Here's a mystery for you. aka How my day started.

[W5LZ]

Towers and hazers. If He had wanted me to get my but that far off the ground He would have made my legs longer. That doesn't count the pilot's license. I can get my but a lot higher if I sit on it.
- 'Doc

 

[paws264]

Now, I'm gonna see if I can re-hijack this thread away from "Hazors"

.........I swept the band with my VFO while TX’ing a carrier into the tribander and notice the problem is only between 14.050 and 14.300.........

Is that what you Canucks call "Spread-Sprectrum" up there?

 

[Captain Kilowatt]

Well I should be able to get up the tower either today or tomorrow and check things out. One thing I did do was connect my MFJ-269 antenna analyzer to the feedline in the shack and have a look. On 20m the match stays good as noted on an SWR meter.I then tuned the analyzer to a much lower freq,down around 2.900 MHz just so I could see something that had a fairly high impedance.The readings were R=550 ohms and X=600 ohms.Everything was stable until I moved the antenna.The readings were jumping all around until I stopped and then they were rock solid.The numbers only changed when the antenna was in the "right" position.I am now convinced I have a bad cable,possibly worn from being in contact with the rotor.I still can't figure out why the SWR stays good however. :? I'll try to remember to take along a tape measure and check for resonant/non-resonant lengths while I'm up there.

 

[W5LZ]

QRN,
If you want to take a tape-measure then by all means do so, but I think it's just gonna be extra weight. I also think the problem is going to be at least fairly obvious once you get close to that 'wiggly' section of coax around the rotor (most likely spot, but not the only one). Good luck.
- 'Doc

 

[Captain Kilowatt]

I also suspect the problem will be obvious but I was curious as to why the SWR did not go bad. I figured I would measure the overall length of cable to the fault and see if there was a mathematical reason why it was not affected even though there was a definate fault present.I really have no idead how long the cable is.It consists mainly of a long run of Andrew LDF-4-50 with a piece of Beldwn 8214 on each end for flexibility into the shack and around the rotor.Both cables have a differant velocity factor. You know me,since cable length does not matter I never bother to measure. I just run it out until it reaches,cut it off and install a connector.

 

[Captain Kilowatt]

Ok,I am beat after two climbs up the tower in the wind. I went up the first time and removed the 6 foot flex jumper from the LDF-4-50 to the tribander beam. It looked fine on the outside but since it was Belden 8214 foam cable I thought about core migration since it was in the heat of the sun and had a fairly tight radius bend around the rotor.I came down and made a new cable and went back up to replace it.While up there the wind really started to pick up and I started to get rather uncomfortable.I sealed the connections and came back down.I performed a forensic autopsy on the old cable and found NOTHING wrong. :x The problem still exists.I did find that with the tribander disconnected and 100 watts into an open circuit it did not cause a problem.Then I thought about the W2DU balun feeding the tribander. Too late for today as the wind was whipping up pretty good and my arms and legs won't take another climb anyway. :? So I then started poking around the shack looking for bad grounds etc.Now,for those who do not know,the HF port on the FT-857 is also the antenna port for 6m.It has a separate port for 2m and 70cM.Since my antenna switch is not that great on 6m I switch the antenna separately.I have a Daiwa CS-201 antenna switch with the common port going to my FT-857 and one antenna port going to my main HF antenna switch and the other going directly to my 6m beam.If I disconnect the 6m beam all is fine.I have gained HF operations on 20m with the beam but am still at a loss as to WTF is going on.I tried 6m with 100 watts and it works fine. The match on 51.500 is 51 ohms with zero reactance.Somehow RF from the tribander which is mounted a few feet below the 6m beam,just as it has for several years, is being fed back down the 6m feedline and when connected to my antenna switching system, is causing RF problems with my Tripp Lite power supply.

Eureka! I just found out the problem appears to be in the shack! I just made a test and by shaking a cable bundle I can make the problem come and go! What that has to do with the beam direction I could not tell you.I work tomorrow,a call back :? , but the next day I shall be tearing the shack apart. In the mean time I am back on 20m with the 6m beam disconnected.

