I'd first while telling t hem the cause be offering my expertise to assist them
in correcting the issue. This will keep the realtionship open and allow them
to consider you're assistance since your the complaintant. Often though,
people install cheap dog fences from WalMart that can only be fixed by spending
a several few hundred on a new one. I hope this isn't the case because there's
not a lot you can do unless you involve the FCC and then you get a pissed
neighbor.
Good luck!
Cam
WA4JKW
------Original Mail------
From: <towertalk-request@contesting.com>
To: <towertalk@contesting.com>
Sent: Fri, 01 Feb 2008 12:00:28 -0500
Subject: TowerTalk Digest, Vol 62, Issue 1
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Today's Topics:
1. Re: Looking for a good small coax for 160, 75 and 40 (Jim Brown)
2. RFI source found - sort of (Tony)
3. Re: Interaction (john@kk9a.com)
4. Re: RFI source found - sort of (Rob Frohne)
5. Re: Looking for a good small coax for 160, 75 and 40 (K8RI)
6. Baluns (Tim Holmes)
----------------------------------------------------------------------
Message: 1
Date: Thu, 31 Jan 2008 09:02:38 -0800
From: "Jim Brown" <jim@audiosystemsgroup.com>
Subject: Re: [TowerTalk] Looking for a good small coax for 160, 75 and
40
To: "towertalk@contesting.com" <towertalk@contesting.com>
Message-ID: <20080131170246.3537958381@gw1.nlenet.net>
Content-Type: text/plain; charset="us-ascii"
On Thu, 31 Jan 2008 04:17:34 -0500, K8RI wrote:
>like something more flexible like RG8-X, but RG-8X has relatively poor
>shielding.
Hang on a minute. RG-numbers for coax are VERY generic -- there are at least
a dozen cables that fit the RG8X designation, and they are different. RG8X
is simple an intermediate SIZE between RG58 and RG8. LMR240 is simply
another RG8X, and, IMO, a very nice one. The Wireman sells at least two
RG8Xs, and they are different. I've used both his CQ118 and a Belden RG59
designed for transmitting on dipoles running 1kW and never had a problem,
even when on a part of the band where the VSWR was pretty high.
>I'll be using crimp connectors and flooded heat shrink for good mechanical,
>waterproof connections. I'm just tryin to get away from the weight of the
>RG8 and LMR 400 cables for these antennas.
I've got high dipoles that require about 150 ft of coax. When I was deciding
how to feed them, I spent a lot of time with NEC studying the antenna
impedances, and TLW computing how much loss various feedlines would
contribute. Taking off-resonance operation into account, the difference
between RG8 (or RG11) and RG8X (or RG59) can be 1.5-2 dB on 160-40M, even
more with higher VSWRs. My 80/40 fans come pretty close to a match on 30M
and 17M, so the fact that I've got RG11 on them rather than RG59 is probably
worth 2-3 dB on those bands. When I had less robust supports for them, I
used RG59. My high 20/15/10 fan dipoles look like 50 ohms, so I'm feeding
them with RG8.
If we want to make intelligent decisions about which coax to use, we need to
stop thinking about RG numbers and start paying attention the construction
and the loss specs of these cables. Belden makes several dozen RG59s, and
they are very different from each other. They also make nearly a dozen RG6s,
also very different from each other. Some are designed for transmitting,
some only for receiving. Some have thin foil shields, some foil with thin
braid, some foil plus heavy braid. Likewise, center conductors vary both in
size and metal, and the dielectrics and outer jackets are different.
We also need to re-think our reliance on 50 ohm cables for 75 ohm antennas.
Thanks to interaction with the earth, a LOW dipole is usually closer to 50
ohms than 75 ohms, but a HIGH dipole is likely to be a much better match to
75 ohm cable. The LOSS in that cable depends on the match between the coax
and the antenna, NOT the match between the transmitter and the antenna, AND
we can use a tuner to match the feedline to the transmitter.
Also, there's a great piece by AI1H in the ARRL 6th Antenna Compendium
showing that below 1 GHZ, loss in coax is primarily copper loss, not
dielectric loss, so coax with a robust low resistance shield will have less
loss than one with a thin high resistance shield, especially on the lower HF
bands. Further, the SHIELDING effectiveness is directly related to the
RESISTANCE of the shield at the frequency of interest.
There is some excellent stuff in these Antenna Compendiums. I've learned a
lot from studying them.
