Topband: 160m Activity Night

[Jim Garland]

Europe is tough in New Mexico, but last evening for about an hour after
sunset (0100Z-0200Z) I worked G3YRO, SM5EDX, and OR18TLS. As often happens,
signals were barely copyable when I worked them, with deep QSB, but got
stronger later, peaking 569-579. W7RH lives in a neighboring state and
always seems to hear better than I do. Pretty humbling, actually! I was
listening on a 720 ft beverage and transmitting on a 70ft base-loaded
vertical with sixty 120 ft radials. Radio was a Flex 6500 and hb amp. Band
was nice and quiet for a change.
73,
Jim w8zr

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of WILLIAM
HILL
> Sent: Thursday, December 12, 2019 12:19 PM
> To: topband@contesting.com
> Subject: Topband: 160m Activity Night
> 
> Last evening like the past month or so I've been having trouble hearing
Europe. I heard
> N2MS trying to work G3YRO but I couldn't hear Roger. Sigh...
> 
> Bill/W3WH
> _
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Re: Topband: Updated K9YC common-mode choke PDF now available

[Jim Garland]

Guy, I agree in principle that coax with a stranded center conductor will be 
more flexible than coax with a solid conductor, although in applications where 
there is mechanical stress on the coax, coax with a solid steel core will be 
significantly stronger than its stranded counterpart.

However, I think you are overstating the supposed weakness of RG142b, which 
appears to be identical to RG400, except for having a silver plated steel inner 
conductor. As a test, I took an eight inch length of new RG142b and bent it in 
a U-shape (about a 1/4 inch diameter) back and forth sixty times, measuring the 
continuity between the ends. Afterwards, I cut away the shield and dielectric 
to expose the solid inner conductor, which showed no perceived wear or damage. 
Afterwards, I continued to flex the bare inner conductor with the dielectric 
and shields cut away and it finally broke after twenty additional flexes (70 in 
all). Frankly, I was surprised at how well the coax held up under this abuse. 
It would be interesting to conduct the same test with RG400. Note that both 
types of coax are specified for a 1 inch minimum bending radius, which I 
believe to be an excessively conservative rating.

 

My little test greatly exceeded demands placed on the coax in any normal 
application, such as winding a choke or toroid, or routing RF around an 
amplifier. I have also used RG142b jumpers in my station for many years with no 
problems. However, the coax is relatively stiffer than, say, RG58, so I'd guess 
the more flexible RG400 is better for that purpose. Because of its strength, 
RG142B would be desirable for long outdoor runs where the coax is 
self-supporting. Basically, however, both RG142B and RG400 are very rugged and 
excellent for almost any amateur use, and both are vastly superior to RG58 and 
its variants in almost any application.

73.

Jim W8ZR

 

From: Guy Olinger K2AV [mailto:k2av@gmail.com] 
Sent: Sunday, February 03, 2019 07:17 AM
To: MU 4CX250B
Cc: Jim Brown; Mike Waters; topband@contesting.com
Subject: Re: Topband: Updated K9YC common-mode choke PDF now available

 

I would not repeatedly bend any coax with a solid center conductor. Which 
leaves RG142 for permanent routing. Jumpers to and from back of TXR and amps 
etc are always RG400. Windings on cores are always RG400. RG400 shield weave 
and center conductor made of very fine strands of silver coated copper. 

 

On K9YC’s latest cookbook he only specifies RG400. Do it right, do it once, 
happily keep it. 

 

RG400 can usually be had in useful lengths off EBay for half retail or better.  
The stuff almost never goes bad. So these are safe buys.

 

There are a lot of jumpers listed. I can sometimes get the stuff with a needed 
connector already installed. 

 

73, Guy K2AV 

 

On Wed, Jan 23, 2019 at 8:07 AM MU 4CX250B <4cx2...@miamioh.edu> wrote:

Very interesting, Jim. I wasn't familiar with RG-400, but I've used
RG-142B for years. I compared the specs and found they're virtually
identical, the only significant difference being that RG-400 has a
stranded center conductor, while RG-142B has a solid steel
(silver-plated) center conductor. They both have a 1 inch minimum
bending radius (for repeated bending), but I imagine the RG-400 Is
slightly more flexible and the RG142B is slightly stronger. At GHz
frequencies, the RG142B has slightly lower loss. They both have
excellent high temperature properties. If you buy it new from a
distributor, either will cost about $5 a foot.
73,
Jim w8zr

Sent from my iPad

> On Jan 22, 2019, at 6:42 PM, Mike Waters  wrote:
>
> -- Forwarded message -
> From: Jim Brown 
> Date: Mon, Jan 21, 2019, 11:36 PM
> Subject: Re: Topband: Inverted L improvements - Part 3 (now with data)
> To: Mike Waters 
>
> After nearly a year of work, I published a new "cookbook" last month.
> For reasons that are detailed in the accompanying text, I no longer
> recommend coax wound through multiple cores.
>
> The short answer for "why not?" is that it's simply not practical to wind
> chokes that way and get anything close to the same result every time --
> turns must go through the core in the same order, a scrambled turn cancels
> a turn, turn diameter matters a lot, and so on.
>
> The new cookbook uses RG400, 12-2 Teflon/silver pairs, or 12/2 THHN or NM
> pairs, all tightly wound around a single core.  There are recommendations
> for chokes in series to increase power handling. There is also data for the
> new 4-in o.d. supersized toroids, which are great for 160M.
> k9yc.com/2018Cookbook.pdf
>
> 73, Jim K9YC
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Re: Topband: Rather use N-type (was Re: The answer to PL-259 soldering/reliability problems)

[Jim Garland]

About twenty-five years ago I started replacing many of my PL259
connectors with N-connectors. I did this mostly because my VHF/UHF buddies
convinced me that the impedance bump of an N-connector was less than that of
a PL259. Also, about the same time I started using mil-surplus Transco
remote coax switches and relays, all of which used N-connectors, and which
were good up to 1GHz. After 15 years of problems, however, I've now purged
N-connectors from my station and have a bunch of Transco relays and coax
switches I'll sell cheap. I've gone back to PL259s and have recently
discovered the new, fancy, DXE "second generation" crimp/solder type PL259s,
which I think are wonderful.
My problems with N-connectors are (1) repeated intermittent
connections in frigid weather with the center pin making poor contact to its
mate. This usually affected only receive signals. (2) flashing over the
center pin/shell at QRO power levels, especially with accidental high SWR.
(3) Weak mechanical durability with flexing and twisting the cable. (4) A
continuing hassle installing the connectors, mostly tinkering with the
braid, having to measure exactly to get the pin to protrude the right length
from the end of the connector, and getting exactly the right amount of
small-diameter solder to flow into the center pin so it doesn't jam up in
its Teflon sleeve. (I realize that practice makes perfect, but in my case
months would go by between connectors and each time I'd have to relearn the
whole assembly process.)
The classic Amphenol UG-21 "N-connector" has six pieces: center pin,
shell, flat washer, metal cone, rubber gasket, and end nut. There are many
things that can go wrong in assembling one of these connectors, and I've
done them all. I realize there are newer designs, with crimp connectors and
fewer pieces. I've tried some of them and while they're somewhat easier  to
install, they're still a nuisance, particularly if the wind is blowing and
you're dangling from a safety belt up on the tower. 
In the meantime, like Tony, I've had decades go by with no headaches
from PL259s. A well installed PL259 is very rugged, will handle much more
power than you should ever be running, and - with the new designs - is very
easy to install. Their much-disparaged impedance bump may be a consideration
at 2m and above, but not at 6m and below. That said, it is important to tape
PL259s properly to seal them from the elements. Scotch 33 or Scotch Super 88
is mandatory for outdoor use, and you should follow closely the instructions
on how to use the tape properly to ensure decades of reliability. If you've
not read the instructions you may be in for a surprise.
73,
Jim W8ZR

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of N2TK,
Tony
> Sent: Thursday, December 06, 2018 08:31 AM
> To: 'GEORGE WALLNER'; topband@contesting.com
> Subject: Re: Topband: Rather use N-type (was Re: The answer to PL-259
> soldering/reliability problems)
> 
> I have been using PL-259 connectors forever. I have switched to crimp
> connectors when I need to make up a new cable. No sense replacing the
> soldered connectors if they are working fine. ThePL-259 is a low loss,
easy
> to assemble connector for up to at least 6M (nothing higher in frequency
> here) that makes good contact and are easy to seal with rescue tape
followed
> by Scotch 33+. Some of my PL-259's have been in use outside for 40 years
and
> still look good and work well. I hope manufacturer's don't change.
> 73,
> N2TK, Tony
> 
> -Original Message-
> From: Topband  On Behalf Of GEORGE WALLNER
> Sent: Thursday, December 06, 2018 9:13 AM
> To: topband@contesting.com
> Subject: Re: Topband: Rather use N-type (was Re: The answer to PL-259
> soldering/reliability problems)
> 
> Greg,
> I completely agree. For all my outdoors applications I use N connectors.
> Unfortunately, amateur radio gear (even seriously expensive gear) is still
> built with SO-239 connectors which perpetuate the use PL-259 male
> connectors. As a result, my station and my DXpedition gear contain both,
> necessitating the use of adaptors. How do we convince manufacturers to
> change?
> 73,
> George
> AA7JV/C6AGU
> 
> 
> 
> On Thu, 06 Dec 2018 17:00:53 +1300
>   Greg-zl3ix  wrote:
> >
> >
> > I continue to be mystified by the fact that the amateur radio
> > community insists on using PL259 connectors. N-type are much more
> > reliable (used by professional communicators), low cost, can be
> > crimped easily and quickly and have a well-defined impedance right up
> > into GHz frequencies.
> >
> > Back in 2005 I started having contact problems with the connector on
> > my SteppIR 3-element. There was a thin layer of oxide that built up
> > around the centre pin of the PL259. I had had similar problems with
> > other connectors around my shack. I decided to change my entire
> > station, including the SteppIR, to N-type, and have never looked back.
> >
> >
> > 

Topband: Observations on a base-loaded 70 ft vertical

[Jim Garland]

Hi All,

I have a 70ft 80m self-supporting vertical, which I've baseloaded to bring
it down to 160m. The antenna is about 800 ft. from my shack, fed with buried
hardline. The vertical has sixty 120 ft radials fanning out over the desert
floor.

 

When I built the baseloaded inductor I didn't have any suitable AirDux coil
stock on hand, so I experimented using a toroid. I wrapped two 2.25 inch
diameter T-43 cores together with fiberglass tape, and wound the wrapped
core with thin RG316 coax. RG316 is thin, flexible, high-temperature coax,
with a silver-plated shield, about 0.1 in in diameter. I shorted the inner
conductor to the shield, so I was just using the coax as flexible, high
temperature wire. I use a shunt coil of about 2 uH (23 ohms reactance at 1.8
MHz) made of plated copper tubing between the toroid and ground, reasoning
that the RF current at this low Z end of the toroid will be pretty large.

