Transmitter RF getting into ethernet

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  • Updated 3 months ago
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I had a problem in the past using an antenna that resulted in enough CM to interrupt the ethernet communications with the Flex. I did two things - toroids on everything and replace the antenna.
I was working 40 CW and 20 CW this morning - all fine.  I went for caffeine and returned to radio and at this point on 20 m the 6400 went "click" on the first ms of key down, the red light was blinking and the message saying communications was lost appeared on screen.  I didn't think anything antenna wise could have changed..but..maybe..

Cutting to chase..
At this time the only cabling to the 6400 is power (about 8 wraps thru a #61 at the radio) and an ethernet cable (6 feet) wrapped loosely about 9 times around an FT 240-31 and 18" of rg8x to a Cantenna.  At the computer end there is power, an HDMI cable (6 feet), and the Ethernet cable with four clamp on toroids. 

Everything is fine except on 20 and 12 meters.  On 20 all is fine up to about 90 watts then we get the "click", red flashing light etc. 

Same thing on 12m at maybe slightly less power. 

The Cantenna and the RG8X checked with a 259B and are good.

The 6400 and the computer case are strapped together with 3 feet of high quality tinned braid (no crimp on connectors on the braid).  In any event, either strapped together or not the result is exactly the same. 

The set up for this testing is linear - that is the dummy load is at one end of the desk, and the computer is at the other.

Since all was okay, and then a bit later not, this is a mystery,
Is it likely the ethernet NIC is failing? Anyone ever see this kind of failure?

Has anyone seen RF getting in thru the HDMI cable? 

Is anyone having success with fiber ethernet and converters?
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N5LB - Lionel B

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  • irritated with RF magic today

Posted 3 months ago

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David Ahrendts

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Lionel, I had similar issues a couple of years ago around my Flex 6500 and spent considerable time working through RFI, shielding, filtering and grounding. A few observations:
1) One of the biggest noise producers was my D-Link switch physically located four feet from the Flex. I replaced all CAT6 cables with shielded CAT7. Here's just one example from Amazon: https://www.tvtechnology.com/news/the-weather-channel-broadcasts-immersive-tornado
2) Although I love red-black 2-conductor zip line and Anderson Power Poles, the zip line is a big factor in picking up RFI and injecting it back into your power supply. It's an antenna. The early pioneers of telephone lines learned this a century or more ago. Solution: twisted pair wire, and even better, shielded twisted pair wire which works with Anderson Power Poles just fine.
3) Just common sense to separate the RF coax from any other non-RF lines. Don't lay any line near the RF coax.
4) Then you add AC line filtering. Heavy filtering of all 12V power supplies. Removing and replacing all switching power wall worts, and finally, plenty of snap on ferrites.

My two cents. For me it worked.

David A., KK6DA, Los Angeles
 
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N5LB - Lionel B

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I have wondered about the power cable and although short still passes within a few inches of the rf out on the back of the radio. The power cable is choked pretty good at the radio but I’ve never had to do that in the past. I know the Ethernet cable was a problem in the past and adding ferrite seemed to have cured it for a long time. Now I’m not so sure.

I’ve been reading K9YC about the “pin 1” problem and he notes that most all ham rigs, including flex connect the cable ground to the circuit board and not direct to the cabinet. That said , I have no idea if that is accurate.

I’ve read that cat 7 has the shield grounded at both ends which can be a problem, though if it works for you then maybe not a problem. I’m going to buy one and try it out.

More cores are inbound from parts and kits.

Tnx
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Martin Ewing AA6E

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I would suspect your antenna and feedline. What is SWR? How far away is the antenna? Do you have current on the outside of the coax? Try a 1 to 1 unun, or try changing the coax length.

My 6500 has little if any trouble like this.

73 Martin AA6E
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N5LB - Lionel B

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Yep, I am sure the feedline is radiating inside to some extent even with a choke balun.

That noted, the issue I am seeing occurs with the 6400 direct to the dummy load thru a good 18 inches of RG8X. And the computer and radio are stripped down to minimum cabling.

