Soundstream PN4.520D FM EMI reduction
Thread Starter
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Intermediate
Joined: Aug 2012
Posts: 36
Likes: 0
From: Austin, Texas
GR - so cool of you to shed some light on this!
have you found any other SS amps with interference on different Frequency(s)? My concern is that it may not be at 100MHz every time depending on the components changing in their power supply (batches vary, let alone suppliers over time).
A long lost HAM... so familiar with interference, just not able to diagnose like you! Thanks again!!
have you found any other SS amps with interference on different Frequency(s)? My concern is that it may not be at 100MHz every time depending on the components changing in their power supply (batches vary, let alone suppliers over time).
A long lost HAM... so familiar with interference, just not able to diagnose like you! Thanks again!!
I suspect you are right about the frequency of the noise signal. It is likely that all of these units radiate some noise, but only the unfortunate few hit right in the FM band.
The core I found should reduce the interference anywhere on the FM band-- and from 1 to 300 MHz... so if you want to get active again in amateur radio on 2 meters, 160 meters, or anything in between you're set!
Tourer
Joined: Mar 2013
Posts: 297
Likes: 1
From: Pacific Northwest
It was fun to investigate this... but give most of the credit to UltraNutz. He sent me a broken one to play with, not knowing me from Adam and with no expectations other than the hope of learning something about the problem.
I suspect you are right about the frequency of the noise signal. It is likely that all of these units radiate some noise, but only the unfortunate few hit right in the FM band.
The core I found should reduce the interference anywhere on the FM band-- and from 1 to 300 MHz... so if you want to get active again in amateur radio on 2 meters, 160 meters, or anything in between you're set!
I suspect you are right about the frequency of the noise signal. It is likely that all of these units radiate some noise, but only the unfortunate few hit right in the FM band.
The core I found should reduce the interference anywhere on the FM band-- and from 1 to 300 MHz... so if you want to get active again in amateur radio on 2 meters, 160 meters, or anything in between you're set!
Should've read the specs on the ferrite core... damn viglink (work blocks the redirect -annoying!).
What did you use to find the frequency of the interference?
I have some spectrum analyzers for 2.4GHz (WiFi), but nothing in the FM range... I guess I could listen for noise on my nicer Yaesu through the range 88-108... not very techie, but probably would work.
Reason I'm so curious - going to try a different class d on my brothers build and want to see if it has any FM interference.
Time to dig out some of the old books and see how to ID freq of interference!
Thanks for the info and help for those with the SS amps!
Thread Starter
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Intermediate
Joined: Aug 2012
Posts: 36
Likes: 0
From: Austin, Texas
A little research on RFI and ferrite cores helped me find the fix. I'm certain one could add a couple of small capacitors between the power lines (both 12V and ground) and the amp case to further reduce the noise, but the core does a pretty good job on its own.
Before I was an amateur radio operator I was in the Air Force and repaired communications and radar jammers on bombers... that experience came in handy here!
Elite HDF Member
Joined: Jul 2008
Posts: 3,524
Likes: 34
From: Maryland
This is awesome GR! Thanks so much!!!
Since these ferrite things came with my TV it is possible that under the right conditions I might have made this connection, but NEVER would have thought of the whole wrapping thing. How much does each wrap help? You say two wraps but could 3 wraps help more?
Also, to confirm, it is best to wrap everything (power, ground, & rem wire) through the same core?
Again, thanks for all your work on this...
Since these ferrite things came with my TV it is possible that under the right conditions I might have made this connection, but NEVER would have thought of the whole wrapping thing. How much does each wrap help? You say two wraps but could 3 wraps help more?
Also, to confirm, it is best to wrap everything (power, ground, & rem wire) through the same core?
Again, thanks for all your work on this...
Tourer
Joined: Mar 2013
Posts: 297
Likes: 1
From: Pacific Northwest
My tools were not very high-tech -- an old Tektronix 465B Oscilloscope and a Radio Shack portable FM radio. The 'scope and a calculation told me there was noise on the power line somewhere in the VHF spectrum, but not precisely where. I tuned up and down the band watching the signal meter on the portable FM radio to find the noise signal. It was pegged (S9+) at about 101 MHz initially, and dropped down to about S1 to S3 with the ferrite core on the power line.
A little research on RFI and ferrite cores helped me find the fix. I'm certain one could add a couple of small capacitors between the power lines (both 12V and ground) and the amp case to further reduce the noise, but the core does a pretty good job on its own.
Before I was an amateur radio operator I was in the Air Force and repaired communications and radar jammers on bombers... that experience came in handy here!
