Signal Forge
Ripoff signal generator - sf800

Once I received my SF800, I was disappointed with the cheap metal box that would bend under the slightest pressure from my hands or the weight of a thick book and the cheap silk-screen printing on the front plate. I also found it annoying that I wouldn't be able to put this unit in any permanent place on my workbench because the power switch is on the back of the box! Also, before I could even hook it up, I had to run to radio shack to buy an rs-232 cable that apparently isn't included. Oh, and if you have a newer computer or laptop that doesn't even have rs-232 ports, forget it!
After I settled down after my bad 'open box experience', I hooked it up to a scope, and optimistically saw what seemed to be what was described - a inexpensive signal solution. But, the old adage was again taught to me, "you get what you pay for". However, for this unit I think it should be priced around $50 for that adage to be accurate.

I hooked the unit up with a cable (again had to purchase) to my board, and typed in the values needed for the 100MHz frequency, quickly verified the freq and amplitude with a scope, and started my development / debug. I quickly noticed that my system would crash every time I breathed the wrong way, or just looked at it wrong. I sat and debugged my problem for almost 2 days when I finally got the nerve to borrow an agilent signal generator. Bingo. Everything worked great. So, borrowing a spectrum analyzer this time, I looked at my source clock from the SF800 and to be fair, terminated it with 50 Ohms just as unit wants. What I saw, Jitter Very bad jitter and harmonics all over the place, and 'horrible' phase distortion, (not to mention the unwanted amplitude modulation). I checked and rechecked my setting and finally I went to the web site and reviewed the specs again. "Best in class jitter performance". What? I called them up and after having to leave them messages 3 times, I finally got a response 2 days latter. A guy named Steve Robalino told me that the spec was describing the main source clock (aka: the TCXO 30MHz internal clock), and after it gets multiplied, this jitter gets multiplied too. So, I figured after 2.5 ppm gets multiplied (30 MHz x ~3.3 = 100MHz), this should give me a jitter of about 250 Hz at 100MHz. Normally, this would be acceptable, but what I was seeing was a jitter bandwidth of about plus and minus 60 KHz (total of 120KHz). I told him this was very unacceptable. His comment to me was, "I'm sorry you feel this way, but we have developed this instrument to industry expected standards, and your application obviously exceeded this level of expectation". After a lengthy discussion about why he thought 1200ppm was a 'normal' expectation, I figured out that Steve was just jerking me around, and clearly knew of the low quality of the instrument and was trying to talk me into just 'going away'. It was at that point I asked for my money back and again, going through a (heated this time) discussion, I went ahead an paid the percent restocking fee, which I now understand is there main source of income.

This SF800 wouldn't even be a good audio generator because the spec says 0 Hz to 800 well, I found that you'd be lucky to get anything less than a 80 KHz sine wave as the internal DC blocking capacitors are creating a filter.

I find it hard to believe that someone, knowing of the problems with the tools, continue to cheat people. It's my interpretation that their main source of income is the hope that someone won't be knowledgeable enough to find flaws in there instruments, and either doesn't return it, or does return it and pays the restocking fee. Stay away from these people!

Company: Signal Forge
Country: USA
State: Texas
City: Austin
Site: signalforge.com

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