I'm loving my KID but it sure generates a lot of hash into my ham radios when in charge mode. I've been experimenting with a lot of filters and ferrite chokes but it remains. It is the only device in my cabin that generates hash. Ham radio is an essential part of my off-grid life but it makes weak signal morse code reception difficult.
Would the Classic operate any cleaner?
Hi Tobit,
As you know, MPPT CCs are, essentially Switching power supplies, and are fairly large ones, at that.
Most of the emissions are Conducted on the PV, and to some extent, the battery cables connecting to the CC.
It sounds like you have tested where there emissions are coming from, by turning the KID, OFF, and noting the change in emission levels. Inverters also often create RFI.
Ferrite Common Mode chokes on these cables are generally the first thing to try. For HF, Mix 31 ferrite cores seem to work well for HF frequencies. Try winding several "turns" of the PV cables through a type 31 clamp-on (if you have large ones), or through a donut toroid core, very close to the CC, if you can.
Isolating antennas from proximity to the PV arrays, above ground power cables, etc will often reduce the emission levels, if you have the room, away from the power system location.
Here is a Link to a very long Thread, from the Wind-Sun Forum, on RFI:
https://forum.solar-electric.com/discussion/4685/radio-noise-from-pv-system/p1
Also, K9YC has a number of articles on his site on using Common Mode Chokes, and RFI Reducgtion:
www.audiosystemsgroup.com/RFI-Ham.pdf
EDIT: The following should be the Common Mode Choke Cookbook:
http://k9yc.com/RFI-Ham.pdf
Please DO let us know how you are doing on this ...
More later 73, GL, VIc
Thanks Vic, it's definitely a work in progress. Hard to isolate much in a 12x18' cabin but I'm trying. No inverters here, trying to keep everything 12VDC. I am also living by candlelight. LOL.
Hash is definitely narrowed down to the KID when in Bulk or Absorb mode, not so much in Float. PV array is negligable and already cleared up with several turns on big 3" mix 31 cores.
Honestly, it isn't that bad but I moved to the middle of the woods so I'd have no noise so I'd like to clean it up as much as possible. :)
Quote from: Tobit on June 05, 2020, 03:35:38 PM
Honestly, it isn't that bad but I moved to the middle of the woods so I'd have no noise so I'd like to clean it up as much as possible. :)
I hear you there ! Are you on HF that you have the noise or VHF/UHF. Typically the noise is OK on VHF/UHF.
Here in the city HF is impossible because of all the appliances and neighbor's noise.
Ferrite common mode chokes on the battery and PV input lines are the first thing to try like Vic mentioned. Right next to the Kid. As close as possible.
If you have a large enough toroid, I would run both battery and both PV lines through the same toroid if it is large enough.
Keep us posted.
K7IQ
Quote from: boB on June 05, 2020, 05:27:34 PM
I hear you there ! Are you on HF that you have the noise or VHF/UHF. Typically the noise is OK on VHF/UHF.
If you have a large enough toroid, I would run both battery and both PV lines through the same toroid if it is large enough.
Keep us posted.
It is all HF though the worst is on 6M where I need the band clean.
I hadn't considered running both the PV and battery lines through the same roid. Because of the PV distance, I run 6 ga. from the combiner box to the breaker in a Big Baby box and then 10 ga. to the KID.
I want to try a couple 3" ID mix 31 rings next but they are a bit expensive. Maybe next month.
Quote from: Tobit on June 05, 2020, 05:36:48 PM
Quote from: boB on June 05, 2020, 05:27:34 PM
I hear you there ! Are you on HF that you have the noise or VHF/UHF. Typically the noise is OK on VHF/UHF.
If you have a large enough toroid, I would run both battery and both PV lines through the same toroid if it is large enough.
Keep us posted.
It is all HF though the worst is on 6M where I need the band clean.
I hadn't considered running both the PV and battery lines through the same roid. Because of the PV distance, I run 6 ga. from the combiner box to the breaker in a Big Baby box and then 10 ga. to the KID.
I want to try a couple 3" ID mix 31 rings next but they are a bit expensive. Maybe next month.
