Re: Topband: B7P

[Rob Atkinson]

>It must be that there aren't very many BY hams that live in rural areas with 
>low noise floors. Hopefully portable operations with verticals on the beach 
>will catch on there.

They need to get phasing boxes and figure out how to use them -- those
things can't fix everything but they can clear out a frequency of one
overwhelming noise source if it can't be controlled any other way.

Rob
K5UJ

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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: INV-L Radiation Patterns: 15 years of experiments with one

[Rob Atkinson]

50 foot high inv. L here; total length 120 feet; 101 radials on
ground, but lengths vary from 10 feet to around 100 feet with most in
the 20, 30, 50 foot lengths.  Also I have an aluminum sided garage
that I strapped into the ground system.  Minimal reactance is at 1840
(I forget, but I think around 10 ohms).  Real component of the Z on
that frequency is 11 ohms.

Rob
K5UJ

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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Inv L Radiation Patterns?

[Rob Atkinson]

A bit more field intensity extends in the direction opposite the
direction of the horizontal part of the inverted L element.

73

Rob
K5UJ

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Using 4 - 6 elevated radials in lieu of 120 buried wires

[Rob Atkinson]

>The radial height above ground clearly did not need to be 50 feet,. It did 
>need to be high enough to easily be well above a tall truck, or more commonly, 
>a horseback rider.

The advantage to this is that you can get away with wire composition
(copper clad steel, or even aluminum if handled properly) that would
not hold up on or under ground.   And obviously, less wire is needed.
The fly in the ointment is that as you and K9YC mentioned they have to
be seriously elevated.  The clearance for a vehicle may matter but the
real reason is antenna physics in terms of wavelength.   Radials on
the ground act like a shield between the vertical element and earth.
When you go elevated, the radials become a counterpoise and the
antenna takes the form of a distorted vertical dipole but for that to
happen it has to be sufficiently removed from earth influence and
that's a matter of wavelength.  That's why on 160 m. they have to be
high -- what I've heard is 1/10 wavelength but as mentioned, things
seem to go well starting at around 20 feet.  Since it's more like a
distorted dipole, the length of the radials matters and they have
voltage on them.  Their spacing should be equal.  So, as usual with
antennas, there's no free lunch.  I occasionally work someone with an
inverted L and "elevated" radials which turn out to be around 8 feet
high or less.  Sorry, but no, not even close.  But I've quit trying to
teach these guys because they believe what they want to believe.

73
Rob
K5UJ

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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: NCC-2 antenna pattern?

[Rob Atkinson]

Since I am on a 50 x 100 foot lot, it is impossible for me to separate
my rx antennas from my tx antenna.  Of course on transmit, preamps and
the NCC1 are deactivated, but even so, the NCC1 had internal relay
chatter (there are around nine PC board mounted relays inside).  Small
RF chokes in series with the DC power line to the box eliminated the
chatter.   I may have added bypass caps inside it but I can't remember
if I did that or not.  But if so, that wasn't enough.  The chokes did
the trick.

Merry Christmas

Rob
K5UJ

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: AM Broadcast Filter recommendation

[Rob Atkinson]

First, get some kind of portable receiver out and put it on 1820 and
verify you are hearing the harmonic.  I doubt it is being generated in
your gear.  You will probably hear it because you are only 2 miles
from the tx site and if the station is running 5 or more KW they're
likely suppressing the harmonic adequately -- you're simply too close.
What we often hear in our own stuff like preamps is products generated
by a pair of broadcast stations mixing.  This doesn't mean that a
broadcast station is never at fault.  Investigation shows your problem
station is a 5 KW directional with 3 or 4 towers depending on the
pattern.  https://radio-locator.com/info/KRIO-AM

There's more to go wrong there.  You should look at the night pattern
and determine if your station is in a lobe or null.  You can observe
if the harmonic strength varies from day to night.  It's true that AM
stations aren't getting maintained as well as they once were.
Problems can crop up in the station's phasor, and tower matching
networks.   The pattern may not be in specification or they may not
even be changing to the night pattern.

A lot of high pass filters do not attenuate well near the top of the
broadcast band so as to not compromise 160 m. performance.  So fellows
with stations nearby that are on 1500 or higher:  Choose your filter
with care.  In the case of 910 you have a wider selection from which
to choose because just about all of them will knock a low frequency
like that down.  Even if the problem is a harmonic, putting in one or
more filters is worthwhile.

What about the harmonic?  If it's coming from the station, all is not
lost because it is a point source.  You can receive with small loop
antennas oriented to put the harmonic in the loop's null, or better,
employ a phasing network using inputs from two separated receive
antennas that can throw a null on 1820 at the offending broadcast
station.   Or you can use both methods.  If you are happy with your
current receive antennas, I'd try a phasing network if all else fails.

73

Rob
K5UJ

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: ICE Model 135B Preamp

[Rob Atkinson]

>How do you operate QSK with that kind of setup ?

I don't operate QSK but I am sure there are QSK ways of protecting
preamps.  This is a question for the QRO CW DX folks.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: ICE Model 135B Preamp

[Rob Atkinson]

On those ICE preamps, check the small dipped inductors, because they
can blow open if the preamp is exposed to a high enough RF field.  If
your preamp is on a rx antenna and you are transmitting with ham QRO
nearby that's enough to do it.  IIRC powering down the preamp isn't
enough.  It has to be behind some kind of feedline relay that opens.

73
Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Digiwave feedline

[Rob Atkinson]

Okay thanks for the explanation.

Rob
K5UJ


> Depends on the efficiency of the antenna and whether there's a preamp at
> the feedpoint of those with low efficiency. It doesn't matter for higher
> efficiency RX antennas like Beverages, or where local noise levels are
> fairly high. And it doesn't matter if there's a preamp at the feedpoint.
> Mostly it can matter for TX antennas.
>
> 73, Jim K9YC
>
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Digiwave feedline

[Rob Atkinson]

>Al shields and CCS centers can be fairly lossy below VHF. CATV coax tends to 
>be much cheaper than the coax designed for transmitting, thanks both the the 
>lower cost construction and the extremely large market for it.

Does this mean we are better off using something like RG8X with copper
shield and center conductor for lines to low band rx antennas?

73

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Topband cw - bugs rhythm, swing

[Rob Atkinson]

There were a few electronic key designs that surfaced in the '50s,
maybe even late '40s, usually appearing in QST.  But then Jim Ricks
W9TO designed his TO Keyer which Halicrafters started manufacturing
and that pretty much ended the other designs such as the MON-KEY.
Vibroplex made a single lever paddle, the Vibrokey, in colors to match
the TO Keyer and the combination was and is unsurpassed in my opinion,
if you want a fully automatic key that feels like a bug.

I never liked sending with a straight key and not long after I was
first licensed I found a J-36 at a hamfest and stuck with that for
years.  I tried an iambic keyer and paddle set around 20 years ago and
never really liked it.  Then I fixed up a used TO Keyer and Vibrokey
paddle and felt like I'd found a fully automatic bug, to me it was
wonderful.  A friend sold me a spare Original Deluxe a few years ago
and I think that model is the best bug you can buy.  If you look at
old photos of commercial radiotelegraph operators, they're usually
using Original Deluxes.  Sadly, I don't operate CW much at all now and
lately have been wanting to get back into it because believe it or
not, I think it might help stave off dementia.  Sending and receiving
CW, if you don't use any gadgets to copy, uses your brain a lot more
than yakking into a microphone.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: AM broadcast multiplexing

[Rob Atkinson]

I am always amazed at the hams who will buy a home within sight of a
broadcast tower.  Rule no. 1 when looking for a new QTH is to find
where all the AM and FM plants are and avoid them; especially QRO AMs
vis a vis 160 and HF.  I remember looking around the 670 site in
Glendale Heights IL around 10 or 15 years ago, just to get a look at
the tower, guying, base pier and insulator and so on.  This is a 190
degree stick so we're talking around 800 and something feet tall.
Then I caught sight of a short free standing tower behind a house with
what appeared to be a TA33 on it, maybe half a mile away.  I know that
ham tower was not there before the 670 site was built.  I just shook
my head in bogglement.  Not sure if that's a real word or not but you
know what I mean.  Maybe he got a really good deal or his XYL insisted
on it.

73
Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: How good is good enough

[Rob Atkinson]

>Just cut 20 more 70' radials.  Time to go play in the yard.

If that were all I could add, I'd switch them to 40 35' radials.

The R component of my inverted L on around 1840 is 11 ohms.  X is
around 20.  That's with 101 radials.  I look for a R of at least 15
ohms where X is minimal on an analyzer sweep.  At that point the
ground system is getting good.  The vertical part of the L should be
at least 50 feet.Just ground the analyzer and put the vertical
element right into it.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Skirted vertical antennas for MF broadcast

[Rob Atkinson]

>I'm surprised that the broadcast industry is just discoving [sic] this topic.

What makes you think it is just being discovered?

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: What antenna would you build?