 

I didn't know how well the toroid would work in this application, but the
assembly came to resonance very smoothly and seems to work well to 2000W. I
use a DPDT vacuum relay to switch in the 160m toroid from my shack. As shown
in the photos, (links below) the assembly is very compact. I mounted it in
an inexpensive (about $22) NEMA waterproof enclosure.) To give a sense of
the scale, one photo shows the toroid and shunt coil breadboarded on a piece
of plastic and resting on a sheet of teflon at the base of the vertical (to
keep it from arcing to the grounded radials.)

 

http://www.w8zr.net/160amplifier/images/160m%20toroid%20assembly.jpg

 

http://www.w8zr.net/160amplifier/images/160m breadboard test.jpg
 

 

Here are some observations about this hookup. As expected, the toroid and
wire get pretty hot at QRO power levels, although I didn't try to measure
the temperature. (It takes two people to do this: one to key up the
transmitter and a second to hold the IR thermometer.) However, intially the
toroid rested on an acrylic (plexiglass) post, but the post got hot enough
to soften and deform. I swapped the plexiglass for a ceramic post with no
further problems. There's no evidence of core saturation, and the SWR is
unchanged over the full power range. There's no visible effect of heating on
the wires either, all of which use teflon insulation. I don't know how much
power I'm wasting in heating the toroid, but I'd guess it be about 100-200W
at full power, or roughly ten percent of total power. I don't know how that
power loss would compare to using an air-wound coil. I can argue it both
ways: an air wound coil wouldn't have any core losses, but the resistive
loss in the wire would be several times greater than that in the toroid.

 

In this sort of hookup, one has to be very careful about high voltage
insulation. With my first toroid, I spaced the turns out around the core,
and at about 500W the bottom of the winding flashed over to the top of the
winding, even though the wire had teflon insulation. Now the winding uses
only about 2/3 of the available core space, and I have an extra length
(probably unneeded) of teflon sleeving over each end of the winding.

 

The little coil wound of stranded 12 AWG white wire (with orange stripe)
visible in the photo at the HV end of the toroid provides about 0.6 uH of
inductance. Its purpose is to fine tune the inductance, since the toroid
doesn't lend itself to fine adjustments. For this vertical, the shunt coil
is about 2uH and the toroid is about 23uH. On 80m, the native 2:1 bandwidth
on 80m is about 400 kHz (1.3 SWR minimum at 3550 kHz), while on 160m it is
only about 35 kHz, with a minimum 1.15 SWR at 1815 kHz.

 

There are only four connections to the NEMA enclosure: RF input, Output to
the vertical, Ground, and +26V (approx) to power the vacuum relay. The
arrangement is exceptionally convenient and compact, and can be connected to
the vertical in five minutes. I use a 24V wall wart to power the relay, with
a toggle switch and LED indicator back in the shack.

 

I have a question for the antenna gurus on the list. I know base-loaded
verticals have a bad rap compared to verticals with top capacity hats, the
rationale being that most radiation occurs at the low Z, high current end of
the antenna. However, with a toroid, almost all the electromagnetic energy
circulates in the core of the toroid and does not radiate. If I'm right that
the core is dissipating only about ten percent of the total power, then that
would suggest that the toroidal baseloaded antenna is actually a very good
radiator. I have no idea how its other parameters, e.g., angle of radiation,
compares to a top-loaded antenna, or to a full 1/4 vertical. My previous
iteration of this antenna used top-loading in a guyed vertical, and while
the BW was a bit larger (and the maintenance was hugely larger!) I've not
noticed any qualitative performance difference. Both versions seemed very
competitive.

73,

Jim W8ZR

 

 

 

 

Re: Topband: Air wound coil

[Jim Garland]

On this general topic, I'm erecting a 68 ft aluminum self-supporting 
pole (DX Engineering) that is four inches OD at the bottom, tapering to 
about 1/2 inch at the top. It is designed as a full size 1/4 wave 80m 
vertical. I'd like to use it on 160m. If I add four capacity hat wires 
at the top, would that sufficiently lower the resonant point? The 
antenna tilts at the base with a hand winch, so it's not hard to add or 
remove wires if I want to restore the antenna to 80m.  The other option 
is to add inductance at the base (easy to do), but I don't know if that 
is the preferred solution or not. BTW, there are sixty 30m radials 
already installed at the base, from a previous antenna. I only care 
about resonating the antenna near the low end of the band. Except for 
cacti and coyotes, the antenna is 200m from any structure, fed with 
buried hardline. Any suggestions? Thanks!


73,

Jim W8ZR



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Re: Topband: Supporting Ladder line

[Jim Garland]

Vic, I've had nothing but bad luck in trying to support long horizontal lengths 
of ladder line. In my case, I have two 720 ft bidirectional beverages, which I 
initially made of heavy duty commercial ladder line. I supported the line with 
wood 4"x4" posts, spaced sixty feet apart, using the little plastic ladder line 
clamps, sold in the US by DX Engineering.

After only a month or so, the plastic clamps broke apart because of the 
repetitive flexing of the ladder line in breezes. I replaced the clamps with 
wood clamps, screwed into the top of the posts. These survived with no problem, 
but the ladder didn't. After six months or so, I started having breaks in the 
line from the flexing, and after spending two years repeatedly repairing the 
line, I gave up and threw away all 1500 feet of the stuff.

Finally, I settled on WD1a military surplus field telephone wire, available 
from many sources for about $50 USD in half mile lengths. I use two parallel 
lengths of the wire, threaded through twin ceramic insulators screwed into each 
4x4 wood support (available from a farm supply store), with a pulley at the far 
end to equalize tension in the two lengths. In three years, it has worked 
perfectly, with no problems at all.

I'm not disparaging ladder line (or the plastic clamps) at all. The commercial 
stuff just isn't designed for long horizontal lengths.

73,
Jim W8ZR

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Vic
> Sent: Saturday, January 06, 2018 01:17 PM
> To: topband@contesting.com
> Subject: Topband: Supporting Ladder line
> 
> Has anyone idea's of how to support a long (750 ft) length of home made
> 450 ohm ladder line ?
> 
> Is it possible to use it supported from posts in a vertical orientation or 
> will that introduce
> imbalance.
> 
> I would prefer not to have it supported  horizontally due to added cross arms 
> being
> required.
> 
> Have scoured internet sources but their appears little information available 
> on the subject.
> 
> I plan to feed a Marconi Tee Vertical (Hairpin Matching) with 9:1 
> transformers at each end
> of the ladder line enabling use of 50 ohm coax at each end for convenience.
> 
> 73
> 
> Vic
> 
> G4BYG  (G6M)
> 
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Re: Topband: Detuning Relay Flyback Diode

[Jim Garland]

I'm always hesitant to challenge anything Jim VE7RF says about amps, 
because he's almost always right, but here I have to respectfully 
disagree with a couple (not all!) of his points.  I, too, call 
protective diodes "back EMF" diodes, because their purpose is to clamp 
the inductive voltage spike that occurs when a relay coil is interrupted 
too quickly. As Jim notes, that voltage spike can be much larger than 
the relay operating voltage and can quickly fry, e.g., a switching 
transistor that operates the relay.


In the olden days, builders just put a diode directly across the relay 
coil (cathode connected to the positive coil terminal), and this clamped 
the inductive spike to about 1V, which is the forward, turn-voltage of 
the diode. The breakdown voltage rating of the diode only needs to be 
greater than the coil voltage rating, so fast signals diodes like the 
1N914, or 1N4148 diodes work fine.


The problem with this simple approach is, as Jim noted, the diode alone 
slows the relay's release time. The forward-connected diode acts like a 
low value resistor R when the back EMF drives it into conduction. The 
current through the coil decays with a time constant of L/R, where L is 
the coil inductance. Depending on the diode and coil inductance, this 
time constant, which determines how long it takes for the relay contacts 
to open, can be many msec.


Jim's fix is to put a resistor in series with the diode. This raises the 
R in L/R and shortens the release time somewhat. Unfortunately, it only 
partially clamps the reverse voltage spike, so breakdown of the 
switching transistor can still happen unless R is chosen carefully. The 
trick to pick a series resistor that is as large as possible without 
exceeding the breakdown voltage of the transistor. I've tried this, but 
under best of circumstances, I still end up with an undesirably long 
release time. It's a tradeoff between zapping the transistor or 
excessively delaying the release time.


My solution is to put a small 24V zener diode in series with the 
clamping diode. This automatically limits the back EMF to 25V (24V from 
the zener, 1V from the forward-biased diode). I've done numerous 
workbench tests and find this is the best compromise solution I could 
come up with. It still delays the release time slightly, but much less 
than a resistor-diode combo.


Two final points: First, none of this discussion pertains to the closing 
time of the relay contacts. When the relay coil is keyed up, an 
inductive EMF fights the buildup of current through the coil, but 
doesn't generate destructive voltages.(The exception is if you try to 
switch the relay on with a high impedance current source, but nobody 
would do that.)


And lastly, there's no need to use a big rectifier diode (1N5408, etc.) 
to clamp a relay coil, and especially no need to series several diodes 
to increase their breakdown voltage. The diode is always forward-biased 
by the inductive spike, so its breakdown voltage is immaterial, so long 
as it is at least 100V or so. The momentary peak current through the 
diode will never exceed the steady-state current of the relay, which is 
100 mA or so. Thus a single small 1/2W zener (1N5252) and a small signal 
diode (1n4148) will work just fine.


73,

Jim W8ZR



On 12/23/2017 10:26 AM, Jim Thomson wrote:

Date: Sat, 23 Dec 2017 10:51:57 -0500
From: Brad Denison
To:topband@contesting.com
Subject: Topband: Detuning Relay Flyback Diode

##  I call em back emf diodes.Use a single 1N5408  or 6A10 diode, reverse
connected across the 12 vdc  winding.  Heres the  simple fix to SPEED UP up the
RLS.  Wire a resistor in series with the back emf diode,  EITHER LEG,  the
value of this resistor will be equal to 2 to 3 times the DC resistance of the
12 vdc coil.

##  IE:  resistor in series with a rvs connected diode..and the entire mess is 
in parallel
with the 12 vdc coil.Use a peak reading dvm, like a fluke 87-A   to measure 
the
actual back emf, without the diode + resistor installed.  If the back emf is in 
excess
of 1kv, then use 2  x diodes in series + the resistor..across the winding.

##  What ever you are using to key the relay coil, will be fried by the back 
emf of the
vac relay, if no suppression device used.

## I have tested the above technique,and it works good.Simple and effective.

##  On a side note,  I use the above diode + resistor  combo on the INPUT vac 
relay
on my hb amps.   On the OUTPUT vac relay, I use just the diode.  I want the 
input +
output relay to operate fast, but want the output relay to have a longer rls.   
 You can also
fine tune the rls time by juggling the value of the resistor in series with the 
diode.  The
higher the value, the faster the rls.

Jim   VE7RF
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Re: Topband: Contest conditions

[Jim Garland]

I think some contest stations had directional receive antennas and omni
transmitting antennas. There were times when S9 stations couldn't hear me at
all, and I suspect they were just listening in a different direction. At
other times, I could work stations just marginally out of the noise. 