OR a separate one just for the battery cables ?
BTW, are these birdies at single frequencies or are you seeing wideband hash ?
Quote from: boB on June 05, 2020, 06:38:52 PMOR a separate one just for the battery cables ?
BTW, are these birdies at single frequencies or are you seeing wideband hash ?
6M is the worst, but also a problem on 160, 80, and 40M where I have very sensitive beverage antennas.
Attached is the waterfall hash on 6M, the blue lines go away when I shut off the breaker connecting the KID to the battery bank.
Hi Tobit,
Thanks for the added info on your system, and for the pic of the radio screen.
Since you have no inverter, your 7300 is probably connected directly to the radio. Have you tried disconnecting the antenna coax from the radio? What effect does this have on the level of the RFI ?
Have you tried a common-mode choke on the battery cables from the KID, or, on the 12 V DC cables, right at the radio itself?
Believe that you may not have a lot of ferrites available, but, you might try moving the ferrite on the PV least, to the battery side of things, to see what happens.
What is the separation between the 6M antenna and the PV array/s? If you have a rotatable directional 6M antenna, do you see a reasonable change in the RFI levels when the antenna is rotated>
Thanks for any added info.73 Vic
Vic, disconnecting the antenna has no affect on the hash.
Primary antenna is a 125' doublet fed with 600-ohm ladder line 60 feet in the air above the PV array below, the ladder line is fed off at a right angle to the other side of the property to avoid the array but I'm not sure of the distance. I have large coax to a 4:1 voltage balun before coming into the cabin. I will soon be replacing this with a hyrbid 4:1 and 1:1 balun to allow for easier matching and better common mode chocking via the 1:1 balun. I do have some common mode choking on the feedline now but it could be better.
At this point, I think I need to invest in larger mix 31's on the KID to allow for more turns. To me, it still seems to be more of a KID problem under charging than a PV input issue.
Quote from: Tobit on June 05, 2020, 07:11:19 PM
Vic, disconnecting the antenna has no affect on the hash.
Primary antenna is a 125' doublet fed with 600-ohm ladder line 60 feet in the air above the PV array below, the ladder line is fed off at a right angle to the other side of the property to avoid the array but I'm not sure of the distance. I have large coax to a 4:1 voltage balun before coming into the cabin. I will soon be replacing this with a hyrbid 4:1 and 1:1 balun to allow for easier matching and better common mode chocking via the 1:1 balun. I do have some common mode choking on the feedline now but it could be better.
At this point, I think I need to invest in larger mix 31's on the KID to allow for more turns. To me, it still seems to be more of a KID problem under charging than a PV input issue.
If you removed the antenna and the RFI is still there, it may be entering either through the battery lines OR through the case itself.
If it is through the battery cable, then the #31 material may reduce it enough to get by with. That is one of my favorite materials too.
How close is the Kid to your radio ?
And, can you take a spectrum shot of it with the Kid breaker turned OFF ? That would give a baseline measurement.
I see that the spikes your analysis is showing are most likely at repetitions of the Kid's switching frequency which is somewhere around 35 kHz
Quote from: Tobit on June 05, 2020, 07:11:19 PM
Vic, disconnecting the antenna has no affect on the hash ...
... At this point, I think I need to invest in larger mix 31's on the KID to allow for more turns. To me, it still seems to be more of a KID problem under charging than a PV input issue.
The more work (the greater the KID's output current) that is being done, the larger the level of the RFI hash should be. Suppression on the battery cables twix the CC and the battery, can cause an increase in voltage drop, often due to an increase in cable length increase for the cable in the ferrite. This can have a larger impact on 12 V systems. Just another tradeoff. So try to use the largest cable that is practical, between the CC and the battery, if you need a CM choke there.
Do not know the source of your ferrites, but, IMO, KF7P.com (Chris, IIRC) seems to have a fairly wide selection and very reasonable prices of most of them ... I have no business relationship with them, just a happy customer.
73, Thanks, Vic
Two photos attached:
KID in "Resting" mode
KID breaker to battery shut off
One thing to note that I had not noticed earlier, as I am usually running weak signal digital modes with the sound turned off, when in resting mode, there is a pulsing noise during receive.
