[Antennas] Distortion problem on quad while trying to work VP6

2002年3月21日 05:46:51 -0500

At 08:18 AM 3/20/2002 -0600, [email protected] wrote:
>Marty,

I also could be a bad connection like a joint or connector with corrosion 
that is causing some rectification that doesn't show up when 
receiving. Check all your coax connectors and any screw type connectors, 
starting outside. It rarely is a soldered joint, but is possible. It also 
could be a metal guy wire connection or a nearby wire or metal object such 
as a metal drain pipe that is picking up the RF, partially rectifying it 
and reradiating distortion and harmonics. It could be power lines picking 
up the RF and rectifying it and reradiating it, but unlikely, as an 
imperfect joint would cause problems for the power company including noise 
which you could pick up. It is more likely it is a guy line on a pole that 
is picking up the RF. Check to see if any of them are in your RF 
field. See if you can pick any harmonics with a VHF hand held while you 
are transmitting.
On the balun, if you have one which has a core saturating, try reducing 
power and see if the disortion goes away.
>If you are using a balun on the quad, the balun may be the source of your
>problems.
>>If baluns are run saturated as can happen with too much power, they will 
>act as
>non-linear devices and create all sorts of IMD. If they are run saturated for
>a while, the composition of the core changes permanently and they can 
>cause all
>sorts of IMD even when used later with reduced power.
>>Of course, if you are not using a ferrite core balun on the quad, the problem
>is somewhere else. I doubt seriously that power lines could be causing this
>problem.
>>Frank Kamp
>K5DKZ
>>>Marty Blaise AG5T wrote:
>> > I discovered why I am not breaking any VP6 pileups (other than they are
> > just so huge) - I went up band on 15 meters ssb and got into a qso and was
> > told my audio had severe distortion. Troubleshooting -- I have a gemquad
> > 5-band antenna up at 34 feet. Power lines behind house - they run
> > north-south. Tower is aprox 50 feet from the power lines, right behind
> > house (bracketed to house eave). Antenna is pointed sw, into power lines.
> > That's not exactly paralle but could be close enough for problems. Could
> > this be some type of interaction with the power lines? I'm going to try
> > turning the antenna due south so it puts the quad at right angles with the
> > power lines, then try to retune and see what happens. -- The other thing
> > happening is this - you can use the tuner to get a 1-1 swr but as soon as
> > you release the key when tuning, the swr needle quickly jumps all the way
> > back to the right and then goes back to the left, so I'm guessing there is
> > pretty bad feedback somewhere. -- I'm now trying to work the vp6 with a
> > 40-meter delta loop tuned for 15 meters with 100 watts so obviously my odds
> > aren't too hot right now. -- I worked XR0X on 12 meters the other day so I
> > know I should be able to get a signal to VP6. Whether I can break the huge
> > pileups is another story, but I'd at least like to think I did everything I
> > could to get a good clean 100 watt signal in my best efforts. -- If anyone
> > has any troubleshooting tips they might offer I'd be glad to hear them.
> > Rather than complain about not getting a new country, I think I would like
> > to concentrate on getting the most of the station setup I have available to
> > me. By the way, when I switched to the delta loop I was told me signal was
> > weaker, but without any distortion. (I worked Tromelin a few years ago on
> > that loop on 20 meters so I know you can use alternate antennas if you give
> > it a shot.)
> >
> > Thanks. Marty Blaise, AG5T
> >
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73, Chas, W1CG