This morning I will return to this odd contest. Why two days before FD? Ahhh.
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N5LB - Lionel B

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Thanks, I see info below.
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Jon - KF2E

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I struggled with RF getting into my ethernet for years. I finally bought two fiber media converters and a fiber patch cable and used them to isolate the ethernet going into the radio. I also used a short(12") patch cable to go from the media converter to the radio. This combination has solved all of my RF issues. I bought all the parts on eBay and my total cost was about $50. In addition to solving the RF issue this setup also provides total surge protection for your ethernet port.
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N5LB - Lionel B

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Jon, can you give me some info on the products used? I see a bewildering number of devices online with varying connector types, and single mode or multimode. I don’t think SM or MM matters in this case, bandwidth being far in excess of what is required.

I am sure there some gotchas out there.
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Winston VK7WH

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John, I've yet to do much with Fibre, or needed it before, but it seems like it would be a good thing to do at my remote site, particularly as the costs seem much much lower than I would have expected.

Would it be too much to ask if you could post the details of the media converters and the Fibre patch cable you used?

Many thanks

Winston VK7WH
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Jon - KF2E

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Winston,

Fiber media converters are pretty much a commodity item. I bought two of these from eBay for $35US.

https://www.trendnet.com/langen/products/gigabit-fiber-converter/TFC-1000MSC

The patch cable can vary depending on the media converters you buy. There are several different style fiber connectors and your patch cable needs to match. Again, I bought mine on eBay for $7.50US.

If you're not comfortable buying on eBay then just search Amazon for media converter and you will get lots of choices. I went with gigabit converters but I suspect 100MB would work just as well.

For the price this offers a lot of protection for your radio. I speak from experience on this, as my previous 6500 was determined to be unrepairable by Flex after the Ethernet port quit operating. Presumably from a surge.

Jon...kf2e
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Winston VK7WH

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Thanks Jon, much appreciated. I'll follow up on your advice

Best 73 Winston
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N5LB - Lionel B

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Bizarre.  Maddening.  So everything is taken apart except for the 6400 (power with 8T #31 at the radio end, Ethernet, and rg213 to ANT1), the computer (with AC-w clamp on ferrite, Ethernet and VGA), VGA LCD (AC and VGA cable), Astron PS (AC and 13.8VDC to Flex).  The Flex, PS, and computer bonded together.  The Ethernet cable has 14 clamp (mixed mu) on ferrites split between each end: it is about 5 feet long.

DL on the end of RG213, about 20 feet and outside tied into the antenna surge arrester ground.  All coax runs have been replaced, more than once, with new cables and shorter.  Grounded, not grounded, inside or out; same though crash magnitude varies.

I have a milliohmeter and checked all of the ground connections end to end. 

It's better but still 6400 shows a software crash (2 blinks) on 30, 20 and 10m at about 80W into the DL.  The only grounds are the AC grounding conductors (PS, Computer and LCD), and the shield of the RG213 to the DL.

Question: does an Ethernet RF problem typically manifest as a 6400 software crash? 

Question: is it likely that the RF problem is due to conduction into the 6400 Ethernet circuitry?  Both ends have ferrites but I wonder.

Question: how much variation is there in computer Ethernet ports insofar as RF immunity? Current theory is a marginal signal level Ethernet transceiver on the motherboard.

I have a large order of #31 clamp on ferrites, several 31 and 43 toroids, a new ethernet card, and a short run of CAT 7 shielded, ethernet cable insulating coupler on the way. 

Clearly there is some RF in the shack not dissipated in the DL (Cantenna-verified good). Most of the RF (I'd say radiated 70-80 dB down) should be contained within the coax and within the DL. 

This is almost certainly a station grounding design problem but what to look at next. Right now the setup is bare bones.   Next, everything comes off the desk-down to wood and start over.

Sorry for the bandwidth and all the detail - no one here to bounce ideas off of except the dog and he lost interest after 10 hours.   It feels near a deadend-hard to accept.
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Tim - W4TME, Customer Experience Manager

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I'd connect the DL directly to the radio with the first run of coax you have and then test working your way down the coax, adding the other elements.  It could be your lightning arrestor (I have seen this cause serious RFI issues).

And disconnect all cabling going to the radio except the minimum needed to operate the radio (power, Ethernet and coax).  Eliminate as many variables as possible.

Question: does an Ethernet RF problem typically manifest as a 6400 software crash?  

Depends on the voltage the radio is exposed to and where the ingress point is, but yes, it can manifest itself as a crash.

Question: is it likely that the RF problem is due to conduction into the 6400 Ethernet circuitry?  Both ends have ferrites but I wonder.

