s between resistance and reactance as things are
tuned.
I would not even guess at a cure for something with a bunch of unknowns that
might not even be a problem. I think this is a bigger worry and more complex
than it should be.
73 Tom
_
Topband Reflector Archives - http://www.conte
All the other 4 conductors are bright clean copper when stripped.
Could anyone tell me why some insulated copper conductors turn black in
this way and whether there's a better way of cleaning it off.
Water inside the insulation plus sulfur and/or irons that formed copper
sulfide or covellite.
of everything, and at a
minimum a feel for how the box and wiring *you* have interacts with the
impedances.
The important thing at this point is how the equipment in the shack behaves
with what you have, because any actual losses are meaningless.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
my 45 - j11 ohms.>>>
The choke is completely unnecessary with a shunt feed tower. It won't help a
thing, so leave it out.
73 Tom
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Topband Reflector Archives - http://www.contesting.com/_topband
I have a MFJ-1025 and I have seen some past post about using this unit for
direction steering using two separate antennas. I am installing a new two
wire beverage and wonder if there would be any steering possible using the
two inputs from the beverage into the MFJ. I had to ask
If
The double female was fine, it was either in the 259 or right after,
close enough that the connector smelled. No idea where it was made, I
have a lot of parts from my hayday 30 years ago & back then it was
pretty much all from here. Some are marked Amphenol, some unmarked.
If you open a connecti
It does not matter if he recorded something or not, the 259B will find the
fault location.
- Original Message -
From: "Jim F."
To: "Charlie Cunningham" ; ;
Sent: Wednesday, February 19, 2014 11:30 AM
Subject: Re: Topband: Coax issues
Gary,
I would try it on a spare length of coax
I can find faults on 3000 ft cable runs within a few feet, so I'm sure you
could get within that range.
That will save you time.
- Original Message -
From: "Gary Smith"
To:
Sent: Wednesday, February 19, 2014 10:25 AM
Subject: Re: Topband: Coax issues
Thank you all for the replie
Is there is a way the information available in the LP-100A in the
shack or the MFJ-259B can be used to locate the defective area?
The 259B, if used correctly, will get you within a couple feet of the
problem.
Download the latest manual.
73 Tom
_
Topband Reflector
on 160) to an extent that occasional mistakes by people trying
to be helpful becomes an issue with score.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
I didn't notice that the K index jumped to 5 until after I posted this.
That doesn't help.
But the 3 or 4 stations that I hear calling CQ are quite strong (S9+) in
SW
Missouri.
W3LPL is S9+, but he had a lot of trouble hearing my 1500 watts. Odd.
He would hear you better if you were DX,
e people who spend a
lifetime "sort of stumbling" on things. Why, I remember when Walt patiently
taught me how conductor losses dominated transmission line loss, and why
that was important! :-)
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
n the element, I can gamma match without a capacitor.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
The lowest loss cable I have here is 75 Ohm 1" General Cable Fused Disc;
its under a differnt name these days. Mostly air with poly discs and used
for the 200' runs for 10M, 2M, and 222 MHz.
For the 160/80 inverted vee it is 450' of regular foamed 3/4" 75 Ohm CATV
hardline with a RG-11 jumper
Dielectric losses become evident at 2M with 1500W and at 432 400W of
steady
carrier will heat up even the best N connectors and RG-213. For that
reason
many are switching to the 7/16 DIN.
That has nothing at all to do with dielectric losses.
N connectors have a tiny BNC size center pin.
Subject: Re: Topband: Still in search of resonance - BTW Resonance
BTW "Resonance" => X=0 or jX = j0>>>
So my dummy load is resonant, and the resistors in my resistor bins are all
resonant? :-)
_
Topband Reflector Archives - http://www.contesting.com/_topband
saw your Yagi antenna off the tower so the
tower moves above 2 MHz. Then you will probably find a 50j0 tap without any
capacitor.
You also might use a large skirt, but why??
Just use a capacitor!!!
If you are trying to eliminate the capacitor, you will have a lot of work to
do.
Jerry Sevick, W2FMI, has an interesting comment about the "120" number in
his book, "The Short Vertical Antenna and Ground Radial." At the end of
the first chapter he notes:
"...it should be mentioned that the world standard for the number of
radials to be used with verticals in the AM broadcast
bands at different locations, and even different with
different antennas. So what happens in one cause is probably not true in
others.
Read carefully, and you will see even Rudy Severns says that, so his gold
standard isn't gold.