I noticed that on 80m some Chinese stations would be booming in, with a
pileup calling, but they'd never work anybody. (I never heard any of them on
Top Band.)That I attributed to likely high noise levels in Chinese cities.
Some of the big Russian contest stations were also blasting in but couldn't
hear any callers, including me. I suspect some them may have been running
"Russian Kilowatts."  By contrast, the big JA multi-multi contesters could
hear and work everything.

One problem I frequently encountered was DX stations sending CW way too
fast. When a station is just out of the noise with fast QSB, as many
frequently are, they're really hard to copy if they're going 45 wpm,
especially if they have a short, unusual call, like T5W. 
73,
Jim W8ZR

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of K6UJ
Bob
> Harmon
> Sent: Sunday, November 27, 2016 08:44 PM
> To: g...@ka1j.com
> Cc: topband@contesting.com
> Subject: Re: Topband: Contest conditions
> 
> Gary,
> Thanks for the report.  I am a newbie on 160 and now I know I cant
> blame all my receive issues on my lame inverted L:-)
> 
> Bob
> K6UJ
> 
> On Sun, Nov 27, 2016 at 7:30 PM, Gary Smith  wrote:
> 
> > Weird condx here for the contest, I could hear plenty of DX but even
> > with a KW, they often couldn't hear me. Sometimes the Rx antenna was
> > less helpful to listen with and other times it was incredibly
> > effective like someone pulled the plug on all directions except the
> > one the DX was at.
> >
> > Wasn't the antennas, I still made great contacts with some faint DX
> > who I could barely hear, it was unusual conditions.
> > Think the uncertainty is one of the
> > reasons I love 160 as much as I do.
> >
> > 73,
> >
> > Gary
> > KA1J
> > _
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> >
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Re: Topband: strange propagation

[Jim Garland]

Guys, seems to me this topic has been worked to death. Maybe it's time to
give it a rest.
Jim W8ZR


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Re: Topband: Received Signal Strengths

[Jim Garland]

Here, 160m vertical had noise floor this AM of -103 dbm, with beverages (720 
ft), about -118 dbm, measured with Flex 6300. No need for a preamp.BTW, 160 was 
poor this morning.
Jim W8ZR

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of C Allen 
> Baker via
> Topband
> Sent: Saturday, January 09, 2016 06:29 AM
> To: sawye...@earthlink.net; topband@contesting.com
> Subject: Re: Topband: Received Signal Strengths
> 
> 
> 
> On Saturday, January 9, 2016 6:52 AM, Ed Sawyer  
> wrote:
> 
> 
>  The 5NN discussion brought up an interesting subject to me.  Signal
> strengths reported on 75M SSB are funny to listen too as people seem to be
> in a "mines bigger than yours" competition on how many dB above S9 a signal
> is.  Meanwhile their noise floor is probably S7 or more - what's the point?
> 
> 
> 
> Here at N1UR, on 160, I have switchable T verticals (EU direction and Omni).
> I NEVER listen on them.  Nighttime noise floor is typically S5 - 7 in the
> winter on them with static crashes well over S9 if there is storming in the
> east half of the US (for CW).  I have done some signal strength comparisons
> with EU stations and Carib stations vs my beverages.
> 
> 
> 
> Typically, on 160M, I leave the preamp off for my beverages.  The received
> noise floor for my N/S beverage (on CW) is usually S2 - 3 and for my phased
> EU beverages is S0 to S1.  I have found the signal strengths of the received
> stations to be 1 to 2 S units down on the beverage and equal or stronger on
> the beverage if I turn the preamp on - with usually a rise in the noise
> floor by a 1 or 2 S units.  Interestingly, on 80M CW, I usually use the
> beverage preamp.  The signal often comes up 3 - 4 S units and the noise only
> 1 to 2 S units.  I often drop in  some attenuation to make the noise floor
> "just" go away.
> 
> 
> 
> What do others see as the difference in transmit antenna vs low noise
> antenna signal strengths?
> 
> 
> 
> N1UR
> 
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
> 
> 
> 
> _
> Topband Reflector Archives - http://www.contesting.com/_topband

_
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Re: Topband: Using shielded CAT5 data cable as feedline for active antenna; benefits of multi-turn K9AY loop/SAL/etc?

[Jim Garland]

I did some tests a few years ago on unshielded CAT6  (UTP) cable. The
twisted pairs in the cable are rated at 100 ohm nominal impedance, so I
paralleled two sets of twisted pairs together and measured their VSWR.
Surprisinlgy I found the cable handled 100W at 20m, with negligible VSWR.  I
thought about using the CAT6 for the feedline of portable antennas, but
found that the noise pickup was very high. To do this properly (which I
didn't do in my esperiement)  one would use a simple 1:2
unbalanced-to-balanced balun for a single twisted pair, as well as STP
cable, but I don't see any problems doing so.
73,
Jim W8ZR

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of PA3CSG
> Sent: Saturday, January 02, 2016 09:53 AM
> To: Topband@contesting.com
> Subject: Re: Topband: Using shielded CAT5 data cable as feedline for
active antenna;
> benefits of multi-turn K9AY loop/SAL/etc?
> 
> Hi!
> 
> I tried to measure this UTP cable as a receive line. For the results see:
> 
>
http://pa3csg.hoeplakee.nl/joomla25/index.php/rf-construction/115-0-10-mhz-r
eceive-over-
> utp
> 
> The plan is only slowly moving forward:
> 
> To use one twisted pair as a receive line
> One pair as the supply voltage
> One pair to communicate via a RS485 protocol to control a several RX
> antennas / K9AY and to control the gain of the preamp as well.
> One pair left.
> 
> Since the discussion is going this way, how about the above idea?
> 
> I have not tried it but would be interested in your comments.
> 
> Regards & HNY!
> 
> Geert PA3CSG
> 
> 
> 
> Op 02-01-16 om 16:45 schreef Pete Smith N4ZR:
> > I was recently reading a web page by LZ1AQ
> > .  It is full of fascinating data and
> > design equations for the use of small magnetic loop antennas.  There
> > were two points, in particular, that caught my layman's attention:
> >
> > 1.  He recommends using shielded CAT5 data cable with RJ-45 connectors
> > as feedline.  The obvious advantage is having three pairs left over
> > for voltage supply and control.  See
> >  for more information.
> >
> > 2.  He cites experimental data showing that coplanar crossed loops and
> > multi-turn quad loops both offer very significant improvement in the
> > recovered signalcompared with a single loop.  See
> > 
> > to check whether I got this right. Anyway, it occurred to me to ask if
> > anyone has ever tried multiturn K9AY, SAL or flag/pennant receiving
> > antennas, and did you see something similar?
> >
> > Any other critiques of his design would be appreciated.  The price is
> > certainly right, and the construction looks good. A couple of 1-meter
> > coplanar loops wouldn't be at all hard to construct.
> >
> 
> _
> Topband Reflector Archives - http://www.contesting.com/_topband

_
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Re: Topband: Anybody?

[Jim Garland]

I have the 26m (85.3 ft) Spiderbeam fiberglass vertical, with sixty 30m
radials on top of sandy desert soil. It uses four 7m top hat wires, and is
tuned to 1.820 MHz, where the VSWR is 1.47:1.  I feed it with about 300m of
buried hardline.  The assembly instructions are clear and the antenna tuned
to frequency very easily. It's a good perfomer, although the radiatmg wire
only extends up to about 24m .

Structurally, the antenna is relatively light duty. It has four levels of
guy lines (16 guys total), the top two levels being 1 mm Kevlar and very
thin polypropylene fishing line attached to the top hat wires.. The top few
sections of mast resemble fishing poles and are very flexible. The bottom
section is roughly 6 inch OD and with the supplied rubber cap fits tightly
into standard PVC plumbing tubing. I anchored a 1m length of the PVC into
concrete and that made a dandy anchor point for the mast.

The top hat is made of very thin wire with a low breaking strength. Rodents
ate through the Kevlar guys last year and toppled the antenna, which broke
into three pieces. I redid the guys, elevating the anchor points, so don't
expect that problem to recur. Don't be deceived by the YouTube video showing
the pole being raised by two people. When the wire is attached to the pole,
including the top hat wires, erection for me has been a four hour job
involving a minimum of six people; four at each guy anchor and two to hoist
the mast. The slightest wind makes erection very difficult because slight
flexing prevents the nested sections from sliding. Last time I did this I
mounted a 12 foot long 4x4 post in concrete next to the pole with an
inexpensive hand winch to raise the sections. That helped a lot.  I can send
photos to anyone interested.
73,
Jim W8ZR 

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Henk
PA5KT
> Sent: Friday, January 01, 2016 09:29 AM
> To: topband@contesting.com
> Subject: Re: Topband: Anybody?
> 
> Bill,
> 
> This is a standard toploaded vertical. Spiderbeam sells the same with
> fiber mast.
>
(http://www.spiderbeam.com/product_info.php?info=p337_160m%20Wire%20Vertical
%20
> kit%20including%2018m%20fiberglass%20pole.html)
> 
> Like any other vertical the performance of your antenna depends on your
> radial system.
> 
> I do not have experience with these commercial available antennas as I
> have  tree of that height which I use.
> 
> 73 Henk PA5KT
> 
> Op 1/1/2016 om 5:16 PM schreef K4OWR:
> >  Does anyone recall that I originally asked about this?
> >
> > http://www.dxengineering.com/parts/dxe-160va-
> 1?seid=dxese1=Cj0KEQiAno60BRDt89rAh7qt-
> 4wBEiQASes2tUOULTlQpNyMARBk4ZWRxw70jODW_FJCuBJ1Td47YMgaAhgQ8P8
> HAQ
> >
> >
> > I appreciate all the advice, but a lot of people recommended antennas
> > that I have had for years.
> >
> > BILL K4OWR
> >
> > _
> > Topband Reflector Archives - http://www.contesting.com/_topband
> 
> _
> Topband Reflector Archives - http://www.contesting.com/_topband

_
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Re: Topband: beverage layout

[Jim Garland]

Steve,
I have two bidirectional beverages (NE/SW and NW/SE), each 720 ft long, 
configured in a V-shape.  I'm using DXE switching and xfmrs, with the vertex of 
the V a 4x4 post. I use additional 4x4 posts spaced every 60 ft along the 
length,  seven ft out of the ground, with ceramic insulators with large holes 
on the side of each post. The ceramic insulators screw into the sides of the 
posts and cost about $1 each from a farm supply company. The WD1a wire is a 
twisted pair, with both conductors tied in parallel for each wire of the pari/ 
(i.e., four wires for each beverage) The WD1 slides thourh the hole in the 
insulators and is anchored only at the end points. A pulley at the far end of 
each beverage equalizes the tension in the parallel wires. My original version 
of the beverages used ladder line from DXE and it was constant maintenance. 
After two years I gave up and switched to the WD1a, which is fabulous. It's 
very strong, which is the primary requirement. I've had no trouble since I 
started using it. The electrical resistance of the WD1a is insignificant. 

