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About JohnSwenson

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  1. Hi GMG, there are two completely independent things that can happen, ground loops and leakage loops. They are caused by completely different mechanisms, ground loops are caused induced current in safety grounds, and leakage loops are a property of power supplies. To make things really complicated these two can interact in strange ways. For example a leakage loop starts at a power supply, it can go through another power supply OR a safety ground. There are no simple "one size fits all" rules with this. As to the question above, having one low leakage supply does not
  2. Hi Mike, there there seems to be a little confusion here on the single, multiple dual thing. I'll attempt clarify a bit if I may. There are two completely different aspects of fiber here: how many fibers there are and the "mode" of a fiber. The number of fibers should hopefully be obvious, you have either one or two fibers. The more common is a two fiber, where one of the fibers carries data in one direction and the other carries data in the other. The one fiber system carries data in both directions over a single fiber. The common way to do this is to use different wav
  3. I don't know of anything specifically for audio frequency use. You could do it with the Si5340-D-EVB which is the evaluation board for the synthesizer used in the ER. BUT you need to have it connected to a computer via USB to program the chip every time it powers up. It is great for testing and exploring but not good for a board you put in a product. And it is a pretty big board as well. John S.
  4. As long as they are the correct impedance I think it is a great idea. Those adapters almost always use teflon dielectric and are machined to tight tolerances. There is a high probability what you have will be better that an equivalent piece of short cable of any type. John S.
  5. There are two possible meanings of that "Manufactured for", one is as you mentioned that Finisar made them and manufacturer listed sold them as their own. But the more likely possibility is that they contain that particular manufacturer's code. The SFP modules contain a code for a specific manufacturer, the equipment (switches etc) from many manufacturers will only work if you insert a module with THEIR code embedded in the module. So Manufactured for means they contain that company's code. None of this matters for the ER since it doesn't look at that code at all. John S.
  6. There is NO need for a specific cable length IF the impedances are properly matched all along (cable, connectors on cable, connectors on boxes and internal board impedances). The issue did exist for SPDIF because the impedances almost never came close. So for a clock cable where everything is properly impedance matched, there is no need for a specific length, in general shorter is better. BUT you have to take into account the bandwidth of the cable. A longer piece of very high bandwidth cable can be better than a short piece of not so high bandwidth cable. Also shieldin
  7. Remember that the LT3045 is just 0.5A. Even 12V OCXOs take more than that when warming up the oven. So you would have to parallel two to three LT3045s, this CAN be done but is a bit more complicated, and WAY more expensive than the 1963A. John S.
  8. I have mine on a 1/2" thick aluminum slab which sits on roller bearings from Ingress Engineering. Over the last 5 years or so I have done a lot of experimenting and listening and this configuration gives the best results, particularly for digital devices. The roller bearing are single base types, the machined aluminum base sits on the shelf with a ball bearing sitting on the base. The aluminum slab has polished stainless steel sheets (outdoor pocket "shaving mirrors" ) glued to the bottom (I use rubber cement) where i want the slab to sit on top of the balls. This comb
  9. I have not tried that particular one, but according to the specs it should work very well. John S.
  10. Yes, this is the correct way to go. With paralleled SET pins you CAN parallel the boards. I definitely think it is worthwhile to do. As you noted you just have to make sure you can get rid of the heat generated. John S.
  11. Yes, clocks ARE susceptible to supply noise. The LT3045s are much lower noise than the ones mentioned, BUT a LT3045 is only good for 0.5A, so you need to put a bunch in parallel to attain the current you mention. Are you thinking about designing your own boards or using someone elses boards? If you use existing boards they either need to be a single board designed for that current, or lower current boards specifically designed to be paralleled. You can't just take two or three 1A boards and parallel them unless they were specifically designed for that. John S.
  12. No it doesn't, the amount of power the devices uses is independent of the supply voltage (within the specified range of 7-12V). John S.
  13. If you have a standard ER then you definitely want a 75 ohm one AND a 75 ohm cable. When we were getting close to releasing the ER we did a pole and almost everybody said they wanted 75 ohm, so that became the "standard" ER. Alex makes a few 50 ohm versions every now and them for people that specifically order 50 ohms. John S.
  14. I just use JSSG, otherwise known a use a silicon rubber wire to connect to the shield at both ends. I don't think the JSSG360 is particularly useful for audio cables, it does work for digital cables. John S.
  15. Hi Richard, my priority is quite different than yours: #1 geometry in order: star quad, twisted pair, zip cord #2 insulation material ie the dielectric. Teflon the best, polypropylene, silicone rubber, worst is PVC #3 gauge #3 metal type and purity Spend your money on the higher up on the list. In other words don't bother with silver or "6nines" until you already have teflon star quad. John S.
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