Good point about ground loops. My supply's output is isolated from the AC line and GND, which avoids the issue.

I agree that >20uf 'should be' fine on the terminal blocks. Indeed, mine is. but such a large cap has too high an ESR to handle higher speed transients that may, or may not, be present. That's what the three decades of smaller caps are for and they'll work less efficiently--or not at all--over the terminal block lead length. In my own case,
operation is just fine with the one cap. but that's only one instance.

if the goal is to be bulletproof, install the full range of caps on the PC board. Also, the solid lead of the cap tends to be a bit harder to secure under the screw terminals of the connector than a stranded wire. if you permanently mount a cap there, make sure it is solidly connected, especially if you have other wires going to the GND terminal.

To be clear, I installed only single cap and it is working fine. To aviod mechanical problems I soldered mine across the PC board power inputs. all I had to do was remove 4 screws holding the case botom. You then have access to the input connector lugs and the cap solders right to them. Total install time, including removing a replacing the case bottom was under five minutes.

The decoupling caps that already exist on the PCB may be sufficient, it just depends what the load looks like.

Anyway, good find.

If I hadn't already returned my MRF-300 and RFX-150 due unreliable operation, I would have given this a shot.

I was curious if you had the equipment to test multiple "like" components on a single or daisy-chained MRF-350 config.

For example, do you have two DVR's or DVD's that are the same brand and model that you can hook up to the MRF-350 and test the IR routing information. I have had success with clean and consistent IR commands over cat5 up to 500' but for some reason lose the IR routing information at 25'...this is troublesome for installs where I am distributing like sources.

Thanks in advance.

I found one of the best way to test reliability was by playing back favorite channel macros.

I will soon be setting up to do a routing test installation. I am planning to use an MSC-400 but I will go ahead and set it up using the MRF-350 to see how it goes. I'll get back to you when done. I have two Oppo DVD players.

As I understand the problem, you assign two like devices A and B to different IR channels of the MRX-350 and create a device for each in the remote. Apparently this works with short cabling between RFX-250 and MRF-350 but fails when the cable is made long? What is the failure symptom? Do commands simply fail to go through or are do all commands appear on all channels regardless of routing setup?

Would it be a good test of your situation if I placed each on a separate IR channel, loaded each with a different DVD and then issued commands to each DVD and verified that each responded properly?

I'm happy to do the test. I just want to make sure I'm testing the right thing.

That sounds like a great test. I don't currently use favorite channels. I'll try to set it up when a chance comes up and see how it works.

I also agree with this. I've found that when I'm having reliabilty issues with an MRF300/RFX150, this is usually where it blows it - even though all other commands might work.

So do i just put 1 of each of these (100uF, a 10uF, a 1uF and a .1uF) in into the Terminal Block?
I tried just putting in a 47uF but that did not seem to make a difference,
Also what voltage Capacitors should i use. I cant find a 5v so can i use a 6.3v?

If you exceed the voltage rating of a capacitor it can blow up, so higher is better. A 6.3V cap is marginal for a 5V signal.

Whatever benefit there is, you'll likely see with the 47uF cap, but there's no way to know without taking measurements.

Keep in mind the original poster is working with 500+ feet of cable, if you're working with 5 foot of cable you're going to have 1/100th of the voltage drop he's seeing.

btw, if the output signal truely is open collector ... such signals are notorious for picking up noise. A lot depends on whether there is any input conditioning being performed and what sort of pulldown resistor is used. The resistance and the capacitance of the wire come in to play.

Even if all the active current was being used to drive the signal (~5mA) then the smallest the pullup resistor could be is 5V/5mA = 1K Ohm, which ain't bad. But much of that current may be instead driving the LED and the circuitry. 10K Ohm, even 100K Ohm would be viable, but again, it all depends on whether the input circuit includes any filtering of high frequencies let alone hystererisis.

You could indeed put all 4 in the terminal block but because of the inch or so of distance, it is unlikely the .1uf would have much effect. On the terminal block, I'd just do a 100, 10 and 1 uf.

The voltage of the cap must be > peak voltage applied to it in any circumstance. In design, that value is usually doubled for extra margin. Since the MRX-250 expects a 5V input, the 6.3V should work but doesn't leave much margin. On the other hand, the worst that will happen is the capacitor will fail. A 10V cap is probably best. You can use a 25V or even 50V capacitor but these do get physically bigger as the voltage grows.

In other wrds, if you have one on hand, there's no harm in trying a 6.3V. If you are buying one, try for a 10V or 25V.

Any cap of this capacitance will probably be an electrolytic. Make sure and attach the + side to the 5V screw and the negative side to the ground screw.

How long is your cable run? What are your failure symptoms?

The OP suggested using a tantalum...you should use tantalum(something about ESR).

Also, definitely include the 0.1uf (ceramic/monolythic), or a couple of them in parallel.

Although the length of the wire(resistance) is a factor, the real problem here would be the inductance of wire. Doubling/triple/quad wiring using CAT5 is part of the fix for a decoupling problem.

My cable length would be no longer than 2 meters. But no matter where i put the rfx250 or the channel. the RF lights is always lit, leaving the system useless.

A lot of different problems can cause the RF light to light--even when it is not RF. From reading the various threads on this forum, lots of people are experiencing mysterious malfunctions which can be tcaused by true RF interference or inadequate power supply or induced noise in the data line or, possibly, improper connections.

Because these devices carry fairly low $$$ margins and high risk of customer dissatisfaction, and because most installers are on a deadline, there's little time or interest in troubleshooting.

I'd like to see UR create a couple of inexpensive test fixtures to prove things out better. The first would be an RFX250 that does not include an RF receiver. Instead, this device would simply transmit a test signal sequence down the wire, over and over again. A second test device would receive IR signals as output by the MRF-350 (or MSC-400) and light each time a proper test sequence is received.

Let's say one test sequence is sent every second. You could look at the receiving device to verify that it is flashing once per second. If it isn't working, it is because of an issue other than RF interference and that issue could be focused on and fixed. When the test fixture proves the basic non-RF components are functioning reliably, you could remove the test device and install a real RFX-250. Problems that occur immediately thereafter would very likely be real RF problems.

My guess is that 90% of perceived RF problems with this system are really due to another cause. I think the UR system is very nearly a great one. With some diligent testing--made possible by some decent, easy to use, test fixtures--these issues could be identified and fixed.

Just a thought....

Just curious, I have been out on yet another service call for possible RF on an older (about a year) MRF-300 with the RFX-150 reciever (not narrow band). The runs of Cat5e to the two RFX-150s are about 80 feet long each. I tested the voltage on the MRF-300's phoenix terminal and it showed 5 volts. At the RFX-150 I got 4.8 volts off of the mini plug. Do you think that just adding a 5volt power supply to the recievers would be enough? Or would I still need the caps? The system is wired with two MRF-300s: on has both of the cat5e wires from the recievers wired into the phoenix connector with a mini from the "RF out" to the "RF In" of the other. So would the caps have to be in the same phoenix that the cat5s are in or would they be effective in the other, which does not have any wire.