[Rob Atkinson]

Good question.  I don't think you mentioned any cost limit.  Given
that I would put up a substantial self supporting commercial tower ~
130' tall.  Solid legs, 5 or 6' face tapering to 1 or 2 feet.  Pyrod
or similar.  I'd put a skirt on it, 3 vertical wires on insulated
standoffs with horizontal loops bonded in, every 20' or so and plow in
at least 100 quarter wave 160 m. radials around the tower base.
Essentially a skirt fed 90 degree monopole on 1800 kc.  skirt feed
means the tower can be grounded and used for other purposes at the top
-- whatever your interests are.  Of course it would have to be sited
to allow room for the ground system.  Forget about anything horizontal
or any kind of dipole on 160.  I guess if you wanted to spend a lot,
you could do a pair of these towers and phase them.  You'll have solid
towers you'll never be hesitant to climb; and never have to deal with
guy cables, or a base insulator like you'd need with a guyed hot
tower.   You will get out unless the band is completely dead.  It will
be interesting to read what others come up with.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: TV coax + F-connectors

[Rob Atkinson]

Good luck with that voltage breakdown rating for foam RG6 running high
power through it and other than a flat line.

As to the milliwatt loss on transmit, okay FB but on rx with
microvolts, I'm already deaf and don't need for it to be any worse
than it is.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: F connector how-to video

[Rob Atkinson]

I know many will disagree but I wish the ham industry had never gone
to RG6 and F plugs and jacks for filters, preamps and various rx
antennas etc.  I know that UHF/BNC/N take up more space and cost more
but the feedline and connector series that works for broadcast TV,
cable and broadcast FM reception doesn't always have the benefits hams
need, in my semi-humble opinion.  There is a confusing variety of
connectors and cables, strip and crimp tools, and quality is all over
the place, I think aluminum shields and crimps are unreliable, and I
don't think this entire line was ever originally intended to carry DC
to power active devices.  I much prefer copper and soldered
connections, plus BNC/UHF/N males can be threaded on and hand
tightened or released with a quick plier assist, and there is no
reliance on a thin copper plated center conductor for the male pin.
The whole move to RG6 and Fs was a big mistake.  Okay for consumer TV
sets and other throw away junk but not ham.  I realize there is
garbage RG8 and 8X and UHF connectors but they are a lot easier to
spot and avoid.  The convenience of solderless cable prep outside is
great, but where are you when a few years later you have all kinds of
intermittent problems out there?

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Radials on ground v FCP

[Rob Atkinson]

I can't comment on the folded counterpoise because I am not familiar
with it.  The "broadcast model" which I take to mean 120 radials is
used because in the case of a 90 degree tower on medium wave, the
earth current intensity is far enough from the feed point to
necessitate a higher number of radials so that as they diverge, they
are not so far apart from each other that the earth losses are
unacceptable.  Few hams have 1/4 w. towers for 160 m., and instead
employ shorter vertical radiators such as inverted Ls* and Ts, (1/8 w.
for example) so the ground current intensity is high much closer to
the feedpoint.  This means that fewer radials can be used because they
are shorter and at their ends, are still an acceptable separation from
each other.  Of course, ground conductivity plays a part also.  This
is good news for hams who want to save money on expensive wire.  All
of this is detailed in the Griffith book I referenced previously.

73
Rob
K5UJ

*Unlike the T, the horizontal portion of the inverted L radiates.
W1BB recommended extending radials that run along underneath it if
possible, and I think that was good advice.

On Sat, Jan 8, 2022 at 9:27 AM CUTTER DAVID  wrote:
>
> Rob
>
> I recall a discussion on here some years ago which proposed that, whilst 
> being an amazing antenna for top band, if you could achieve it, the broadcast 
> model was not necessarily the best use of resources for amateur purposes, on 
> the basis that broadcasters are mainly interested in ground wave to cover a 
> defined relatively short range service area, whereas amateurs a more 
> interested in dx.
>
> I don't recall how that discussion ended, but for purposes of saving wire, at 
> least, the K2AV folded counterpoise (FCP) must be about as good as anyone 
> could attain.  How it performs against that broadcast model would be of 
> interest.
>
> David G3UNA
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Radials on ground

[Rob Atkinson]

For medium wave, every ham who transmits with a base excited vertical
radiator should get a copy of _Radio-Electronic Transmission
Fundamentals_ by B. Whitfield Griffith, Jr.  2nd ed., Noble Pub. Co.,
Atlanta Ga., c2000, ISBN 1884932134.  638 p.  Griffith is a retired
principal engineer with Continental.  This classic college broadcast
engineer textbook explains many fundamentals involving medium wave
transmission in an easy to understand way.  Getting the most out of
your valuable copper wire is more important now than ever because
copper has risen to insanely high prices.

The book is probably out of print but might be available used from ABE
Books https://www.abebooks.com/

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Need antenna help

[Rob Atkinson]

The problem with adding a top wire to your 43 foot vertical is that it
is probably not made to support a wire pulling on it at the top,
unless it's cross section is uniform and it is guyed at the mid-point
and top so it doesn't pull over.  What is often done in this situation
is that a trap is employed at the top between the vertical and wire so
any RF above 160 m. doesn't make it to the wire.  That was the HyGain
HyTower 160 m. add-on kit design.

Or, you can use the 43 foot vertical (if it is strong enough) to hold
a separate wire on insulated standoffs for 160 and feed the wire at
the base for 160.   I do that with my 1/4 w. 80 m. vertical; the
inverted L wire is about 3 feet out from the 80 m. mast.   To be
honest, I recommend something like that for 160 and 80 m., over the
same ground system, with some other solution for 40 on up.  I'm not a
big fan of the 43 foot vertical which has some strange fascination for
many hams.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Horrendous Local Noise

[Rob Atkinson]

>Well he drove the 100 miles up here and arrived with a colleague about 2pm,
spent a while in the shack listening to the noise, and monitoring it on
their equipment connected to my Top Band dipole. After about 45 minutes they
both went out in the street, and an hour later they came back to say they
>think they had tracked it down.

>It actually turned out to be a faulty piece of equipment in a house up the
street . . . but not radiating directly - it was sending these huge spikes
back down the Mains . . . and then I guess the wiring in all the houses
along the street was then re-radiating the noise (which is why I couldn't DF
>it properly).


The key thing is a transformerless appliance that puts noise onto the
power line from the utility and is reradiated by all above ground
wiring that is directly connected to the offender's service drop.
Here in the U.S. that would be every dwelling on the secondary winding
of the distribution transformer.   For the average ham, this would be
almost impossible to locate and deal with directly.  You found how
difficult it was.

Therefore, it would be extremely useful to find out what the officials
did to diagnose the problem.   What did they think when they heard it?
 What detail about it stood out to them?  What apparatus did they use?
 Exactly what did they do to track it down?

Once they found the source, what did they tell the homeowner?  Was the
device replaced?  Confiscated?   Were they ordered to stop using it?
And what was the appliance?

Folks, don't just let these opportunities to learn go by.  These are
valuable opportunities to become better educated so some of this work
can be done by us to save time.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: cheap radial wire?

[Rob Atkinson]

> Dog electronic fence wire via ebay.

Bad idea, except maybe for field day or some other temporary setup due
to rust.  Also, long thin runs of steel may not return RF well.

For permanence it's a lot better to invest in 3000 feet copper that
can provide sixty 50 foot radials.  That will at least get you in fair
shape with an inverted L.  But, I get that copper price is out of
sight now so if you don't mind  wasted effort, experimentation with
cheaper alternatives might be worth it.  Just be prepared to have them
rust away or vanish in the case of aluminum.  It might be advisable to
find out about your soil acidity before doing anything.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Balloon Supported Vertical

[Rob Atkinson]

I'd look into some kind of drone for this.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Anyone using a NCC-1 with 2 magnetic RX loops?

[Rob Atkinson]

I have a NCC-1 with a pair of rotatable pixel loops.   I have one
filter in the NCC-1, a high pass broadcast band filter.  It really
hits the stations around 1000 and below.  Doesn't have much
attenuation near the top of the band but the problem stations are down
below 1200 here (Chicago).

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Inv L corner insulator

[Rob Atkinson]

My hunch is that your problem is the wire you are using.   My inv. L
is strung with hard drawn 7 strand bare AWG 14 copper.  Multi-strand
or solid soft drawn will probably break on you eventually.