Yes.  And RFI can enter through the power connection too 

Question: how much variation is there in computer Ethernet ports insofar as RF immunity? Current theory is a marginal signal level Ethernet transceiver on the motherboard.

Cheap cards or chipsets will be more susceptible that ones designed to be used in "extream conditions"

What I'd focus on if it was my shack having the problem is eliminating the common mode currents coming back into the radio (kill the source).  Ferrites for this type of application are band-aids.

This article may help.
https://helpdesk.flexradio.com/hc/en-us/articles/204779159-Grounding-Systems-in-the-Ham-Shack-Paradi...
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Bill -VA3WTB

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Tim makes a good point, if your using a dipole antenna a common mode chock,,or line chock is called, at the feed point on the antenna is important. Some build an ugly balan for this.
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k3Tim

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Careful Bill, bsluns have feelings too.

I had an EFHW that gave a lot of rfi in shack. A choke at feedpoint, entry into home and at the back of flex helped. A good oudoor ground also seemed to help.

GL
(Edited)
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David Ahrendts

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Hang in there, Lionel. Bet the CAT 7 solves it. 
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Bill -VA3WTB

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No problem,,this is not so easy to fix, Wondering, if you tried using the radio with a laptop or something other than the computer you use for the radio and see if there are any problems then?
At least that will narrow things down to the Flex computer and not the radio?

I would try and disconnect the Lan from the computer and connect the radio directly to the computer to see if it is really the lan.
(Edited)
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David Ahrendts

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One question: how is the Astron PS cabeled to the Flex. If it's zip line, consider replacing it with shielded twisted cable. Make sure all of that is well physically separated from the coax. 
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N5LB - Lionel B

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Thank you all!I have connected the DL with  a 18" RG213 to the radio and the only cabling to the radio besides the RG213 was the CAT6 and the Red/Black parallel DC power (with a 31 toroid at the radio).   I'll give the power cable some attention next.

The Ethernet cable is short and goes direct from the radio to the computer Ethernet port. It has a number of clamp on toroids though not sure of the mix anymore; probably not 31's. 

Sadly I do not have a laptop but will probably move a desktop from another room to the shack for a test.  At the moment the entire radio desk, except the wooden part, is taken apart and laid about the room to be redesigned and reassembled this evening. 

I believe I've read the document Tim is referring too but will make sure and look again. 

Generally, it seems there are differing opinions in the literature about RF bonding, or for that matter do you need it at all between equipment connected by coax.  This is ignoring safety and lightning which can confuse things.  It would seem that if the RF side is solid and without computer, network or radio crashes then adding the safety grounds should have no effect, that seems to be the W8JI view; there should be little to no RF outside of the cabinet or coax or DL. For the moment I'll focus on the RF issue.

Thanks Tim for answering my questions. This helps.

Back to it.  The dog came by, looked at the stuff on the floor and turned tail. 
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Martin S. W7RU

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In the past with a Flex 1000 running a HB 4-1000. I found grounding the shield of the coax just before entry to the shack to a large earth ground setup. ie: wire fence etc... helped. However at other freq resonance ground loops could enter. This setup is in a 20 acre rural area where grounding can be taken advantage of. I only used toroids for tv and telephone cable interference at 15 m and above. Am getting a 6400 as soon as they make it and send it :-) Getting new Coax also. I often wonder if old coax with high loss can be a culprit? Grounding outside of Coax To Earth Outside of Shack will push Lightning Strikes outside. No Guarantee but it is conductive there through external baluns.
(Edited)
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N5LB - Lionel B

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I've jumped thru hoops for two and half days, like the universe cares,  and still the 6400 crashes, depending on the band, somewhere between 80 and 100W.  20m seems to be the worse.  Some bands are okay but this changes with changes to feeder and balun.  Changes have been made to the feedline routing, the balun checked, and a second inline choke unun added. 

Ethernet is now Cat 7 shielded with one end isolated - though I am not sure the shield adding anything since the crash points did not significantly change.  I also put in a new ethernet card -

Another FT240-31 with 7T at the radio end of the ethernet cable had some effect, though small. 

I do not understand why, when using the dummy load the radio still crashed at around 80-100W.  Maybe the DL (Cantenna) has a problem-though SWR is as expected.   Same result on different cables: 20 feet of rg58, 10 feet of LMR400, 18 inches of RG213 for example, direct to the radio.   Same result, crash at the 80-100W area. 

