Author Topic: KID RF Hash  (Read 1343 times)

Tobit

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Re: KID RF Hash
« Reply #60 on: June 09, 2020, 09:17:17 AM »
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.

boB

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Re: KID RF Hash
« Reply #61 on: June 09, 2020, 12:11:34 PM »
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.

K7IQ

Vic

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Re: KID RF Hash
« Reply #62 on: June 19, 2020, 01:42:38 PM »
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   .  .
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

Tobit

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Re: KID RF Hash
« Reply #63 on: June 19, 2020, 01:48:25 PM »
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.

Vic

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Re: KID RF Hash
« Reply #64 on: June 19, 2020, 02:34:30 PM »
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
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

MountianComm

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Re: KID RF Hash
« Reply #65 on: June 21, 2020, 03:36:39 AM »
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

mike90045

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Re: KID RF Hash
« Reply #66 on: June 21, 2020, 10:07:29 AM »
......
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
http://tinyurl.com/LMR-Solar

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Vic

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Re: KID RF Hash
« Reply #67 on: June 21, 2020, 10:32:12 PM »
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
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

Vic

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Re: KID RF Hash
« Reply #68 on: June 22, 2020, 05:04:40 PM »
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
« Last Edit: June 22, 2020, 05:11:44 PM by Vic »
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!