73

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Question on active vertical spacing

[Rob Atkinson]

My rx antennas are around 40 to 50 feet separated.  I get good peaks
and nulls on 160 and the top of the AM broadcast band.   80 m. doesn't
work as well.  But 160 is where you really want it to work.  That's
where noise is a big problem.  Use a groundwave broadcast station on
1400 or higher to test your setup and practice using it.  It helps if
you have some kind of receiver with a panadapter.  As you rotate
through the phasing you can see the broadcast carriers move up and
down.  Using phase and balance between the two antennas, you should be
able to take a pretty strong carrier and put it into the noise.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: RX loop antenna RX protector

[Rob Atkinson]

You probably have a preamp on your rx loop.  The first thing to do is
kill the dc to it on transmit to shut it down.   I have an Airspy
HF+Discovery SDR which has a fragile front end.  To keep tx RF out of
it, in addition to shutting down the preamps, I put a pair of coax
relays in series, the little ones with SMA jacks on them, between the
antenna feed and the SDR.  I used a pair because each had 12 v. coils,
and my sequencing system runs on 24 v.  I also put the SDR in a metal
box and put pie wound chokes in series with the DC control lines into
the box.   As I recall, that was enough to protect the SDR.  A lot
depends on prox of tx antenna to rx antenna and also tx antenna
relative to shack.  If all are spread out, job is much easier.  I also
used an ice cube relay in the feedline to break open both the center
conductor and shield to interrupt RF on the outside of the shield.   I
looked at the commercial rx protectors (not the one posted here by a
fellow in the U.K.) and the specifications were not sufficient for the
Airspy.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Shunt-fed Tower Ground Ring Insulators

[Rob Atkinson]

Tower base concrete should not be in series between the tower and
ground.  There should not be a voltage gradient across the concrete
base.  All ground paths should be strapped around the concrete base.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Hygain hytower on 160

[Rob Atkinson]

No personal experience but I've heard repeatedly over the years that
the inverted L kit works way better than the loading coil.  This makes
sense.   I think the inverted L kit consists of a trap you hang off
the top of the BX section.  You probably supply the wire but on that
I'm not sure.  I don't know if this kit is still being made or not but
you might be able to fabricate a trap yourself.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: NCC-2 for phasing RX antennas

[Rob Atkinson]

If you are having a problem it would be faster if you wrote what your
problem is.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Adding 80 m to 160 m quarterwave vertical

[Rob Atkinson]

A ham can certainly try a voltage fed 180 degree vertical, but the
physical conditions at the feedpoint change dramatically because it's
quite possible a few KV of RF v. will be there, unlike what we have
with a current maxima at the feedpoint.  So insulation and keeping
surfaces dry become much more important.  You can't just use a block
of wood exposed to rain for an insulator and if the base is on a
concrete pier, it has to have copper strapped around it so the
concrete isn't part of the v. gradient between the antenna and ground.
Besides arcs, RF loss is a consideration, plus the ground system has
to be extended because the induced earth currents are farther out.
It's a lot of trouble and expense for a slightly lower take off.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Elementary Inverted L questions

[Rob Atkinson]

>I have been trying to replace my inverted L, which broke a few weeks ago, and 
>am having all sorts of puzzlements. Please be kind - I was a history major. 1. 
> The inverted L broke at the turn, so I went looking for sturdier >wire.  I 
>wound up with some #14 insulated recommended by our local RF maven,

I advise ordering a roll of number 14 bare, 7 strand hard drawn copper
wire.   Put up a continuous length of it.  It will be less likely to
break.   On-ground radials can be solid soft wire.  Not the vertical.

> and put up 140 feet initially, figuring I would prune it *up* into the CW 
> part of the band.  Imagine my surprise when it showed up resonating at 1977 
> KHz (on an AA-55 Zoom).

Your plan is okay, but something is causing a problem.  Firstly, you
need to putdown  more  radials.

>  Does insulation have such a profound effect on velocity factor? 2.  My 
> feedpoint arrangement has 17 turns of RG-400 as a common mode choke, with the 
> radial field connected to the RG-400 shield at the antenna end.

Ditch the choke and put your measuring instrument right into the
driven wire and ground system.If you have 60 or 70 radials, you
don't need that stupid choke.

> Initially I tried measuring the resonance without the radial connection.  No 
> resonance and infinite SWR.  I connected the radial field (8 X 70-foot 
> radials on the ground) and that's when I saw the 1977 KHz resonance (X
> crossing zero).  SWR at minimum was above 2:1.  Does this make sense?  I know 
> the radial field is inadequate for good performance, but...

The vswr only 2:1 makes sense because you have a poor antenna.  It
should be 4 to 5 to one minimally on some frequency on an analyzer
that is normalized for a 50 ohm load, IF you have a decent ground
system.  With few radials Z is higher up and closer to 50 ohms instead
of 10 to 15.  This also depends on the vertical height.  I'm assuming
a typical inverted L that's around 50 feet vertical.  Analyzers
put an extremely low amount of power into whatever they're testing.
The highest power unit I know of is the MFJ 259 family which puts out
around 20 mW.   Poor continuity such as corroded surfaces at hardware
joints or cold solder joints or contact surfaces such as banana plugs
and jacks will be high enough R to throw off the instrument.  Put 100
w. into the antenna for a few seconds to blow through these problems
and check it again without the choke.  Ideally an RF source should not
fold back.  The old Ten Tec rigs were good for that.  Better still is
a tube rig like a DX100.  It will dump 100 w. and not give a flip
about the load Z.  Hit it for a second or two with whatever you have.
The excited wire may be broken, or ground system bonding flawed, or
something else.

Example case:  I have an inverted L 50 feet high that's held up with a
guyed 3" o.d. aluminum mast that's 50 feet high in two sections.  The
mast has one point at 31 feet where the sections are bolted together
and guyed.  The top 19 feet is free standing.  Naturally there's some
interaction between it and the driven inverted L wire.   When I put it
up, I stupidly neglected to put Noalox on the joint at 31 feet.  Now,
on extremely windy days and nights, the mast bends and flexes and that
joint becomes intermittent.  This affects the inverted L Z.  My L
network matches the antenna to 50 ohms under normal conditions but
when the wind gusts up continually to 50 mph or more, I see the vswr
jump up to 3 to 1 roughly, as if a switch is being flipped.   I have
to tilt the mast over and disassemble that coupling, clean and
reassemble it with Noalox.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Ground Radial question - Perimeter connections

[Rob Atkinson]

It depends.  If you have two or more verticals for a phased antenna,
and full length radials, the points where the ground systems intersect
is where the radials should be terminated and bonded to copper strap
running along the boundary where they cross each other.  If you have
an out building in the radial field, a strap is usually run around the
foundation of the building, radials run up to that and bonded to it,
then continued on out on the other side.  These are methods prescribed
in broadcast engineering texts, and what you'll find at a commercial
ground system installation.

If you have one vertical and a ground system for it, you don't need to
do anything.  Some professionals terminate compromised lengths (i.e. <
1/4 wave) with short ground rods or strap but I am not sure there is
any real benefit to that.  If it were me, I'd put my money and effort
into more radials rather than perimeter strap.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: New Subject: 160M array feedline question

[Rob Atkinson]

Inspect your feedline you plan to use (sounds like it is Heliax) and
make sure the jacket is undamaged.  If it is okay, you can bury it or
just lay it on the ground and it won't matter if water covers it.  Of
more concern is keeping the junction where the feedline divides dry.

If you use enough radials, you won't have to worry about the feedline
shield becoming a radial.  It will be one, but the RF on it will be
minimal because it will be one among many radials.  But you have to
have a lot of radials.  I am taking your description of the field
being under water for only a couple of weeks a year into account.

If you are concerned about animals chewing on the line, burying it or
elevating it may be needed.  I've had something chew on my 1/2 inch
line but I guess rodents realize the jacket isn't the same as wood so
they don't go very far.  The line is fine due to the solid copper
shield.  This is one of the reasons why Heliax is superior to braided
shield line and a worthwhile investment.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: New Inv-L Questions

[Rob Atkinson]

To clarify:

> The sign your antenna is efficient will be a
> narrow R and X sweet spot.  R should drop down to around 14 ohms and
> (depending on the length of the driven element) X should hit zero over
> a few kc.

I should have written:

X should hit zero over a few kc at some point in the band, depending
on the length of the driven element.   Sorry for the confusion.


 73

 Rob
 K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: New Inv-L Questions

[Rob Atkinson]

> My questions are these - is a
> relatively flat curve to be expected, or a sign of something wrong?

A flat curve is to be expected and it's a sign something is wrong.
And that something is that you do not have nearly enough radials in
your ground system.  Your radials are on the ground.  Such a ground
system should be augmented with about 10 times the number of radials
you have, but they don't need to be 70 feet long.  50 feet is okay,
but you need many more.  The sign your antenna is efficient will be a
narrow R and X sweet spot.  R should drop down to around 14 ohms and
(depending on the length of the driven element) X should hit zero over
a few kc.  If there are structures around re-radiating you may not see
0 X; it may dip down but not get to zero.

73

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: The WD8DSB mini-flag antenna

[Rob Atkinson]

Bi-directional loops lose their directivity for the most part, when
being applied to skywave signals.  Is this mini-flag still
unidirectional on skywave?  I would think not, but must ask.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: 160 Receiving Loops source?

[Rob Atkinson]

How much is "affordable?"  I mean, if you pay junk money, you'll
probably get ... disappointment either right away or after a few
months.

A possible exception is some place warm all year with no broadcast
stations nearby, so fixing and improving any time is easy.  OTOH if
you are in blizzard country, a budget priced loop may decide to quit
working during snowmageddon.  Consider a sturdy mount too.

BTW, while I'm dispensing free advice, if you power your loop preamp
via the feedline, use some sort of copper coax that can be soldered.
The RG6 aluminum stuff with crimp males will fail eventually -- okay
for RF but not DC.  Eventually there will be just enough corrosion at
the surfaces where the crimps are, that you'll get just enough v. drop
and the preamp won't come on.

