Interference from PVR

[RenHoek]

I've recently built up a Sage-box with the following:

-Epia M10000 w/512MB RAM
-Seagate Baracuda 160G HD
-DVD drive (slim-line)
-Haup. PVR250
-Cubid 2699 case w/standard 55W PS board + external PS
-WinXP

Generally, it's working great and the picture on the OTA channels 9 and above are pristine! However, channel 3 (RF out from DishNetwork stb) is REALLY noisy while the box is turned on. Ch's 4 and 5 are better, but still not as good as with the PVR turned off.

I saw a reference somewhere to adding a ground wire between the motherboard and case on older versions of this Cubid case...Anybody seen/fixed this problem??

TIA-
RenHoek

[RenHoek]

[repsonding to my own post to help out future searchers...]

Well...since I didn't get any posts of other people's epia-based htpc's being noisy (RF-wise, in this case), I wen't looking around for the problem.

Turns out that the culprit is the 60W DC-DC converter in the case (Morex D2D v2.0.1). It apparently makes TONS of RFI when under load. Any tv in the house would be rendered useless on channels 3, 4 and 5 when the HTPC was turned on.

To rule out the "pig-in-the-python" laptop power supply, I ran the HTPC mobo and DC-DC converter off of a battery and still got the noise. Then, I ran my HTPC off of a normal ATX power supply with no RF noise seen in the TV at all - crystal clear!

So, I tried to RMA just the converter , but they want the whole case returned, since the dc-dc converter was part of the case...bummer. I'll have to dremel out the new one when it comes in...

In the meantime, I've decided to super-size the converter anyways, and ordered a 100 W PW70-A from iTuner. Hopefully, that one won't be noisy too.

[justme]

Hope the new converter works for you. Please post either way, so you continue to help other users.

[astroturf]

I'd like to know also, I am looking into a fully passive cooled htpc using a mini itx solution but don't want the problem your having...

[RenHoek]

BBBBUUUUMMMMEEEERRRR!!!!!

Got the new PW70-A in today (actually two of them, since I'm using an Epia-CL6000 for a work-related project, too) but I STILL GET THE RFI on channels 3, 4, and 5!!!

BTW, for those of you thinking about the PW70-A, even though it's "designed for the M10000" board, according to their website, it interferes with the case fan's power pins. You can connect the fans, and then bend the connector over a little and plug in the power supply all the way so everything works, but it's not as smooth of an installation as I'd prefer. There's another fan header on the board that's out of the way, but it's got a different type of connector than the 2699's case fans...nothin's ever easy - simple: yes, easy: no.

One plus about this PS, the box seems to always boot up on power-up now (original PS was too whimpy for my setup).

I've sent off an email to the mfr about this RFI issue - we'll see what happens....for now I've got the HTPC running off of a regular (HUGE, relatively) ATX power supply.

Am I really the only mini-itx user out there having this problem?? Please chime in if you've got this setup working.

Thx
-Ren

[astroturf]

bummmer, not only for you, but for me, I was looking at a fanless front end, but with the RFI, I may be waiting or settling for a fanned solution.

[RenHoek]

Well I got to thinking about all this some more and remembered that I had an RF amp in the circuit that might be making this a worse problem than it actually is...so today I spent the afternoon (!! man this stuff eats away at the spare time, doesn't it !!) sanity checking my hookups.

Short story: I got rid of MOST of the RFI - it's now usable

Caveat: My other TV no longer has the satellite's output going to it -- just the OTA channels.

Long Story: I have an attic antenna for the OTA channels, but it's UHF side kinda sucks, so I've got an amplified desktop UHF antenna that I'm combining with the attic's signal for VHF/UHF. From there, I am (was) using a combiner to feed the DISH stb's rf-out (channel 3) and the OTA VHF/UHF signals to a 4-way RF amp - one output to the VCR (for now...), one to the HTPC (PVR-250), and one to the rec room's tv.

Through trial and error, I found that if I didn't try to combine the satellite output to the antenna's output, then the HTPC's RFI didn't become a problem - yes...I've been running this way for several years now with no issues, just having the HTPC turned on anywhere in the vacinity causes the loss of Ch 3/4/5...go figure...

So, for now, I'm leaving off the satellite to the rec room.

So, let me say that you might not have an RFI problem with this power supply...

BTW - the new 100 Watt AC/DC part of this power supply actually has a little fan it in, too. The brick is a little longer than the original 60W PS, and its fan comes on occationally (temp controlled).

[mikesm]

Technically, this was a bad approach to doing what you want. Modulators aren't that clean, and generally require a guardband of a channel in each direction around them to assure non interference. Also, the OTA signals and the sat modulator output are almost guaranteed to be at very different signal levels without the use of attentuators. This is a problem because the amp has a certain amount of dynamic range, and if one signal is too hot it will cause the amp to clip!

I don't understand the failure mode in your system, but CATV networks need to be thought through to avoid these issues.

Thanks,
Mike

[RenHoek]

Mike-
Yup - I understand the issues involved and frankly, was supprised it worked when I tried it on a whim when I switched to DishNetwork a few years ago. But it simplified the setup at the time:

The cause for this goofy setup is the way the DISH STB handles its RF in/out: Instead of just modulating the satellite signal up to Channel 3 (or 4, depending on the switch setup) and summing it in with the OTA antenna's signal, you get either channel 3 (w/Sat) OR the OTA channels, depending on the TV/Video selection via the DISH remote. I didn't want to have recordings of OTA or Sat channels hosed if the TV/Video switch wasn't set to the correct position.

Anybody else here using the Dish STB's RF In/Out while recording via Sage?

[astroturf]

Thanks for the update RenHoek, you have reestablished my hope for a quiet front end!