(((((RFI))))))

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k5kab
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(((((RFI))))))

Post by k5kab » Tue Oct 30, 2007 9:18 am

This VOODOO is killing my alarm system (((((HELP))))))) . As soon as I got that watt meter swing with a tad bet of real audio at about 1 killowatt the house alarm goes hay wire. With the audio gear off (pre mic and all) with 1500 watts no problem. The alarm key pad is about 20ft from the amplifier in another room ,but only about 15 feet through the wall. (((((HELP)))) :shock: :x : :?:

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w5cul
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Post by w5cul » Tue Oct 30, 2007 10:53 am

It sounds like you possibly have a grounding issue with the Rack Gear if it all works fine without it in the picture. Try this, strap all of your rack gear together using a braid or wire (good size gage). This can easily be done using the casing screws either in the back or towards the front on either side of most audio equipment. The object here is to bring all of your Audio equipment to the same ground potential. Then using one more strap, take it from your rack gear to either your amp or radio or station ground. The idea here is a star ground system with one focal point, which should bring your Rack Gear as a whole to the same ground potential as the rest of your radio gear. Some guys designate their station grounding focal point as a piece of equipment, ie Amp, or radio…etc. Others use a station ground buss bar as the focal point for all grounding, and take everything to it. Either method will work just fine as they both accomplish the same thing, bring everything to the same ground potential so that there is minimal if any erroneous voltage flow between each piece of equipment. Grounding everything in this manner goes a long way towards preventing any RFI issues within the shack itself.

Next, if you have not already done so, deploy an audio isolation transformer between your rack gear and your radio’s audio input. Jensen makes a real nice one with a 20Hz – 20Khz flat spread. When choosing an audio isolation transformer, pay close attention to where you are interjecting your audio to the radio. If it is through the mic jack then you want a transformer that will step the power down for a mic level input, such as a Jensen JT-DBE. If you are interjecting your audio directly into the Balanced Modulator, which accepts direct line input levels from your rack gear, then a JT-11P will work for that application. In either case, doing this should prevent a ground loop between your rack gear and your radio and minimize the chances of hum and all kinds of other nasties on your transmitted audio.

Hope this helps out.

73,
W5CUL

Live from the Texas Hill Country......VMSDX# 21

k5kab
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RFI

Post by k5kab » Tue Oct 30, 2007 2:03 pm

I will try this grounding this week and bring back a report of my success. I must be possitive . Wher do one goo to down load this SPECTRALAB AUDIO GRAPH?

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ruisgc
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Post by ruisgc » Tue Oct 30, 2007 3:36 pm

Hi, K5KAB

Yes, do that, and let as know the result.

You can go here http://www.spectraplus.com/ .

Good Luck,

Rui
CT1HAR

The VOODOO from Portugal .........

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Post by Voodoo Guru » Sat Dec 08, 2007 2:34 am

Howdy!!

Mike has hit on just about everything except one.
Thanks Mike!!
How do you have all the Audio Equipment connected on the AC end?
If your not using a power conditioner for the Rack Equipment like the Furman, then you run the risk of the audio equipment picking up the RF and sending it into the AC power lines inside your house.
Of course what Mike is suggesting will normally fix this problem, the Furman is always a great addition to the Rack.
We have heard of lots of people having issues with their Ham Equipment getting into and setting off the Alarm in their House.
This is also due to poor installation and/or equipment tolerance to external RF Fields.
If the installer will not come and correctly isolate the system and/or contact the manufacturer for proper use inside high RF Field areas, then you might have to start installing ferrite cores on the AC power leads to the alarm system and also on all the wires leading to and from the unit.
The ferrite to use is Mix #31 and can be gottin in the snap type cores that snap over the wires.
Good Luck!
Voodoo Guru
From Deep in the IDD of the Sub-Harmonix Realm

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ECC82
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Post by ECC82 » Sat Sep 14, 2013 12:44 pm

Have some RFI issues, especially on 10 meter. Thanks for pointing me towards Furman. Learned from their website that there is also a European version, suitable for our 220-240 volts
http://www.furmansound.com/product.php? ... ies_Export
As I see it on their info page: three versions. Normal, improved and the executive version :wink:
I might be able to get my hands on the simplest version, hope it works as well as the others. Only difference: no volt reading by leds or display? 10A must be enough for my audio gear. Is the PL-8 C E enough to get rid of the RFI?
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ECC82
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Post by ECC82 » Sat Nov 30, 2013 10:31 am

I installed the Furmann Power conditioner, works fine, but didn't get rid of all RFI Issues. The audio cables (XLR) are self made. I didn't connect the earth/shield wire to the chassis soldering clip (if you know what I mean) Just connected the shield to pin 1. To get rid of "ground loops" RFI would it be better to connect all XLR connectors pin 1 to the chassis connector inside the XLR plug? Tnx for any advice.