For RF and RG6, it is important that you get quad shield (yes even on
160) and make sure the males match the coax.  The crimp tool,
connectors and coax should all be made to go with each other.   One
trick is to look for a cable TV guy who's out on a job with a truck
and approach him.  My experience is that they don't mind talking for a
few minutes about their tools and materials after you explain why you
are interested.  Find out  what he uses for "drop cable," crimper,
prep tool, and plugs.  Companies like Comcast don't use junk.  Then go
get what he uses.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: S meters

[Rob Atkinson]

I estimate that my receiving loops are 20 or 30 dB down from a full
sized antenna such as a 1/2 wave dipole at 50 or 60 feet, an antenna
that a lot of casual operators use (often to their detriment) on 160
m.  Sometimes I'll just add 30 dB to the S meter reading.
Alternatively, I'll tell the guy I'm working that I am either using a
speaker or headphones to hear him and with the latter, what % of his
transmission I copied.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Cage wire performance

[Rob Atkinson]

The problem with cages isn't electrical; the thing to consider is
physical.  If you are in an area where you can have ice you have to
consider if your cage and its supports are strong enough to hold ice
under high winds.   You don't want a relatively inexpensive wire cage
to pull down more costly supports that are a lot harder to rebuild.
Good idea to build in a weighted antenna that will sag to the ground
under a lot of ice, or a fail safe that is easy to fix.

73

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: standoff for inv L

[Rob Atkinson]

I've used a PVC pipe around 1.5 or 2" o.d. and ~ 3 feet long, for the
past 11 years.   No problems so far but it is braced with dacron from
the insulator end, back up to the mast a few feet above where the PVC
is clamped to the mast.   Mine is unprotected from sun but the sun
exposure is less in the Chicago area.  Of course when it eventually
fails, it will be in January, hi.   If I had it to do over again I
would have used the gray PVC that is supposedly UV resilient, and
taped over it as K9YC suggested.   Mine is hung the same way--wire
through dog bone insulator on rope through pulley, pulley attached to
PVC.

I'll bet that an aluminum pipe would work okay since the wire is well
isolated by the insulator, rope, pulley, rope series but use dacron
not wire and a decent insulator.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Low Dipoles

[Rob Atkinson]

> I do take offence at people suggesting that I am somehow lying about the
> results I have always had with a 160m Dipole at 50ft !

I don't think anyone believes you are lying, but perhaps instead, that
you seem to imply that your experience can be generalized and that you
are therefore, misguided.  This is because your results run counter to
decades of experience and observations by countless others when it
comes to antennas and 160 meters.  I invite you to come to the middle
of North America, Nebraska let's say, and set up the exact same
antenna in a rural location and report how it performs after a full
winter operating season.

Merry Xmas
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: I need help proofing an Inverted L model I made please. 40

[Rob Atkinson]

> IMHO, for that number, on-the-ground radials do not need to be anywhere near 
> that long.  Personally, I subscribe to the same-length-as-the-vertical 
> guideline.

The only thing about this I advise in the way of a change is something
W1BB recommended, which was that the radials on the ground going out
underneath the horizontal L wire should be as long as the horizontal
wire.  My horizontal component has some bends in it and I routed
around 10 radials under it to follow it.  It probably doesn't make
much difference, but it isn't that hard to run a few that are under
the wire all the way out.

73

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: I need help proofing an Inverted L model I made please. 40

[Rob Atkinson]

I've never understood what is gained by using a balun at the feedpoint
in this application.   The feedline is unbalanced as is the load.
What's the point of a balun.   The wild variations in R and X over the
range of the band will likely result in heat and loss at the balun.
If the point is to keep RF off the exterior of the feedline, that
problem vanishes if you have a lot of radials which are needed
regardless.   The best solution is to put the matching network at the
feedpoint but if you opt to match the line to the transmitter at the
shack, the vswr loss for 70 feet of 213 won't be terrible and the
dielectric will probably withstand the voltage maxima.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Good valve homebrew rig

[Rob Atkinson]

Are you sure you want to homebrew a vacuum tube _transceiver?_   How
about starting with a separate transmitter and receiver?   A tube CW
transmitter for 160 is certainly feasible.  A transceiver is too in
theory at least, but kind of a tall order.   If you pull that off,
you'll certainly have my unending admiration, but I for one can't
recommend anything.  A transmitter is different.  What power level do
you have in mind?

73

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Stainless Steel for coil taps.

[Rob Atkinson]

> There was also some mention to the effect that nickel was
> a "non-ferrous" metal and therefore would be good at RF.
> Nothing could be further from the truth.  Although technically
> "non-ferrous", nickel is nevertheless "ferromagnetic".
> I once measured some nickel strap material for RF loss
> and it was horrific.  Much worse than even what its DC
> resistivity would suggest.

This got me reading (https://en.wikipedia.org/wiki/Ferromagnetism) and
I must state that I was mistaken about nickel, which of course is part
of AlNiCo speaker magnets for one thing.  I apologize and thank N6RK
for this correction.  The Wikipedia article mentions some types of
stainless steel as being non-magnetic as I discovered by trial and
error years ago (but even so s.s. has a lot of resistance as has been
mentioned).

Brass is also a poor conductor.  I failed to mention that some metals
such as brass in a tank circuit are okay as threaded fasteners but are
not good for use as strap.   If you routinely build or modify RF
matching networks or run strap for grounding etc., it's very nice to
have on hand a roll of copper strap, pair of sheet metal scissors, and
a Roper Whitney Jr. hand punch.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Stainless Steel for coil taps.

[Rob Atkinson]

> Rob, are you implying that I shouldn't use a steel lattice tower to conduct 
> RF as a radiator?

Good question and I wondered the same thing.  Firstly not "implying"
that at all.

It comes down to mass and surface area.  The problem with steel, iron,
etc. is when you have a lot of RF current over a small area like a
narrow piece of steel strap or a steel nut, bolt and washer.   The
surface area of a tower is so big that it doesn't present the same
amount of problem.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Stainless Steel for coil taps.

[Rob Atkinson]

We all learn this sooner or later:  Don't use ferrous metals to
conduct RF.   If a metal fails the magnet test, it's out.  Every time
I get some item of homebrew or something that's had a previous owner,
(transmitter or matching network) I go through with a magnet and see
if a previous owner or builder used steel around RF stages or matching
networks.   Some steel alloys may be better than others but it's
impossible to tell, so out they go.  Brass, copper, aluminum, silver,
nickel all okay.   EF Johnson and perhaps others used steel nuts and
bolts that were plated with nickel.  That's okay as RF current has the
skin effect.

What's wrong with ferrous metals?  They don't conduct as well but more
important, at the microscopic level, they vibrate at the RF frequency.
This does two things:  Generate heat, and slowly loosen clamp, as in
the case of a nut, bolt and washer for example.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: OT - Bonding Radials at Intersections

[Rob Atkinson]

Scroll down to drawing 5 and 6 to see the proper way of handing
intersecting radials.

http://www.hatdaw.com/papers/groundsystem.pdf

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: CW Activity

[Rob Atkinson]

If you want to find out about QRN somewhere you don't have to ask on
an email list.  You can just go to windy.com or www.lightningmaps.org
and see for yourself.  Also lightningmaps has a gray line plot so you
can see where dawn and dusk are.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Rohn 25 Vertical questions.

[Rob Atkinson]

The proper way to use a tower like yours as a base excited monopole is
to construct a pier of concrete with a bottom plate pin bowl that is
steel and bonded to copper strap that goes down on each of four sides
of the pier to the ground ring.  The reason for this is so that there
is no voltage gradient across the concrete.  You need to obtain a Rohn
25 bottom tapered section and a porcelain Lapp or Austin insulator
that has a bottom cap and pin that seats in the bowl.  Now your tower
is correctly insulated in a single point so it can rotate under wind
stresses.  The insulator should have all of the voltage across it in
the event of a lightning strike, and you need to have a ball gap
between the tower and the grounded steel pin receptacle on the top of
the pier.   Your tower should be guyed according to Rohn
specifications, but the guys if steel, must be broken up with johnny
ball insulators.

If I were planning such an antenna I'd opt for a free standing tower,
skirt fed with insulated standoffs holding vertical wires, one off
from each face, and tied together with horizontal rings about every 25
feet of height.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Windows 10 Update heads up

[Rob Atkinson]

Seems to me that for the money hams pay Flex in that annual service
fee, (or is it monthly?) you ought to get professional Windows
maintenance.  There are ex-MS techs out there who can be hired.

I've had a Mac at home for the past 15 years at least.  Since 2008
it's been a mac mini.  So far, Apple has set it up so that I can
choose between automatic and manual updates.  I always have mine on
manual.  I get a notification when updates are available and then I
pick a time when I'll install them.  Macs have their share of nuisance
problems and I am not heavily invested in computerized ham radio.  If
I had to depend on a computer for ham radio I'd probably find another
hobby.

Microsoft forces these updates because if they didn't millions of
users would blow them off, and updates are vitally important for the
security of your machine against outside threats.   A lot of the
updates have to do with patching vulnerabilities, many of which are
immediately getting exploited in the wild.   So many windows PCs have
been hacked over the years the Company got serious about it beginning
around 10 years ago and this is part of the result.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: 1610 KHz AM Channel in USA

[Rob Atkinson]

Tnx for clarification.

> I don't know what "noise is usually AM" means.

Hi, I guess I was thinking of RFI from appliances and arcing contacts
on power lines.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: 1610 KHz AM Channel in USA

[Rob Atkinson]

>All of this success for BCB listening doesn't mean jack on 160 meters.

>On the BCB, you are never fighting noise, rather just separating different
>stations. They did also do that on 160 meters, for example, letting me
>work JA's even when stateside stations were also calling me.

