ebay chinese 2mhz function generator - Page 1
Forum section: electronics / general

author: peterthenovice
author_rank: Regular Contributor
timestamp: March 31, 2013, 03:45:01 pm
content: are these function generators any good.http://www.ebay.com/itm/New-2MHz-DDS-Function-Signal-Generator-Module-Meter-UDB1102-/251195886696?pt=LH_DefaultDomain_0&hash=item3a7c710c68

author: SeanB
author_rank: Super Contributor
timestamp: March 31, 2013, 04:09:47 pm
content: Good luck, will not sell to me...............

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 31, 2013, 04:12:31 pm
content: You can hardly complain at that price - unless they're loading a lot onto the (unspecified) shipping cost.I predict that at the very least the user interface will suck ass though.

author: marmad
author_rank: Super Contributor
timestamp: March 31, 2013, 04:28:54 pm
content: Ha, ha.... I love the design - it's a "Speak & Generate"

author: iloveelectronics
author_rank: Frequent Contributor
timestamp: March 31, 2013, 04:48:35 pm
content: I have one of these (the 10MHz version):http://www.ebay.com/itm/UDB1200-DDS-signal-generator-TTL-drive-IGBT-ADC-/200723853639The sine wave signal looks ok up to near the claimed bandwidth, but you can't expect the same for the triangle and square waves. They look okay-ish only up to about 2-3MHz (for the 10MHz version). For the price (I got mine cheaper from China) I think they are not too bad if all you need is just a simple waveform source.

author: peterthenovice
author_rank: Regular Contributor
timestamp: March 31, 2013, 04:58:35 pm
content: Quote from: mikeselectricstuff on March 31, 2013, 04:12:31 pmthe shipping is free.

author: smashedProton
author_rank: Frequent Contributor
timestamp: March 31, 2013, 06:33:43 pm
content: NO!! You can get old analog 5 mhz signal generators off of ebay for extremely cheap. I payed 15 dollars for my 5 mhz analog function generator. Unless you are buying an arb gen, don't go for any of the new stuff.

author: ivan747
author_rank: Super Contributor
timestamp: March 31, 2013, 06:54:34 pm
content: I second smashedProton. Old gear doesn't mean useless gear. In fact, you can buy some pieces of used equipment that beat the shit out of their contemporary chinese equivalents. One example is power supplies.

author: ddavidebor
author_rank: Super Contributor
timestamp: March 31, 2013, 07:22:42 pm
content: I've a used 13Mhz 110€ generator and it is super! Superb quality, price, function....Who need this cinese crap!

author: RCMR
author_rank: Frequent Contributor
timestamp: March 31, 2013, 08:53:09 pm
content: These are cheap DDS-based units that work okay for the price (I've got the 20MHz uncased version and it's "adequate" but not brilliant.Buying old stuff from eBay is a nice idea -- unless you live on the backside of the planet, in which case the shipping costs kill you. Those cheap DDS units cost less than the shipping alone for a second-hand bit of retro analog gear bought from the USA -- and then we have the fact that much of the older gear isn't voltage-agile (ie: if you buy it from a US source, it will demand 110V rather than the 230V we have here in NZ/Aus.So... for what they cost, it seems silly *not* to have one of these tucked away for when you might just need/want to use it. Even if you've already got a 2-channel arbitrary waveform sig gen, there may be a time when you need both those channels *plus* another ;-)

author: Unknown
author_rank: Unknown
timestamp: March 31, 2013, 09:08:39 pm
content: How is this relevant to this thread? Neither of two people who agreed with smashedProton are from the US, or from a country with a large electronics industry. Peter is from the USA, according to his flag, so shipping for most used equipment on eBay should be quite affordable.

author: smashedProton
author_rank: Frequent Contributor
timestamp: March 31, 2013, 10:05:29 pm
content: Look at all that resolution on the frequency. I wonder how many of those digits are the truth!

author: tom66
author_rank: Super Contributor
timestamp: March 31, 2013, 10:45:50 pm
content: Well, if they are using an AD9850 or clone... they have 28 bit resolution so with 4MHz master clock you have 0.015Hz resolution.

author: Unknown
author_rank: Unknown
timestamp: March 31, 2013, 11:12:50 pm
content: Out of interest, and more curiosity than a great need, I purchased this generator !... in actual fact it's not that bad.My interest was for the low frequency side since my home designed generator being analogue, was unable to go below 20 Hertz, and I did-not want to re-design the output stage for 20 to .5 Hertz's end.What let's this model down is the control pots... they are no more than pre-sets with pot size shaft for a control knob; so after a few rotations they became intermittent. By replacing the amplitude pot solved this problem, and I found the DC off-set pot far too coarse in it's range, so replaced with a pre-set and value, that gave better wave form shape; once set, their is not much need to change the off-set.Frequency: .001 Htz to 2 Mhz... Max out-put level = 300 mV with -32dB switch-in... and 9 volts P-to-P.The adjust pot control is an encoder, no problem found with it; and selects the frequency input... the frequency meter input is reasonable having a range between 1 Htz to 60 Mhz.

author: vk6zgo
author_rank: Super Contributor
timestamp: April 01, 2013, 02:07:08 am
content: Quote from: RCMR on March 31, 2013, 08:53:09 pmOK,it doesn't automatically adjust for you,but a lot of the older US made stuff I've seen uses a tapped transformer & a selector switch on the back--why not ask the seller?If it is made by someone like HP,Tektronix,Wavetek,or similar,the cost of a tapped transformer & switch isn't very large compared to the selling price at the time,so for some products,it may have been easier to just include the switching facility,rather than make a special 220/250V one.After all,a very large proportion of the world outside North America have 220/250v supplies.Even though they make their own equipment,Europe is still a very large market for US made gear.Conversely,quite a lot of European & Brit equipment made its way to that country.Or,why not look for a Philips function generator from Europe?Can't do anything about the shipping costs,though!