 

[W5LZ]

On your antenna switch, is the unused terminal grounded? Or at least, is it supposed to be? If it is grounded, and the 'ground' isn't unreasonable, I honestly can't see why it would be getting into the PS. If it isn't grounded, I think I would see about changing it.
As for the 'bundle' of cables, around my 'shack' it's called a "rat's nest". Cable not used anymore? Drop it behind the desk. Never loose them that way! Bet I've got a 'six pack' or two of 'capper' back there.
- 'Doc

 

[Captain Kilowatt]

It appears I may have a problem with the shield on the feedline to my 6m beam. I get continuity to ground but that may be through another cable shield which all connect together at the switchbox and supposedly connect together at the antenna/tower end via antenna mounting plates to the tower. The plot thickens however when it comes to beam direction,unless it has something to do with the two wire antennas fixed in position underneath the yagis.I suppose if I had an open shield that was isolated from a direct path to ground then RF could flow on it back tio thge shack end but how it would get into the power supply is another mystery. I have NEVER had a problem with this power supply even when running a random wire and I KNOW I had RF in the shack then. :shock: I got too close to the D-104 and it told me so. It looks like a good time to COMPLETELY go over all the cables both RF and whatever else there is.That in itself is a big chore. I have a LOT of cables here and yes Doc. they are all in use,no unused cables floating around. I'm still suspect of a bad or floating ground/shield somewhere.Man this one really has me stumped but at least if it is on the shack end it will be easier to find.I'll get to the bottom of this or die trying. Oh,man I shouldn't say that.This involves tower climbing and possibly bad grounds. :shock:

 

[W5LZ]

For some reason, I tend not to doubt that 6 meters is almost always a lot of trouble. Doesn't matter how/where/when, it always seems to be the source of problems. One of the local 'cable' companies uses 50-60 Mhz in their distribution system so 6 meters is always an RFI magnet here. The company raised all kinds of @#$$ with me for just having 6 meter capability in the car. (Think I had actually used 6 meters maybe twice.) Finally asked them if they would like going to court. They said they didn't want to sue me, and I told them they wouldn't, but I would certainly sue them for harassment because of their inability to shield their @#$ system! Guess who didn't hear any more complaints? (Shielding so bad that you can listen to cable TV with a 2m hand-held anywhere in town, besides the 6m linking system.)
So, getting into a power supply just doesn't seem all that 'odd' to me. You know, a few extra, unused, cables actually 'absorbs' some of that 'stray' RFI that goes around. You ought'a try it.
- 'Doc

 

[Captain Kilowatt]

PROBLEM SOLVED! Well almost. I have discovered that the problem is not antenna,feedlines,power supply, or anything cable related at all.It would appear that I have a problem with the 6m section of my FT-857 and the rest will be up to Yaesu to solve :x .The problem seems to be presenting itself as RF coupled to the DC rail inside the Yaesu.I can see it on a 'scope.I am still not sure what the freq relationship of 20m has to do with it or why 20m is fine without the 6m antenna connected but it probably has something to do with harmonics and bandpass filters etc.The problem only occurs when the Yaesu is connected to an antenna and turned even when I am using the Kenwood as a test TX'er.It still has me baffled as to how and why but I believe beyond a doubt the problem is related to a 6m TX problem I have. I heard a good opening on 6m today in the mobile and called on 50.125 USB. When I paused talking the power meter was reading 100 watts carrier.I was on USB. :shock: I unkeyed and the carrier went to zero. I keyed up but did not speak and all was well. As soon as I spoke the meter shot to 100 watts and stayed there as if I was on FM. The variable power output control has no effect on 6m at all regardless of mode. I think maybe I will save all the operating parameters and memories and do a complete CPU reset before I look at sending the rig back to Yaesu. I don't really have the money to do it right now anyway. At least I can save the info in a file and reload it back in a few seconds using the ADMS programming software.This has been a real head scratcher for sure and it just figures that the 6m section goes TU just as 6m is opening. :?