73 Tom
_
Topband Reflector Archives - h
of the ropes
running through pulleys could be released.
I have not looked at Beverages and in woods and fields, but I have a lot of
tree and building damage so I expect some chain saw and receiving antenna
work.
All in all not bad for such a large amount of ice.
73 Tom
__
Gee, that should work great, Tom! How is the shaft rotatoion speed
controlled to maintain 60 Hz?
Tractors are like almost any other thing that has an engine and a manual
throttle control, including lawn mowers. They have engine speed feedback
that works like "mechanical ALC". It
I'll have to look into that, Gary! Mine is much bigger.
I have a 25kW continuous 50 KW intermittent at the power pole.
It runs from a tractor PTO. All I do is back one of tractors up to it and
away we go. What I like about this arrangement is I don't have to exercise
it. It is always in good
We have about 3-4 in. of snow on the gnd, and just started to
sleet, and maybe some rain, abt an hr ago. We are in the country
I have about a half inch of radial ice at the moment. The ropes for almost
all of my wire antennas have snapped, and the Yagi's all look like noodles.
It smells like P
l could happen. But that may be nit picking.
Jim - KR9U
From: JC N4IS [mailto:n...@comcast.net]
Sent:
Wednesday, February 05, 2014 10:45 PM
To: jbw...@comcast.net; 'Tom
W8JI'; he...@vitelcom.net;
topband@contesting.com
Subject: RE:
Topband: circular polarization on 160m
Regardless, I am not sure if any sort of "descriptive logical explanation"
will ever allow me to understand what is going on with this antenna but I am
beginning to get comfortable with the modeling. The bigger question to me
is; do you think the 4NEC2 model results faithfully represent what i
good null.
The no free lunch rule is, as usual, in full force. We simplify by using one
support and decrease length, and we lose other nice things.
We have two short verticals phased, instead of what would be three or four
with wider spacing.
73 Tom
_
Topband Reflector
spent 400 hours so I could work two JA stations.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
antennas. We
have a WA3 claiming the rotational direction makes a difference, that
implies the wave is circular. But if the wave were circular, he would not
have fading on a linear antenna.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
ess unless you could time-sync rotation at that
slow fading rate.
Someone correct me if I am wrong.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
Do a second test when you mix the antennas or audio directly, listening to
the combination in mono, and you will see it decreases readability no matter
what phase you settle on.
:)
- Original Message -
From: "Dave Olean"
To:
Sent: Wednesday, February 05, 2014 10:46 AM
Subject: Re:
rotation? I'm assuming this is actually a circular signal, and not
something rotating very slowly that is causing fades?
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
You can temporarily use an inductor in series with the cap to extend the
range. It will not be a good idea for transmitting, but OK for tuning.
- Original Message -
From: "Carl Braun"
To: "Tom W8JI"
Cc: "160"
Sent: Tuesday, February 04, 2014 10:27
Here's what changed though...when I had the gamma arm at 90' with the 14
gauge gamma wire 24" away from the tower I was able to insert my Johnson
60-160pf variable cap in series with the gamma wire to get approx 58-60 ohms
at X=20. The cap was 2/3 meshed at this point. >>>
That's the right w
mmercial systems with scattering or multipath
propagation, a circular polarized system is a net detriment.
73 Tom
- Original Message -
From: "Carl Luetzelschwab"
To:
Sent: Monday, February 03, 2014 12:16 PM
Subject: Topband: circular polarization on 160m
I hope everyone h
So, i'm assuming you're suggesting that I drop the gamma arm down to the 67'
level and see what the impedance looks like? If so, I'm guessing the series
C required to tune would increase in value?
There will be some tap point where the shunt capacitor is not required.
Eliminating the shunt
the vertical section was still suppressed and the top 29' was resonating.
With this in mind I decided to run a shunt wire from the top to see where
the antenna resonates. Here's what I found..
I was afraid the tower was messing up the L. This is what happens when they
are are nearly reson
The major issue with dielectrics is dissipation factor at 2 MHz, which
affects losses and Q. Dissipation factor is not published all the time. I
can't find dissipation factor for mineral oil.
- Original Message -
From: "Bill Wichers"
To: "Tom W8JI"
Cc: &q
Tom
<reading of 4 0hms at 1825? Does this reading mean that the L is near ground
potential and 'in union' with the grounded Skyneedle at that freq?>>
It could be from a few things, but two closely spaced conductors, with the
"parasitic" conductor resonant ne
Very true but the RF is still in the oil "dielectric" from the coax
connector to the hot end of the resistor.
