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| FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator |
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| Labrat101:
--- Quote from: Johnny B Good on May 17, 2020, 02:37:15 pm --- Even the the most expensive of high quality components can fail (just ask NASA) and relays being 'relays', this doesn't necessarily indicate the use of a fake or counterfeit part. NEC relays can fail, just not so frequently as the more cheaply made versions is all. Just be thankful that it lasted a whole year before failing. >:D JBG --- End quote --- BTW Johnny my Last mod with the 2 x 10pf Caps on the op amp worked wonders with signal Quality . . NEC relay that's a blow out news. Well I do hope NASA is Not using Feeltech / FeelElec Equipment other wise we are going to have all sorts of Stuff falling out of Orbit :-DD |
| Labrat101:
I was messing with my FY6800 mumbling to myself . The wife was standing behind me . She reached over and unplugged it and said " I can fix it.. I know what's wrong. :-* I thought what the heck .. Don't mess with a woman . Five minuets later she returns with a grin .. "I told you I could fix it !! " OK. Show Me . :-\ Pointing to the back Door .. See I have fix the Jitter .. the door is now quiet . "No more noise from the Wind" O Thank you G-D for creating Woman >:D Great Now I have an excuse to buy a Aglient :-+ :popcorn: .. I said I would find a solution. But this One, completely slipped my mind . |
| maxwell3e10:
Once I started playing with my FY6600 to replace the NEC relay, I thought would be nice to replace the switching power supply as well. There has been a lot of discussion of various power supply options here, but I noticed this triple +5V, +/- 12-15V low-leakage linear power supply is available inexpensively: https://www.ebay.com/itm/SL-Power-Electronics-Linear-Power-Supply-MTLL-5W-A-5V-5A-12-12V-NEW/172432850496 It's a bit underpowered, rated only for 0.1A for +/- 12V, but fits nicely in the box. I measured the current limit is actually about 130 mA, which is sufficient for most cases. Reducing the current sense resistors from 3 Ohm to 1.5-1.8 Ohm increases the current to 250 mA without introducing any ripple. Here is the spectrum of the 10 MHz sine output (taken with Owon XDS3062A scope), showing that linear supply gets rid of some spikes in the spectrum. The box runs a little hot, so probably putting a small fan in there would be a good idea. |
| pizzigri:
--- Quote from: jchw4 on April 22, 2020, 03:02:41 pm ---Another PS mod. Original one just died, so I had to invent something quick and dirty. I had old laptop power adapter and a few cheap dc-dc buck modules ($0.7 delivered), so you can see the result. One is connected according to http://www.ti.com/lit/slyt516 to get negative voltage. The output now is much more stable, so it's an upgrade for about $2 ;) If somebody is going to follow me, note that I disassembled the original adapter. Don't do it! I wanted to save cables, which turned out to be a bad idea. Disassembly is messy, everything is glued inside and it's very easy to damage something. Just cut the two cables. --- End quote --- Hi! I’m really sorry, however in the TI document linked, after the phrase “ where s is the complex Laplace variable and He(s) repre- sents the higher-frequency...” and a host of equations, I got quite lost. I’m a hobbyst and trying to learn, but not to the point of learning at 50+ this level of math.... could you please post a wiring diagram, as obtaining a neg rail from standard buck converters would be incredibly helpful not only in this application but generally as well? I would really appreciate it. By the way, I want to publicly thank both JBG and Masterx81 for their help and incredible patience in helping me in the PSU mods and TXCO replacement sourcing. I sincerely felt that the level of questions I asked both of you guys was really too low for the very high level of competence and skill this forum is known for, and that is why I sent you guys PM’s. To contribute in some way to the thread, here’s the thermal images of the main board and the psu board. On the PSU there is a frankly unsettling resistor (R3) that is running really hot, about 93 celsius. On the board, the three voltage regulators near the usb connector, are in dire need of a heatsink. The small and inexpensive ones built for the Raspberry are perfect for this. The rest of the board is running around 40or so celsius, and I think can go as is - see the other two images, one with the Cyclone, and the other of the components near the opamps under the big existing heatsink. Boy, I’m learning sooo much just by following this one thread.... |
| Labrat101:
--- Quote from: maxwell3e10 on June 13, 2020, 05:09:11 am ---Once I started playing with my FY6600 to replace the NEC relay, I thought would be nice to replace the switching power supply as well. There has been a lot of discussion of various power supply options here, but I noticed this triple +5V, +/- 12-15V low-leakage linear power supply is available inexpensively: It's a bit underpowered, rated only for 0.1A for +/- 12V, but fits nicely in the box. I measured the current limit is actually about 130 mA, which is sufficient for most cases. Reducing the current sense resistors from 3 Ohm to 1.5-1.8 Ohm increases the current to 250 mA without introducing any ripple. --- End quote --- Hi if your interested I totally rebuilt my power supply on the 5volt side I use the 2x CVCC buck converters they are a $ more but they run perfectly well and very little noise .Plus I set the CC side to 500 ma & 1200ma on the OCXO. I did put 0.1pf ceramic and 470uf ripple class cap . (red) not viable on the pictures. Also I put a shield cover that fits over the OCXO board to thermal isolate it. the whole thing with the OCXO draws 8 Watts . On the mains side 8 watts is about 0.04 Ma @ 240vac . Ripple was just readable on 10mv on my scope. Also found using 20Mhz OCXO x2.5 reduced the the jitter to 2ns . Opposed to 10Mhz x5 as the PLL also multiplies the jitter as well. Its Now reads 0.02 PPb :) RNS |
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