I will accept that my antenna may be a problem, when it is connected.  This is a non resonant dipole with 600 ohm feeder - outside and then a 1:1 balun for coax into the house.  There are many ways to achieve this so I am tearing down the antenna and feeder.  But why the crash on the DL? 

So far this morning changes to the routing and unun location have not been helpful.  As you have probably guessed, this antenna location is suboptimal.

The siding on my house is steel, yep steel, on three sides and the coax enters thru the rear with a long bulkhead fitting thru the steel and then interior wall.  I'd never seen this prior to moving here last July. Unlikely to matter.

I have been running this station setup and wiring for months and this radio software crash is new, since Wednesday.  I have never seen a loss of comms without a crash-I am not sure if that means anything. 

The computer itself has never missed a beat and I do not know how to, or if, I can catch anything useful in the Event logs.  But, why the crash on the DL. 

I will try and borrow a DL and eliminate that source.  If the borrowed DL works okay then it will isolate to the antenna. If not?

Next after the DL test is fiber optics and many more #31 snap ons and FT240-31 toroids.
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Dudley - WA5QPZ, Elmer

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Lionel,

Sorry that you are fighting these issues,  but sounds like the correct voltage/current is not get to the radio if it is flashing at you..   Verify either with a volt meter on the rear of the radio at the PowerPoles,  or use FRStack or SDR Monitor for giving you the internal voltage, and that you are staying above the 10 volts DC under full Tune load.  The radio will shutdown at 9.2 volts DC, too small of wire (has to be #10 at least )  or poor connections can cause an issue ..   Also do not use shielded CAT cable from the radio to the computer /  switch..   With the station ground like several had stated,  can cause ground loops ..   A balanced feed line will not radiate if both sides are EQUAL  in every way ,  can't have one side shorter or one side running over a metal building...  :-)   

But since it is failing into the dummy load,  input voltage could be dying under full load.    Into a dummy load you should be clean to full power.  

73,Dudley
 
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N5LB - Lionel B

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Hi Dudley, very good point. I thought the power supply was solid by looking at the analog voltmeter on the ps. But, maybe the transient response is poor but too fast for the analog meter to show.

I’ve used FRfrack and it seemed solid but I don’t know it’s read time. If it were a fast rise/ fall change, maybe not picked up. This would surprise me, but this would explain an odd behavior. I hadn’t looked at this enough.

Always something to learn, so little time,

Thank you Dudley and good to see you here. I’ll look closely.
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Mark WS7M

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Lionel,

I'm sure you have received lots of suggestions here.  But here are a few things to try if you have not already tried them.

1) Setup ethernet directly between your computer and flex.  Use as short of a cable as possible.  Disconnect any ground from the flex.  Connect a short coax cable to your dummy load.

In this setup see if you can transmit to a full 100w without a crash on all bands.

2) If you run fine under #1, then try connecting your flex to ground and repeat the test.

In my case grounding the flex was actually a bad idea.  It was like a ground loop developed between the ground of the power supply and the ground of the flex.

3) If you are good to go in 1 and 2.  Now reconnect your flex using ethernet to your router as before.  Leave the short coax and dummy load in place.

If you crash in this case, then once again remove the flex ground and repeat.
If you still crash then as you have probably figured out the issue is when connected to your network.

If that is the case I would skip the troubles and go direct to fiber net.

Basically in my experience ground loops can be horrible and can cause many different issues.
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K5ROX

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Had same problem till I grounded my Power Supply, it had a 2 wire ac cord, I changed to a 3 prong and also added a ground lug and grounded it to everything else, no problems since.
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N5LB - Lionel B

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I am direct connected, short, and have tried a short run to the DL, with DL sitting on top of the flex. No joy. The supply is an Astron that ha always been solid and in fact have an identical spare that I swapped out.

The 12vdc cable from flex is shorth and heavy gauge and has not shown steady state voltage drop. But, power poles do fail, so maybe.

I have tried grounded, not grounded with not much effect so I am thinking Dudley may have the right idea.