I'm not following the reasoning here.  How are listeners never
fighting noise below 1710 kc?   In some cases noise (or by noise are
we thinking of QRM?) is worse on medium wave broadcast channels
because noise is usually AM and so are the desired signals.  Also the
receiver passband is wide.   Those TIS stations usually run only 30 to
50 watts and use physically small antennas.

73

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Adding connectoirs to CATV Hardline

[Rob Atkinson]

For 160 m. frequencies, connectors on hardline that preserve the
geometry (Z) of the line aren't needed.   You can dress the line (i.e.
strip back the jacket and dielectric) and make connections to
transmitters and loads with copper strap that's wrapped around the
center and shield and held with brass nuts and bolts or hose clamps.
Use brass clamps if working with aluminum.

73

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: 160m Vertical

[Rob Atkinson]

On 5/15/2020 8:27 AM, donov...@starpower.net wrote:

""A more reliable approach is a tuner in your shack. The extra coax
cable loss from elevated VSWR is insignificant on topband.""

We don't really have enough information to make that claim.  First,
you ought to get a copy of Radio-Electronic Transmission Fundamentals
by B. Whitfield Griffith, Jr.  It is a standard college textbook for
EE students interested in broadcast engineering and focuses mostly on
medium wave and is easy to understand.

We shouldn't advise you to put a matching network at the transmitter
end of your line until you tell us what sort of feedline you are
using, how long it will be, and what your transmitter power to the
line will be.  The wrong line with too much power over enough fraction
of a wavelength, with a high vswr, could cause a dielectric breakdown.
There's more to this than loss.

73

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: BCB Filter Recommendation?

[Rob Atkinson]

Most AM plants have been where they are for decades.  I remember being
at the local 670 site several years ago.  That tx site has been there
since the 1930s.  This is a ~800 foot tower, now with two signals on
it, 670 and 780, each 50 KW which means the total peak power on
positive modulation is roughly 400 KW.  I recall seeing a little 60
foot ham tower about a block away with a 3 el. beam on it, and
wondering how any ham could be dumb enough to buy a house in the
shadow of a major market ND class A-1 station.I would not even
consider buying a house near a 1 KW daytimer.   I'm about 10 miles
from the 670 site and that's bad enough.  Being a quarter mile from it
would be a nightmare.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Ground Conductivity

[Rob Atkinson]

It is indeed true that variations in liquid soil moisture will
dramatically affect ground system performance and base fed vertical
impedance when an on, or below grade ground system is used.  Frozen
ground moisture is on a par with dry ground.  This is one of the
reasons for going beyond the point-of-diminishing-returns number of
radials--the more radials used, the more stable the feedpoint Z is,
over varying soil moisture in the radial field.   Antenna efficiency
is related to radiation resistance relative to the ground system.  If
you have a short vertical (inverted L) with a low resistance that you
cannot increase, you can improve it by lowering the ground resistance
by employing more radials.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Receiver protectors.

[Rob Atkinson]

Last year I purchased an Airspy HF+ Discovery SD receiver.  Eventually
I got around to trying to use it with a second hand Windows laptop.  I
was concerned about blowing out the front end on transmit because I
had heard of that happening with these receivers that are not designed
exclusively for ham radio.  A lot of the SD receivers are designed and
manufactured by non-hams for lots of uses other than ham radio.  They
are not made to be  used in an environment where they are in the near
field of a transmitting antenna excited by a few hundred watts or
more.

I looked at the DX Engineering product and saw this specification:
Max Output Level: RG-5000HD:+14 dBm at 10 W input. RG-5000: +10 dBm at
10 W input
The corresponding specification for the Airspy rx is:
+10 dBm Maximum RF input

These are sensitive receivers.   The DX engineering products were
marginal so I did my own thing.

I put the rx in an aluminum box with a UHF jack mounted on it an a
grommetted hole for the USB cable's exit.  I mounted a pair of relays
in the feedline to the receiver inside the box and put RF chokes in
series with the DC line to the relay coils (24 v. DC) at the entrance.
I figured two relays in series in the line would add some protection.
Amazingly none of this  helped much as a 20 w. carrier on 160 m.
produced a disturbingly strong signal trace on the receivers
panadaptor.  I wanted to see little or no signal at a few hundred
watts to feel comfortable about operating at higher power.  I was
using typical ice cube style relays.  The contact spacing isn't much
so I think the relays were just acting like low value air dielectric
capacitors in the line.  RF went right through them.

What finally did the trick were a pair of small DowKey style coaxial
feedline relays with SMA jacks on them.  Something kind of like these:
https://www.ebay.com/b/SMA-General-Purpose-Relays/36328/bn_7684024  I
found them at a hamfest and bought two because they had 12 v. coils so
I figured I could put two in series with their coils in series for my
24 v. keying system.  The same hamfest also had a guy selling small
coax jumpers with SMA males on them.  Perfect.  I wired them up  and
put them in the aluminum box with the rx and all the other stuff.
That did the trick.  I see little or no signal on transmit and the SDR
is safe at high power.  I really didn't want to zorch a $170 throwaway
item by making an avoidable mistake.  It took a long time of fiddling
and experimenting to get it right so I'm posting these notes to save
others some time.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Restoring the Signal to Noise Ratio

[Rob Atkinson]

>This is only half tongue-in-cheek.

>With the ambient noise going up, and there being limits to the size and cost 
>of receiving arrays most amateurs can build, the next logical step is to raise 
>the output power. Perhaps the FCC should be >petitioned to raise the legal 
>limit? They were supposed to safeguard our frequencies against interference 
>(man-made noise included), but since they have failed to do that, they should 
>allow more >power to restore the original signal to noise ratio? (Which some 
>already do, anyway.)

It's a legitimate idea and probably one of the best ways of dealing
with the problem when you think about what can and can't be
controlled.  I've been seriously suggesting the power limit be raised
or eliminated for a few years now.   Eliminating the power limit isn't
as horrible as it sounds at first, because there are a lot of other
factors that would prevent a ham from running crazy high power, but I
don't want to digress off into that here.   Unfortunately just raising
the power limit is probably never going to happen.  U.S. hams already
have it pretty good compared to some other countries, and the RF
exposure hysteria, which disregards the fact that about 99.9% of ham
operations are harmless, would prevent it.  Also, the power socialists
who think everyone should be limited to 100 watts would jam FCC with
objections.   By the way, the power limit debate goes back to the
1930s; it isn't new, but the noise floor problem is relatively new.
You can only do so much with rx antennas, phasing, DSP (which always
adds distortion from my experience), filters and tx antennas.   Of all
the ham band allocations, medium wave is probably most in need of
power.

73

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: .TX Mica Caps

[Rob Atkinson]

My opinion:  the PCB scare is overblown, just like lead in paint,
asbestos, etc.  If you are intelligent about it, taking prudent
precautions, PCB in caps and dummy loads should be fine.  I'm sure
hand wringers will weigh in with all kinds of nanny state far fetched
what ifs, but I have PCBs around here and I'm fine.

>-It catches on fire and fills the transformer vault with thick smoke when the
>monster transformer melts down?

At a ham station?

>-When a few drops leak out of a filter capacitor in one of our radios or
>transmitters?

Mop up with a paper towel and drive on.

>-If an electrician working on very big transformers puts his arm down in the
>oil to make connections and does it for some years?

I've heard of guys exposed that way and they were fine but again, that
doesn't sound like a likely ham radio scenario.

>-If I have a dozen 1000 and 2000 volt oil capacitors in a box in my barn?

Usually these caps use a paper dielectric impregnated with pcb oil.
What happens over time is that the seals around the lugs dry out and
there's a gradual ingress of air which compromises the dielectric and
the cap shorts out.  Store them upside down or better yet, do a
leakage test (methods for this can be found using google), use or sell
the good ones and properly dispose of the leaky ones.

>-If my want list has the RCA AR-88 on it which has oil filter caps?

That set has a one-can three section filter cap bank made of of three
500 v. 4 mfd paper dielectric oil caps.  In the transmit position on
the front panel ("Trans") the high B+ can hit 480 v. with no load on
it.  That will usually cause those old oil caps to fail.  The best fix
is to buy 15 or 18 1 mfd 600 v. polypropylene axial leaded caps and
make three clusters of 5 or 6 each and replace each can section with a
paralleled cluster.  Remove the stock cap unit or leave in place for
looks.  The new caps will fit underneath.  They will not leak and
they'll out last us all.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Topband resource

[Rob Atkinson]

>So how is it that I consistently work all over the world on 160m with my
>horizontal dipole at 50ft?!

Oh boy, here we go again.  As I believe I have pointed out before,
your QTH is not that far from a fairly vast amount of salt water.  You
can believe anything you want, but your experience if not embellished,
is atypical and does not refute the general guidance that vertical
monopoles with good ground systems perform better for relatively long
transmission distances on medium wave.   So you "consistently work all
over the world on 160m."   Over what period of time?  40 years?  One
contest?   Have you ever tried some sort of T or inverted L over 60+
radials using your dipole for receiving?  Perhaps you'd find you can
"work all over the world" in a much shorter time period?
Your repeated bragging/questioning about your installation as a thinly
veiled argument is disinformation and it is not helpful.  The physics
of antennas do not get suspended for your location.