My only complaint about my beverages is that the F/B ratio is often only about 
10-15 db, a fact I attribute to the lousy sandy soil at my QTH. I have a couple 
of ground rods at the ends of each beverage, but I don't think that's adequate. 
 The side-to-front ratio when I switch beverages is very good, by contrast. 

73,
Jim W8ZR 

> -Original Message-
> From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Steve 
> Baughn
> Sent: Friday, November 06, 2015 8:52 AM
> To: topband@contesting.com
> Subject: Topband: beverage layout
> 
> I am planning to put up two bi-directional beverages at my QTH. Being as this 
> is the first
> time I have had the real estate and time I have a couple questions regarding 
> same:
> 
> 1) Since these will be running at 90 degree angles to one another, can the 
> feed points for
> both be relatively close to each other i.e. a few feet or so or do they need 
> to be farther apart?
> 
> 2) I have read some contradictory material as far as type of wire to use for 
> these. A few
> sources say WD-1 field phone wire but then another says there is fairly high 
> loss in this.
> Same for 450 ohm ladderline who some say has its drawbacks during rainy/snowy 
> periods.
> It appears that electric fence wire may be the best option given its 
> durability (these antennas
> will probably be running through the woods).
> 
> 3) If I do go with the fence wire as I understand it the spacing should be 
> fairly close
> between the two wires such as an inch or so and mounted about 10’ off the 
> ground. I am
> considering a metsl T post with pvc slid over it then holes through each 
> vertical pvc piece to
> run the wires.
> 
> I am located just outside Mount Vernon Ohio if anyone in the vicinity is an 
> authority on this
> any help would be appreciated.
> 
> Thanks much!
> 
> 73,
> Steve, WD8NPL
> _
> Topband Reflector Archives - http://www.contesting.com/_topband

_
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Re: Topband: ADC Overload

[Jim Garland]

Hi Jim and the group,
I apologize for creating confusion in my earlier post about the Central Limit 
Theorem. Let me try to clarify a few points that I glossed over. My example 
considered an SDR transceiver that received two signals, each with 
instantaneous RF voltage that varied from +3V to -3V, and for simplicity I 
assumed each signal could have only seven values spanning this range. I didn't 
make it clear that these are independent signals on different frequencies. Thus 
every time the ADC in an SDR samples the voltage sum of the two signals at its 
input, it will get a different result. For example, with one sample the SDR may 
see a voltage of +1V, which comes from +2V from one signal and -1V from the 
other signal. A later sample might produce a voltage of -2V, which could come 
from +1V from one signal and -3V from the other. In other words, with each 
sample, the SDR will measure a different voltage, because the signals have 
different frequencies and are not in phase with each other. 

Suppose now that we let the SDR sample the voltage a million times, one after 
another. Then the Central Limit Theorem tells us how those million measurements 
will be distributed, in other words how many times the SDR will measure 6V, 5V, 
4V...0...-4V,-5V,and -6V.  What the CLT tells us is that the distribution of 
these measurements generally follow a bell-shaped curve, with the peak at 0V. 
This means that most of the time, the SDR will measure approximately 0V at its 
input. Only infrequently will it measure the large +6V and -6V voltages, 
because those large voltages are at the extreme edges of the bell-shaped 
distribution. If the SDR overloads at, say, +/-6V, then it will only overload 
when the sample measures that extreme voltage, which is not very often. Note 
that this doesn't have anything to do with the AGC action of the radio.

Now, here's where I treated things too glibly in my earlier post. I asserted 
that with more independent signals, as one might find on the entire crowded HF 
spectrum, the distribution of the instantaneous RF voltage from the entire 
spectrum tends to peak sharply at zero volts, which means paradoxically that 
the more signals the radio hears, the more immune to overload it becomes. (The 
explanation of the paradox is that all these signals tend to cancel each other. 
For every positive voltage from one signal there is a negative voltage from 
some other signal.)

Having said that, here's the fly in the ointment. There are several assumptions 
buried in the Central Limit Theorem, so its validity isn't as universal as I 
was suggesting. One assumption is that all these signals have to have about the 
same amplitude. If one signal is vastly stronger than the others, as Tom W8JI 
finds in his contest station, then that will dominate the input of the SDR and 
you won't get this cancellation effect. Similarly, if you have a really strong 
AM broadcast station near your QTH, then that could still overload the ADC in 
your SDR transceiver. Keep in mind that the Central Limit Theorem is a complex 
mathematical statement whose validity is only as good as the validity of its 
underlying assumptions. To me, the CLT provides a ballpark guess as to how an 
SDR will perform, but it shouldn't be taken too literally. The real world has a 
habit of not conforming to mathematical theorems! 

As I've thought more about this issue, I think a key advantage of an SDR 
actually comes, not just from the cancellation effect, but from the fact that 
an SDR has no front-end RF amplifier or subsequent IF amplifiers. Basically the 
HF spectrum goes directly into the SDR's analog-to-digital converter. I believe 
(hope someone can verify this) that modern, fast ADCs can handle a volt or more 
at their inputs without overloading, which gives them a tremendous advantage 
over superhet radios which use high gain RF and IF amplfiers. Signals in the 
millivolt range that fall outside the IF passband in conventional superhets 
won't capture the receiver's AGC and can therefore overload or dessense the 
front end. That won't be a problem with SDR radios that can handle a volt or 
more without overloading their ADC. 
73,
Jim W8ZR


> -Original Message-
> From: James Wolf [mailto:jbw...@comcast.net]
> Sent: Monday, October 12, 2015 9:45 PM
> To: 'Jim Garland'
> Cc: topband@contesting.com
> Subject: RE: Topband: ADC Overload
> 
> Jim,
> 
> I sense a flaw in the CLT argument, which is likely a lack of understanding 
> on my part.
> What you are describing sounds more like AGC action.  In-other-words, moving 
> the
> minimum detector level up the bell curve such that we have now lost any 
> capability of
> listening down into a hole between strong stations and copying the weak 
> station (which is
> really what we are talking about).  That scenario now sounds like a corner 
> case.
> Other wise, what happened to the two +3V stations that a

Re: Topband: ADC Overload

[Jim Garland]

Interesting comments, Steve, and to me quite on the mark. (In an ealier life, I 
was a physics prof, though I've forgotten most of what I once knew).

Re the comment by another list member that "there are various distractions such 
as the Central Limit Theorem...that don't add much to the discussion":  On the 
contrary, I believe the CLT is actually crucial to this discussion. Here's my 
attempt at an intuitive explanation of the CLT using a _very_ simplified 
example. I hope this contributes to this interesting discussion.

Suppose we have an SDR radio that hears two identical signals, and that the ADC 
in the receiver overloads when the instantaneous antenna voltage at the 
receiver input is greater than +/- 5V. Now let's assume that each of our 
identical signals has a maximum instantaneous RF voltage of +/- 3V, so that the 
receiver will overload when both signals add up to give either +6V or -6V. The 
question that the Central Limit Theorem addresses is how frequently this 
overload condition will occur. Here's how it works.

We'll keep things simple by assuming each of our two signals can take on only 
seven values of voltage: +3V, +2V,+1V, 0V, -1V, -2V, and -3V. (In reality of 
course, for a CW signal, the signals are sine waves varying continuously from 
+3V to -3V.) Every time the SDR samples these signals, it sees the 
instantaneous sum of their voltages. Since each signal has seven possible 
values, the sum of the voltages can have 7x7=49 possible values, which range 
from +6V down to -6V. 

If you make a list of all possible combinations of these two signals, you'll 
find that of the 49 possibilities, 0V comes up seven times, 1V comes up six 
times, 2V comes up 5 times and so forth, until you get to 6V (when the maximum 
value of signal adds up exactly). The reason 0V comes up seven times is because 
there are seven ways to get 0 by adding the voltages from the two signals, 
i.e., 0V plus 0V, +1V plus -1V, -1V plus +1V, +2V plus -2V, -2V plus +2V, +3V 
plus -3V, and -3V plus +3V. By contrast, there is only one way to get +6V, 
which is +3V plus +3V, and similarly for --6V.

Now if the ADC in the receiver overloads at any voltage greater than  +/- 5V, 
as we have assumed, then it will overload only two times in every 49 samples, 
once when the voltage is +6V and once when the voltage is -6V. If you draw a 
graph of all the possible combinations of voltages, plotting the numbers of 
times each combination of voltages comes up, you'll see that the graph 
resembles a bell-shaped curve, (called a "normal" distribution) peaked at zero. 
The maximum values of +6V and -6V are at the tail ends of the distribution.

So in this simplified example, our SDR radio will overload 2 out of every 49 
samples, or about four percent of the time. That's not terrible, but not 
wonderful either. It means that we'd hear a pop in our receiver about four 
percent of the time. But suppose we let our two signals take on a continuous 
range of values between +3V and -3V. instead of only seven possible values. 
Unforunately, things don't get much better. The data points on our bell-shaped 
curve would smooth out, but we'd still overload roughly four percent of the 
time. The general shape of the curve doesn't change.

But...here's the interesting thing. Suppose instead of only two signals, we 
have thousands of signals appearing at our antenna terminals, and we'll 
continue to assume each of our thousands of signals varies from +/- 3V. Now 
when we add up the voltages of each of these signals, we find something 
remarkable. The sums of the voltages of all these signals is still a 
bell-shaped curve peaked at zero volts and extending from +6V down to -6V, but 
with one significant change. The bell-shaped curve narrows in, becoming very 
sharply peaked at 0V. The extremes of the curve, which would overload our 
receiver, almost never happens. This peaking of the curve is what the Central 
Limit Theorem tells us, and basically it is the reason SDR radios are in most 
cases nearly immune from overload. The more signals we're hearing with our 
receiver, the closer those voltages add up to zero. One can dress up this 
example with sophisticated math, which is what the CLT does, but the concept is 
actually very simple.

To me, this immunity to overload is the huge advantage SDR radios have over 
their superhet counterparts. In a conventional superhet receiver, with roofing 
filters and IF crystal filters, the averaging of signal voltages takes place 
only within the passband of the receiver. That's why a guy with a S9+60db 
signal who is 1 kHz away from the weak DX station you're trying to copy can 
wipe out your receiver: the RF voltage from his signal overloads the front end 
and IF amplifiers in the receiver. In an SDR, by contrast his RF voltage gets 
averaged out by all the other signals in the entire spectrum. Once the spectrum 
is digitized, which the DAC does immediately at the antenna input terminals, 
there are no more 

Re: Topband: K1N DQRM Tracking Project

[Jim Garland]

Hi Charlie,
You/re right of course, it's 1 ft/nanosecond. Don't know what I was
thinking.  I was also focusing on CW DQRM,  since that is 99% of what I
operate, and since carriers and CW jamming havw been endemic on the Navassa
dxpedition's top band and 80m operations. I agree that for SSB interference,
the concept would be harder to implement since there would be no sharply
defined turn-on time for the interference at the receiving stations. 

I was also envisaging receiving stations spaced, e.g., 100 miles or more
apart,  and for those the time delays coould be a msec or longeer, and not
just a phase shift.  Of course, multipath and ionisspheric reflection would
be a problem on the higher frequentices, although the accuracy would be
improved with more than three receiving stations. I've nothing against
direction finding, but that's likely to have much more inherent error than a
technique which involves only time measurements.

