Possible RF problem in Shack

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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
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Philip Graitcer

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Posted 2 weeks ago

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allenfr

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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
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Rick - W5FCX

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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
(Edited)
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Philip Graitcer

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Thanks for the reply. Did you make your RF choke or just use a torroid and loop the coax around?
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AH0U

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Have you tried it with a dummy load to see if it freezes??
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Bill -VA3WTB

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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.
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Al / NN4ZZ

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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

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Ted VE3TRQ

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Great thing about glass is, it does not allow lightning to follow it!
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Clay N9IO

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Exactly, and fiber is not nearly as expensive as was stated.
My situation is not RF on the feeding coaxials but rather close internet modem with 900mhz yagi a few feet from the transmit antennas.
Grounding the PC was also helpful but at the end of the day fiber works greater than you might think.

An aside I no longer worry about a lightning pulse taking out my network along with my Flex.
(Edited)
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Clay N9IO

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You might ask why the modem on the tower.
I need the height to hit the access point until time civilized cable comes to my area.
(Edited)
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Ng Rocky

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I add an abandon old router, using its LAN side with DHCP off as a switch, between my radio cabinet and the main router.
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Ng Rocky

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Congrad for DXing in area without civilized cable.  Quiet station assured.
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Bill W2PKY

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May want to try a sleeve balun at the antenna, such as Wireman 827. My 6300 was sensitive to long earphone cables.
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N8AUM

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

Good luck !  N8AUM
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Philip Graitcer

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

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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
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Erika - KØDD

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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
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Erika - KØDD

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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
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Philip Graitcer

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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.
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Erika - KØDD

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I'm rooten for you to have success! 
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Erika - KØDD

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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
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N2WQ

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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.
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bahillen

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Don’t forget to check your coax for a poor shield connection.
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Clay N9IO

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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 screw it, this works for me.

Good luck,
Clay N9IO

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Bob Gerzoff, WK2Y

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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
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Erika - KØDD

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

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Thanks all for your replies. They sent me to the books, the web, and the bank.

Here's what I did.
I made sure that all equipment was bonded and the bond was grounded (could not ground the computer, a mac mini. I had no screws or protrusions, so I left it alone). I have a copper pipe running behind the boxes and ran braid from the tube to the boxes. The tube is connected by braid to outside ground.
I purchased snap on ferrites in various sizes and went to town with them on coax and internet cables, 
I purchased a pair of copper/fiber converters (GTECK on Amazon for 40/each) and fiber cable and ran fiber from my router directly to the flex.
I am also in the process of dressing the rabbit's nest of usb, power, ethernet, control cables behind the boxes.
So far, I am no longer seeing the lock up pattern from RF as  before. I may have solved this one. Thanks all for your help.

Phil, K3UT

 (The fiber was primarily for ESD protection; I live in an area of lightning strikes, power outages  on the GA coast)

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Philip Graitcer

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These are the converters I used.  One is on top of the Flex connected with a .5m ethernet cable and the other is next to the router with a .5meter ethernet cable

https://www.amazon.com/gp/product/B06XBSZJL3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

This is the optic cable I got.  

 https://www.amazon.com/gp/product/B079J6FDBG/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Sets up in a few minutes, no programming. I now have the peace of mind that surges through the internet cable are a thing of the past.

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Erika - KØDD

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We have Buried Power and Cable here, but it wasn't always that way.  Here's the house's original power service panel from 1896 (120v DC one circuit fused Plus and Minus side) that was still feeding 1/2 of the house on AC when we got here Sept '16...  Just screw in larger fuses was SOP..
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Craig Williams

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Very cool.
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Alan

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Erika - Where is your home?

I spent part of my electric utility career in New York City, Consolidated Edison.  At the time, ConEd was supporting portions of the old Thomas Edison DC distribution system.  Some of the older NYC buildings continued to use DC for their elevators.

Later on, ConEd was paying for the old buildings to use MG sets (Rotary AC to DC converters) to replace the need for DC distribution.

Alan
WA9WUD
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Erika - KØDD

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Rock Rapids, IA.  The far NW Corner of Iowa 6 miles south of Minnesota and 20 miles east of South Dakota.  The utility switched over to AC in 1921 or 22...  I have the book here...  Everything WAS heated via coal around here back then.  A deposit was found in the eastern part of the county way back when. They didn't get Natural gas here until 1955.  Erika DD
(Edited)