73

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: FT-8 Contest would be great for Topband

[Rob Atkinson]

>Modes over last 2 hours

Some may say this is nit picking but to me it is important:

MOST of those so called modes listed are NOT different modes of
transmission, they are digital protocols.  A mode of transmission is a
method for altering a RF carrier so it conveys information.   CW is a
mode.  So is AM.  Spark is not a mode; it is an altogether different
way of generating RF.  FSK is a mode.

With most computer generated digital data transmissions, the method is
the same; only the digital protocol changes.  Therefore, they are not
separate discrete modes.  Let's not aggrandize computer generated
transmission--a lot of digital stuff is one mode, but many different
formats or protocols.

73

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: 160m vertical saltwater grounding

[Rob Atkinson]

Interesting information here:

http://www.arrl.org/files/file/Antenna%20Book%20Supplemental%20Files/22nd%20Edition/Seawater%20Grounds%20-%20by%20N6LF.pdf

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: K9ay loop not performing

[Rob Atkinson]

Actually, if you have a quarter wave driven element and you are
disconnecting it at the feedpoint, your relay concern shouldn't be
voltage so much as current.   Fast switching and large contact surface
is more important than voltage handling.

73
Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: K9ay loop not performing

[Rob Atkinson]

If you open the tx antenna feedline for rx, from my experience, you
need to completely open the entire feedline, namely the coaxial cable
shield as well as the center conductor.   coaxial relays that maintain
conductivity of the shield when N.O. won't detune/isolate the tx
antenna.  I use a pair of open frame relays for this.  Fortunately on
1800 kc the Z bump is almost nonexistent.   What will govern your
choice of relay is tx power and tx time, and whether or not you
require QSK.  I do not, but if you do, you may have to consider
something like multiple paralleled reed relays tor speed and power, or
vacuum relays.


73
Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: spark gap construction ideas for 160m tower

[Rob Atkinson]

>Curious as why non resistor spark plugs aren't on the list of choices. Easy to 
>gap. Pt-Pt electrodes last forever (100k miles). There was a ham mounting two 
>on a Cu plate for ladder line, but that was many years ago. <

That can work but the other construction methods offer a wider range
of v. breakdown.  keep in mind the articles were for broadcast with a
variety of feedpoint voltages.  But for 160 m., there's nothing wrong
with looking to medium wave broadcast for ideas to take away.

73

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: spark gap construction ideas for 160m tower

[Rob Atkinson]

There are a number of ways of making a ball gap.  but more important
is arriving at the correct spacing for the gap.
The way rain is handled is usually by positioning the balls one above
the other so a water bridge doesn't form between the balls.

Read this by Mark Persons:
https://www.radioworld.com/tech-and-gear/understanding-arc-gaps-for-am-systems
Here's another treatment:
https://www.thebdr.net/articles/steel/twrs/LimitingStatic.pdf
Kintronic sells them
https://www.kintronic.com/shop/tower-ball-gap/

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Furnace RFI

[Rob Atkinson]

Went through this about 2 years ago.  Firstly, define "efficient."  If
you mean over 90%, as in one of those two stage furnaces with PVC
handling moisture then you are consigned to having to use a variable
speed DC motor (there are no variable speed AC motors, only speed
settings you set manually at installation) that will cause RFI because
it is run on variable duration square wave DC.  You will have to have
the HVAC contractor install a manufacturer supplied hush kit, or do it
yourself.  The hush kits are over priced and many contractors are
unfamiliar with them and RFI.

Or, you can do what I did and get a single stage 80% efficient furnace
that runs on an AC blower and accept 10% less efficiency and get on
with life.   Mine is around 80K BTU, not extremely big.   There are
larger ones, or were.  I went with American Standard, an Ingersol Rand
brand name.   There are around three companies that make all the
furnaces; IR is one of them.  I've heard the AC blower furnaces are
going to be history in a few years after which they'll all be high
eff. DC because gov't is obsessed with this, but that's another topic.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: inverted l

[Rob Atkinson]

If you have a properly constructed typical inverted L, i.e. 50 or 60
foot vertical and similar length horizontal, AND a good ground system
serving as the other half of the antenna, your feedpoint Z will be 10
to 20 ohms.  The reason you need a matching network is that most coax
(this assumes you are feeding the antenna with a coaxial transmission
line) has a characteristic impedance of 50 ohms or more.  If you found
coax with a characteristic Z of 15 ohms you probably wouldn't need a
matching network.  Let's say you don't bother with a network.  Your
line will have voltage maxima and current maxima on it and exhibit
more loss but it may be okay depending on the line used and its
length.  The other problem is whether or not your transmitter has an
output network that can handle the other than 50 ohms Z it will see at
the end of the line with this arrangement.  If all of this is a
problem for one reason or another, you need a matching network.   With
antennas that have feedpoints near the ground, you can place it at the
feedpoint which is nice.   Any inverted L with an adequate ground
system, elevated or buried, will have a pretty narrow impedance
bandwidth for matching purposes.  Anything that exhibits a fairly flat
bandwidth, say 50 or more kc, is probably not radiating efficiently.
You can improve this, but the way to do it is to widen the width of
the driven element, for example instead of using a single wire, employ
a cage.

You can raise the impedance of the L by increasing the vertical
length.  Eventually with 1/4 wave length vertical, the ideal Z will be
around 36 ohms, but then it ceases to be an inverted L.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: RFI on TB

[Rob Atkinson]

>This has got to be on a case-by case basis.  I don't have any listening 
>antennas, so i listen on my transmit vertical.  It works fine.  For me.  Most 
>of the time. Would I hear more stuff with listening antennas?  I bet the 
>answer is yes under certain conditions.

Yes under certain circumstances using the tx antenna is okay for rx,
the most obvious example being local communications with a ham a few
miles away.  But I don't know of any serious 160 m. operator who does
not have separate receive antennas.  The reason is that the
reciprocity that allows the tx antenna to also work on rx starts to
break down as we go lower in frequency, beginning on 75 m. but by the
time we tune down to medium wave, it is very noticeable and receiving
becomes more about signal over noise than pure signal strength.  As
new hams, we probably all had the experience of mistakenly tuning
across 160 with the wrong antenna, maybe a 40 m. dipole, and wow, we
hear a lot.   We excitedly hooked up our 160 m. antenna only to hear
nothing, or a lot less.  What went wrong?  Ah, the education begins.

The other problem with the same tx/rx antenna for anyone except the
few lucky ones with no noise sources, is transmitting on top of a QSO
without realizing it.

73
Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: RFI on TB

[Rob Atkinson]

> Over past few months, I have picked up an S5-S7 noise signature on my TB inv
> L antenna with K2AV FCP system.

I would not use an inverted L for receiving.  Unusable for rx at my
QTH but FB for transmitting.

73
Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: FT-8 My Recent Experience

[Rob Atkinson]

> I can't get into any computer mode, mainly because I've been a software
>engineer for almost 40 year and dealing with computers at home is a
>non-starter with me.I like ARC-5s, BC-348s,  and Navy RBB's
>myself..

Same here.  Computer science major; 30 years in front of monitors and
keyboards all day; database management, writing codeand I know
hams who spend days and days fiddling with PCs and logging
softwareWhy?   What a waste of valuable radio time in my opinion.
Not only do I reject computer "modes," but I run a computer free
shack.   Great FT8 story by the way.

73
Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Voltage at top of vertical and scaling?

[Rob Atkinson]

I'd also put RF chokes in series with the DC relay lines, at the base
of the vertical antenna to further keep RF off it but also to break it
up so the relay line doesn't detune the 80 m. vertical, perhaps with
another pair at the shack entrance. All this sure seems like a lot
of work which is why I simply hung a wire for 160 inverted L from a 3
foot standoff at the top of my 80 m. mast and did my dual band that
way, using the same ground system for both.

73

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Lack of Activity

[Rob Atkinson]

There's activity and then there's "activity."  I take it that
"activity" in this discussion really means DX.   It so happens that
there's other kinds of operating going on on 160 m. besides DX chasing
if you can tolerate the tedium and torture of an enjoyable ragchew
with an ordinary ham nearby.

As for DX, I imagine that all hams are going SK at the same rate
everywhere, meaning that an entity with a ham population of 50 in
1980, now has a ham population of 5, with maybe one active on 160.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Inverted L improvement question

[Rob Atkinson]

> It doesn't work very well. Last night it was much poorer on receive and
> transmit than my existing 43' vertical setup. I'm not sure what to think.

Your fundamental problem is a lack of understanding of how a monopole
works, specifically a base fed vertical with a ground system.  Anyone
who tries to use a ground system that converges on a point removed 10
or 20 feet from where the vertical element is excited does not really
understand how these antennas work.   You can't expect good
performance by distorting the geometry of the antenna to bring the
feed point to the counter poise convergence point.  You can't just
throw out physics.  it will radiate something, it just won't meet your
expectations, as you mentioned.  If I were you, I'd fall back and
start doing some reading.These antennas in their various forms
have been developed since the 1930s.  There's a pretty vast amount of
information about them, but what you will probably benefit most from,
is a college text book treatment, the kind of text used for a class on
radio broadcast engineering.  One such text is Radio-Electronic
Transmission Fundamentals by B. Whitfield Griffith, Jr. 2nd ed.   It
has a few chapters on medium wave verticals, ground systems, radiation
resistance, current and field intensity but is written for students in
an easy to understand way.  Perhaps you can find a used copy on-line.
It's better to take your time and study these things, then use your
knowledge to correctly construct the antenna, even it it means waiting
until next fall to try it.

