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THE AM BULLETIN BOARD => Technical Forum => Topic started by: KM4RHK on December 27, 2017, 08:11:15 PM



Title: R-390a tripping ground fault GFI
Post by: KM4RHK on December 27, 2017, 08:11:15 PM
A simple effective and safe solution.
https://youtu.be/W0DiPqjzRbI (https://youtu.be/W0DiPqjzRbI)


Title: Re: R-390a tripping ground fault GFI
Post by: K4RT on December 30, 2017, 09:57:50 AM
Interesting video.  It seems to me that replacing the offending AC bypass capacitor(s) would be simpler, cheaper, and just as safe, but I'm not familiar with the R-390A.

My Hammarlund receiver started making a GFCI outlet buzz but not open, and that was without closing the receiver's power switch, just plugging the line cord into the outlet. The schematic shows that the bypass caps are on the AC side of the power switch so that was the first thing I checked.  One of the original caps turned out to be leaky.  I replaced it, which eliminated the problem.


Title: Re: R-390a tripping ground fault GFI
Post by: WD8KDG on December 30, 2017, 12:05:36 PM
FL101 is a sealed metal can. I used a Dremel tool to cut one open an take a peek. Yes the caps can be replaced. Its (FL101) purpose is to lessen/eliminate noise coming from/thru the power cord.

So if there is noise, from "where" is the first question. If the GFCI is tripping and the noise is Part 15 Chinese RFI, a person could just remove FL101 and solve the GFCI issue. A new modern line filter may not do much, if anything for Chinese RFI.

Some of my R390/A receivers have FL101 removed (no modern line filter), others still have FL101 in place and not tripping a GFCI. When living in Springfield, OR the carrier meter was never below 20DB, lots of Chinese noise makers. A new modern line filter wasn't the cure. Now living in La Pine, OR; the carrier meter needle rests very close to 0 (zero) on all the R390/A's. Go figure!

Regards,
Craig


Title: Re: R-390a tripping ground fault GFI
Post by: KD6VXI on December 30, 2017, 09:45:19 PM
Since most of the chicom interference is radiated, not just limited to the transmission line mode, it comes in via the antenna lead in as well.

A simple ferrite choke at the feed point and at the tuner or swr/wattmeter has knocked down //several// s units of noise in the past.

Since most noise is brought in via common mode, you could ditch the line filter, and add a couple beads of ferrite, stacked (different mixes) and a few turns of line cord passed through would give as much, and in some cases a lot more, rejection of the noise.

Jim Browns rfi and choke cookbook would be a good reference here.

--Shane
KD6VXI


Title: Re: R-390a tripping ground fault GFI
Post by: Ron NU6F on January 30, 2019, 11:29:33 PM
I found one cap leaky in my R390 line filter.Replaced  both caps and no more issues with the receiver plugged into GFI or the Arc Fault breakers in the ham shack.

Ron,NU6F


Title: Re: R-390a tripping ground fault GFI
Post by: WBear2GCR on January 31, 2019, 09:36:58 PM
One might also commit heresy and replace the original line filter with a "Corcom" or other
recent manufacture common mode RFI line filter...

                                 _-_-bear

PS. using the balanced input with a balun (1:4 if ur using coax) seems to also drop noise a
bit.
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