rfi into hd receiver

Yep, see post #27.  

the tech made it as scheduled.  after i explained to him the problem,....we went through the testing procedure and sure enough it reset all receivers. 

i had printed the response and i made the suggestion to try a h24 receiver with the p/s built in the receiver.  he retrieved a receiver from his van made the installation and we again made the test.  problem solved on one receiver with 1200 watts to antenna on 75 mtrs.  he then retrieved two more receivers, installed them and resolved the problem with the other two receivers. 

This was a dedicated service tech that was concerned with my problem and went above the call of duty to correct the problem. 

thanks for all advice and will shut down this for now. 

thanks to all that replied.

john 

Awesome.  Thanks for the update.  Enjoy!

Great to hear!  Obviously something about the H25's doesn't do well in strong RFI fields. 

It is not an AC power supply problem. I reported it as far back as November, when I got my two new H25 boxes. Using only 5 Watts, from a 12 Volt 24 AMP battery, the two H25's reset. My HR20-700 and H20-500 don't even flinch. My antenna is grounded per NEC code ( have been a Radio/Broadcast Engineer for 37 years, and a Ham for 41 years). I also have a First Class FCC Radiotelephone license. The H25 receiver has interference problems from nearby transmitters. One of my company's customers, a radio station, had a problem, when replacing an H21 with an H25. The H25 would constantly reset. Had to get an H24 from the studios to make it work. So all from H20 and HR20 through the H24/HR-24 series work under those conditions, but the H25 doesn't. I called your Tech Support, and they want to send a Tech. All most of them do is install antennas and set up the receivers, but they will not replace my receivers. I tried shielding the receivers, adding ferrite cores to the coaxial cable (Using Mix 43 ferrites). No help. I put a core around the input cable, and no help either Now, when I replace the H25 in the same location, with the H20, no problem. And normally my H20 is in my Ham room, with the tower a floor above us. The H25 are about 20 feet further. I rest our case. I think maybe the small switching Power supply might dropping out when there is RF around it. I happens mostly on 40 Meters and 15 Meters. Also on  20 Meters when using high power 600 Watts).

I wonder if DirecTv has come out with any kind of service bulletin yet. When I first had my problem resolved back in October (see post 14), I thought it might be a fluke. Obviously I was on to something. I have had NO problems since getting rid of the H25 in favor of the H24. I have even added another dipole over the roof of the house.

WAKE UP DIRECTV!!!

73

Dave

(John, you got me by 9 years.... HI HI)

After three days trying to work with Directv Tech Support, I have found the culprit. I put the Switching power supply for the H25 receivers into an oscilloscope. When I key the transmitter on 40 Meters, the Power Supply does a power drop down to 2-3 Volts, probably what is left in the output capacitos, and comes back slowly to 11.3 Volts, one volt down from the 12.3 Volts normal when I am not transmitting. I replaced the power supply with a 12.8 Volt 7 Amp battery, and I can do whatever I want in transmission, and the H25 doesn't flinch. I did a test like that previously, but I had both boxes next to each other, and I must have looked at the one without the battery. So the problem is the power supply. The wire going from the PS to the H25 is a thin coaxial cable, shield outside and a small wire inside, like 24 gauge. They do have ferrites at the end by the connector. Maybe the problem is coming in from the AC power connector. Now my question, since the Tech Reps don't want to own up to it, who do I talk to at Directv to solve the problem???? They said that if the H25 works OK when I am not transmitting, it's my problem. What if one of my neighbors gets an H25 box, and it starts re-setting? What will they tell then. Help!!!!

Excellent information!  But I doubt that DirecTV will make any changes to the H25 power brick to solve this problem.  It's simply not something that affects very many customers.   But now we know why using a different HD Receiver model typically works just fine.  

You might want to email this information to DirecTV so that they can at least inform the CSRs that H25s SHOULD be swapped with other models when folks encounter this problem with high RFI fields. 

johnnywilde1  1) Glad to hear your problems are taken care of.

                        2)  Please do not use that large of font, it is the same as yelling at us, people that keep doing this will not be responed to and your

                             post maybe deleted.

Thank you

PS I am also a ham and have been working with other hams on this problem since Oct. 2011

Only you can decide how hard and how far you want to push this. The simple fact is that the H25 is especially susceptible to strong RFI fields, so you'll need to replace your H25 with a different model.  You can get specific models from dealers like Solid Signal since DirecTV can't guarantee a specific model (their ordering/shipping systems don't support that).   Then the question becomes whether you can negotiate a return credit for your "defective" H25.  Maybe you just need to tell them it died. 

Hello.

Been having a problem with the H24-200 receiver since I went back on the air a couple of weeks ago. I haven't seen any of the reset problems reported by others (N5AD, I can appreciate your frustration – I’ve more to say on that later) but the device turns itself on and off (just as though you touched the power control on the front panel).

This behavior occurs with ONLY the ac line cord is connected, ruling out many possible problem sources.

I should add that even in that stripped down configuration the H24 was creating substantial RFI to my station rig. This was greatly reduced by adding a single snap-on ferrite bead (I only had one) near the device-end of the power cord.

The auto on/off however persisted. Until yesterday.

