Possible RF problem in Shack

PhilipG

My 6400 was returned from repairs weeks ago, but I had not gotten to setting it up again due to  Thanksgiving, Christmas and a houseful of guests. This week I put the Flex on line, adding a new Elecraft KAT500 antenna tuner and KPA500 amp. All seems to work, but I have an issue. 

Intermittently, with or without the amp/tuner on line, following a transmission, the display freezes, and I am unable to tune the receiver and am no longer able to transmit.

If exit Smart SDR (3.1.8) and then load it agaiin, I have a side tone, but I can't transmit and I do not see any indication of transmission in the panadapter or in the TX panel. The display is still frozen and I can not receive. If I turn the Flex off completely using the power switch on the transceiver, the transceiver returns back to  normal, and I am able to transmit and receive, I am able to make contacts Until the next time this happens..

This problem occurs whether I am at 75 watts or 500 watts but I am wondering if it might be RF getting into the Flex or the computer. It also occurs if I completely turn the AMP and tuner off and use the Antenna Tuner in the FLEX. Do you thik I have an RF problem?

If not RF in the shack, can you point me to other issues?

Thanks,
Phil, K3UT

allenfr

After going through similar problems, with a 6500, I made changes in my grounding and the routing of my network cables. That ended my issues.

Frank  W1FRA

Rick - W5FCX

Phil,

I have experienced similar lockup’s with my 6700. It turned out to be common mode RF causing problems. Powering the 6700 down and back up resolved it. It happened with or without the amp.

I inserted a 1:1 RF choke on the coax between the amp output and antenna, which resolved it. The 6xxx are somewhat sensitive to RFI from common mode, perhaps due to the Ethernet interface or power supply (not sure where RFI gets in there). In my case, I was using an OCF multiband dipole, which is well known to be buddies with common mode.

Hope that’s helpful.

Rick W5FCX

AH0U

Have you tried it with a dummy load to see if it freezes??

Bill -VA3WTB

Yes, it sounds like RF to me. Also make sure your lan cable is away from any coax. And put chocks on the lan cable. Really any cable could be an antenna.

Al_NN4ZZ

Hi Phil,
I had a lot of lockups with the 6700 before I made a number of changes to address RF getting back to the radio.    Here is a link with all the details.

http://www.nn4zz.com/FLEX6700.htm#RF_issues_and_solutions

Before you change anything, here is another test to try.  Lower the power to 40-50 W and see if the problem goes away.  

I also noticed that if I use the internal tuner and change frequency, it would happen on some antennas.  ( i.e. the SWR would go up and before the tuner could adjust it would lock up).   Not sure if that is still a problem since I quit using the internal tuner a few revs (i.e. years ) ago. 

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com
6700 Win10 SSDR V2.4.9

Bill W2PKY

May want to try a sleeve balun at the antenna, such as Wireman 827. My 6300 was sensitive to long earphone cables.

N8AUM

Did you ever have any problems BEFORE you added your new toys ?

Good luck !  N8AUM

Erika - KØDD

When I upgraded from the Flex-1500 (5W) to the 6500 (75W) the first time I transmitted on 40 meters KERBLOOIE.  Turns out I had popped the AFCI-GFCI breaker on the operating desk.  Reset it and KERBLAMMO this time It took out the workstation and the next thing I knew I was completely rebuilding my computer.

It took out my HRD logbook and Q's going back to 2003 and loaded from DXBASE and hand loaded from paper were all gone.  The only working files I had Started in Feb of 2017...  So I loaded them.

Discoed the AFCI, and put a regular breaker in, and REDID ALL OF MY GROUNDING Can't wait to see what happens with an amplifier connected.  Oh yeah your problem is all RFI.

Start rebuilding and use all of the highest level of RFI techniques and you'll have it taken care of.  With 4 monitors here, when I rebuild the operating desk.. ALL of the computer external wiring is going to be shielded in metal tubes.  Stay on top of it and you'll get it cured.

Erika DD

bahillen

Don’t forget to check your coax for a poor shield connection.

Clay N9IO

Phil,
Your issue is totally RF getting into the network and/or computer, radio somewhere in the network chain.

My issue is antennas and tower to close to the house and particularly the internet radio modem on the tower is a few feet from my 160 inverted L, 10 feet down from the HF tribander. Didn't matter if I was qrp or high power.
This is what I learned through experimentation and am now running full leagl limit AOK except 160 I can run comfortably at 1KW.