A little research on RFI and ferrite cores helped me find the fix. I'm certain one could add a couple of small capacitors between the power lines (both 12V and ground) and the amp case to further reduce the noise, but the core does a pretty good job on its own.
Before I was an amateur radio operator I was in the Air Force and repaired communications and radar jammers on bombers... that experience came in handy here!
I could totally do this to see if there's any FM interference w/ the BT4180, and/or the Massive BX2. I can use my Yaesu handheld (VX7R/VX8R) to go up down each freq - step by step to see what's impacted and how much. Using them might be easier than figuring out the 465 O scope. Nice signal meter on those HT's!
I was thinking about before/after # stations i can receive, but tough to do unless back to back and not moving. Vary more than a couple hours or days and might as well start over w/ atmospherics and other interference too likely.
great food for thought and really appreciate your work helping with this!
rob
Tourer
Joined: Mar 2013
Posts: 297
Likes: 1
From: Pacific Northwest
Going to try this on my brother's bike after confirming how much the Amp is interfering.
Ordered the hard to find Fair-Rite 2631801202 - .75" opening, .5" long, little over 1" across:
Will see how many wraps i can get w/ 8g through one. looks like (due to min order) i will have a few extra... like 23... Might throw them on for sale for anyone else who needs one. 5$ and send SASE?
Ordered the hard to find Fair-Rite 2631801202 - .75" opening, .5" long, little over 1" across:
2631801202 029.00 ą0.75
1.142 19.00 ą0.50
0.748 13.85 ą0.40
0.545
1.142 19.00 ą0.50
0.748 13.85 ą0.40
0.545
Road Warrior
Joined: Feb 2011
Posts: 1,269
Likes: 7
From: Liverpool UK
Read this whole thread, a bit lost on me tbh, I've pretty much picked up on the fact that these SS amps have an interference problem, and I've just bought one, although yet to fit it as I need some better speakers, and I cant get the MM651's over here in the UK,so I'm going to have to order them from the States.
I want to get some of these Ferrites before I install my stuff,, Help me with which ones please.
I can get these ones
http://www.fair-rite.com/cgibin/cata...select:onepart
I want to get some of these Ferrites before I install my stuff,, Help me with which ones please.
I can get these ones
http://www.fair-rite.com/cgibin/cata...select:onepart
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Tourer
Joined: Mar 2013
Posts: 297
Likes: 1
From: Pacific Northwest
Read this whole thread, a bit lost on me tbh, I've pretty much picked up on the fact that these SS amps have an interference problem, and I've just bought one, although yet to fit it as I need some better speakers, and I cant get the MM651's over here in the UK,so I'm going to have to order them from the States.
I want to get some of these Ferrites before I install my stuff,, Help me with which ones please.
I can get these ones
http://www.fair-rite.com/cgibin/cata...select:onepart
I want to get some of these Ferrites before I install my stuff,, Help me with which ones please.
I can get these ones
http://www.fair-rite.com/cgibin/cata...select:onepart
A 28.50 ą0.60 1.122 _ B 13.80 ą0.40 0.543 _ C 28.60 ą0.80 1.125 _
That should work great - depending on the gauge of wire you are running for your amp. 10g should be fine if tight, 8g you'd need to cascade a couple in a row for best effect. Since i got 8g wire, i ordered the larger diameter opening (.75" vs .54") on the 2631801202.
what gauge power and ground wire do you have for your amp?
GL!
Road Warrior
Joined: Feb 2011
Posts: 1,269
Likes: 7
From: Liverpool UK
The Fair-rite 2631101902 dimension:
So it's opening is .54", 1" long, and 1" across,
That should work great - depending on the gauge of wire you are running for your amp. 10g should be fine if tight, 8g you'd need to cascade a couple in a row for best effect. Since i got 8g wire, i ordered the larger diameter opening (.75" vs .54") on the 2631801202.
what gauge power and ground wire do you have for your amp?
GL!
So it's opening is .54", 1" long, and 1" across,
That should work great - depending on the gauge of wire you are running for your amp. 10g should be fine if tight, 8g you'd need to cascade a couple in a row for best effect. Since i got 8g wire, i ordered the larger diameter opening (.75" vs .54") on the 2631801202.
what gauge power and ground wire do you have for your amp?
GL!
I have no idea what cables I have, I bought the amp and some cables from someone who never used them, they are brand new, how do I tell what size the power cable is?
if it's not right I'll order the right ones, as I only really want to take my fairing apart once, heres a pic