For topband DQRM, I've assumed most of the jamming came from US stations,
but that's just a guess.
73,
Jim W8ZR

 -Original Message-
 From: Charlie Cunningham [mailto:charlie-cunning...@nc.rr.com]
 Sent: Monday, February 09, 2015 11:54 PM
 To: 'Jim Garland'; 'Lee K7TJR'; Topband@contesting.com
 Subject: RE: Topband: K1N DQRM Tracking Project
 
 Actually ,Jim,  the velocity of propagation of radio waves (or light
waves)
 in free space is about 1 foot/nanosecond, NOT 1 foot per microsecond. It
 would seem to me that one needs to have a measure of directivity as well a
s
 time, an  the time factor might boil down to phase difference
measurements.
 Thinking of applying all of this to something complex like SSB modulation
 sounds pretty messy. And a lot of the interference originates outside our
 borders, so I don't see who would be the enforcement body?
 
 
 Just my $0.02
 
 73,
 Charlie, K4OTV
 
 
 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim
 Garland
 Sent: Sunday, February 08, 2015 9:08 PM
 To: 'Lee K7TJR'; Topband@contesting.com
 Subject: Re: Topband: K1N DQRM Tracking Project
 
 I agree, Lee. Locating a DQRM station involves accurately time stamping
the
 arrival time of their transmissions, at (at least) three receivers at
known
 locations. Once the arrival times are known, one can use trigonometry to
 calculate the location of the interfering station. Since radio waves
travel
 about one foot in a microsecond, and since a microsecond is an eternity by
 modern frequency counter standards, it should be possible to get very
 precise locations. The city block mentioned earlier should be readily
 doable. Of course, this requires that the three receivers be able to copy
 the DQRM ground wave signal, since the arrival times would otherwise be
 dependent on ionispheric reflections. More than three receivers would
result
 in more accurate position measurements.. There's no need to use direction
 finding equipment, which are very low resolution by comparison with time
 measurements..
 
 I'm no authority on FCC rules, but I'm under the impression that
 deliberately interfering with other licensed transmissions is against the
 law. Every month or so, the FCC nails some renegade ham or CBer for doing
 just that. Probably just publicizing the callsign of the culprits would be
a
 large deterrant for all but the most sociopathic offenders.
 73,
 'Jim
 
  -Original Message-
  From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Lee
 K7TJR
  Sent: Sunday, February 08, 2015 4:47 PM
  To: topband@contesting.com
  Subject: Re: Topband: K1N DQRM Tracking Project
 
 
  Greetings top-band community,
 
  Interestingly enough the technology exists right here in our own Ham
  community that could go a long way toward finding these DQRM culprits.
  There are some beam forming arrays that operate with SDR
  technology where a recording can be made of a target bandwidth and
  later reviewed
 with
  beam forming techniques to DF using a peak or notch completely after
  the event has long gone. In fact directional and strength data can be
  stored
 in
  perpetuity.
   So my comment is don't underestimate the ability to identify these
 idiots.
Being able to actually replay an entire contest and do a strength
  and directional analysis in a narrow bandwidth after the fact to me is
  the ultimate receiving system.
 
  Lee K7TJR   OR
 
 
  I'd be interested in some project like that, but I'm afraid it would
  only get to a general area. With maybe 3-10 idiots at any one time,
  and the
 3-10
  active at any time probably varying every hour, it might be pretty
  tough
 to
  do anything meaningful.
 
  Since attention is what they want, I wonder if this effort would not
  encourage participation in jamming at a faster rate than it solves
 anything?
 
  Has anyone ever looked to see if there is any correlation between
  intentional QRM and the DX station spreading people over a wide swath
  of
 the
  band? More than once, I've

Re: Topband: K1N DQRM Tracking Project

[Jim Garland]

I don't remember the article, Charlie, but that's a fabulous idea, and at
first blush it doesn't sound all that hard to implement. One way might be to
set up three receivers at different locations, each with a 10 MHz GPS or
rubidium time base (both inexpensive and readily available.). For each
receiver, a simple frequency divider could produce a pulse every 100
milliseconds from the time base. The pulse would trigger a frequency
counter, which would then count the elapsed time from the ttrigger pulse
until the DQRM signal started transmitting (or stopped transmitting -
doesn't matter which).  Once the differences in elapsed times were known
between the three receivers, the DQRM signal could be accurately
triangulated. Sounds ike a fun project. Sure wish we'd had something like
that for the Navassa DQRM jerks.
73,
Jim W8ZR

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of
n0...@juno.com
 Sent: Sunday, February 08, 2015 12:18 PM
 To: topband@contesting.com
 Subject: Re: Topband: K1N DQRM Tracking Project
 
 IIRC, quite some years ago, QST had a photo  description of
 a FCC signal locator (for lack of a better description) consisting
 of several remote receivers that were linked together.
 
 Anyway, these could instantly locate the origin of a
 skywave signal with a resolution of a city block(!!) using a
 precise timing equipment/technique.
 
 I looked for the article using the ARRL's periodical search...no luck.
 Does anyone remember reading/seeing that article...perhaps in the
 Strays column of QST?
 
 Charlie, N0TT
 
 On Sat, 7 Feb 2015 17:05:04 -0600 Doug Renwick ve...@sasktel.net
 writes:
  Is anyone using this DQRM Tracking Project report?  They want reports
  of
  deliberate QRM like 'tuner uppers' and other types, but not QRMers
  like cops
  or 'no splitters'.  I don't know how accurate they can be to
  identify the
  guilty station on any band especially 160m with or without a
  directional
  antenna.
  See below:
 
 
  THE DQRM TRACKING PROJECT --- Recently, the amount and  intensity
  of  DQRM
  (Deliberate QRM) has been  growing  logarithmically,  targeting
  DXpeditions
  all over the world. DQRMers attempt to spoil communications and
  disrupt  the
  joy of chasing DX. Without going into the  motivation  of  DQRMers,
  the  DX
  Community is taking steps to eliminate this practice.
  The KP1-5 Project, which is producing the 2015 K1N Navassa
  DXpedition,  has
  been  working  with  tele-communications  agencies  around  the
  world.  The
  objective is to identify stations who are acting as DQRMers  and
  use  legal
  means to stop this behaviour. The  technology  is  in  hand  to
  solve  this
  problem and, with your assistance, we can stop this blight that  is
  hurting
  hams worldwide.
  HOW IT WORKS: Locating  the  stations  engaging  in  DQRM  is  a
  matter  of
  triangulation. When the DQRMer is 60db over S9 at your location, you
  can  be
  pretty  sure  that  station  is  nearby.  If  you  fill  out   the
  form  at
  www.dqrmreport.com, the data will be collected and  analyzed  to
  produce  a
  reasonably accurate map of the DQRMer's location. This  data  will
  allow  a
  close-in search in the DQRMer's area and, using  local  transmitter
  hunting
  devices, the offender will be identified. This is a real-time system
   that's
  been in development for several years; its first  major  test  will
  be  the
  2015 K1N Navassa DXpedition.
  WHAT YOU DO: Fill out the form with as much information as you can
  provide.
  All information will remain confidential. The form will go into  a
  database
  and the DQRM Project software will do the rest. We can stop DQRM -
  and  you
  can help!
 
  Doug
 
  There are some ideas so absurd that only an intellectual or lawyer
  could
  believe them. - George Orwell, 1984
 
 
 
  ---
  This email has been checked for viruses by Avast antivirus
  software.
  http://www.avast.com
 
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Re: Topband: K1N DQRM Tracking Project

[Jim Garland]

I agree, Lee. Locating a DQRM station involves accurately time stamping the
arrival time of their transmissions, at (at least) three receivers at known
locations. Once the arrival times are known, one can use trigonometry to
calculate the location of the interfering station. Since radio waves travel
about one foot in a microsecond, and since a microsecond is an eternity by
modern frequency counter standards, it should be possible to get very
precise locations. The city block mentioned earlier should be readily
doable. Of course, this requires that the three receivers be able to copy
the DQRM ground wave signal, since the arrival times would otherwise be
dependent on ionispheric reflections. More than three receivers would result
in more accurate position measurements.. There's no need to use direction
finding equipment, which are very low resolution by comparison with time
measurements..

I'm no authority on FCC rules, but I'm under the impression that
deliberately interfering with other licensed transmissions is against the
law. Every month or so, the FCC nails some renegade ham or CBer for doing
just that. Probably just publicizing the callsign of the culprits would be a
large deterrant for all but the most sociopathic offenders.
73,
'Jim

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Lee
K7TJR
 Sent: Sunday, February 08, 2015 4:47 PM
 To: topband@contesting.com
 Subject: Re: Topband: K1N DQRM Tracking Project
 
 
 Greetings top-band community,
 
 Interestingly enough the technology exists right here in our own Ham
 community that could go a long way toward finding these DQRM culprits.
 There are some beam forming arrays that operate with SDR technology
 where a recording can be made of a target bandwidth and later reviewed
with
 beam forming techniques to DF using a peak or notch completely after the
 event has long gone. In fact directional and strength data can be stored
in
 perpetuity.
  So my comment is don't underestimate the ability to identify these
idiots.
   Being able to actually replay an entire contest and do a strength and
 directional analysis in a narrow bandwidth after the fact to me is the
 ultimate receiving system.
 
 Lee K7TJR   OR
 
 
 I'd be interested in some project like that, but I'm afraid it would only
 get to a general area. With maybe 3-10 idiots at any one time, and the
3-10
 active at any time probably varying every hour, it might be pretty tough
to
 do anything meaningful.
 
 Since attention is what they want, I wonder if this effort would not
 encourage participation in jamming at a faster rate than it solves
anything?
 
 Has anyone ever looked to see if there is any correlation between
 intentional QRM and the DX station spreading people over a wide swath of
the
 band? More than once, I've heard people intentionally threaten to QRM DX
 because they were POed that their QSO was interrupted by a pileup.
 
 73 Tom 
 
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Re: Topband: Elimination of Treadmill RFI on 160 meters

[Jim Garland]

Guys, I'm not following all this, possibly because I'm confused by Jim's
distinction between filters and chokes, because in both cases they're
just lossy inductors, although used in different ways and for different
purposes.

 Consider common mode noise on a simple parallel wire transmission line.
Identical in-phase noise currents would flow on each of the parallel wires.
A common mode choke around the line would insert a high impedance equally
onto both wires.The choke's effectiveness at suppressing the common mode
currents would depend on the shunt impedance to ground of the two wires. The
shunt impedance between the two wires e.g., the impedance of the
transmission line, is immaterial since there is no common mode voltage
difference between them. 