73,
Jim Brown K9YC
------------------------------
Message: 2
Date: Thu, 31 Jan 2008 16:28:44 -0500
From: Tony <dxdx@optonline.net>
Subject: [TowerTalk] RFI source found - sort of
To: towertalk@contesting.com
Message-ID: <00ac01c86450$425531e0$6601a8c0@TOSHIBA>
Content-Type: text/plain; format=flowed; charset=iso-8859-1;
reply-type=original
All,
I was able to track down the general location of an RFI problem I've
been hearing since December. It's in the vicinity of 3 new homes on a
cul-de-sac not far from my QTH. I'm told the pulse noise sounds like the
RFI from an invisible electric fence.
At this point, it's hard to tell which home it's coming from with the HF
mobile because the signal strength is overwhelming at the location. I'll
have to get up close with a portable AM radio; I'll probably need some
shielding around it.
Wish I knew exactly what the noise was; I'd hate to 'accuse' a neighbor
of causing RFI and have it turn out to be the power company. I have a
recording if anyone is interested.
The question is, what to do in the worse case scenerio if the home owner
decides not to take action to remedy the problem? Anyone on the
reflector been through this before?
Apologies for the off-topic note -Please reply direct...
Tony -K2MO
------------------------------
Message: 3
Date: Thu, 31 Jan 2008 22:02:32 -0000
From: <john@kk9a.com>
Subject: Re: [TowerTalk] Interaction
To: <TOWERTALK@contesting.com>
Cc: andersonww5l@sbcglobal.net
Message-ID: <000501c86454$fc371d40$7df90641@KK9A>
Content-Type: text/plain; charset="Windows-1252"
I think the biggest problem is the antenna was much too low and it was
picking up the local noise more than the DX signal.
To: Mike Bragassa <bragassa@consolidated.net>
Subject: Re: [TowerTalk] Interaction
From: Tom Anderson <andersonww5l@sbcglobal.net>
Date: Wed, 30 Jan 2008 08:00:27 -0800 (PST)
List-post: <mailto:towertalk@contesting.com>
Mike:
Tnx. kept missing some stations on 40/80 that were in
the nulls of the dipole.
It reminds me of a situation years ago in the early
1990s when VP8SSI South Sandwich was activated. I had
worked them on 20m when they first came on, but my XYL
hadn't worked them yet. It was the last night of the
DXpedition and they were shutting down in a few hours.
To complicate matters we were in the midst of moving
from one QTH to another and the shack was the last
room in the old house I had scheduled to be
disassembled, at least not until my XYL had worked
VP8SSI.
So my XYL Cheryl (WY5H) and I went over each night
around 0600Z or so to try them on 40 or 80.
Not thinking I had worked them fine on 20m with a beam
no problem since I knew the leader Tony WA4JQS fairly
well, but Cheryl was busy taking kids back and forth
to school, etc. and could only get on the radio at
night.
Anyway we were over there on the last night and I
didn't think at the time that VP8SSI was actually in
the nulls of our 40/80 inverted vee at 40 feet.
Cheryl could just barely hear VP8SSI so she kept
calling them, not sure if they had heard her.
Finally on the DX cluster about 3 a.m. CST (0900Z)one
station posted a message if VP8SSI was being heard in
North Texas, and we quickly posted a msg where they
were and where they were listening. Ok, this station
came back about 30 seconds later and said he had just
worked them phone no problem. Well I sent him a
message that we were having trouble hearing a
confirmation of Cheryl's 2x2 report to VP8SSI. A
couple minutes later he came back and said for her to
quit calling and giving her report, she was in the log
5 or six times hi hi. She did get a card by the way.
Cheryl thought they had confirmed her, but with the
QRN, etc. it was difficult at best to get a
confirmation back.
So much for being in the nulls of a dipole.
73 de Tom, WW5L
------------------------------
Message: 4
Date: Thu, 31 Jan 2008 14:51:52 -0800
From: Rob Frohne <frohro@wallawalla.edu>
Subject: Re: [TowerTalk] RFI source found - sort of
To: Tony <dxdx@optonline.net>
Cc: towertalk@contesting.com
Message-ID: <1201819913.7592.70.camel@frohro-d600.wwc.edu>
Content-Type: text/plain
Hi Tony,
I suggest you take an AM or SSB VHF (or UHF) receiver and a directional
antenna to your neighborhood. You can pin point it much better with
that equipment than you can with your mobile.