73

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Inverted L improvement question - Part 2

[Rob Atkinson]

Hmmmyou DID relocate or rebuild your ground system so it converges
on a point below the bottom of the 100 foot tall wire right?  I mean,
you aren't using the 43 foot vert. ground system with the 100' wire?
A series fed vertical isn't rocket science so let's not over think
this.  If it doesn't work well it is probably inefficient.  I'd make
sure your ground system is adequate.  No, you can't use an existing
ground system that converges on a point 30 or 40 feet away from the
100' wire.  Yes, I've had people ask me if they can do that, so it is
worth mentioning.

You can go the elevated route, but it is _critical_ that it be
constructed correctly to adequately replace a full ground system at or
below grade.   You need four radials parallel to earth extending out
90 degrees from each other and their lengths must be equal and 90
degrees long (1/4 w.) at frequency.   The ends must be h.v. insulated.
They should be elevated 20 feet on 160 m. to completely de-couple from
earth.

73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: RF in the DX Eng. NCC-1 (and a fix)

[Rob Atkinson]

Merry Christmas and Happy New Year:

On 160 m. (probably due to the close proximity to my inverted L) my
NCC-1 rx antenna phasing box would snap crackle and pop on transmit,
most likely the result of RF getting into the nine relay coils inside.
If you employ phased rx antennas and a tx antenna, all in a small
space, running over 1 KW you may have noticed this also.  The stock
box has some small bypass caps on the DC supply line in, and the T/R
control line in, but they were not enough to keep RF out entirely.
The fix for me was a small 100 micro-Henry choke inside the box in
series with the floating center of the T/R line, along with a 0.015
mfd cap on the cold side of the choke to ground, and a pair of the
same chokes  in series with the DC +,- supply line into the box at its
entrance.  The DC supply jack has an adequate amount of stock bypass
capacitance so I didn't add any more.  0.1 mfd if I remember
correctly.  These fixes quieted the NCC-1 down for me and were a lot
easier than trying to bypass each relay coil to ground with
capacitors.

73

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Inverted L improvement question

[Rob Atkinson]

If your inverted L is any good at all it will suck as a receiving
antenna.  This is one of the key things to accept about medium wave
but many casual 160 m. operators can't wrap their heads around it.   A
flame throwing tx antenna will probably have a completely unacceptable
noise level on receive.  Tx/rx reciprocity works on HF but not as well
on medum wave.   Separate rx antenna(s) are mandatory.A
significant irritant on 160 are the operators with poor antennas that
hear great, therefore they expect to be heard equally well, and can't
be made to believe they are piss weak when they transmit.

I'll pass along one idea I got from a friend of mine regarding your
tree holding inverted L.  Since the tree is probably a substantial
support, I'd lower the L (this is assuming you have a pulley on a rope
over the branch, through the pulley another rope attached to an
insulator through which the top of the inverted L transfers from
vertical to horizontal, all to facilitate raising and lowering) and
bolt three more copper wires to the current wire, near the point at
the insulator, with one wire continuing on through the insulator.  The
3 new wires should be long enough to drape down to the ground.  Now
pull it back up and spread your four wires so that near ground, each
one is in the corner of a square with 6 to 12 feet on a side, each
wire attached to an insulator which in turn is attached to a rope that
proceeds on to an anchor stake of some sort.  Next, run a ring of wire
around the square you have made so all four vertical wires are bonded
to each other, the square wire being around two feet off the ground.
Bring in your feedline and connect it, or your matching network if you
have one out there, to the ground system and the square ring wire.
I'd use awg 14 7 strand hard drawn bare copper wire for all of this.

What you will have done is a wire simulation of a free standing tower
insulated from ground with a 6 to 12 foot face around 100 feet tall.
You should have a very flat impedance curve with this which will
greatly simplify covering the band with minimal matching network
adjustment, and at much less cost than what a 100 foot 12 foot wide
skirt fed tower would cost.  If I had a tree like what you must have,
this would take me all of two seconds to decide to do.

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Rather use N-type (was Re: The answer to PL-259

[Rob Atkinson]

Some of you fellows who want to use Ns may benefit from this hint and kink:

https://www.radioworld.com/columns-and-views/repair-and-protect-type-n-connectors

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Rather use N-type (was Re: The answer to PL-259

[Rob Atkinson]

>>W6NL asked me this question - would you run 1500 watts with BNC connectors?

It depends on the duty cycle, length of transmission and vswr.

Brief contester type transmissons at 50% d/c into a load with Z = line
characteristic Z is probably okay.

AM broadcasting 1 KW carrier for 24 hours probably not.

What's the way to Carnegie Hall?

Practice, practice, practice.

What's the way to solder a UHF male?

See above.

It's similar to baking a cake.


Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Impedance of inv l?

[Rob Atkinson]

My inv. L is 50 feet up and 70 horizontal.  Wire is #14 bare 7 strand
hard drawn.  3 feet out from mast.  101 radials, two ground rods and
aluminum siding on garage strapped in to ground sys.  on around 1840 Z
is 11 R and ~ 20 ohms X.  A typical inverted L with a good ground
system should be down around 15 ohms at feedpoint from my experience
and rapidly change above and below the minimum reactance point.  High
resistance flat antennas have an inadequate ground system.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: 160m Condx

[Rob Atkinson]

>Why is it ever necessary to call on 1830, 1820, 1822 etc. exactly? Call CQ on
>1820.3, or 1820.4 or 1822.6 or 1827.8.

This only started with plastic radios and digital displays and got
worse with dial resolution down to one cycle.  Back when everyone had
VFOs like the HA-5 with dial markers only every 50 kc no one ever
thought about it.  All that mattered was being inside the band and
zero beat to the fellow being worked.  Now for some reason hams act
like the bands are channelized every 5 kc.

Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: RG6 connectors and installation

[Rob Atkinson]

Don't re-invent the wheel.  There are cable installers all over the
place--these are people who are given the tools and connectors by
Comcast and other big companies to make high reliability
installations.  When you see a cable truck out on location stop and
ask the guy what he uses.  If you explain why you are interested, you
will probably get all the information you need to order the F males
and tools yourself, but also find out what they use for cable.  It's
usually Belden "drop cable" high quality outdoor RG6.  My experience
has been these materials and tools are superior to what the ham radio
vendors sell.

73

Rob
K5UJ
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Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Radial wire

[Rob Atkinson]

>Rob, Not barbed wire, but electric fence wire.  This wire stays good for
>decades. Look at the horse and cattle farms around you. It has the same
>conductivity as your galvanized steel tower.  Nor does anyone consider
>making a tower out of copper or copper clad steel.☺ A radial system of 60
>1/4 wave of #10 copper cost 50 times what the electric fence wire costs.

Big difference between wire on fence and buried.  I've mistakenly
installed galvanized steel ground rods here.  Pulling them back out 10
years later they were nothing but rust and useless.  The surface area
of a tower's galvanized legs is much greater than the surface area of
a skinny wire, therefore the RF conductivity is NOT the same.  copper
has in fact become expensive compared to 15 years ago but all antennas
have gotten expensive.  The ground system is 1/2 of an antenna.  But,
unlike the directly excited part, you don't have to do the ground
system all at once.  You can put it in at affordable segments over
time, assuming you will use it for years to come.

73

Rob
K5UJ
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Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Radial wire

[Rob Atkinson]

Oh man, any time this topic comes up anywhere the guys come out with
all kinds of suggestions for wire that won't last like galvanized
steel and electric fence wire.  Nix nix nix...if you want a permanent
ground system go with copper, insulated or not.  Stranded doesn't lie
down as well; you want soft drawn copper sold.  Stranded wants to
spring up and stay coiled, especially if it is hard drawn antenna
wire.  Use that for antennas.   Copper clad steel can be hard to work
with too unless you have a spool on a radial plow and are laying it
into a slit a few inches deep with a tractor.

But if the installation only has to last a few months then use the
barb wire, etc.

73
Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: OT - US Hams, WWV closure

[Rob Atkinson]

>Some folks have commented on WWV's
>minuscule operating expense when compared to the total federal budget, but
>the problem with that thinking is we have thousands of federal programs and
>departmental budgets that also contribute just a tiny fraction to federal
>expense.  Collectively, it adds up to a much larger figure.  No matter what
>goes away, the impact is felt by someone.

I've heard Fed. Gov't burns through $6 Mil. every minute (maybe it's
every second).  In the time it took to read this far, Bam another $6
million.  Sure there are lots of dinky things the U.S. blows money on
and if no one defends them then they go away if they're up for a
defund.  NIST is sending up a trial balloon maybe?   Well, if there
are enough tech. trogs using WWV and we make enough noise, maybe this
dinky little program will get saved.  Let them cut funding for some
stupid study on why moss only grows in shade.   Bam, there went
another $6 million.  Don't know about all of you but I have a hell of
a lot of things to do besides mess around trying to set up my own
rubidium  doohicky because WWV went away.  Bam there went another $6
million.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: NEW CALL for WA8WZG

[Rob Atkinson]

>Finally I get an email from the FCC this morning , I won a lottery!!

FB on the new call, but is this all you get?   Don't they mail out
something on paper?