On the other hand, the choke's ability to shield differential (as opposed to
common mode) currents depends a great deal on the differential shunt
impedance. The lower the shunt impedance, the more effective the choke.
Seems to me this is quite apparent if one draws out the circuit and includes
both the impedances to ground and the differential impedance beteeen the two
wires. But, like I said, maybe I'm not following something.
73,
Jim W8ZR


 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim
Brown
 Sent: Friday, January 30, 2015 2:27 PM
 To: topband@contesting.com
 Subject: Re: Topband: Elimination of Treadmill RFI on 160 meters
 
 Tom,
 
 You simply don't get it.  The choke is NOT a filter. It is a high
 impedance added to the common mode circuit. The common mode circuit is
 acting as an ANTENNA, either for RX or TX.  If for TX, the noise source
 is inside the box, and the current will depend upon the voltage of the
 source and behavior of the circuit as an antenna. If for RX (that is,
 the noise is received on the wiring by simple antenna action and coupled
 into the box via failure of the wiring to go the shielding enclosure)
 the current will again depend upon the behavior of the circuit as an RX
 antenna.
 
 When we add a choke of sufficiently high resistive impedance to that
 circuit, we reduce the current at frequencies where the choke is
effective.
 
 When preparing to publish my first research on this in 2003 (to the
 AES), I found references in ancient applications notes from EU mfrs of
 ferrites showing that they clearly understood this principle.  Those
 ferrite cores molded onto cables emerging from electronic equipment are
 not filters, they are chokes. They do work in the frequency for which
 they are designed, and the only capacitance in the circuit is their own
 parallel capacitance that forms their resonant circuit -- it is the
 capacitance from one end of the core to the other via the dielectric of
 the core.
 
 73, Jim K9YC
 
 On Fri,1/30/2015 3:16 AM, Tom W8JI wrote:
  Any filtering or decoupling system works by the ratio of series
  impedance to shunt impedances.
 
  A series choke is useless unless there is some value of shunt
  impedance in the system. As a matter of fact, lack of established
  shunt impedances is what can drive choke requirements to unrealistic
  values. This is true in baluns, just like it is in line filters.
 
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Topband: No 160m contest for me this year

[Jim Garland]

Rodents chewed through a set of kevlar guy lines for my Spiderbeam 26m
vertical while I was out of town last week. Down came the vertical, which
broke into three pieces, and when the guy lines fell to the ground, the
rodents ruined them all. Looks like I'm off 160m for the winter. It will be
a big job to reinstall everything. Hope I can get replacement sections for
the broken Spiderbeam pole.

Jim W8ZR

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Re: Topband: Recommended Antennas for 160M/80M Receiving

[Jim Garland]

Mack, I use two DXE bi-directional beverages, each 720 ft long, fed with a
single 300 ft length of direct burial quad shield RG6. The DXE transformers
and relay switching boxes use high quality weather-proof construction. That
said, the ladder line caused me nothing but continuing maintenace headaches.
Furthermore, the little DXE plastic ladder line clamps are very flimsy and
broke within a few months. I finally gave up and replaced the ladder line
with parallel lengths of WD-1a field telephone wire (the twisted pair
version), supported on 4x4 posts with ceramic insulators. The electrical
performance appears to be the same as with ladder line, but it makes for a
much more robust installation and the field wire is much cheaper than ladder
line. 
73,
Jim W8ZR

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mack
McCormick
 Sent: Sunday, December 21, 2014 7:12 AM
 To: topband@contesting.com
 Subject: Topband: Recommended Antennas for 160M/80M Receiving
 
 Friends,
 
 I need to really increase my country count on 160M so I've decided to
 installed dedicated receiving antennas. My home is on a 6 acre rectangular
 lot so I have room for a couple of 800 ft beverages at 90 degree angles or
 an 8 element circular array.
 
 I've been carefully following the discussion about the merits of various 8
 element arrays and beverages.
 
 *I believe the consensus is that a set of bi-directional beverages will
 generally perform better than any 8 element circular array. Am I correct?
 I'm specifically speaking about working countries on 160M and 80M.*
 
 I also believe the bi-directional antenna choices come down to two
 flavors.
 
 The DXEngineering ladder line version or the BevFlex-4 that uses RG-6.
*I'm
 leaning toward the BevFlex-4.*
 
 I would REALLY appreciate your views on the recommended receive antenna
 system if space and money are not big concerns. I'd like to do it
correctly
 one time and the first time.
 
 Vy 73,
 
 Mack
 W4AX
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Re: Topband: Unknown Pulse Signal Wiping out 1900-1925 kHz

[Jim Garland]

Intruders are becoming endemic on all the hf bands, not just top band. Every
morning I hear SSB stations on the low end of 80m and 40m, and the worst of
all are 10m-12m, which have become a nightmare of swishing signals,
carriers, buzzing sounds and illegal CBers. I hadn't realized how bad the
situation had become till I could see the spectrum on my Flex transceiver.
Most ot the problem seems to be coming from the North in the afternoon, when
those bands are open into Asia. I can't imagine how bad all this crap must
sound to our JA friends.
73,
Jim W8ZR

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Donald
Chester
 Sent: Sunday, December 07, 2014 1:55 PM
 To: topband@contesting.com
 Subject: Topband: Unknown Pulse Signal Wiping out 1900-1925 kHz
 
 
  Kind of a pulsating buzzing sound, centred around 1915, but audible down
to
  slightly below 1900 and up to approximately 1925. At its centre
frequency last night
 (Saturday), it was just as strong as any CW contest signal.
 
 It was particularly loud (S9 + 30) in the Northeast and ops with
 beverage antennas are reporting that it appears to be coming over the
horizon
  in a south easterly direction, while others say it is possibly coming
from Europe or
 Polar Russia. Whether this is a harmonic, a spur or something coming from
an intentional
 radiator, it has made regular QSO operation between 1900 and 1930 almost
unbearable for
 the past three nights now.
 
 All the more reason to hope that the FCC goes ahead and adopts their
 proposed reallocation of 1900-2000 to delete sharing  with radiolocation
and to restore
 amateurs to primary status. Although many 160m
 ops seemed to blow off this NPRM while the comment period was still open
as if it were
 much ado about nothing, a  few of us maintained that it was of utmost
 importance for the amateur community to flood the Commission with comments
supporting
 their
 proposal.
 
 Although GPS has pretty much killed 160m radiolocation for the
  moment, we never know when some new service might attempt to start up in
this part of
 the spectrum under the guise of Radiolocation.  That could be what's
happening right now.
 For those only interested in DX and contesting in the bottom end of the
band and who
 sometimes appear not to even consider 1900-2000 as part of the band, still
must remember
 that if some new service were to displace amateurs
 from the top half, congestion in the 1800-1900 kHz segment (including the
DX window)
 would likely become unbearable.
 
 The FCC proposal, if adopted, would protect
 amateur status in the entire 160m band once and for all, and let's hope it
is not already too
 late.
 
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Topband: Beverage Question

[Jim Garland]

I want to replace the 450 ohm ladder line for my two DXE 720 ft long
bi-directional beverages with two lengths of WD-1/TT field telephone wire.
The wires will be secured only at the ends, but will be suported along their
length by ceramic insulators mounted on 4x4 posts spaced every 60 ft.  The
spacing between the parallel wires will be about six inches. Here are my
quesetions: First, does anybody know what the likely impedance is of this
configuration, or if not, how to measure it?  Second, if I keep the DxE
matching trnsformers used with the 450 ohm ladder line, will beverage
performance be degraded noticeably with the new wures if, say, the impedance
of the new line turns out to be 600 ohms or so? In other words, as a
practical matter how important to performance (e.g., F/B ratio and
low-noise) is it to make sure impedances are matched.

 

Finally, a mechanical question. I want to have a pulley at one end of the
parallel wires to equalize the tension in the wires. I've not been able to
find a good pulley with a five or six inch diameter, except for nylon
pulleys used for clotheslines. Do you think one of these could be used.
There will be no motion of the pulley, since it is only used to equalize
tension. The field telephone wire is rated at 200 lbs maximum tension, and
I'm guessing the actual tension will be about half that.

 

Thanks!

Jim W8ZR

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Topband: , Re: Deployable radials for 80/160M

[Jim Garland]

Here in sunny NM, with nothing resembling grass, I just laid my sixty 120 ft
radials on the top of the desert. It's stranded 14 AWG with a brown THHN
insulation that matches the dirt.  I figure in a couple of years the
insulation will pretty much be gone, and then it will just be bare copper.
Ain't nobody going to be bothered by that except the coyotes.  The antenna
is 750 ft from my station, and fed with (buried) 50 ohm 1/2 inch CATV
hardline.

Don't know how Carl finds that cheap PTFE stranded wire. I wire all my
homebrew projects with it, and am always on the lookout, but never see any
at the local surplus places. Los Alamos National Labs is nearby but never
seems to have any.  I'm guessing they must use something else to wire up
nuclear weapons. 

73,
Jim W8ZR

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Topband: Beverage wire question

[Jim Garland]

I've been using 450 ohm ladder line for my two bi-directional 720 ft
beverages. These are supported on 4x4 posts, spaced 60 ft apart. I'm in a
windy area, and the ladder line requires constant maintenance. I want to
replace it with parallel wires, which run through ceramic feedthrough
insulators screwed onto each post. The wires will be anchored only at their
ends and under considerable tension. I'm thinking of using solid 14 awg or
12 awg copper clad steel wire (Wireman 502 or 503).  I know there are less
expensive choices, but at this point I'm so tired of working on the
beverages, that the durability and reliability is more important to me than
the expense.  I want to make sure that The Wirmean coils the wire on a
spool, so that it can be easily unwound, and also that it's not too stiff to
handle. Obviously, I don't want wire that's going to go sproing and start
tangling itself when I try to thread a 720 ft length through the insulators.
I'd appreciate any suggestions or comments from people who have used this
stuff. Is 14awg adequate, or do I need to go with the heavier gauge wire?

Tnx,

Jim W8ZR

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Re: Topband: DU7ET needs Ky

[Jim Garland]

He was on top band for two hours this mornig, easy to work from NM. Probably
much harder from KY, but he's a fine operator with good ears on 160.
73,
Jim W8ZR

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Bill
McDowell
 Sent: Wednesday, April 16, 2014 7:16 AM
 To: Topband Reflector
 Subject: Topband: DU7ET needs Ky
 
 Help Robert, DU7ET finish his Top Band WAS.  He needs KY for the last one.
He is
 usually QRV around local sunrise on 1823.  Works split as directed.
 
 Give him that last one for what is probably the first and only 160 WAS
from DU-land.
 
 He also needs XE too...
 
 Thanks!
 
 73
 Bill, K4CIA
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Re: Topband: DX Window

[Jim Garland]

I agree completely with Bud's take on the contest. This was my first year of
participating and I found the rules unclear and  poorly written.In fact,
until a friend corrected my misunderstanding, I hadn't even understtod that
USA-USA contacts were allowed. The official objective of the contest says
 For Amateurs worldwide to exchange information with W/VE amateurs on
160-meter CW. I (mistakenly) interpreted amateurs worldwide to mean
non-USA stations, and that the  goal for them was to work as many USA
stations as possible.  I also observed that the supposed DX window was a
sham, with USA stations monopolizing the 1830-1835 window, even after other
stations reminded them that it was reserved for DX. (Seems like the ARRL
contest software could automatically penalize participants for non-DX
contacts in the window.)