Not the same at all.
Loss tangent is meaningless in the dummy load application because impedance
is low (weak electric field). There is very little displacement current
compared to
You might be dealing with AM BCB being detected by the meter - and masking
what you are looking for.
No, because he gets a dip to zero reactance.
If that happens anywhere, there is no BCI.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
I cannot get the inverted L to provide a dip on my MFJ 259 analyzer anywhere
in the 160 meter band. I get dips at 8.2 MHz (R=36 ohms X=0) with reactance
on each side of X=0. At 5 MHz R=40 ohms X=0 with reactance on each side of
X=0. I cant get any significant dips neat the 80 or 160 band. Ho
Still I am intrigued by the thought of a remote tuning capacitor via
hydraulic tubing :-). The capacitor plates could be as simple as two
concentric cylinder conductors with appropriate spacers. I betcha crud
collecting on the top of the oil would set voltage limit.>>>
I would be as concerned,
g but
bad things to both, but no one can say how much. The last resort for me
would be no "hats". Perhaps you can use T elements with loading wires away
from foliage that might change tuning or losses?
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
I have an omega matched 120 foot tower and I apparently have a bad vacuum
variable capacitor. Upon applying more than about 300 watts, the SWR goes
off scale. Tuning it out and trying again, yields the same thing.
The question is which capacitor is the culprit. These are surplus Soviet
caps ob
ll lined up the way we want, but it
virtually never happens.
Good engineering plans around the imperfections.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
most people would have a much
worse situation.
Advising people to not isolate grounds on audio lines between different
"cabinet grounded" pieces of gear is a reversal of progress made with
interfaces. It really can only bring problems to all of us in the long term.
73 Tom
_
icant height increase are:
1.) reducing foldback of the hat
2.) improving the ground system
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
le for any damage to the radio mic input circuit by
accidental grounding of the + power supply lead
Sincerely, MFJ"
but silly me, I went ahead and added the transformer so they could
pretty much connect it any way they like without blowing up their radio or
having distortion.
73 Tom
ave almost no effect. The loading wires effect would depend
on angle.
73 Tom
73 de Björn,
SM0MDG
8Q7BM
SE0X
_
Topband Reflector Archives - http://www.contesting.com/_topband
-
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2014.0.4259 / Virus Da
othing but long term grief. I can assure you no
manufacturer in their right mind would listen to that advice. ANY good
interface by almost any manufacturer has shield isolation, with a chassis
bond only at one point. If they don't do that, the help lines get busy with
complaints.
73 Tom
My headphone lines, because they serve multiple desks, all have isolation
transformers. I suppose I could run a big copper buss bar across the room,
but it seems more logical and safer to just spend $2 on a transformer at
each radio. :)
73 Tom
_
Topband Reflector Archives -
and besides the NH0 being on 1826 this morning listening up, there were no
spots on the FT5.
:-)
- Original Message -
From: "Merv Schweigert"
To:
Sent: Monday, January 27, 2014 10:50 AM
Subject: Re: Topband: FT5ZM
Now thats a strange one Milt, I was up and ears peeled at 1330Z
er
linear inch.
I certainly would not lose any sleep over what you are doing.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
e guessing not many of the old radials
were still there, make measurements with 3 dB of wobble in the readings and
pick the numbers they liked, and call it conclusive evidence.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
After making all of the recommended changes, I hooked up my MFJ and got
>650 readings regardless. When connected to a 75 ohm dummy load, it
reads completely normally, as does shorting the input (R=0_ If I had
managed to damage the MFJ with DC voltage on the input, would you expect
no readings
The Hammond is 400 mA and probably OK, I never used one.
I use something like these 100 uH from Mouser Electronics:
542-73F104AF-RC
or depending on current
542-5250-RC
- Original Message -
From: "Pete Smith N4ZR"
To: "Tom W8JI" ; "Richard (Ric
Hi Pete,
You are going to have to trust me on this one.
You really should ***NOT*** be measuring the input of the bias T with the
MFJ 259 B analyzer with the configuration you have.
You can damage the 259 unless you use a smaller series cap and a shunt choke
to protect the 259. The most impo
Thanks to everyone for their suggestions - consensus seems to be that the
homebrew chokes are not enough reactance at 1.8 MHz, so I'll get some
store bought ones at 220 uH or more. I tried battery power for the whole
system, but no difference. I'm going to try battery power for the remote
has any noise or hum.