About a month or so back I spent better part of a week and an entire weekend RFI problem solving with a lot of experimentation.
My internet out here in the country is a Motorola Canopy radio modem on the tower at 45 feet (read very) close to many of my transmitting antennas.

I finally got a good handle on the fact that RF was coming into the CAT7 run down the tower into my router combined with the rest of the network (computer, radio Maestro, etc.)  Monitors locking up, radio rebooting, computer freezing the list goes on.

First and foremost I greatly improved my grounding situation, let's just say it wasn't correctly done.
I installed a ground buss behind the amp and radio, connected them with large braid, also grounded the 19" equipment rack where the computers housed (AND) grounded the desktop computer the the ground buss as well which really helped.

PROBLEM TOTALLY SOLVED when I broke the CAT7 run from the tower at the operating position with a pair of L-C fiber optic network converter's (cheap at Newegg) and a 3 foot premade L-C fiber optic jumper feeding the router internet input.
The Flex 6600, Maestro and computer are connected to a separate 5 port 10/100 switch that is connected to the router via yet another pair of L-C fiber optic network converter's and 3 feet of L-C fiber.
For good measure I added RJ-45 Network common mode filters from RF Engineering at the Flex 6600 and Maestro.
(My adult kids wanted to know what they could get me for Father's day so that was it, yes I've been sitting on those until now.)

I know initially this may sound extreme but remember the Flex is a radio server unlike legacy radios
so a little inginuity can get you around the obsticles that abound. You just have to get your head wrapped around
the potential issues you face.

If I were starting over I would have put the tower out further giving me more separation and fed the coaxials undergound.
My HF2V verticle for 40 and 80 is the only antenna on the other side of the yard fed underground through flexible PVC pipe and gives my little to no issue at all because of the separation.  I put that tower up replacing a smaller tower in 2005 and I'm too close to retirement and frankly not limber enough to start over so **** it, this works for me.

Good luck,
Clay N9IO

PhilipG

Thanks for the reply. Did you make your RF choke or just use a torroid and loop the coax around?

PhilipG

Al, Thanks so much for the reply and the link to your extensive documentation. I have already installed the bonding cables to a 1/2 inch copper pipe that runs along the wall of the shack and then gets grounded to two rods outside, I have used only 1/4 inch braid, which may be enough  for bonding, but not for lightning protect. .So far, I still have an RF problem, mostly when I run over 50 watts. So the next step, following your guide, is to get some ferrites on the cables. Behing my desk is a rabbit's nest of wires - speaker wires, 12v low amp wires to power the antenna switch, speakers, weather station, headphone, key, headset wires. Not to mention the Ethernet wires running all over the place. Following your lead, I will start with the jumpers between the Flex, Amp, and tuner, then move on to the Ethernet wires. Thanks

PhilipG

Yes I had the problems but only with the Flex, not the K3 (now sold) or the K2 which is only 10 watts

PhilipG

Thanks, I am starting over with grounding and ferrite beads on the wires 

Erika - KØDD

no offense at all...  But with what you are describing.  The FIRST thing I'd do is remove EVERY PIECE of wire and cable from that installation INCLUDING the weather station.  Setup the radio, and absolutely the minimum of a computer.  See if you have RF then.  Then start adding USING best practices your gear back in...  There WILL be a point the offender will light up your shack... Then throw that piece away! Erika DD

Erika - KØDD

Really Phil...  Disconnect everything and rebuild a piece at a time.  I have 4 monitors here.  When I rebuilt the computer only one monitor had power and a video cable on it.  I stripped the desk clean,  wiring wise.  But in my case the issue was an afci breaker.  That got replaced first and then the station was wired up.  If you just start hanging ferrites on everything... (Somethings do not like large inductance slapped on them) It will wreck waveforms and cause other issues.

It doesn't take very many wires to get a Signature Series to work at minimum connections...  You're going to find a cable that is running somewhere not related to the radio is going to be your huge offender.  If you don't start with it out of there, you'll never find it.  Erika Dd

PhilipG

Thanks, Erica. You are right. I just rebuilt the station, and I am totally exhausted from that, but going back to basics is the way to find the issue. As I said elsewhere, I did not have this problem with the K3 and Amp (and the weather station also in the shack), so I am guessing that it is one of the cables involving the flex - let's see there is the Ethernet, the key, headphone, headset, speakers all connected to Flex box. Thanks for the advice.