I really appreciate all who are putting out ideas. It’s a ham radio think that’s fb.
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Martin S. W7RU

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Ahh into a dummy load and still having problems. Then time to think out of the Box. Also consider a bad coax connector or connection. I threw 2 coax connections away that fooled me for awhile. They may test ok at low power levels but.
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N5LB - Lionel B

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This is a long thread but I wanted to close this out with the successful steps taken.  Looking for "the one" cause in these cases is probably hopeless and several contributing factors were involved.  The solution seems to be influenced by all of these to some degree (#1 being a biggee)
Feeding 600 ohm open wire (70 feet) to 40m dipole with remote 1:1 balun outside.  On its face, this is a challenging installation – I was aware.
  1. Replaced an intermittent jumper coax-tested ok on MFJ259 and DVM but seemed to fail under power.  Perhaps a high voltage point on some frequencies but not all.  This seems to have been the initial cause of the major RF problem, and intermittent at that. Never seen that before.(Thanks Martin)
  2. Shortened ground braid to single point buss bar near Flex for Flex, antenna tuner, computer, and Alpha switch.  These were too long and haphazard before, though still to a single point: poor installation.  
  3. Replaced Astron PS with Samlex and shortened power cable to 10”. #10 AWG, twisted plus two snap on cores.  I’m not sure if the longer power cable is a factor but I wanted to try a smaller PS on the desk.
  4.  Replaced RG8X jumpers with LMR400 Ultraflex.
  5. Shortened RG213 coax from station to wall penetration from 6 feet to 4 feet and replaced with LMR400.
  6. Carefully built a new 1:1 current balun and replaced existing. 
  7.  Relocated Alpha switch from the output of the tuner to between the Flex and the tuner. This is potentially a serious problem with high RF voltages on the antenna side of the tuner and the arc plug.  Just bad practice I think.
  8. Shortened ground braid from operating desk to outside single point ground from 6 feet to 4 feet. 
  9. Began installing buried #4 bare copper from outside single point ground going towards the utility ground at service entrance.  45 feet installed, another 65 feet to go.  This is primarily for lightning and safety and had been in work, but it seems to have made a difference – maybe.
The Cantenna is suspect-I don't know if they have a history of failure.  Not much there to fail. 

Now, the watt meters on the Flex and the tuner are in closer agreement and both show approximately the same SWR.  Clearly, previously affected by common mode RF with the tuner showing 135W forward on some bands and 5W reverse-not possible with the 6400 to have net 130W out – RF getting into autotuner. I can run 100W on all bands 40 - 10.

Maybe these autotuners (MFJ 993B in this case) are far more susceptible to common mode than I expected.In any event, the DC power needed multiple ferrite cores.

RF in the shack has been significantly reduced in effect.   I don't believe it is ever gone, just managed to an acceptable level. With what I’ve learned I know there is more to do but it feels great to not have the rig crash on some bands.  I have a bunch of #31 snap on cores from Palomar on the way just in case.

RF in the shack can drive one to consider taking up a less frustrating hobby, like golf.

This feels closed out. Thank you for the great suggestions and contributions to the fixes. 
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N8SDR

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I'm curios what 1:1 RF choke your using, I have seen quite a few that are truly GARBAGE, and have caused more issues then helping things, I have had great success with the ones made by Balun Designs, there not cheap, but they work and work well..  
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N5LB - Lionel B

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Being cheap, and having read the comments online about commercial choke effectiveness, I built one.  Kits and Parts furnished the FT240-31 toroid and Home Depot the 4x4x4 plastic electrical box and THHN.  I wrapped the toroid in plumbers teflon tape and then 13T of #14 THHN solid, bifilar wound.  This is about a 100 ohm transmission line choke.  The mismatch loss is very low according to those who test such things.  It is doing the job 40 - 10m. 

I've looked at Balun Designs and that company seems to make good products, but running 100W max and of course, cheap, my $20 cost seems pretty good.  It's probably okay to around 300W. 

I can send you some jpegs if you want.
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N8SDR

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No need for the JPEGs thanks though. Curios have you tried it without your homemade 1:1, The 200W model 1110W Balun Deigns has very good RF isolation for around $50.00 
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N5LB - Lionel B

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Inadvertently while rushing around, yes, and the RF into the shack lit the place up.  It was unpleasant.  That bump from a balanced feedline to coax seems like a big deal.  I have seen some say that you don't really need the choke but I think unlikely to work well. 

By the way I am using a current choke 1:1.  I've never tried 4:1 but suspect the result would be a low impedance at the tuner, on some bands, that would be out of range. 

$50 isn't a bad price from that company. 

Good luck with your installation.