You should use the .01 as a coupling cap and the .1 as a bypass if that is
all you have. :-)
The RF choke may also be changing inductance from DC current, but first you
need to make life easier on the 259 by changing the caps around and by
bypassing the RX port wi
However, I did run into an antenna design that was significantly different
(to me, anyway) last month, in an old article about inverted-Ls by L.B.
Cebik. He showed an inverted-L fed at the transition from vertical to
horizontal. Open-wire line ran down and away from it at a 45 degree angle.
Basica
Indeed. I've had problems with ICE 196 receiver protectors for several
years. I assume the intermod is generated by the diodes in those devices,
though I do not know that for a fact. The problem occurs on nights when
propagation is very good both in the AM BC band and shortwave in the 5-7
MHz r
I use protection diodes on the front end of my W1FB preamps (as well as
before an IC amp in the preamp, and on the output of the preamp) and have
never been able to detect receiver performance degradation on 160 meters
due to the clamping diodes (had to include the diode clamps before the IC
amp i
o very low milliamperes in severe stuff. The transients from nearby
strikes can be amperes, but the slew rate is so high they will not go
through a choke or resistor anyway. Reducing any voltage from close
discharges takes a close gap or a low impedance RF path.
73 Tom
_
Topband
pression of the cable they are "grabbing", and it's a fairly even
pressure over the length of the gripped area. If one could be found that
was the correct diameter for the cable being used it might be worth a
shot, but I completely agree with Tom -- TEST ANYTHING YOU TRY BEFORE
USING
bar with multiple champhered holes,
with the Phillystran woven through from side-to-side? With enough weaves,
this should self-tension with just a single clamp on the far end.
Regardless, I would test pull and see what breaks first at what tension.
73 Tom
_
Topband Reflector
I am nervous as well, Tom...hi Hi
I'm really thinking of employing a separate relay that I control with a
simple switch, vice depending on the rig to switch "correctly"
using a simple switch is antiquated and slow butfor certain I can
control the switch over mo betta AND pr
nable way to do it, it is better to add a RX port in the
radio and avoid all this. :)
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
Well, I agree. And if I follow your reasoning, it doesn't take much of an
increase in line voltage to push the HV from 825 VDC to over 900 VDC., as
Bill observe. Might be the choke, but I'd be really surprised at the
entire
winding being shorted. I'd surely want to start by measuring line voltag
elow 20 meters for old boatanchor use like AM.
73 tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
Tom asked about bleeder current. I didn't try to measure it but I watched
the high voltage decay to zero in a very few seconds when I switched it
off with no 6146s in the sockets.
Line voltages in the late 1950's were 115, and 117 at the time the DX100 was
made. The standard since t
I had used four caps rated at 450 volts/100 uF. They were in two pairs
series parallel for 100 uF/900 volts. Some hams cautioned me against using
so much capacitance. So I removed one pair of the caps and ended with 50
uF at 900 volts. The plate supply remained over 950 Volts until I keyed
the
I have a 60' tall top loaded vertical for 160M and would like to know how
best to feed it to use it on 80M as well. On 80M there will be some
pretty
high voltages at the feedpoint.
What is the top loading? Because something resonates on 160 m with something
on the top doesn't mean it will a
..sorry, posted to wrong reflector!
_
Topband Reflector Archives - http://www.contesting.com/_topband
G4FKA:
What do you mean 'Once upon a time'? Have you listened on 160 lately?
Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
op of it.
These are just the hard, cold, facts of life. It's just disappointing we
have no technical people who think things through before picking frequencies
for "new modes".
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
Anyone
with a computer and a little skill can invent a "new mode". It's just bad
engineering to stick that stuff near weak signals, because the problem can
only be fixed at the transmitter.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
How is this different than RTTY using the AFSK method?
In my FT-1000D, if you try to use FSK mode for RTTY it
turns out that the rig is still running AFSK, using
an internal audio source.
I've never looked at the FT1000, but I doubt that is a clean system. It
would still be like a SSB transmit
Actually, IMD can be produced by ANY keying waveform -- for example, the
envelope of a CW or RTTY signal.
Let's not divert the issue.
A rise and fall is always composed of many frequencies making up sidebands,
otherwise it would have no shaping. Even CW is an AM signal, when we look at
rise
W8JI said:
.as did KW with their KW2000 over here.
