Signal-Generator-Simple-Spectrum-Analyzer/222781714688?hash=item33ded33100:g:r2YAAOSwh2FZ4B1lbut it will be PC dependent, fwiw...

author: Yansi
author_rank: Super Contributor
timestamp: February 07, 2018, 02:47:55 pm
content: That is a garbage at best, as a meter.

author: McBryce
author_rank: Super Contributor
timestamp: February 07, 2018, 03:20:20 pm
content: Quote from: Mechatrommer on February 07, 2018, 02:40:51 pmThanks. The first one would be enough to do the job. However, the description is confusing, I have a feeling that it measures up to 4.4GHz, but only outputs a much lower frequency. I'll contact the seller.McBryce.

author: casinada
author_rank: Frequent Contributor
timestamp: February 07, 2018, 03:28:25 pm
content: Probably based on the ADF4351https://www.ebay.com/itm/NEW-35M-4-4GHZ-ADF4351-PPL-module-RF-signal-source-generator-board/262899938438?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20160908110712%26meid%3D57b834038f814fad8bc91370f24a4b39%26pid%3D100677%26rk%3D5%26rkt%3D26%26sd%3D182963511827%26itm%3D262899938438&_trksid=p2385738.c100677.m4598https://www.ebay.com/itm/ADF4351-RF-Sweep-Signal-Source-Generator-Board-35M-4-4G-STM32-TFT-Touch-LCD-New-/173108662352?_trksid=p2349526.m4383.l4275.c10and then, may be not

author: HalFET
author_rank: Frequent Contributor
timestamp: February 07, 2018, 05:30:41 pm
content: Have you checked minicircuits? They should have VCOs and synths in that range.e.g.https://www.minicircuits.com/WebStore/dashboard.html?model=ROS-3000-819%2Bhttps://ww2.minicircuits.com/pdfs/ROS-3000-819+.pdf

author: jpb
author_rank: Super Contributor
timestamp: February 07, 2018, 06:28:36 pm
content: At 1GHz you could get a simple oscillator:https://www.digikey.co.uk/product-detail/en/crystek-corporation/CCSO-914X-1000.000/744-1254-ND/1767708or more expensive but easier to use as it is packaged:https://www.digikey.co.uk/product-detail/en/crystek-corporation/RFPRO33-1000.000/744-1326-ND/2074652Unfortunately they don't seem to do them at higher frequencies

author: McBryce
author_rank: Super Contributor
timestamp: February 08, 2018, 08:10:50 am
content: Quote from: casinada on February 07, 2018, 03:28:25 pmThanks, the second product is exactly what I need. I also appreciate their honesty about the design: "PCB board has beautiful appearance, reasonable layout and design". The layout and design are only reasonableMcBryce.

author: Mr. Scram
author_rank: Super Contributor
timestamp: February 08, 2018, 08:46:37 am
content: Quote from: Mechatrommer on February 07, 2018, 02:40:51 pmIs ebay.com.my a legitimate eBay site? It could be, but it also could be a phishing variant.

author: McBryce
author_rank: Super Contributor
timestamp: February 08, 2018, 09:56:27 am
content: Quote from: Mr. Scram on February 08, 2018, 08:46:37 amIt seems to be the ligitimate Malaysian ebay site. I wouldn't order via that link anyway, I'd just look for the same item on my local ebay.McBryce.

author: langwadt
author_rank: Super Contributor
timestamp: February 08, 2018, 10:09:53 am
content: Quote from: Mr. Scram on February 08, 2018, 08:46:37 amjust delete .my , look like it is just the Malaysian ebay url to get the currency

author: Yansi
author_rank: Super Contributor
timestamp: February 08, 2018, 11:39:48 am
content: Quote from: McBryce on February 08, 2018, 08:10:50 amThat layout looks anything but reasonable. Not trying to be mean, it seems to be only 2 layer (that should not be a problem by itself), but there seem to be some nonsense going on under the RF traces, ground is missing under them in quite mind blowing way. Also, one of them is being sliced by a (presumably) power supply line. That is a big NO.//EDIT: If the chip bottom is the solder blob on the PCB, then both RF traces are also sliced by another two thin traces. I am no RF expert by any means, but I would not ever do that.

author: Bicurico
author_rank: Super Contributor
timestamp: February 08, 2018, 12:26:57 pm
content: The "SMA Simple Spectrum Analyzer 35MHz-4.4GHz" or the cheaper 138MHz-4.4GHz variants are very cheap and actually not bad at all, considering the price.The main problem is that they are shipped with a non-authorised copy of WinNWT/LinNWT, which was dveloped for the original NWT500 devices, these chinese clones are inspired by.I wrote my own software, implementing many useful measurements (http://vma-satellite.blogspot.pt/).They do work as spectrum analyser and signal generators, if you want to do SWR measurements, you should get a noise source or the more expensive NWT4000 or NWT6000 models, as they have what could be considered a TG function.Again, you cannot compare these devices to Rohde&Schwarz or Agilent, but at 50-150 Euro, you simply cannot complain. Read about the hardware, there are many blog entries on my blog and there is the manual for my software, giving further insight of the capabilities.While I do not own the model with build-in TFT screen, I know it is NOT compatible with my software and it will certainly not have better specs than the regular SMA models.Regards,Vitor

author: Ice-Tea
author_rank: Super Contributor
timestamp: February 08, 2018, 03:54:42 pm
content: Should you go looking beyond the very cheap option: I have a bunch of R&S CMU200's that include an SG up to 2.8GHz. Cheap, but not as cheap as the other suggestions

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 08, 2018, 06:04:47 pm
content: Quote from: Mr. Scram on February 08, 2018, 08:46:37 amduh what country are you in? btw casinada's suggestion is better because the gen has better GUI. now i think i want one 6.8GHz variant i need to go to Test Equipment Addiction (TEA) Therapy threadhttps://www.ebay.com.my/itm/ADF4355-250M-6-8GHz-LCD-RF-Signal-Generator-VCO-Microwave-Frequency-Synthesizer/232587754406?hash=item36274f7ba6:g:0RoAAOSwi0xaJ2qMQuotecant they be more innovative in choosing words rather than just copy paste?