73'
Chris
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!KANT
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Post by !KANT » Wed Dec 18, 2013 3:54 pm

You can try it and see what occurs--couldn't hurt anything. In some cases "floating" your audio rack might also work. [Lot's guys did this in the past and many still do. I do NOT condone lifting the ground on components, so I don't follow that practice.] Sometimes changing to another breaker/line can solve the issue. Troubleshooting can be tedious and I say this because you may want to disconnect all components and reintroduce them one at a time until the alarms blares to discover to the "offending" component.

I am curious though, which band(s) did this occur on??

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ECC82
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Post by ECC82 » Fri Dec 20, 2013 12:43 pm

Tnx for your input !Kant. It occurs on several frequencies, 10 meters but also on 40 meters I discovered lately. The cables are home brew, bought good cable and Neutrik XLR connectors. Will go through all the connectors and connect the chassis clip to the shield connector and see what happens. If the problem is still there than it is good advice to connect them one at the time and see which device suffers from the RFI symptoms. Tnx again.

73'
Chris
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!KANT
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Post by !KANT » Tue Dec 31, 2013 10:36 pm

I inquired with a fellow ham bud/Electrical Enginneer of mine in regard to grounding the clip. His suggestion, if it's less than 6ft. don't bother shorting it to ground. Installing .001 bypass caps on inputs are still suggested.

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ECC82
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Post by ECC82 » Wed Jan 01, 2014 2:03 am

!KANT wrote:I inquired with a fellow ham bud/Electrical Enginneer of mine in regard to grounding the clip. His suggestion, if it's less than 6ft. don't bother shorting it to ground. Installing .001 bypass caps on inputs are still suggested.
I already soldered the clips in the XLR connectors, but thanks for the addition anyway. Maybe some other guests are reading this thread/face the same problem. For those who don't exactly know what " Installing .001 bypass caps on inputs are still suggested." means, could you specify this a little :wink:

Cheers,
Chris
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!KANT
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Post by !KANT » Wed Jan 01, 2014 3:29 am

C&P from NU9N.com...

Bypass Capacitors:
RFI Bypass Capacitor Installation

Another trick you can use to suppress RF is the installation of ceramic disc bypass capacitors. For balanced audio signals, use .001µF ceramic disc caps between plus and chassis ground, and between minus and chassis ground. This can be accomplished either in the equipment, or better yet, in the XLR shell to your equipment input. Place the .001µF caps between pins 1 & 2, and between pins 1 & 3. Thanks to K6JRF for this tip! For unbalanced connectors, place one between the Tip and Sleeve lugs inside the 1/4" plug.

For AC power bypassing, use .01µF 2000 Volt ceramic disc capacitors between chassis ground and hot. For grounded or balanced AC, use 2, one between chassis and one side of the AC line, and another between chassis and the other side of the AC line. Make sure that you use 2000 WVDC caps for AC so that there will be no breakdown or excessive heating.

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ECC82
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Post by ECC82 » Wed Jan 01, 2014 4:51 am

Thanks for the info !Kant, will definitely give this a try.
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Post by !KANT » Wed Jan 01, 2014 11:28 am

You're welcome. Continue to keep us updated on this.

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Post by K6HP » Fri Jun 20, 2014 3:24 am

I tried the rack grounding, lifting the ground for the power line to audio rack, and several other typical fixes. The grounding helped some but not on all bands.

The .001 "trick" and using a line that was not on same circuit as radios (pwr supplies etc) or non-shack related equipment (for the rack gear) plus the power conditioner resolved my RF issues, except on 80 and 160 meters.

Changing the length of the ladder line for those two antennas was the final nudge that resolved RFI problems in the house or on the audio.

Good luck. Finding and curing RFI is often a challenge and can involve one or more solutions.

73,
Ed

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