| Author |
Message |
    
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 317
Registered: 10-2002
| | Posted on Thursday, March 20, 2014 - 2:11 pm: | 
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I have a 100 amp Samlex power supply and I am getting a lot of noise on my radio. I have added a very large stereo cap to the dc side of the power supply. I have a independent frame ground going to the case of the power supply. Still I am getting rf noise from this. Even if the power supply is not connected to anything ( Just turn on) I get rf noise on my base station also. I need help on this one. |
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 322
Registered: 10-2002
| | Posted on Sunday, March 30, 2014 - 7:44 pm: |
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O.K. I have installed every filter I can on the ac side of the power supply and it is now quiet on the ac side. Now, I have done everything on the dc side ( disk cap's, electroletic cap's, snap on rfi magnet's) and I still have about a 3 to 5 noise. I have even taken the shield off of coax and put it on my dc cable's. Still the same noise. The power supply even has it own ground to the frame. I need help. Does any person know what else to do. Oh, by the way my antenna is 500 foot away and I have the power supply on a different ac circuit. |
Tech237
Moderator
Username: Tech237
Post Number: 1771
Registered: 4-2004
| | Posted on Monday, March 31, 2014 - 11:39 am: |
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!) When you placed the shield over the cables did you shielded each cable individually or one over both red and black wires? Did you ground the shield at one or both ends?
2) If you are getting noise with the supply not connected to anything, but turned on, it is more than ;likely you are getting radiated noise, not noise transmitted via power cabling. I'd bet it's using Switch Mode Regulation.
How far is the supply form the radio, not the antenna?? If it's close try getting it as far away as possible.
Had a commercial site, years back, with a similar issue (OK not my site, but called in to take a look), an the only way we could REDUCE the noise, was to stick the supply inside a second large, well grounded metal box. Brazed copper screening across all vents, used shielded cabling from Supply to terminals in front of second box for feeds in and out, with common mode chokes on the DC cables.
Not saying this is what you'll need to do, but advising you that if it is radiated noise from a switch-mode regulator you may have to take big steps to reduce the noise.
Tech237
N7AUS
God made me an athiest, who are you to question his wisdom?
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 323
Registered: 10-2002
| | Posted on Wednesday, April 02, 2014 - 6:47 am: |
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Thanks 237, Yes I did put the shield individually on each of the dc cable's but, I did not ground each of the shield's. The power supply is about three foot from the radio with it own frame ground. I will do as you had said on getting another box to shield the main power supply. That is a very good idea. Once again thank you very much. |
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 324
Registered: 10-2002
| | Posted on Thursday, April 03, 2014 - 2:49 am: |
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TECH 237, Here is an update on what I have had time to do so far. Like I had said before on the ac side I have got the noise under control after I had put on a lot of filter's. Now, on the DC cable's I have done as you had said and put a ground on the shield that I had placed on the DC power cable's and wow what a difference.It has gone from a 3 to a 5 noise to a 1 to a 1.5 noise. But, I would like to get that even lower. Remember without the DC cable's no noise. I want to thank you for the great advice. If it were not for the noise the SAMLEX 100 amp power supply would be a great power supply. Now that the noise is getting low perhaps I can start to enjoy it now. |
Tech237
Moderator
Username: Tech237
Post Number: 1773
Registered: 4-2004
| | Posted on Thursday, April 03, 2014 - 11:33 am: |
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Glad I could be of some help.
Tech237
N7AUS
God made me an athiest, who are you to question his wisdom?
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Dale
Senior Member
Username: Dale
Post Number: 2061
Registered: 12-2002
| | Posted on Thursday, April 03, 2014 - 3:44 pm: |
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huh i had a samlex in the mid 90s must been
reulated cause it didnt put any noise in my recieve
and radio was right beside the power supply 1inch away proberly as room was very small.hope ya get it figured out
dale/a.k.a.hotrod
cef426
cvc#64
454 [dx numbers]
38lsb
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 327
Registered: 10-2002
| | Posted on Saturday, April 05, 2014 - 7:16 pm: |
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Mine is a 100 amp constant with a 123 amp surge. It is a switching power supply. Samlex knew they went cheap on the design of this and they to had told of some thing's to help for this trouble. 237 hit the nail on the head though. My hat is off to him. If you want Dale I will give you the model number for it. I do not think the Samlex smaller power supply's have this problem. |
Tech237
Moderator
Username: Tech237
Post Number: 1774
Registered: 4-2004
| | Posted on Sunday, April 06, 2014 - 1:48 pm: |
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CB thanks for the kudos, but put it down to over 35 years of experience..
Tech237
N7AUS
God made me an athiest, who are you to question his wisdom?
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Dale
Senior Member
Username: Dale
Post Number: 2065
Registered: 12-2002
| | Posted on Sunday, April 06, 2014 - 3:13 pm: |
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oh i got a jetstreama 70 amp p/s with much needed
multi binding posts for those exra items
dale/a.k.a.hotrod
cef426
cvc#64
454 [dx numbers]
38lsb
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