Erika - KØDD

I'm rooten for you to have success! 

WK2Y

One thing that has helped in my shack has been using optical connections where ever possible.  I have an optical coupler for the audio and the connections between my router and pc and between the router and flex are optical.  If I could get optical power, key and microphone connectors I would. I was surprised at how small the optical cables were and how easy it was to set up. Had I known, I would have done it sooner. 
73 and Happy New Year.
Bob
WK2Y

Erika - KØDD

Oh yeah, when I put things back together the computer is now as far away from the radio and antenna leads as I can get it and all the video and ethernet are going two different ways to the radio and computer.  RF on one side and computer on the other side of the desk...  That did help considerably...  I do remember a weirdness back in the early 70's ALL OF A SUDDEN on SSB I had RF on the mic audio.  It just started up seemingly on its own.  It was a Drake setup...  The audio was completely broken up though.  I climbed up on my desk and found a coax junction two pl259's a barrel connector and it over time had moved slightly and the connectors were brushing up against the old Steelcase desk...  While that wasn't a flex issue, strange things do happen and a new jumper of RG8 and a pair of connectors without a barrel fixed that one.  1 hour repair...  Erika DD

Erika - KØDD

Wave of the future...  That and virtual cables.  What  huge difference between the early flexes and these units.  DD

PhilipG

Thinking about ethernet to fiber converters, since the Flex has already been repaired for some kind of ESD problem. Whats the best way to do this? Converter at the router, run fiber towards router and then another converter, running CAT5 to switch, then run CAT5 from switch to FLEX and other devices? Or should I buy a switch that has a fiber port? I already have a switch but it doesn't have fiber port.So one way I would have to buy a new switch, plus a converter. The other way I need two converters.

Bill -VA3WTB

Try doing a search on this here in the community,, I remember reading a lot about this and the people using it telling how they do it.

WK2Y

I would go fiber and minimize CAT cables wherever possible, but you would probably need a switch with two or more fiber ports.  I presume they make something like that, but I never looked.  I just bought the two pairs of converters.

Al_NN4ZZ

Hi Philip,
Here is a link to my fiber setup.   

http://www.nn4zz.com/FLEX6700.htm#Ethernet_Lightning_Protection

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com
6700 Win10 SSDR V2.4.9

PhilipG

Thanks, Al. I can't find a reasonably priced switch with ethernet and fiber ports.

Lasse Moell

Philip, you may look at Routerboard router/switches they have often one or more SFT ports. And you can use a fiber converter if needed. I just bought some converters from FS.com. Great prices and speedy shipping, all with-in EU.

N2WQ

Before you go crazy rebuilding the station, running fiber, adding new routers, start with the root cause of your RFI. Common mode chokes are not particularly effective unless they are the antenna feed point.

Neal Pollack, N6YFM

:-)  You don't need the expense of Fiber ethernet.  You just need to nail the common mode RF from getting back into your shack.  It rides the COAX shield.  

1.  Does your coax go to a lightening arrestor that also serves as a connection point to a ground rod right outside your shack?

2.  Are you using a common mode choke where your coax comes into the shack?
     ref:  https://palomar-engineers.com/antenna-products/1-1-balun-kits
or
     The one I use;  https://myantennas.com/wp/product/cmc-130-3k/

3.  Have you also put simple toroid chokes on your ethernet cables?
     Type 31:   https://palomar-engineers.com/ferrite-products/ferrite-cores/ferrite-ring-toroid-combo-pack
  You really don't want the combo pack, you just want type 31 toroids.  Call them.

4.  Is your PC Chassis grounded to your station ground bar the same way your Flex, Tuner, and Amp are grounded?   Each item should have a braided ground strap from the chassis over to the common ground bar.   The ground bar then connects through
the wall to the ground rod outside.  This is not only important for the type of problem you describe, but also critical to your safety!

If you have not done the above, it is a total roll of dice if things will work or not.
Most people forget to ground their PC chassis, so end up with a difference in potential between that, and the other equipment. (That can, in certain circumstance, burn up the USB port on the PC.)

By doing the above, which is really just standard practice for RF equipment, I use regular ethernet cable with a cheap $19.00 ethernet switch from China and have ZERO problems using a KPA-500 amplifier. 
And yes, one of my antenna's is a wire, the other a rotating dipole.   No problems.

Neal

WK2Y

I totally agree with these recommendations, even if you go optical.  One unrelated reason for using the optical connection is the spikesurge isolation.