Vic, I've been buying my roids from Palomar Engineers They've seemed to be very reputable and reliable over the years.
Sorry for the overly large size on the "off" image, I thought I resized it.
Hi Tobit,
What did you do to get the KID to Rest? Looks like the Converter in it is still running, in the first pic.
Fine on Palomar. Recently, some have said that they are not responding to messages/orders ... may well be CoVid related.
Thanks, Vic
Vic, the KID just happens to be in REST because of a thunderstorm. It is terribly dark here.
OK, is there any chance, that the KID awakened, and was producing a very small amount of power, at the time of that pic?
If you shut off the PV input breaker, and looked at 6M on the radio, does the display look any different?
Thanks, Vic
Vic, the KID was "resting" for a good five minutes before I flipped the breaker to shut off the battery breaker. I did not shut off the PV breaker in either pic.
If you want to make your own 4 to 1 1 to 1 combination Balun watch the 3 part series on TRX bench youtube . There is a lot of information packed in there - I had to watch them a few times ! I built the combination this winter and it works well .
https://youtu.be/kMlKfHHR8FY
Larry
Larry, thanks! I'm a lazy old goat but I will check it out.
Quote from: Tobit on June 05, 2020, 08:35:30 PM
Vic, the KID was "resting" for a good five minutes before I flipped the breaker to shut off the battery breaker. I did not shut off the PV breaker in either pic.
Tobit,
It is always good practice, to turn off the PV breaker, before the battery breaker, when powering down an MPPT CC, and to turn on the battery breaker first, then the PV breaker, when powering up.
Some CCs can run, just with the PV breaker on … you still might try shutting off the PV breaker with the battery bkr on, just to see what the radio screen looks like.
FWIW, Vic
Vic, how can I do that? As soon as I do, the KID goes into REST because of no input? I'm confused.
yeah the Kid will stay on if you shut off the battery breaker first but the PV breaker is on and power to it.
Larry
Tobit - Do you have your battery negative grounded ?
Larry
Quote from: ClassicCrazy on June 05, 2020, 08:57:20 PM
yeah the Kid will stay on if you shut off the battery breaker first but the PV breaker is on and power to it.
Not here, KID shuts down instantly with the battery breaker off. If I shut off the PV breaker, it goes to REST.
Quote from: Tobit on June 05, 2020, 09:00:14 PM
Quote from: ClassicCrazy on June 05, 2020, 08:57:20 PM
yeah the Kid will stay on if you shut off the battery breaker first but the PV breaker is on and power to it.
Not here, KID shuts down instantly with the battery breaker off. If I shut off the PV breaker, it goes to REST.
First, if you have some PV power available, the KID might still operate with the battery breaker off, just have never had the PV breaker on with the battery one off.
Second, I was hoping that if you switched off the PV breaker, with the battery breaker on, that the KID would definitely be resting, and then the view of the 7300 screen might reveal something , more.
Would think that the KID, when in a normal rest, to shut off the Buck Converter (the primary hash-maker), and open its input relay, and just sit there waiting for something to do.
Vic
Vic, you are right. Attached image is the radio with the PV breaker off and KID resting. Still some spikes but a bit better.
OK, Thank, Tobit,
SO, now, wonder what that screen looks like, when you shut off the battery breaker to the KID, with the PV breaker still off?
Thanks, Vic
Vic, I posted that earlier..
Off, both PV and KID. Silence!
YES you did, sorry Tobit,
Did not pay enough attention … nothing on the screen, BUT, that's cause there is no aerial connected … duuuuuhhhhh on my part.
So it looks like there is s bit of stuff from the KID when it is Resting, probably caused by its processor, and perhaps a power supply, housekeeping stuff. This may be helped by some ferrites in the DC to the radio, KID, or both.
More later, thanks for your rapid response. 73 please keep in touch, VIc kilo six italy charlie ..
Thanks Vic, the big torroids I want are $50 each and I just cant afford them right now. Hopefully next month.