My personal goal in the contest was to work DX, in order to test my new 1/4
wave transmitting antenna and build up my 160m DXCC total. My antenna worked
great, and I worked every DX station I could hear, usually on the first
call. Unfortunately, that was only about 20 stations. Admittedly, conditions
weren't good, but my impression is that the international DX community
pretty much ignores this contest, and for good reason. With every part of
the spectrum monopolized by USA contesters, there's no way they could break
through the clutter.

Frankly, I think the entire concept of this contest needs to be reasssessed.
There's really no point in awarding points for DX-USA contacts, if there's
only a miniscule DX participation. Better just to make it a ARRL/RAC section
contest, the objective of which is to build interest and drum up activity on
the band. 

73,
Jim W8ZR

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of W2RU -
Bud
 Hippisley
 Sent: Sunday, December 08, 2013 5:59 AM
 To: Mike Waters
 Cc: topband
 Subject: Re: Topband: DX Window
 
 Whatever the ARRL intent may have been, the wording of that particular
rule is defective,
 and has been for as long as I can remember.
 
 Consider:  How does one _start_ an intercontinental QSO?  Usually one
party or the other
 sends CQ.  So to make a QSO in the DX Window someone has to send CQ
TEST or
 self-spot, then deliberately choose not to answer anyone from his/her own
continent!  Sure
 sounds like an intelligent rule to me.  Not!
 
 The only way I can see an intercontinental only rule working would be to
say something
 along the lines of Only stations outside North America should CQ in the
DX WIndow, and
 North American stations should transmit in that window only when calling
and working
 those DX stations.
 
 But the ARRL 160 always was -- and still is -- first and foremost an
ARRL/RAC Sections
 contest.  Given that, it's not clear why there should be _any_ rule giving
favors to
 intercontinental QSOs.  Contest rules might be better advised to simply
prohibit _all_
 contest contacts and their solicitation in the DX Window, so as to leave
that 5 kHz segment
 for non-contest CW DXers.
 
 Bud, W2RU
 
 
 On Dec 7, 2013, at 11:34 11PM, Mike Waters mikew...@gmail.com wrote:
 
  I see a lot of USA station, including a couple of regular contributors
to
  this reflector, calling CQ TEST between 1830 and 1835.
 
  According to http://www.arrl.org/160-meter The segment 1.830 to 1.835
  should be used for intercontinental QSOs only. I hear a lot of contacts
  being made between stateside stations.
 
  I thought this was for DX stations, and that's mostly what I've heard
call
  CQ TEST there. Maybe someone can clarify this.  :-)
 
  73, Mike
  www.w0btu.com
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Re: Topband: Verifying integrity of 75 ohm coax.

[Jim Garland]

Helpful advice, Tom. Thanks. I've always worried about using silcone grease
on connectors. I understand it helps seal the connector, but my fear is that
it could interfere with the electrical bond.  On the face of it, getting
non-conducting grease on, e.g., the center terminal of an N-connector or
PL259 seems like asking for trouble.
73,
Jim W8ZR

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom
W8JI
 Sent: Tuesday, November 19, 2013 5:26 PM
 To: Bill Wichers; g...@ka1j.com; Topband@contesting.com
 Subject: Re: Topband: Verifying integrity of 75 ohm coax.
 
  Just a suggestion: the TB Snap'n'seal connectors also have Seal nuts
  which can be bought separately. They're intended to seal out water from
  the thread area on the F connector. They are basically a metal shell
with
  some threads that captivates an O-ring such that tightening them against
  the connector seals the o-ring between the threads and the F-connector
  itself. They're intended to be a water seal, but they also make a pretty
  decent locknut for an F connector even if you don't care about the
weather
  proofing function.
 
  The newer CATV splitters, etc, have rubber boots that the male end seats
  into. Those also reduce the possibility of loosening but probably not as
  much as the seal nuts. If you have a problem with F connectors loosening
  over time the seal nuts used as lock nuts might be worth a try. Note
that
  the seal nuts will require about 1/8 or so of extra threaded area on
the
  female connector compared to using the F connector alone so they don't
  work with all female connectors. You need to make sure when using them
  that the mail connector still seats properly (i.e. the coax shouldn't
  rotate within the threaded ferrule of the male connector after it's been
  tightened).
 
 
 If the connectors are properly tightened, there is no reason at all to use
a
 lock nut or any locking aids. It is as unnecessary as a lock nut or lock
 washer on a car lug nut.
 
 I dealt extensively with F connectors in the 1980's for a company that had
 dozens of small CATV and MATV systems. They never had problems with
fitting
 getting loose. They had ten's of thousands of F connectors.
 
 You have to **snug** the connector with a wrench or tool of some type. Be
 sure the threads are clean and use some light pure silicon or Teflon
 electrical rated grease. It does not take much pressure, around 10
 inch-pounds of torque is enough. With a four inch wrench, that's about 2
 pounds of push. DO NOT use the common 30 inch-lb wrenches. They will do as
 much harm as good. If you do not know what two pounds is to push a wrench,
 push on a bathroom scale with two fingers and get used to the feel. Then
 push the same way on a regular 4 or 5 inch wrench.
 
 The worse tools of all to judge torque are pliers and connector drivers
that
 you spin with your wrist. End wrenches are the easiest to learn, because
you
 can snug with two fingers and really learn the pressure.
 
 One way to avoid water problems on low frequencies is to flood the
connector
 with a pure silicon grease. Dielectric tune up grease for automobiles is a
 nearly perfect grease. There are some good Teflon based non-petroleum
 greases, also. DO NOT use Noalox or any other anti-seize. Noalox is
nothing
 but trouble.
 
 On higher frequencies, like UHF or higher, you do not want to flood the
 connector. On lower frequencies, you can just flood it.
 
 Connectors coming loose is like having connecting rod nuts falling off, or
 wheel lug nuts falling off. It has nothing at all to do with lock
hardware.
 They all stay on just as well when greased or oiled as they do dry or
 locked. They only loosen when not tightened properly or when the
mechanical
 connection is seriously abused.
 
 73 Tom
 
 _
 Topband Reflector

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Topband Reflector

Re: Topband: Wanted - Hardline connectors

[Jim Garland]

Many thanks to everybody who responded to my inquiry. I received over twenty
responses, with many excellent suggestions. Turns out most folks homebrew
their own connectors, using brass plumbing fittings, and I received a number
of innovative designs. The aluminum jacketed 1/2 inch 50 ohm hardline
(RG-331/U) is rather unusual these days (a decade or so ago, large quantites
were surplused by the CATV industry), and off-the-shelf connectors are hard
to find at a reasonable price. Connectors are readily available for Heliax
and Superflex, but unfortunately these don't work with the cable. 

 

I think 50 ohm aluminum hardline is excellent for long runs without a lot of
bends. It's very stiff but also very tough. The vinyl jacket that covers the
shield is 1/16in thick (total diameter 5/8), and the aluminum tube is
virtually varmit proof. My version of the cable has a solid copper inner
conductor, .161 diameter, so losses are very low. I have a 500 ft run from
my 160m vertical to the junction panel at my tower, and another 200 ft of
heliax to my station. The antenna and radial field has been under
construction throughout the summer, and this afternoon some friends are
coming by to help me erect the 26m Spiderpole. With luck, I should be on the
air with it this weekend.

 

Thanks again to everybody for your help and suggestions.

73,

Jim W8ZR

_
Topband Reflector

Topband: Wanted - Harline connectors

[Jim Garland]

Hi All,

I'm looking for one or (preferably) two connectors for 50 ohm 1/2 inch
hardline - the CATV type, with a solid 1/8 in (approx) copper inner
conductor, solid aluminum tube for a shield and an outer vinyl jacket.
Again, this is the 50 ohm CATV hardline, not the more common 75 ohm type.
I'd prefer PL-259 connectors, but SO-239 or N-connectors will work. 

Tnx and 73,

Jimi W8ZR

_
Topband Reflector

Topband: 160m/80m duoband vertical question

[Jim Garland]

My 160m vertical is 79ft high (wire running up a 26m Spiderbeam fiberglass
pole), with a capacity hat. Is it workable to put an 80m 1/4 wave wire on
the same mast join both antennas at the base, in the same way people make
multiband fan dipoles? The idea would be that when operationg on 80m, the
160m antenna would present a high Z, and vice-versa when operating on 160m.
I don't have a feeling for how much interaction there would be between the
two wires, separated by only a couple of inches. Another option would be to
electrically isolate the wires and select one or the other with a relay.  If
possible, I'd like to avoid matching networks and complicated switching
arrangements, because the antenna is 700 ft from my station. Any advice is
most welcome.

73,

Jim W8ZR

_
Topband Reflector

Topband: Beverage Woes

[Jim Garland]

I have two bidirectional 720 ft beverages that use 450 ohm ladder line,
oriented NE-SW and NW-SE. The ladder line is supported by 4x4 wood posts,
about 7 ft above ground, spaced every 60 ft. The antenna works well, but has
turned out to be a maintenance nightmare. My first mistake was to anchor the
ladder line to the top of each 4x4 post using little plastic clamps (DX
Engineering). Those lasted about a week before being pulled apart by the
wind. I replaced them with wood pressure plates screwed down over the ladder
line with 2 lag screws into the top of the posts. Those lasted about a year
before cracking and splitting. The ladder line turned out to be very
fragile. The plastic material gets brittle and cracks, and the wind causes
metal fatigue and eventual failure of the strands.

 

I've spent the past three afternoons patching up the beverages for the
winter DX season and am only about half done.Yesterday, I thought I had
everything fixed and only needed to phase the ladder line properly. I left
one wire open and grounded the other wire at one end, and then used a DMM to
identify the grounded wire. To my dismay I found an open circuit on both
wires. A spent a couple of hours with a toner trying to find the break, but
to no avail. Then, it occurred to me that my Fluke 87-V DMM may be giving me
erroneous readings. I replaced the Fluke with my trusty Simpson 260 and
discovered the wire was actually intact. Evidently, the Fluke's sensitive
solid state ohmmeter circuit had been overloaded by the
inductance/capacitance of the ladderline or possibly RF pickup. I should
have known better from the get-go.

 

So now, I've got one of my beverages working and will start repairs on the
2nd one. I've decided ladder line is a terrible choice for a beverage
antenna, at least in New Mexico, where there is intense UV sunlight and
windy Springtimes.  My plan is to replace the ladder line with parallel
strands of 12 AWG copperweld wire, with pass-through insulators on each 4x4
post, and the wire anchored at each end. I'll use turnbuckles to adjust the
tension. I'm really tired of repairing the damn antennas, and my feet hurt
from hiking back and forth to each end. 

73,

Jim W8ZR

_
Topband Reflector

Topband: Spiderbeam mast UV Resistance?

