Mike:
The shield of the coax is connected to a counterpoise, and the sloper is
grounded to my galvanized steel mast via a ground wire and a ground rod.
Based on what you say, then, I will not worry about the extra coax, at least
for now.
This is all a major learning experience for me, and I appreciate everyone's
patience.
I am replying to a number of posts privately here, but I will post replies
to the list if I think they might help others, and also because I want folks
to know that I am listening.
Thanks again, Mike, and all.
73 from Tom Behler: KB8TYJ
----- Original Message -----
From: "Mike Cozzolino" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, November 11, 2011 10:53 PM
Subject: Re: Need helping making sense out of contradictory SWR readings
> hi again tom, yes the broadcast station is messing up the
> analyzer. i can not use my mfj 269 here because of the a.m.
> broadcast and have talked to others that have found the same to be
> true. so forget the analyzer, and go by the swr bridge. leave the
> coax to your 160m antenna alone, 100 feet is nothing to even to
> consider. adjust the length of the 160m antenna and by the way what
> do you have the shield of the coax connected to? the shield at the
> feed point. you need to work against a tall tower or a counter
> poise. but like i was saying earlier tom the only to get a accurate
> swr reading is right at the feed point or through an electrical half
> wave or multiples of that. since you really can't do the latter then
> adjust for the best swr that makes the radio happy. the tw1 is a
> very poor device, it is not very accurate, and remember swr bridges
> have diodes and again the voltage that is coming down the feed line
> from the local broadcast will also effect the swr bridge. so put
> your radio at about 10 watts to override the broadcast effects. good
> luck, c u 73 mike
>
>
>
> At 07:00 PM 11/11/2011, you wrote:
>> Mike:
>>
>>You have a very interesting point here about local broadcast signals.
>>
>>I happen to live about a half mile from the tower for the only commercial
>>A
>>M radio station in our little Michigan town. ... It broadcasts on 1460 AM,
>>with a night-time power of, I believe, 1000 watts.
>>
>>Are you saying that this is what's messing the analyzer up?
>>
>>Again, just to be sure I'm understanding you, are you saying ignore the
>>analyzer, and just go with what my TW1 and TS590 meters are saying?
>>
>>Obviously, my 160 meter antenna is still too long electrically, so that
>>will
>>need to be shortened.
>>
>>But, here's another question: When we put up the 160 meter sloper, I only
>>had a 100-foot piece of RG8X coax to connect between the antenna and the
>>rig, which gives me about 40 feet of excess coax. ... Should I cut that
>>coax
>>to only what I need? Would that change anything?
>>
>>Again, you are giving me some very interesting observations here.
>>
>>73 from Tom Behler: KB8TYJ, Big Rapids, MI
>>
>>
>>----- Original Message -----
>>From: "Mike Cozzolino" <[log in to unmask]>
>>To: <[log in to unmask]>
>>Sent: Friday, November 11, 2011 9:30 PM
>>Subject: Re: Need helping making sense out of contradictory SWR readings
>>
>>
>> > hello tom, the analyzer is almost useless on 160 and 80m
>> > antennas. the reason is because you have so much broadcast signals
>> > coming down the feed line that the analyzer is all messed up. in
>> > areas where folks don't have the broadcast crap the analyzer does the
>> > fine job. so go by the swr bridge and ignore the analyzer. even a
>> > swr bridge is influenced by the length of the feed line, you could
>> > have a 1:1 some where along the coax where the swr is really much
>> > higher. the only way to use an swr bridge is through a electrical
>> > half wave to the antenna or with the swr bridge at the feed
>> > point. you can also use multiple electridal half waves between the
>> > swr bridge and the ant. take care, c u 73 mike
>> >
>> >
>> >
>> > At 05:28 PM 11/11/2011, you wrote:
>> >>Hi, folks.
>> >>
>> >>Well, I have managed to get hold of an MFJ 259B antenna analyzer to
>> >>help
>> >>try
>> >>to figure out what is going on with my 80 meter and 160 meter sloper
>> >>antennas that we put up a few weeks ago.
>> >>
>> >>However, when taking some preliminary readings with the analyzer
>> >>tonight,
>> >>and comparing them against what my TW1 watt meter and the SWR meter on
>> >>the
>> >>TS590 say, I am getting very confusing results.
>> >>
>> >>Let me give a few examples:
>> >>
>> >>On 80 meters, my sloper has an SWR of about 5 to 1 on the top and
>> >>bottom
>> >>of
>> >>80 meters, with a dip of 1.0 to 1 around 3.887 mhz. But, when we put
>> >>the
>> >>analyzer on the antenna, it shows the lowest SWR to be about 1.3 to 1
>> >>at
>> >>3.887 MHZ, but the SWR's skyrockets quickly on either side of that null
>> >>to
>> >>infinity on the lowest part of the band, and to over 8.1 to 1 on the
>> >>top
>> >>of
>> >>the band.
>> >>
>> >>With my 160 meter sloper, my lowest SWR is about 5 to 1 at the very
>> >>bottom
>> >>of the band, according both to my TW1 and the TS590 SWR meter, but the
>> >>needle on the analyzer doesn't even budge when tuning through the
>> >>entire
>> >>band, and stays up at some ungodly figure of an SWR of about 20 to 1.
>> >>
>> >>I just checked for a short on my coax feed lines, and there does not
>> >>appear
>> >>to be any problem there.
>> >>
>> >>We are using fresh batteries in the analyzer which were just bought
>> >>tonight.
>> >>
>> >>Are we perhaps not adjusting the analyzer correctly?
>> >>
>> >>I am sure that, to some, all of this seems very elementary, so please
>> >>bare
>> >>with me while I do some learning here.
>> >>
>> >>73 from Tom Behler: KB8TYJ
>> >
>
|