Quote from: Tobit on June 05, 2020, 10:06:19 PM
Thanks Vic, the big torroids I want are $50 each and I just cant afford them right now. Hopefully next month.
Try this one from either Digikey or Mouser.... Probably big enough for all 4 wires...
https://www.digikey.com/product-detail/en/fair-rite-products-corp/2631626202/1934-1078-ND/8593980
OR
https://www.mouser.com/ProductDetail/Fair-Rite/2631626202?qs=JTtBSkyWskgiFt1KtbsXbg%3D%3D
Hi boB,
The first Link gives a 403 Error -- Blocked …
KF7P has some Mix 31 cores. The one on the left at the bottom of the following page is huge. Probably not needed to be this large a window area, it is 4" OD, 3" ID, but only 1" high, for $20.00. Should be easy to get a number of turns of large cables, although one might want a stack of 2 - 3 :
https://www.kf7p.com/KF7P/Ferrite_chokes.html
The above is a very good price, as, our club ordered at least 100 ea of these, about 2 years ago. Our cost, delivered was $16.00, and that was before the Tariff added.
FWIW, 73, Vic
gee Vic - what did you do to Digikey that they blocked you ! ha ha
That first link works for me - here is a screen shot
Larry
Hi Larry,
Thanks for the screen shot. Do not know just why the blockage. Probably Windoze 10, or more breath mints are needed here.
73 Thanks, as always! Vic . .
$11.00 or so is a pretty good price for these in onsies. We bought 25 or something like these a few years ago for about $8 each.
Thnks guys, will try to get some in a few weeks and report back.
Hi boB, that is a handsome core, and looks like a lot of core for the $$.
And, Tobit, one additional "thought"; It is possible that your 7300 radio is more susceptible to noise entering via its DC power cable, than other radios (possibly)might be.
If you have another HF+6M 12 V radio, it might be worth a try to see how any other radio handles this situation. This is probably not a solution, but, just another experiment.
73 to all, and Tobit please let us know of any results of your efforts. GL, Vic
I just bought a switchmode 13.6V 30A power supply from Powerx for $100.
My ham friends SWEAR that it did NOT cause RFI. It does make RFI.
Maybe not on 20 meters and up but certainly does on 40 meters and below every 35 kHz or so
Hi boB,
There sure many, many variables, when it comes to RFI.
I have had good luck with Astron SMPS 12 V supplies: SS-30s in particular for VHF/UHF base and mobile rigs.
For the main Hammie XCVRs here, have used 200 W rigs, that have built-in power supplies, for the past 15 years. The built in supplies probably give some level of reduction in any Line Conducted emissions. But, of course conducted emissions on DC cables are quite a different animal, than are those conducted on the AC mains.
Also, many 12 V HF base station, really prefer about 13.8 VDC, and 12 V LA batteries that are not on-charge cannot supply this voltage level. So line-operated supplies can maintain constant output voltages, etc.
FWIW, IMO, 73 Vic
Quote from: Vic on June 06, 2020, 04:57:42 PM
Also, many 12 V HF base station, really prefer about 13.8 VDC, and 12 V LA batteries that are not on-charge cannot supply this voltage level. So line-operated supplies can maintain constant output voltages, etc.
My 7300 is doing well on the 12V bank. While a steady 13.8VDC is nice, it is spec'd for +/- 15%. Power output does start to fall off when you get down below 12VDC. I believe 70W PEP around 11.7VDC. I don't run more than 50W here as I want extended transmit time out of the battery bank. I also don't like running the battery bank below 40-50% SOC so I have a low voltage disconnect wired in.
Having said all this, I do want to add this battery booster as I'd prefer to keep things at 13.8VDC. MFJ also makes a couple but this is a better product and I don't buy MFJ.
http://www.westmountainradio.com/product_info.php?products_id=battery-boost
Some good testing data on running the 7300 at lower voltages.
Hi Tobit,
Some HF base radios can have elevated IMD, on voice modes with PS voltages around 13 V, and below. This could even be a bit of a poorly-controlled variable.
But, it is also quite possible that modern radios might do better at low Vin, compared to vintage rigs.