I usually don't start worrying about what to do if they aren't helpful
until they actually aren't. Be friendly. Perhaps it is bothering them
as well. Sometimes you can offer to purchase them a replacement device
that doesn't make the QRN.
Good luck! 73,
Rob, KL7NA
On Thu, 2008-01-31 at 16:28 -0500, Tony wrote:
> All,
>
> I was able to track down the general location of an RFI problem I've
> been hearing since December. It's in the vicinity of 3 new homes on a
> cul-de-sac not far from my QTH. I'm told the pulse noise sounds like the
> RFI from an invisible electric fence.
>
> At this point, it's hard to tell which home it's coming from with the HF
> mobile because the signal strength is overwhelming at the location. I'll
> have to get up close with a portable AM radio; I'll probably need some
> shielding around it.
>
> Wish I knew exactly what the noise was; I'd hate to 'accuse' a neighbor
> of causing RFI and have it turn out to be the power company. I have a
> recording if anyone is interested.
>
> The question is, what to do in the worse case scenerio if the home owner
> decides not to take action to remedy the problem? Anyone on the
> reflector been through this before?
>
> Apologies for the off-topic note -Please reply direct...
>
> Tony -K2MO
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Message: 5
Date: Fri, 1 Feb 2008 01:06:27 -0500
From: "K8RI" <K8RI-on-TowerTalk@tm.net>
Subject: Re: [TowerTalk] Looking for a good small coax for 160, 75 and
40
To: <TOWERTALK@contesting.com>
Message-ID: <002501c86498$95369cd0$6600a8c0@SecondOne>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Subject: Re: [TowerTalk] Looking for a good small coax for 160, 75 and 40
> My thought are what freq. are you operation on ? Also how much loss are
> you
As the subject line says, 160, 75, and 40.
The dielectric is thick enough, but there might be two problems. One would
be arcing across the end of the dielectric so trimming the foil back to give
plenty of space in the connectorshould help. The other potential problem is
the power handeling capability of the small center conductor.
> willing to have ? Yes there are alternatives to LMR-400 and you can look
> at
> options, but you need to answer your needs first other than weight etc.
400 is relatively light compared to the older coax cables being Copper
plated aluminum center conductor and foild with single braid covering, but
it's stil heavy and it's also stiff. As the slop-ers are near 95 feet on
the top end that leaves a lot of coax hanging down and over to the tower.
This is quite a bit of wind load and that stuff can really swing around. in
50 to 70 MPH gusts. Also in spring and fall, ice is quite common. The LMR
and CNT 240 are strong enough, but only testing will tell if it'll stand up
to the power and voltage. On 75 the SWR will probably get as high as 3:1
while on 40 I doubt it makes 2:1.
73
Roger (K8RI)
>
> On Jan 31, 2008 3:17 AM, K8RI <K8RI-on-TowerTalk@tm.net> wrote:
>
>> I have some LMR 240 as well as CNT-240 which works quite well. Running
>> the
>> legal limit on these bands is right at the limits for these cables, but
>> they
>> are light and work well for dipoles as well as half wave slopers. OTOH
>> I'd
>> like something more flexible like RG8-X, but RG-8X has relatively poor
>> shielding. OTOH it might work quite well for these installations. And
>> 8X
>> is *inexpensive*
>>
>> I'll be using crimp connectors and flooded heat shrink for good
>> mechanical,
>> waterproof connections. I'm just tryin to get away from the weight of
>> the
>> RG8 and LMR 400 cables for these antennas.
>>
>> Any thoughts?
>>
>> Roger (K8RI)
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>
------------------------------
Message: 6
Date: Fri, 1 Feb 2008 09:43:30 -0500
From: "Tim Holmes" <w8tahradio@gmail.com>
Subject: [TowerTalk] Baluns
To: towertalk@contesting.com
Message-ID:
<236403920802010643o66fad696p4b403643761a190b@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hi folks:
Im in the final design stages of my new dipole for home -- the current
plan is for an 80m dipole fed with window line -- im still refining
my modeling, but right now im looking at between 18 and 21 meters on
each half. IM wondering about the balun....
this morning one of the guys in the club asked if i was looking for
current or voltage balun (I have no idea) and others have suggested 20
turns of coax on a 2L bottle to make a choke balun --
it will be attached to my LDG PRO200 tuner and need some way to go
from coax to window line -- any and all input welcome!
TIM
--
Tim Holmes
W8TAH - Amateur Extra Operator
Medina County AEC
Skywarn Advanced Storm Spotter Certified
StormNet Chase 9
------------------------------
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