MFG-3005 Function Generator??? - Page 1
Forum section: electronics / general

author: dopplershift
author_rank: Contributor
timestamp: June 02, 2011, 06:40:04 am
content: Hi all,Just wondering if anyone has heard of the MFG-3005 function generator? I think the brand is "Meili"?I've found it on Ebayhttp://www.ebay.com.au/itm/Function-Signal-Wave-Generator-0-1Hz-5-MHz-AUS-/110694819556?pt=AU_B_I_Electrical_Test_Equipment&hash=item19c5ece6e4. How do you post a proper hyperlink btw? I can't work out how to post html?From the specs, it looks like very good value. Has anyone heard of the brand or this model before? Is it just a cheap chinese brand?Cheers,Dopplershift

author: Bored@Work
author_rank: Super Contributor
timestamp: June 02, 2011, 07:37:50 am
content: Quote from: dopplershift on June 02, 2011, 06:40:04 amGeneric Chines badge engineering. Google LW-1642 for comparison.OEM might be Jinteng Instrument Equipments, aka Longwei Instruments (HK) Co., Ltd., aka Dongguan Longwei Electronic Technology Co., Ltd.I wish Chinese companies wouldn't change their name more often than I change my underpants ... It of course might be that this company is also only doing badge-engineering, and the original manufacturer is yet someone else.

author: EEVblog
author_rank: Unknown
timestamp: June 02, 2011, 08:47:27 am
content: Quote from: BoredAtWork on June 02, 2011, 07:37:50 amThat's why simply refer to them all as OneHungLow brand!Dave.

author: dopplershift
author_rank: Contributor
timestamp: June 03, 2011, 03:51:24 am
content: QuoteI know its not very PC, but I must admit it always makes me laugh when you refer to OneHungLow branded parts/devices in your reviews Dave!Thanks for the info guys, I went for quality (and price) over features in the end. I hope it pays off. I managed to snag a 2nd hand Tek CFG250 on Ebay last night for 150US delivered:http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&rt=nc&nma=true&item=280685537057&si=ABQ52T43VZtfIg3g9fxK%252B6WA%252FAM%253D&viewitem=&sspagename=STRK%3AMEWNX%3AIT(The seller has more btw).Cheers,Dopplershift

author: Unknown
author_rank: Unknown
timestamp: June 03, 2011, 10:57:57 am
content: If a OneHungLow function generator is rebadged as Tektronix, at least you know they won't change their name overnight.

author: dopplershift
author_rank: Contributor
timestamp: June 03, 2011, 12:19:40 pm
content: ...and at least you know that Tek is willing to put their name to whatever the hardware actually is.

author: DaveW
author_rank: Frequent Contributor
timestamp: June 03, 2011, 02:29:47 pm
content: Ahhh, I actually have one of these under a different name, but the 15MHz variant.With regards to using it, it's an analog generator as opposed to DDS so there's some frequency variation at the top and bottom end, but you can always change ranges. I'd certainly say it's no worse than most other cheap generators.It has quite a few features like the DC offset and VCF which are normally quite a bit more on other generators, the VCF in particular is useful for generating basic FM signals and sweeping. I did measure the THD when I first got it but I can't remember the exact numbers-was fairly typical though.Right, as you're interested, I finally got around to opening it up and having a poke around. My impressions...It's a through hole, very discrete parts heavy design. It uses lots of through hole resistors, caps and to-92 transistors.The resistors are all metal film 1% accuracy aside from some (look like they're in the signal path) which are 0.5%-nice to see, and should translate to much better performance over temp than carbon resistors.Some of the resistors haven't been pulled flush to the board-not perfect, but shouldn't be too much impact on something like this.The caps look decent quality ceramic, although some are the wrong spacing on the board and have been bent over a bit.There are quite a lot of variable capacitors around for tuning which probably partially explains the frequency instability. Definitely a compromise compared to a top quality generatorThere are some integrated circuits around in DIP packages, lots of standard op-amps and some matched transistors pairs. There's some 7400 chips as well, oddly enough only the 7400 chips are socketed.The power supply is a standard linear jobby, seems designed well enough and should be nice and clean. However some of the TO-220 packages are heatsinked, with only the chip holding the heatsink down. Glob of RTV on there before reassembly methinks... On the bright side, a proper mains power switch mounted on the front.The frequency counter, unusually, is on the same board as the rest of the circuit. Controlled by an Atmel MCU (AT89C52 24), and has a proper xtal oscillator on there so the accuracy & stability should be fine.There are some signal wires run alongside power rails to the panel, not great but should be a steady load from the display so not too much dI/dT to affect the signalThe frequency is controlled by a proper 10 turn pot-impressive! Has a smooth feel to it as well, as well as fine frequency controlsPictures,Sorry about the quality of the pictures, using a little sport camera. Bottom line, a good generator for the money if you need the bandwidth or functions. If you need rock steady frequency accuracy get a DDS generator. If you want any better pictures/details just say

author: dopplershift
author_rank: Contributor
timestamp: June 04, 2011, 12:43:24 am
content: Wow DaveW!Thats awesome! Thanks for your detailed thoughts... and the bonus teardown! Nice work!It does look pretty neat, except for those heatsinks that need fixing down. Pretty densely packed board.If I hadn't ended up with the cheaper Tek, I think your comments would have convinced me that the 3005 was ok. Definitely one to look at if/when I need higher frequency or some more features.Thanks again!Dopplershift