As you probably know, the ARRL did review the battery boosters, a while back.
IIRC, the MFJ was not junk. IMO, they can, and do make some quality products, they do also make some value-priced products. Also IMO, their Ameritron products are often well-made.
Just more opinions. 73 GL, Vic
Vic,
I think I'm learning towards the WM booster because it can handle up to 40A whereas the MFJ units are only rated to 25A. I can run everything in the shack and a couple more things at 13.8VDC better than with the MFJ unit. N8XJK has done a great job improving his boosters over the past 15 years, it's a solid product.
73
OK, Tobit,
I have no experience with any of the Boosters.
Poked around on the Web, for reviews, the following one popped up:
http://www.w0qe.com/N8XJK_battery_booster.html
The main reason that we built this off-grid location, was due to the desire/need to get away from ALL of the ever-increasing broadband noise sources, in town.
We are only about 5 - 6 miles away from the power grid, and it is quiet. Our power system makes some noise, but it is at a very low level, compared to in-town.
Have fun ! 73, Vic
Quote from: Vic on June 06, 2020, 07:09:34 PM
Poked around on the Web, for reviews, the following one popped up:
http://www.w0qe.com/N8XJK_battery_booster.html
Wow, that is 12 years old. A lot of improvements have been made since. Looks like he did some solid testing, I will read it in more detail tonight anyway. Thanks! This one I'm looking at is a brand new version and hasn't been released yet, they are anticipating shipping in July.
QuoteThe main reason that we built this off-grid location, was due to the desire/need to get away from ALL of the ever-increasing broadband noise sources, in town.
We are only about 5 - 6 miles away from the power grid, and it is quiet. Our power system makes some noise, but it is at a very low level, compared to in-town.
Same here, it is very quiet. Right now the only noise is being generated by the KID but I know I can get that knocked down eventually.
Coming out of the KID, I run two short 10 ga. leads to powerpole connectors so I have a quick disconnect before the 12" run to the breaker box.
Should I stack two of the 3" ID mix 31 rings and wrap as many turns as I can on BOTH the battery and PV leads coming out of the KID on the same core? Or should I use a separate core on each set of leads?
Quote from: boB on June 05, 2020, 05:27:34 PM
Quote from: Tobit on June 05, 2020, 03:35:38 PM
Honestly, it isn't that bad but I moved to the middle of the woods so I'd have no noise so I'd like to clean it up as much as possible. :)
... Ferrite common mode chokes on the battery and PV input lines are the first thing to try like Vic mentioned. Right next to the Kid. As close as possible.
If you have a large enough toroid, I would run both battery and both PV lines through the same toroid if it is large enough.
Keep us posted.
K7IQ
Hi Tobit,
I have always used separate toroids for PV in, and CC to battery cables. But, boB did mention using a single core for both, it you can make that work.
A 3" ID core is large, but there should be no problem getting a lot of turns of your 4 conductor with that core size.
I got some of those 4" OD, 3" ID cores for use with large cable. You may not need cores that are that huge, on your system.
Sorry for the ambiguous, kinna not an answer, answer. Later, 72 Vic
My solution for a constant 13.8v is to have 24v battery and then use a Samlex 24 to 13.8v converter. You also get the advantage of being able to get more power out of your Kid that way too and use smaller gauge wires compared to 12v. The Samlex converters are not too expensive - less than a switching power supply would cost.
Larry
Quote from: ClassicCrazy on June 06, 2020, 10:37:37 PM
My solution for a constant 13.8v is to have 24v battery and then use a Samlex 24 to 13.8v converter. You also get the advantage of being able to get more power out of your Kid that way too and use smaller gauge wires compared to 12v. The Samlex converters are not too expensive - less than a switching power supply would cost.
Upgrading the 400AH battery bank to 24V is very expensive however.
Interesting about that booster. It's like an MPPT controller in reverse and with the keying feature so it only runs when transmitting...
Personally, I wouldn't use one. I would buy more/better battery for the job. Allowing the battery to run that low could hurt the battery. And I don't believe the 5 extra hour run time unless he was just receiving most of the time. A battery that is 10.5 volts is dead.