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: Baker Island DXpedition on 160

[Rob Atkinson]

I respectfully suggest the Baker Is. dxpedition be postponed for a few
years until band condx improve.  It makes no sense to me to mount this
costly undertaking to a limited access location when propagation is in
the toilet.   If USFWS is managing access, they've lately shown that
they'll only approve trips to islands under their custodianship every
10 years or so.  If this is the case with Baker Is., then this trip
will make another one in a few years impossible.

Another point I'd like to make is that a later trip might afford a
chance to renegotiate what I consider a ridiculous antenna limit,
which seems to be based on a ridiculous antenna design, namely the "43
foot all-band vertical."Such a height with top loading might work
okay on 80 meters but on 160 its efficiency will be poor.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Adding chicken wire or mesh on top of radial field

[Rob Atkinson]

for permanent installation it's a waste of time because thin wire
steel mesh (chicken fence mesh) will rust away in most ground in a
short time.

Recommend copper mesh but professionally it only seems to be employed
around the base pier of voltage fed towers.  For a current fed tower a
lot of radials near the feed point, >= 90, is good enough.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Soil conductivity maps

[Rob Atkinson]

Suggest that for Hawaii or other locations where you want specific
soil data, contact local small AM or walk in and ask to talk to C.E.

Big corp. owned stations will give corporate hq. run around.


>>#1 As far south in the country as possible due to better propagation.

bzzt, sorry but South = high thunderstorm QRN.  nix nix.  QRN is
everywhere but in South you get shut down due to noise level or
proximity to lightning.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: low inv-vee

[Rob Atkinson]

1.  You never use an inverted L or other vertical for receiving,
unless maybe, you are in a QTH so remote and noise free it might work.
But in-town, forget it.

2,  From my experience, 7 or 8 out of 10 hams on 160 m., have poor
antennas, usually low horizontal wires.  Most of these fellows are
casual operators who ragchew and are okay as long as they understand
the limits of their antennas.

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: decoupling Inv L for loop on Rx

[Rob Atkinson]

I found I had to put a relay in the feedline to my inverted L to
completely open the line on rx.  Your typical "coax relay" only opens
the center conductor.  Fortunately on 160 m. an open frame relay that
opens the entire line isn't much of an impedance bump.  It is
essential that the relay be between the antenna and the shack ground
system, matching network etc.  The inverted L must be isolated from
the shack and rx loop antenna system on receive.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: 1/2 wave inv L

[Rob Atkinson]

A 180 or 190 degree vertical radiator presents a few different
problems compared to one 90 degrees long, due to the high voltage at
the feedpoint.   You can have ground loss there, but since it is more
of a coupling problem than a return current problem, the earth shield
is usually a copper mesh that extends out around the pier about 20
feet.  Think in terms of the loss at the ends of an inverted V when
the ends are anchored near the ground.

Since the feedpoint is high voltage, the way in which the base of the
radiator is insulated becomes more important, and the ball gap must be
adjusted accordingly, and access to the area kept more secure to
prevent casual contact with the excited base of the radiator.  If a
concrete pier is used to hold a ceramic base insulator, the pier must
be bypassed with copper ground strap so it is not part of the voltage
gradient between the mesh and the radiator, as concrete is conductive.

For ham (in my opinion) none of this is worth the trouble, and I'd go
with a quarter wave antenna.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: Radial Wire System Comparison - (was adding a parasitic reflect

[Rob Atkinson]

 >> I have researched Laport's material, and find nothing that compares
multi-tower array performance when using insulated radial wire versus
uninsulated wire when using a bus wire at the radial overlap points.  Since
his worked in the 1950s mostly focused on directional broadcast tower arrays
-- and the use of heavy-gauge wire, possibly insulated radial wire wasn't
considered because of long-term insulation decomposition that one day
>> results in electrical contact between overlapping radials.

I doubt if you'll find anything in the broadcast literature.  The
reason is that the standard DA ground system as far as I know, has
always involved strapping radials to a copper strap running along the
line of radial intersection, clipping off the radial wire that runs
past the strap.  And the standard ground system wire is AWG solid bare
soft drawn.  I think engineering firms like everything done the same
way from one site to the next to reduce variables for a full proof and
get a DA dialed in to the licensed pattern.

Why the teflon insulation?

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: FT-8 question

[Rob Atkinson]

> As is, its infuriating listening to high noise
> levels on 160m.   If I cant hear on 160m...except for the usual louder
> stations,  Im not going to even try TX.


Don't let noise stop you from transmitting.

>Right now, Im trying to evaluate if 160m is even worth
>the effort required.   Are the  rest of you on 5 acres out in the woods ?

Nope, I am on a 50 x 100 foot lot in town.  Try getting a pair of
small rx loops, two rotators, and a phasing network.  I have two pesky
noise sources from two directions and I can put one in the nulls of
the loops and phase out the other.   Of course all of this is a lot
more trouble than just putting up a dipole so 160 isn't for everyone,
but the challenge sort of gets into you.

I refuse to submit to the plasma TV authority and let 160 m. be the
province of those with "vast tracts of land."  You don't have to have
a S0 noise level to have a nice QSO with someone.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: FT8 discussion

[Rob Atkinson]

Actually the problem with the alleged QRM and FT8 is more about simply
identifying ham computerized modes of digital transmission and
reception and separating them out from the rest of the noise generated
by poorly filtered appliances, leaky cable TV, power line data
communications etc.  I am evidently a troglodyte who does not have a
computer in the shack and I refuse to run one for no reason other than
to be able to demodulate and identify ham digital signals.  I believe
the onus is on the digital mode operator to make his emissions
identifiable as ham radio to others, who like me, may be operating
analog equipment capable of demodulating common basic transmission
modes such as analog phone, and CW keyed with radiotelegraph code.

What I'm getting at is that a big mistake was made in the 1980s with
the CW ID requirement for RTTY and SSTV was dropped to convenience
those operators.  It was burdensome then, but SSTV and Baudot RTTY was
pretty easy to ID (although you couldn't tell a ham station from an
intruder).  Now, with seemingly zillion digital computer modes, it's
impossible for someone like me to tell a licensed ham from an
intruder, or a variable speed furnace motor.Ironically, an
automatic fast CW ID at the end of each transmission would be easy to
encode in a computer and implement, and it would not be disruptive
since the transmission is ending anyway.  It's time for FCC to
reinstate the CW ID requirement.  Until then, my default is to assume
any emission I cannot identify, to be either an intruder, or noise
from an appliance and carry on accordingly.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: Fwd: Fw: Solar Storm September 6th in real time Video - K5UJ de DK7PE

[Rob Atkinson]

Posting for Rudi

R.A.

-- Forwarded message --
From: Rudolf Klos 
Date: Fri, Oct 6, 2017 at 2:58 PM
Subject: Fw: Solar Storm September 6th in real time Video - K5UJ de DK7PE
To: ranchoro...@gmail.com


Hi Rob,
I tried to post this infor regarding the latest strongest solar storm
since 12 years. Unfortunately I can not post it as my email is not
known.
Could you please load it up into the Topband site.
Thanks 73s Rudi DK7PE



Hi all,

September 6th 2017 we had the biggest solar storm since 10 to 15 years
(ref. NASA). During that time I was in Northern Norway on a photo
excursion.
When the particles arrived on earth, on Sep 8th, I was able to make a
short video what shows some of the extreme Northern Lights in real
time.

What caused the Bands to collaps looked like this:

YOUTUBE: https://youtu.be/mdcwEGra1Ts

To me it woul'd be interesting to know what happened on 160m in
advance between Sep. 6th to 8th.
In the past I observed great DX openings on Top Band just before the
bands completely broke down.

Any observations?

73s Rudi DK7PE
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: RX/TX Antenna decoupling, (OFF LIST)

[Rob Atkinson]

> Thanks for sharing this info.
> Would you please provide more information on the relay model number and how
> it is wired into your system.

I used a P open frame relay 4PDT but a single throw will work.
What's important is that the relay use metal other than steel (or
other magnetic metal) for the RF path.  The P PM17DY satisfies this
requirement.  I mounted it in a plastic box and mounted UHF jacks on
the ends and ran copper strap and AWG10 stranded to the relay, using
the AWG10 for the center conductor.  I used two poles for the center
and two for the cable shield.  On rx the relay is open and the
inverted L is disconnected from the shack and common mode RF prevented
from continuing to the shack.  The plastic box is important for this
-- a typical metal box would allow the shield RF to continue from the
UHF jack flanges around the relay at all times.  The relay I used has
a 24 v. coil because my T/R sequencing system runs on a 24 v. DC
supply.  This as all antenna relays should be used with a sequencer to
avoid hot switching.   Obviously this is not a solution if one desires
QSK.  In that case a faster switch is needed.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: RX/TX Antenna decoupling, (OFF LIST)

[Rob Atkinson]

I discovered my rx antennas worked much better if my tx antenna was
completely disconnected from the station.  Most coaxial relays or T/R
switches only break the center conductor.   That's not good enough.
There has to be a complete disconnection which I provided by using an
open frame relay mounted in a plastic box.  On 160 m. such a device
will not present an impedance bump but this solution worked for me
because I don't care about QSK.  This may not be necessary if the tx
and rx antennas can be separated by one or more wavelengths.

73

Rob
K5UJ
_
Topband Reflector Archives - http://www.contesting.com/_topband