[Jim Garland]

My 26m Spiderbeam mast is made of a shiny black fiberglass material. Have
users of this or the shorter Spiderbeam masts had experience with how well
the masts hold up to UV radiation? My QTH is at 7000 ft elevation and the
sun shines 330 days/year, so UV degradation is a big problem.  I've used
Krylon UV-resistant spray on my SteppIR yagi and it didn't seem to help at
all. I've heard that a water-based urethane paint works well, but don't know
if it would bond to the Spiderbeam mast. Also, the top of the mast is very
flexible and thin, so the weight of the paint might also be a problem. Any
suggestions?

73,

Jim W8ZR

_
Topband Reflector

Topband: Best coax for direct burial?

[Jim Garland]

My forthcoming 160m vertical requires about a 700 ft run of coax. I'd like
to bury the coax over most of the run, but some of it will be elevated, with
high UV exposure. (I'm at 7000 ft elevation and sun shines 330 days/yr.) The
climate is very arid here (about 4-6 in rain/yr), so water ingress isn't a
major consideration. 

 

I'd like an RG-213 type coax with a solid dielectric, rather than an LMR-400
type, or anything with a foam dielectric. The losses aren't an issue, since
this will be used exclusively on topband and 80m. I'm unclear about what
direct burial coax means, especially with respect to the outer jacket. Is
polyethelene to be preferred over PVC with respect to toughness and UV
resistance?  Stranded center conductor is mildly preferred but not
essential. Mostly what I'm looking for is long-term reliability. I'd
appreciate advice and suggestions, and also any recommendations about
suppliers (some of whom give very little technical info about their products
and are rather cryptic about who actually makes the coax.)

Tnx and 73,

Jim W8ZR

_
Topband Reflector

Topband: Spiderbeam mast suggestions needed

[Jim Garland]

Hi everyone,

I'm _finally_ trying to erect a decent vertical for 80m and 160m, and have
purchased a 26m (85ft) Spiderbeam mast. I'd really like to hear from guys
who have used this mast for these bands. I'll have about 60 120ft radials.
I've seen sheet from the manufacturer about using the mast as a monoband
160m shortened vertical. The diagram shows a wire wound aound the mast, with
4 7m wires near the top for a capacity hat, but wonder what other
configurations people have used?  Also, if possible I'd like to be able to
use the mast on both 80m and 160m. It will located about 600 ft from my
house.

73,

Jim W8ZR

_
Topband Reflector

Re: Topband: Bead balun waterproofing

[Jim Garland]

Hi Jim,
I think we may talking at cross purposes! I certainly agree with your
explanation about how a choke is in the common mode circuit, but not the
differential circuit. In fact, that just what I said in my posting. I also
agree that in the common mode equivalent circuit, the coax feedline looks
like a single wire whose electrical length is shortened by the inductive
reactance of a common mode choke. So we're in complete agreement on those
points.

What I was wondering about, however, is why you believe the distributed
intrinsic cable capacitance, in pF/m, has anything to do with this
explanation? The intrinsic cable capacitance is what I was referring to as
differential, and it, along with the distributed inductance per unit
length of the cable, is what determines the cable's characteristic
impedance. Any _series_ (differential) inductance or capacitance added to
the cable will electrically shorten or lengthen it, just as you said, but a
common mode inductance, such as a ferrite bead choke, will not do this
because it adds reactance to the inner and outer cable conductor equally. In
other words, I believe a common mode inductance always reduces the common
mode currents along the feedline, as one can easily visualize by drawing out
the equivalent circuit. I can't think of any mechanism that would cause a
common mode inductance to increase the common mode currents, which is what I
thought you were asserting. 
73,
Jim W8ZR

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim
Brown
 Sent: Monday, August 19, 2013 12:28 AM
 To: topband@contesting.com
 Subject: Re: Topband: Bead balun waterproofing
 
 On 8/18/2013 9:41 PM, MU 4CX250B wrote:
  I agree that strings of ferrite beads don't present a lot of inductive
  reactance on the low HF bands, but you lost me with your comment about
  the reactance canceling the capacitive reactance of the cable. I've
  not thought about this deeply, but it seems to me the cable
  capacitance is differential, between the center conductor and the coax
  braid.
 
 You're confusing the differential circuit with the common mode circuit.
 A choke is in the common mode circuit, but not the differential
 circuit.  In the common mode circuit, the feedline is a longwire antenna
 -- it's that current on the outside of the shield in the commonly
 discussed diagram.  An antenna shorter than a quarter wave looks
 capacitive, longer than a quarter wave looks inductive, and that repeats
 in increments of half waves.
 
 There's a simple analysis of this in my AES paper, and in several
 tutorials on my website. When I did literature search for the AES paper,
 I found app notes by major EU ferrite mfrs  from'50's/'60s that made it
 clear that they understood this (because of the advice they gave),
 although the concept was not directly stated.
 
 If you doubt this, build a simple NEC model with a short feedline and an
 inductive choke and compare currents with and without the choke. W7EL's
 manual for EZNEC discusses how to model the common mode behavior of a
 transmission line, and you insert the circuit model of the choke as a
 load in that line.
 
 Think about this -- a common method of matching a vertical antenna to 50
 ohm line is to make it a little long so that it's 50 +j xxx, then tune
 out jxxx with -jxxx ( a series cap). I'm doing this with one of my 160M
 TX antennas, and  I'm doing the opposite with a 160 antenna that's a bit
 short, adding a bit of L at the base. In both cases, adding the
 reactance lowers the impedance of that antenna, and that's what an
 inductive choke does in a capacitive (short) line. And when we lower the
 common mode Z, we increase the common mode current, which is the
 opposite of what we want to achieve.
 
 73, Jim K9YC
 
 
 _
 Topband Reflector

_
Topband Reflector

Re: Topband: Zo of an individual CAT5 twisted pair

[Jim Garland]

I believe that if you parallel two twisted pairs of a CAT5 cable, you'll
have a 50 ohm transmission line.(Each twisted pair is 100 ohms).  I've tried
this with CAT5e cable and find it works well, even for transmitting, up to
about 100W.  The VSWR match was very close to 50 ohms. The problem is that
there is very poor noise rejection. When I used it as transmission line for
a receive antenna I picked up all the computer hash, fluorescent lights,
etc. in the area. I quickly abandoned the experiment and went back to coax
cable.
73,
Jim W8ZR

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James
 Rodenkirch
 Sent: Monday, August 12, 2013 10:32 AM
 To: topband@contesting.com
 Subject: Topband: Zo of an individual CAT5 twisted pair
 Importance: High
 
 In an earlier post to this reflector, Carlos, N4IS, mentions using one
pair of twisted wires
 out of a CAT5 cable to feed the delta loop antenna used by T6LJ.
 
 I am assembling the pieces/components needed to put an FO0AAA style
delta loop
 receive antenna up and want to use the twisted pair cable as well.,
 
 My question is:
 
  Does it matter which twisted pair of wires I use?
 
 Thanks, in advance, for any thoughts72, Jim Rodenkirch K9JWV
 
 _
 Topband Reflector

_
Topband Reflector

Re: Topband: Problem with compression F connectors on Quad RG-6

[Jim Garland]

Hi Pete,
The Ideal blue-banded connectors for RG6 are part number #89-055, and the
black-banded ones for quad shield are #89-056. They both use compression
tool #30-603.
73,
Jim W8ZR

 -Original Message-
 From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Pete
Smith N4ZR
 Sent: Sunday, May 05, 2013 1:39 PM
 To: Topband@contesting.com
 Subject: Re: Topband: Problem with compression F connectors on Quad RG-6
 
 Very interesting, Jim - I have been using Ideal connectors from Home
 Depot, and they have no color band at all (nor do they have decent
 instructions for installing).  I will try to find some of the
 black-banded ones (I have red-banded ones for RG-59).
 
 73, Pete N4ZR
 Check out the Reverse Beacon Network at
 http://reversebeacon.net,
 blog at reversebeacon.blogspot.com.
 For spots, please go to your favorite
 ARC V6 or VE7CC DX cluster node.
 
 On 5/4/2013 11:13 PM, Jim Garland wrote:
  I'm sure most of you know this already, but there are different
compression
  F-connectors for ordinary RG6 and for quad-shield RG6.  I use Ideal
brand
  connectors with matching compression tool, and there is a color-coded
band
  for the two types of cables (blue for RG6 and black for quad-shield). It
is
  not always easy to find the installation instructions, but for quad
shield
  especially, it is very important to follow the directions so as to make
sure
  the multiple aluminum foil and braided shields make appropriate contact
at
  the connector, just as Tom cautions.
  73,
  Jim W8ZR
 
  -Original Message-
  From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom
  W8JI
  Sent: Saturday, May 04, 2013 6:08 PM
  To: Topband@contesting.com
  Subject: Re: Topband: Problem with compression F connectors on Quad
RG-6
 
  I'm having a repeated weird problem with compression F connectors on
  quad-shield RG6.  When I connect a short length (say 4 feet) of cable
to
  my MFJ-259B, I would expect R650.  Instead, when I wiggle the coax,
  occasionally I see the display change to R=0 and X= several hundred
ohms
  at 1.8 MHz.  This makes no sense to me - the R implies ashort, but
  where's
  all the X coming from?
  R doesn't come from a short, it comes from no loss resistance, or more
  correctly very low loss resistance.
 
  It sounds like the connector you have is not contacting all the
shields.
  This is typical for mismatched connectors and cable,  or improperly
  manufactured cables. It could be somewhere else also, but I've seen
this
  before with quad shield. That's why I avoid it.
 
 
The problem seems to vary with the same
  connector and different PL-259 to F adapters, which makes me wonder
what
  might be happening inside the adapters, but I can't imagine anything
  producing this result.  I have also been unsuccessful in detecting a
  short
  using a simple DC multimeter.
 
  Remember how RF current flows. It flows on the outside of cables,
unless
  it
  has a connection path to the inner shield. If you have cable with Mylar
on
  the inside of one or more shield layers, and a connector that only
  contacts
  the outside of the outer shield, the inner shields that carry nearly
all
  of
  the desired transmission line currents will be insulated and isolated
from
  the shield at the connector.  Every shield has to be contacted at the
  connector, or at least the inner shield does.
 
  This might not be it, but it is a common issue with quad shield. Dual
  shield
  is much more forgiving of connectors.  You'll never detect the leakage
in
  dual shield in outside runs. If you have nasty common mode problems, a
  thicker shield will help. It is also just as simple to add a few dozen
or
  few hundred ohms of common mode choking to regular dual shield cables
and
  knock down CM ingress to levels that cannot be noticed.
 
  I;'m wondering if I should go through my RX antennas and replace all
the
  F
  connectors and particularly the F to 259 adapters with something else,
  but
  what?  BNCs?
  BNC's are worse yet, as a general rule. They rely on spring pressure
for
  the
  shield path. Look into a type match error between the cable you have
and
  the
  connectors, or a connector installation error.
 
  73 Tom
 
  All good topband ops know fine whiskey is a daylight beverage.
  _
  Topband Reflector
  All good topband ops know fine whiskey is a daylight beverage.
  _
  Topband Reflector
 
 
 All good topband ops know fine whiskey is a daylight beverage.
 _
 Topband Reflector

All good topband ops know fine whiskey is a daylight beverage.
_
Topband Reflector