For those who care about such things, please check this extensive reference about RFI prevention and cures.

http://www.hamuniverse.com/rfi.html

In particular, check the section on "Touch Lamps." There, the author discusses the difficulties such devices present in strong RFI fields. Effectively, touch controls use a local oscillator (read transmitter) the frequency of which is changed by a touch. Thus such devices both CAUSE RFI, and are sensitive to RF.

But wait (I said to myself a couple of days ago) the H24 ALSO features a touch panel for its on/off control.

Reviewing the referenced link, the fix for touch lamps is pretty trivial - a resistor and/or an RF choke in line with the connection to the touch-sensitive part - i.e. the lamp’s metal base.

I communicated this analysis to DirecTV tech support last week - my first and only contact with DirecTV on the matter to date - I found the tech intelligent - even knew what a Faraday Cage was when I broached the subject. However, neither he nor techs he consulted were able to offer a solution.

I considered opening up the H24 and trying to reverse-engineer what was there and effect some internal fixes, but was dissuaded, for the time being at least, by the "warranty void if seal broken" tag, as well as by the fact that how to open the box was deliberately obfuscated - showing DirecTV's dedication to keeping the consumer out. I can figure out how to open the device later if need be: but sure wish I had a circuit diagram :-).

But what about a Faraday cage? Typically such devices are closed on all sides and grounded; not too easy to jury-rig.

But yesterday my while contemplating solutions, just for the heck of it (and the ease…) I wrapped a layer of aluminum foil around the front half of the device, leaving about half the foil’s width  extending past the front, making sure to contact the metal chassis, then crumpled the front part like a sandwich bag over the front panel.

No more RFI problem.

I was both delighted and surprised (gotta get lucky once in a while - obviously I don't know everything about Faraday shields 🙂

Of course, with the front panel completely covered by aluminum foil, the remote wouldn’t work, so I tried something even cornier: I opened a hole in the crumpled aluminum – about two inches - large enough to permit the remote to have a peek at the panel. And guess what, the remote works and NO RFI PROBLEM.  

Clearly more testing is required: I don't know the limits of what must and must not be shielded, that will wait for another day, and will precede making something more permanent and attractive than crumpled tinfoil.  

I have closing comments but rn over the 10K character limit so I'll include them in a post immediately after this one.

Chris NW6V

(continued from preceding post)

A couple of comments:

1. CLEARLY this is a design flaw in the receiver which any competent RF engineer could correct VERY INEXPENSIVELY if DirecTV demanded that the manufacturer do so (in new models at least). Likewise, the manufacturer COULD reverse engineer a solution and provide this to hams who request it (even with the understanding that doing so voids the warranty. I couldn't care less).

2. The "it's caused by circumstances beyond our control" argument given to N5AD is just a corporate cop-out. The REAL cause is "sub-standard engineering." Strong nearby RF fields may be infrequent, but they are predictable, and the fixes tend to be easy. Truth? I suspect the designers just didn't think about it - or more to the point, no one gave the engineers the requirement.

3. Of course the added component(s) would cost a few pennies, which somebody has to eat - and nobody's hungry.

4. The interference coming out of the power line is likewise easily curable but the same "reasons why not" apply.

5. Relating this back to N5ADs problems, given that it is NOT an electrical surge caused by his transmitter causing the problem with the voltage drop in the brick, this is clearly a FAULTY brick designs. How may bricks do I have hooked up to equipment in my home? Dozens for sure. How many are sensitive to RFI? Zero – unless, apparently, I happen to have an H25. CLEARLY, the brick is equally poorly designed.

6. As I said in #1, for anything to change, DirecTV must accept ownership for their portion of the problem. In that context I might remind them that while it appears to be an infrequent problem, and there are those pesky pennies involved, there are >738,000 radio amateurs in America alone, so as a class we are non-negligible portion of their market.

7. In the real world, a single voice complaining, no matter how vociferously, is unlikely to get DirecTV to shift their position. It is too easy to tell an individual (as they did to N5AD) "take your business elsewhere." As a result the only effective tactic is to create larger group pressure. That is, engage the remainder of the Ham population in the issue. Contact the FCC, and in particular, attempt to engage the ARRL, if nothing else, ensuring that the Ham population KNOWS about this problem with DirecTV, and suggesting that they AVOID DirecTV if possible until the company takes responsibility is quite "fair" and has a much better chance of getting DirecTV's attention. A nice letter writing campaign with big sacks of mail from Hams would also get their attention.

8. I would involve other news media in the issue. What issue you say? The Amateur Radio Service exists because of our value to the nation, both as innovators, and for our role in emergency communications when Amateur Radio is often the ONLY means of communication in or out of areas hit by disaster. So here's a possible press release headline: "New DirecTV receivers disrupt Emergency Communication Services." (Remember, these devices CAUSE RFI too...)

In closing, I’ll pass on this tid-bit: when I first looked at my “fixed” DirecTV receiver, covered in crumpled foil, sporting an eye-shaped passage for the remote, the first thought that hit me was: "A tinfoil hat" just fixed the RFI problem for the crazy guy who designed this.”  I laughed out loud…

Best,

Chris NW6V