In the link that Vic posted, that toroid sure looks kinda like the size of toroid I posted a picture of.
I would try and run ALL 4 power wires through the same toroid. That way, it will help insure that not common mode noise goes through one of the wires that are NOT going through that toroid but through the 2nd or 1st toroid.
Another thing to remember is that although wrapping more than one turns through the toroid is better, there can come a point where too may turns make it worse due to capacitance bypassing the filtering action from one side to the other side of the toroid. So, if you can get 2 or three turns, that should be good.
If you don't get some RFI reduction with say, 2 turns, you probably won't get much more with 3 turns. Not guaranteed anyway.
Also, place the toroid as close to the Kid as possible.
Quote from: boB on June 06, 2020, 10:52:10 PMPersonally, I wouldn't use one. I would buy more/better battery for the job. Allowing the battery to run that low could hurt the battery. And I don't believe the 5 extra hour run time unless he was just receiving most of the time. A battery that is 10.5 volts is dead.
I never would run the battery that low either. In fact, in my DC circuit running all the devices, I have a low voltage disconnect configured to shutdown at 11.8V. You are probably right, I don't need it. My 7300 seems to do fine even when the bank dips a bit low on transmit.
Back to the ferrites, I'm trying to decide between that inexpensive Fair-Rite 2631626202 or a stack of two of the 3" ID. Should I try the less expensive first? I'd like to do two turns of 4-wire 10 ga. ideally.
Thanks again.
Hi Tobit,
On the ferrite, why not try the smaller core (2631626202) to see what happens. Would guess that 4ea #10 AWG THHN cables would fit easily, even with three turns.
Speaking of turns, am sure that you know, that the first pass through a core (without a loop back), is counted as one turn. Turns are the total number of passes through a core.
Why not take three loops (passes) of the 10 Ga wire that you will be using, tape them together tightly, to estimate if that number will fit through the 1.00" ID of that candidate core. You might want to try two turns, vs three turns, so you might leave enough cable to make that extra turn.
Also, the intensity of the RFI signal should be in proportion to the output current of the KID, so try to keep that fairly constant when doing comparisons of differing approaches. As noted previously, place the core as close to the KID as possible.
All IMO, 73 GL, please let us know how things are going. Vic
Not to veer too fara off-topic, how would the RFI be on a PWM controller such as the Brat! compared to MPPT's such as the Midnite's KID and Classics? My KID is about maxed out with 3x 150W panels and I don't want to buy another KID or switch to a Classic just yet. However, I have a spare Brat! on the shelf along with a panel I'd like to wire into the bank. Would I be fighting too much hash?
Tobit,
PWM CCs, like the Brat, should be much quieter, RFI-wise. They still do switching, but this should be quite tame, compared to MPPT CCs. Also the Brat would be handling a lower power (lower current) than does your KID.
Some PWM CCs do have a low RFI mode that is said to reduce, further, any RFI from standard PWMing. Do not know it the Brat has this function.
FWIW, VIc
Hi Tobit,
The Brat manual says the following:
S1-8 PWM DISABLE - Slide switch up for On/Off charging - Reduces EMI. Not recommended.
Looks like the Brat would be worth a try as an auxiliary CC. Perhaps if needed, you could switch the KID to OFF, if you really needed QUIET, and the Brat could do some charging during the day …
FWIW, Vic
Vic and boB,
Since it is very overcast here today, my KID is switching frequently between Resting and BulkMPPT. Attached is a recording of the hash and birdie. Since 6M is completely dead here right now, you can hear the hash while Resting and then the birdie while in Bulk. This matches the Resting and Bulk photos I posted earlier.
I have that Fair-Rite bead on the way, just ordered today from DigiKey.
73
Tobit,
The recording appears to have a very faint tick tick tick tick tick tick in the background, early, and then the "birdie".
If the tick, tick sound is coming from your RX, then it sounds like the Converter is running, which is unusual for a Resting MN CC. Perhaps it is another SMPS in the KID … perhaps a power supply that runs the electronics in the CC (?).
