Another - RMB 1095 Ground Loop / Satellite

[hamiltong]

Like many others before me - after installing all my new toys (RSP 1068 & RMB 1095) - I now have the infamous ground loop hum. God it's annoying.

It's definitely attributed to my satellite coax feed. When unplugging the coax from the SAT receiver hum is gone. Or unplugging the S-Video cable from the SAT receiver {which is going into the RSP1068} hum is gone. The culprits are the SAT and the 3 prong of the RMB 1095 - both hitting different grounds.

I've tried a cable/vcr ground breaker feed-thru surge protector (isolator). It worked - the hum has been completely eliminated - but the higher channels (higher frequencies) off my SAT are not working. Lower channels are working. More than likely due to the limit range of this particular isolator (900Mhz).

I tried a Monster Cable power bar (HTS 1100) - which has a satellite coax pass through. I hooked up only the coax feeds from my SAT through the power bar and no difference - still get the hum. Then I plugged the RMB 1095 into the power bar and the hum is reduced greatly (95%) but still present. Not acceptable.

Finally, I decided to do the dirty deed. Clip the ground pin on the RMB 1095. This of course works beautifully. I know this is highly not recommended but until I get a new coax isolator this will suffice.

I have found (on the internet) several coax isolators that operate in the +1GHz range which I will hopefully test out in the future. -gh

[aud19]

Sorry to hear about your hum Greg. Hopefully the new Isolator will fix the problem. Is there any chance of fixing the ground of the satellite system? Get it grounded to the same point as the rest of your home?

Jason




Need a new display? Questions about new display technologies? Visit RPTVs, plasmas, and other monitors @ HTguide

[hamiltong]

As I understand it - hot wiring the two grounds together defeats the purpose of the satellite ground (prevention of lightning surges from entering the house) - hence the two different grounds. I'm surprised more people are affected by this. In talking with several audio shops around town - they mentioned that this only happens with certain audio manufacturers: Rotel, Adcom, some Bryston - they all quietly say that ground pin clipping is the only real answer.

Hopefully, somebody can enlighten me on the method of curing this problem and going back to a 3prong AC power cable for my RMB 1095. -gh

[Azeke]

Greg,

You must purchase a coax isolator at 1.6GHZ, to retain all channels, the 900Hz only provides channels in the 900Hz region or lower. If the coax isolator solved your problem, the 1.6Ghz coax isolator should also provide resolution and all channels.

Good Luck,

Azeke

[hamiltong]

That's exactly my thinking..

The coax isolator I tried was meant for CATV (max 900Mhz) not satellite (higher frequency required). I've found online a +1GHz coax isolator at the Jensen-Transformers (ISO-MAX ground loop isolator - 1.3GHz). I've emailed Jensen-Transformers to check the compatibility of their product to a comparible DISH satellite provider that being ExpressVu.

Beyond the Jensen ISO-Max product I'd be left with something in the +$100 range, which is not an ideal solution to the problem. I'm not willing to spend +$100 to patch a problem, I'd rather fix the problem.

I've even checked the wiring outside - I loosened and rewired all the grounds from the DC-Ground block of the satellite to my AC entrance service panel. Checked the wiring inside - tightening the ground wires hooked to my water pipe. No luck.

Know of any other coax isolators that fit the bill?

[renzo]

Hamiltong

Let me know if the Jensen ground isolator works. I posted the same problem a month ago on this site. Jensen suggested a $500 composite ground loop breaker which I tried but did not work. I later bought a decent power strip which helped a little. However, when I only had cable TV I totally eliminated the hum with a CATV ground loop isolator...when I used the same isolator with my new Direct TV- all channels were blocked. Please let me know if your Jensen product works with satellite HD/TV. I am anxious to eliminate the hum once and for all.

[jimmyp58]

Azeke:

Do you know who makes a coax isolator @ 1.6GHz?

I had an RMB-1095 that had the hum problem and I tried a number of different remedies including the Jensen device others are talking about. It didn't work as my amp was defective and I got rid of it. Got some other amps and the buzz went away but I left in place the Jensen isolator because it cleaned up my signal a bit. I never had a problem with getting all my channels including the high-def ones until the last few weeks. I do not HAVE to replace this device as I took it off the other day and now I get all my channels again (no buzz either) but my eyes see (or at least I think they see) a bit of signal degradation. Hence, my reason for considering replacing the Jensen unit.

So, where can I look for one? I've tried a number of internet searches to no avail. Please advise.

Thanks....

Jim

[Azeke]

Actually these items must be obtained at specialty electronic stores (not RatShack), the following URL hopefully can help, you may also what to give them a call to provide specifics.

http://www.elect-spec.com/faqgrdl.htm#Table%20of%20Contents

Hope this helps,

Azeke

[jimmyp58]

Thanks....

[Azeke]

You're welcome.

[renzo]

Ground Loop Isolator

Azeke,

Did you find a coax ground loop isolator that fixed your problem?

Thanks.