Carter,
Your two feedlines are WAY off from being balanced.
Feedlines don't have to be perfectly balanced.
10% is good enough. Even 20% probably isn't too bad.
Yours is 44% out of balance. That needs to be addressed.
You can place a 50 Ohm imbalance at the output side of your JVM and try it.
Why not? You can place a 1:1 balun between it and the JVM if you like.
If you have a piece of coax 10' long than you have a 1:1 currant balun for
the high bands.
Just coil it about 5 or 6 turns, about 6" in diameter.
Tornado was an EF5. The movie "Twister" showed a cow flying. It was based
on a true event (the cow flying, not the whole movie - hi).
You asked us to suggest things to try.
Yet you reject some of the stuff because you can't see why it would make any
difference.
Man, I wish I had a dollar for every time in my life where something that
shouldn't make any difference turned out to be the culprit.
You have to try stuff. All kinds of stuff. Eventually something will cause
the problem to dramatically change. When that happens, that gives us the
next clue as to what the ultimate source of the problem is.
It's a tough problem. Finding it obviously is not easy.
Yaesu hasn't had white panels for 30+ years, have they?
Must be an FT-107 out of the late 70's, or early 80's.
It would be nice to try as new of a radio as you can find - at least out of
the mid 90's.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Carter
Sent: Saturday, May 17, 2014 11:57 PM
To: tentec@contesting.com
Subject: Re: [TenTec] Eagle problem?
On 5/15/2014 5:25 PM, Rick - DJ0IP / NJ0IP wrote:
> WOW, lots of data now.
>
> For a while I was beginning to sway to the side of the Pin-1 > problem.
However considering all of the new data you have given us, I > am leaning
strongly to the transceiver possibly being defective, and > second in line
is common mode current.
>
> The best thing would be to find someone with an identical transceiver >
and just swap it. This may be impossible.
A bit unlikely. However, a few years ago, I used a Drake TR-7 on SSB at full
power (antenna and everything else the same) and it worked fine.
Caveat: I am sure that the TR-7 is a lot less "computerized" and
microprocessor dependent than the Omni VI. Maybe I should have kept the
TR-7. :-) A good friend and ham neighbor offered to bring over an
older Yaesu (model = ? but has a white panel). It's worth a try.
> You didn't specify how you measured the current in the two wires of >
the openwire. Do you have an RF Ammeter in-line with them, are you > using
lamps, or how are you measuring? How much imbalance is there?
Using a Palomar Engineers clamp-on RF ammeter. 0.9 A in one leg, 1.3 A in
the other leg as measured yesterday on 20 meters.
> If we knew for sure that it was not the transceiver, my next >
suggestion would be to try two things on the antenna side.
>
> <> First, I would disconnect the feedline from the dipole and connect >
it to a 50 Ohm dummy load. Then match it in the shack with the JV >
Matchbox. If the problem continues, it is probably something back at > the
house. Unless it's the feedline. So you might want to check the >
feedline. Put a 4:1 balun at each end, connect a 50 Ohm dummy to one >
side and an analyzer to the other. If no analyzer available, check > it
with a transceiver running low power. Check 80m, 20m and 10m to > make
sure it's the same SWR across all bands. Note: Most 50 Ohm > dummy loads
rise slightly in SWR on 10m so don't let that trouble > you.
Interesting experiment but:
1) Don't have any 4:1 baluns
2) Any issues with the balanced output of the JV Matchbox to an unbalanced
dummy load? (Cantenna)
> <> Second, only when you have a dual-RF Ammeter inline so that you > can
monitor it, I would record exactly how much current is in each > leg with
10w (a little more if you can), then begin shorting the leg > of the
antenna that over the house. I would shorten it in increments > of 6
inches. Check RF current balance after each adjustment. WHEN I > SAY
'SHORTEN', I do not mean cut; simply fold it back from the > insulator and
wrap around the rest of the wire, fixing it with a > wire-tie. The goal is
to get the current close to equal (less than > 10% difference) in each leg.
If your problem is really CMC, that > just might solve it.
Again, an interesting experiment that sounds like it would indeed balance
the current in each leg of the window line. However, I put up the antenna
when I was 49 and now at 69, I really don't trust myself to do any climbing.
> OTHER THINGS TO TRY:
>
> <> Replace the coax between the transceiver and the JV Matchbox. Try >
it both with and without the RF choke.
>
> <> Replace the JV Matchbox with something else. Use a 1:1 current >
choke between an asymmetrical matchbox and the openwire and try it on >
80m. Don't use the built in balun on any matchbox. There are very > few
on the market that have the correct type of balun. Use a balun > you know
will work. This is the last thing I would suspect, but > sometimes... hey,
in Oklahoma we've even seen cows fly. Ya never > know until you try.
When the cows were flying, was that an EF4 or EF5 tornado???
> <> Try another power supply.
Not sure what effect this would have. Using the TT 961 PS that I got with
the rig. OTOH, anything is possible.
> <> Move your transceiver out into the back yard and run your > openwire
to it. Try to keep the feedline at a 90 degree angle to the > dipole.
>
> One thing for sure: there's always a reason. You just have to keep >
trying stuff until something shouts out at you and gives you a clue.
Right now, I am leaning towards the radio itself. I've gotten a bit more
info since this all started but don't want to post it to the reflector for
fear of stepping on toes (NOT the toes of anyone that has posted here. If
you want to give me your direct email, I can share that info).
> One thing for sure Carter, you have one of the most interesting >
problems we've seen here in a long time!
Well, I posted this same problem here 2 or 3 years ago and got maybe one
response, so why it is generating all these comments now is a good question.
<grin>.
Let me take this opportunity to thank you and all the others for their
thoughts, ideas and suggestions.
73,
Carter K8VT
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