The "birdie" sounds very pure -- no modulation to speak of. Most carriers, or birdies from the Classics (and the OB MX-60) CCs have a lot of modulation (racket) on the carriers. The more work that the CC is doing, the louder the racket. But, maybe, if the KID was working harder, the pure-ish carrier would have more hash on it, or maybe, your RX was in a Digital mode, with a fairly/very narrow filter … dunno.
The KID here, is on a back-up 12 V system, so have not studied its noise profile.
Fine on having that ferrite on its way. 73 Thanks for the info, Vic
Vic,
I've isolated it farther. Upon resting, the hash appears to be coming from the PV array, it is lessened when I turn off the PV breaker to the KID but a little remains on the waterfall.. The birdie is definitely a result of the KID in Bulk.
Definitely need to get that ferrite here.
Thanks for the recording.
The click I think that Vic is referring to sounds kind of like a beat-note to me.
I think it stops wavering or beating near the end of the recording ?
So, what was the approximate S meter reading during that recording and the background reading ?
Seems like there was almost no background noise.
boB
boB,
No noticeable S-meter reading at all. I'm in the woods a couple miles from anything and everyone. My noise floor is very low. 6M was also dead at the time.
Hmmmm... OK, so the hash is actually very low.
But I'm sure it can be improved a bit more with some help which you are working on.
It will probably never be "zero" unless it is turned off but doesn't hurt to try and reduce.
I really like those inexpensive cores. Ten or 12 bucks isn't bad at all
Now, you can also add common mode and differential capacitors. In fact, you could use two of those large cores and CM caps in the middle and on the PV outside from each +/- to GND
But no need to make it that difficult until after you try on core first.
Hi Tobit,
We are wondering if you have any reports on the effectiveness of that core you ordered, or ... ?
Just wondering, as we all are learning. 73 Thanks, Vic . .
Have the core but haven't wound and installed it yet. Having some financial hardships suddenly and the 7300 might have to be sold. Been more depressed than usual.
Hi Tobit,
Very sorry to hear of your present situation.
Sure do hope that you will be able to work your way out of this.
Please take care. 73, wish you the very best of Good Luck! Vic
I thought I might throw my 2 cents in here.
I suggest using two different mix cores in series on the DC power cables. First mix 31 is most effective for frequencies 1-30 MHz, second mix 43 is good for 25-300 MHz. Next the number of winding on the core increases the inductive reactance by the square of the number of windings. The more winding that are placed on the core the higher the choking impendence, however as the number of winding are increase the "curve" of this impendence goes up but become narrower (think higher Q circuit). Also as the curve goes up and becomes narrower it shifts down in frequency.
Choke or isolation baluns can be an effective measure against CM currents. DC grounding is equally important. However what I saw in your pics are actual signals being generated appearing as harmonics? I would suggest using a phase noise canceling unit something like the JPS/Timewave ANC-4. The will take the offending signal and cancel it by delaying the signal 180 degrees. I suggest using a vertical receive antenna as most human made noise is primarily vertical polarization.
Regarding buying ferrite, Fairite barnd is what I buy. I usually buy from Mouser or Arrow electronics (Arrow's warehouse is in my town so they usually arrive the next day). I have used all of the materials and cores discussed here with varying degrees of success. For a short while I built and sold OCFD antennas and the hybrid balun Tobit mentioned. If I may suggest use a 4:1 voltage balun using two Mix 52 stacked cores and a 1:1 isolation balun using 2 stacked mix 31 cores. All cores are 2.4" ODX .5 H. Through extensive testing and design I found these to be least susceptible to heating and eventual cracking when loading antennas with large impendence mismatches/ unbalance currents. I still debate over which is best for the 1:1 balun windings: bifillar #14 thermalize enamel wire or RG-400. maintain as constant impedence (50 ohms) is important. If you want suggestions on balun building that can be had else were as it gets off the topic of this thread.
