--IMA.Boundary.087936948
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Content-Description: cc:Mail note part
Hi Jim,
Sounds like a real problem!! I would suggest you start looking around
the beverage as well as at the beverage.
1. Do you have good connections at the impedance transformer? Maybe
swap out the UnUn for another to see if there is a bad solder joint.
Cold joints act like diodes. Maybe the ferrite is bad? I do know
that good ferrite can be cut and then clamped with a hose clamp
similar to the large split beads used on computer leads. Casting
defects do play like cold solder joints!
2. Are all the wire connections good along the beverage? Maybe there
is a defect in the wire hidden by insulation? Is the termination
resistor (if used) good and well connected? Is the miniground plane
at each end of the beverage OK and well connected?
3. If you use voltage relay switching along the feed line, check the
isolation capacitor(s), or swap them out. Check the power source for
defects, or just remove it temporarily.
4. If you can, provide an alternate feed line to the beverage just to
check out the quality of the hard line. Swap switch positions for
the beverage cables to make sure you have good switch contacts &
connectors in your switch box.
5. If the JA beverage is at the edge of transmit tower ground plane &
it is OK, then look on the other side of the EU beverage to see if there
is something else metal rusting to give diode effects, like a fence,
shed, green house, etc. (I assume you didn't do a perimeter wire around
the radials.) If you did, then maybe those connections near the EU
beverage are the problem and are far enough from the JA beverage to not
effect it?
6. Let your mind surf. I know it is frustrating, Read the repeater
freq. problem in middle of Dec 1996 QST. It is just after the editorial
on modifications called "demods". They never found why it moved
from 146.88 to 138 Mhz, but they changed tubes and tweeked circuits
until the problem disappeared! The cavities and their wiring were the
first suspects, but were OK all along. So maybe your beverage is OK and
something nearby is rotten beyond what I mentioned above?
7. Maybe a portable radio along the line peaks somewhere and points you
in the right direction?
Good luck and Happy Hunting.
I am only 1/2 mile from a 930 khz AM station 5KW days and 1KW nights
and have been lucky on 160 so far.....just a 2nd harmonic at 1860.
73 George, K8GG
PS: anyone have a noise cure for neighbor's SCR dimmers on lights?
I have one or two beyond the end of a beverage on Africa! In the
morning I hear great off the back side... good way to work FW2EH and
VKs..... but it gives me a fit when something like 9X or 5V is on and
the neighbors are still up! Now I turn our light off and kick in some
noise blanking in the transceiver. It does part of the job. Oh for
plain old resistors and incandescent bulbs!
______________________________ Reply Separator _________________________________
Subject: TopBand: Beverage Help
Author: jfenster@hpux.mesd.k12.or.us (Jim Fenstermaker) at BC_INTERNET
To: <topband@contesting.com>
Date: 12/3/96 7:01 AM
K9JF/7 wrote:
I just read some comments about beverage problems and I can relate. Last
weekend, I put up my 600' European beverage for this weekend's contest as
well as for the fabulous DXing this winter season. It is fed with 250' of
1/2 75 ohm hardline. I then turned on the RX and, low and behold, broadcast
stations every 10Khz! This condition is true only on the European beverage.
Neither the east coast beverage nor the JA beverage has this problem. Just
to the south of my QTH about 3 miles is a 10KW broadcast station on 1550 Khz.
Based on the configuration of my property, the European beverage runs about
70 feet from the shunt-fed tower. However, the JA beverage does the same.
I would like to tap the collective wisdom of the Lowbanders concerning this
condition. Where do I start??? I suppose I could try shorting the shunt on
the tower to see if there is some kind of coupling between the tower and
beverage. BTW, I did try ferrite cores around the connector at the RX end
of the feedline without any noticable difference.
Any additional advise would be welcome as Friday is drawing near!
73 Jim K9JF/7
Vancouver, WA
(snip)
--IMA.Boundary.087936948--
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Sponsored by Akorn Access, Inc & KM9P
|