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Switchng PS noise

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N9JIG

Sheriff
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#1
I am getting a weird signal with multiple beeps etc. on one of a batch of BCT15's and a HomePatrol 2. I do not hear the same signal on any of the other radios and was able to track it down to a 12VDC/4.6A laptop switching power supply used to supply the 4 multicouplers in my shack.

(View the short vid at https://youtu.be/-VJ-QMikvm4)

When I connect the multicoupler to a different power supply the noise goes away on both scanners.

Weirdly, there is no such noise on any of the other 2 dozen scanners, nor my R8500 in the shack, just the 1 (of 8) BCT15's and the HP-2. I swapped out the multicoupler with a brand-new out of the box MCA208M and the same noise was there.

I can live with this for now until I find a suitable replacement but am curious why I only get it on these 2 radios and none of the others. There are 6 other BCT15's connected to the same multicoupler, and both of these radios get the noise when all other radios are off. Otherwise the laptop power supply is ideal, it is regulated, provides plenty of current to run 4 multicouplers and generates no perceptible heat.

Has anyone else had this issue?
 
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#2
If you tune any of the other unaffected radios to same freq and mode as the affected ones you dont hear the noise? That would be weird... it will be affected by load, so turning stuff on and off should affect load and switching frequency or pulse width.
 

N9JIG

Sheriff
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#3
That is exactly correct. The power supply handled the multicoupler and a couple scanners, but not the scanners I hear the noise on. Other radios connected to the same multicoupler do not hear the noise, just one BCT15 and the HP-1.

I tried pulling the power cord on a couple of the multicouplers and turned on and off a couple of the 3 radios connected and no changes were discerned.
 
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#4
Very odd. Could the RF grounding be different on the affected ones? Also, a switcher might not be best solution for this critical application. Switchers are getting better, but linear supplies usually don't have any spurious oscillations (unless badly designed). Also try reversing plug polarity if two prong AC.
 

N9JIG

Sheriff
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Messages
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#5
It is a 3-prong AC. I have since removed it and reconfigured things a little. I reduced the amount of radios in my shack and am now using only 3 multicouplers. I have 1 4-port that handles the 2 HomePatrols, a 536 and a PRO197. I have each of these connected to individual wall-warts (for now) and the other two multicouplers and 15 radios are on a 25-Amp supply.

This eliminates that switching laptop supply from the equation and the associated noise. I will keep an eye out for a decent low-heat 5 amp supply for the stuff that stays powered on all the time.

I have another issue that I have been fighting with though. I have several BCT15/BCT15X/BCD996XT/P2 scanners that I use for searching the MilAir and other bands. I get a whole boatload of externally generated RF noise on various frequencies. Most of the signals are just loud static. I lock them out as I find them but more seem to pop up from time to time.

Some I know are generated by computers, some come from routers or other electronics. I have so much stuff here that it is impossible to get around it. Between the alarm system, 2 WiFi units, 2 routers, and all the other home automation crap there is a lot of RF noise. I even get weird 160-162 MHz. signals from my wine cooler door alarm system!

When I rebuild my antenna cabling system this wither (I hope!) I plan on running all the cables to a patch panel and connecting that to a nice cold-water pipe ground. Hopefully that will reduce some of the stray RF around here.
 
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