Next I strongly suggest using isolation baluns on all interconnecting cables between the radios, tuners, amplifier, power supplies, even you computer. Here I suggest using both mix 31 and mix 43 in series on all interconnecting cables. Last and this should go with out saying ground ground ground, and bond these grounds! Every piece of equipment must have its own ground to a common ground buss. The common ground buss must have a very low impendence ground (copper foil/ 3"X20ga sheet/roll works well) to the actual grounds outside. This must also be the same grounding system for the rest of you equipment (solar stuff). I go by the Motorola R56 grounding manual.
As an example I use Mix 43 beads on all the interconnects (patch cables) for my LAN. I use these on the patches between the switches, routers and other equipment in my network racks and the CAT5/6 going to every piece of equipment near where the cable plugs into the equipment. Ethernet is a notorious nose generator! At communications sites I am switching to solid copper jacketed CAT5 that is bonded to the tower and entrance panel. the stuff is expensive but so is causing interference!
One last though and I am by no means an expert here, you mentioned something about the signal being worse when the solar array was connected? could it be possible that a barrier diode in on the panels be rectifying a signal? Again when it comes to solar I am a novice but its a though.
Good luck!
Jim
Quote from: MountianComm on June 21, 2020, 03:36:39 AM
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One last though and I am by no means an expert here, you mentioned something about the signal being worse when the solar array was connected? could it be possible that a barrier diode in on the panels be rectifying a signal? Again when it comes to solar I am a novice but its a though.
Good luck!
Jim
Solar panels ARE diodes. and they have Blocking Diodes in them PN junctions everywhere. But the SUN is DC (not flickering AC like you would get from illuminating them with light bulbs)
And connecting panels, there's lots of wire there to carry a signal. But at night, the charge controller should not be generating any hash
Hi Jim, Welcome to the Forum,
Thanks for your perspectives. Wrote a fairly long Post, hit a wrong key on an unfamiliar keyboard/computer, and, instantly, it was gone …
Appreciate you taking the time to mention your experience with noise reduction/mitigation.
Will try posting some responses tomorrow, but wanted to acknowledge you and your ideas/thoughts RE RFI.
Thanks, and 73, (if that is appropriate). Later, Vic
Hi Jim,
Agree with you about using mix 31 material for HF, plus mix 43 (if needed) to help on 6 M up, and perhaps help on 10 M. We have never needed anything other that Mix 31, although 6 M is not of particular interest here.
Also agree with you about shielding -- placing all power conductors and control cables that are above ground in metal pipe (mostly EMT, here). Also burying AC power runs 24 - 30 inches below grade, seems to work. Bonding all equitment/enclosures/pipe is essential.
For AC wiring in structures that is not in metal pipe, we use CorraClad (a Coleman product). This is customary THHN individual conductors, inside a continuous AL tube, which is corrugated. There are still unshielded line cords, but this approach seems adequate.
To me, the interference that Tobit is experiencing, is essentially Line Conducted (on the 12 VDC cable to the radio). This is not Line Conducted in the literal FCC sense, as that only applies to AC mains conducted emissions, using their LISN design. Seems to me that electronic devices which are not connected to the mains, and run on DC, are not tested for Emissions below 30 Mhz. It is possible that this noise is not is not Radiated, or only a small portion of this interference is radiated. Guess that this noise rides on the radio DC cable, and enters the radio and causes the interference (who knows, at this point). This is why it was suggested that a different radio be substituted for the 7300, (or, at least use a completely sepearte 12 V battery be substituted for the Solar DC system that was directly powering the radio in the present setup).
Certainly, using a common mode choke on coax feed lines is a good precaution.
So far, we have not needed chokes or shields on communication cables, but would use them when needed. The Network comm system here is relatively simple, compared to any serious comm site.
We have not done many experiments, to try to determine which measures were the most effective in our situation. Just felt that we kinda knew what the most likely noise sources would be, and what would probably be the most effective mitigation. We have tried changing the Charge Controller to battery chokes, as the added cable that is turns through a toroid, adds voltage drop, and this causes a bit of an error in what the CC sees as the actual battery voltage.
Thanks again Jim, for your hands-on experience at sites that have intensive RF environments.
All, just IMO, FWIW, and so on. Take care. Thanks again, Vic