Tom G3OLB
_
Topband Reflector Archives - http://www.contesting.com/_topband
Well, I certainly have to agree, Tom, if the signal on the desired
sideband
is just a single shifting tone. Might get messier if an sudio stage or A/D
is driven into limiting and producing harmonic distortion at audio, I
guess.
The entire thing for digital modes was poorly planned. I&#
Thanks everyone for the suggestions. I'm going to have to install some
software to identify some of the signals.
I would think that IMD products in a high-level PA that is over-driven
beyond good linearity limits could add some junk in the "undesired
sideband"? FWIW
IMD **requires** two or
to popular weak signal
areas, especially when sideband selection produces a supurious that falls in
weak signal areas, are unlikely to rethink the poor placement or poor advice
on selecting sidebands
4.) With a little work to convince them, most digital ops with radio
problems would avoid ope
BTW, Biii - tip/suggestion - for those series-connected electrolytics you
probably should put a pair of equal value resistors - one across each
series
capacitor, as the leakage currents will not be equal in each capacitor in
each series string and the DC voltage won't divide equally across each
Using grommets to create additional leakage/creepage distance is clever! I
never would have thought of that!
I'm cheap and lazy, not clever.
_
Topband Reflector Archives - http://www.contesting.com/_topband
with (like the
current Comtek and the DXE), are not the same as slapping a 50-ohm 90 degree
hybrid on four elements and calling it done. They have some planning to
correct for mutual coupling shifting element impedances around. A 4-square
built with a perfect textbook hybrid is a dismal performer.
or you can
improvise with other materials like you did.
They put polymer ribs over fiberglass rod insulators for good reason. :-)
http://www.victorinsulators.com/polymerindex.htm
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
If he wants to get a special grade of Delrin, 527 UV would be most UV
resistant. The little bit of carbon pigment won't hurt a thing at HF.
Greg is in New Zealand, so he will probably have to buy what is available.
Since nylon lasted a few years, the material doesn't have a high bar to
hing ever repeatable is a wide bandwidth impulse noise from one
source.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
2) I always thought that nylon was a pretty good dielectric, and did not
expect problems, especially at 1.8 MHz. The gap in the insulator is
7.5mm, or about 0.3". I estimate that there will be around 2 kV across
this gap. Is nylon perhaps not as good as I thought it was?
Nylon is one of th
might NOT be. That way I can
drive past things I know it absolutely cannot be. Whatever it is, as Jim
suggested, you will eventually have to DF it and then walk or drive that
direction and find it. That is what ultimately matters.
73, Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
o earth, nearby radials,
things 1 wavelength away, and on, they would also have to not radiate
(receive). If it receives, it will receive from the mess of things all
around it from the dirt below it to the wires down the road.
The only way we know is to actually build it,
unidirectional to improve rear null
depth.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
20 kV and 250 watts is 10 kV peak.
This is the actual voltage **if** you can manage to get that power level
into the antenna.
Doubling the antenna tubing size reduces voltage by about 10%.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
it is
to null one side (in which case it is actually an endfire-endfire
combination).
This means the base cells have to be somewhat in line with the direction or
directions you want to null or peak.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
large east coast stations. Since most of
the influence is from east coast stations and big guns, the people away from
the coast, in particular with smaller or modest stations, are out of luck.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
elease time significantly.
I wasn't expecting a homebrew answer, so I still have no idea what type of
relay you have. I don't know relay speed and reliability. I guess the normal
mode is closed on transmit and open on receive.
73 Tom
_
Topband Reflector Archives - http://www.contesting.com/_topband
I am finally getting around to detuning my 160/80 meter vertical on
receive and plan to use a simple 12v relay to turn off the power to the
antenna switch and the DXE Time Variable Sequencer to make sure the on/off
timing is correct.
Before I go down that road, does anyone have any suggestions
According to http://www.arrl.org/160-meter "The segment 1.830 to 1.835
should be used for intercontinental QSOs only." I hear a lot of contacts
being made between stateside stations.
The rule is very easy to understand.
When operating between 1830-1835, all stations cannot work other stations o
160 sure is a "target rich environment" right now.
Running a DX100 in a contest is like car pooling after eating beans and
eggs.
_
Topband Reflector Archives - http://www.contesting.com/_topband
added in an available hole near the 5V4. The original cord and fuse
holders get big prices on Fleabay.
They are standard on some electric fence chargers.
At farm supply stores, they are seven dollars or less. Here is a 15 second
search, there are probably better deals.
http://www.agrisupp
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