CBS' KFWB shuts off IBOC at night
 

"Telamon" wrote in message
...
In article ,
"Brenda Ann" wrote:

"Telamon" wrote in message
...

I would say bandwidth. Large aspect ratio antenna elements have a
narrow
band of resonance. It seems to me that there are some companies out
there that have tower kits that run 3 to 4 wires on spreaders so the
electrical diameter of the tower is increased. This will allow the
tower
to have lower VSWR over the +/-15KHz required.

I've been in on installing one of those kits.. lot of fun when you have
the
backup tower for the station only a few dozens of yards away.. you don't
want to forget to connect that ground in at least two places on the way
down
the tower.. :)

That's great. Tell us how it works out when you tune it up.



This has been about 8 years or so ago now, at the 970 AM site in Portland,
OR. We didn't do the tuneup, that was left for their CE to do. We did the
tower work.

I've had the opportunity (mostly doing grunt work) to work around lots of
high energy RF. I had the really fun job of resplicing all the ground wires
at the former Sunny 1520 (also a Portland market station) during a new site
install. We built the new transmitter shack (moving the 50KW box out of the
back room of a preschool of all places). I got to, as I said, reattach all
the radials, about 300 of them, on a 3 tower system, then, when the concrete
and block work were done (in different stages) I had to lay expanded copper
mesh on the foundation, walls and roof of the shack (Faraday cage). Then I
ran a few thousand feet of 50 pair icky-pick for control wiring. All this
fun in August. :) Sure loved the $$$ though..

CBS' KFWB shuts off IBOC at night
 

David Eduardo wrote:

"dxAce" wrote in message
...


David Eduardo wrote:

"dxAce" wrote in message
...


David Eduardo wrote:

Wrong. I received it in 1969 at the FCC offices on M Street in DC.

So, in what year did you receive your non-existent amateur radio
license?

The authorization, which was not a license certificate, but an "oficio"
was
in '66 or '67.

Guess that's why it never shows up anywhere! "oficio" must mean "faux".


An "oficio" is basically an "edict" and is a folio with fiscal stamps and a
notification text.

Gee!

CBS' KFWB shuts off IBOC at night
 

David Eduardo wrote:

"dxAce" wrote in message
...


David Eduardo wrote:

"Steve" wrote in message
ups.com...
On Oct 10, 2:27 pm, dxAce wrote:

Good grief, is it possible that this guy's been caught in yet ANOTHER
lie?

Tardo, you might want to try telling the truth. Your attempts at
deception just aren't working for you.

The 1974 license on my website is a RENEWAL.

NOT!

Since I was chief operator of WUNO from late '70 to mid-'72, and that
requires not only a 1st ticket but notification of the Engineer in Charge of
the FCC field office, there is, no doubt, somewhere record of it.

So you 'claim'! Was your legal name, "David Frackelton Gleason", on that forgery
as well?

CBS' KFWB shuts off IBOC at night
 

On Oct 10, 11:31 pm, "David Eduardo" wrote:
"Steve" wrote in message

oups.com...

Of course, none of this justifies your lying about your academic
background.

It's obviously past your bedtime.

But, before you go, there is a Boise 50 kw AM on Craigslist for $800
thousand dollars... why don't you buy it and impress us all with your radio
talent and knowledge? Of course, the potty words you erupt with here will
have to be controlled, perhaps with a muzzle.

You're much closer to Boise than I am. Why don't you buy it? Perhaps
you can solve all of it's problems by putting a fresh coat of paint on
the station.

CBS' KFWB shuts off IBOC at night
 

On Oct 10, 11:33 pm, "David Eduardo" wrote:
"Telamon" wrote in message

...



I don't see the need to be so defensive about what I posted. I made it
clear it was an assumption and explained my logic for those
assumptions. The reasoning was technical and there is no need to try to
make it into something else.

By the way, thank you for an interesting and civil discussion. Your
technical knowledge is obviously extensive, and some of my anecdotal or
field experience may be unknown to you. Goes to show... we can learn from
each other. I hope...

I'll bet you could also learn from on-topic posts. You might want to
give it a shot. Maybe start off slow, with one or two on-topic posts,
and see how it goes.

CBS' KFWB shuts off IBOC at night
 

On Oct 10, 11:33 pm, "David Eduardo" wrote:
"Telamon" wrote in message

...



I don't see the need to be so defensive about what I posted. I made it
clear it was an assumption and explained my logic for those
assumptions. The reasoning was technical and there is no need to try to
make it into something else.

By the way, thank you for an interesting and civil discussion. Your
technical knowledge is obviously extensive, and some of my anecdotal or
field experience may be unknown to you. Goes to show... we can learn from
each other. I hope...

Let's all join hands now and sing "We Are The World"...

CBS' KFWB shuts off IBOC at night
 

On Wed, 10 Oct 2007 06:41:56 -0700, "David Eduardo"
wrote:


"David" wrote in message
.. .
On Tue, 9 Oct 2007 19:01:29 -0700, "David Eduardo"
wrote:


The bandwidth for AM is, by NRSC, 10 kHz in each sideband... actually, a
little less. This is to avoid 10 kHz harmonics with adjacent channels.

Not harmonics, just plain old splatter.

Sorry. The word should have been heterodynes.

The 10 kHz heterodynes are from the carriers, not the sidebands. They
can easily be notched out, by the way.

CBS' KFWB shuts off IBOC at night
 

On Thu, 11 Oct 2007 01:53:51 GMT, Telamon
wrote:

In article ,
"Brenda Ann" wrote:

"Telamon" wrote in message
...

I would say bandwidth. Large aspect ratio antenna elements have a narrow
band of resonance. It seems to me that there are some companies out
there that have tower kits that run 3 to 4 wires on spreaders so the
electrical diameter of the tower is increased. This will allow the tower
to have lower VSWR over the +/-15KHz required.

I've been in on installing one of those kits.. lot of fun when you have the
backup tower for the station only a few dozens of yards away.. you don't
want to forget to connect that ground in at least two places on the way down
the tower.. :)

That's great. Tell us how it works out when you tune it up.

There's a couple of mountain top AMs in Santa Barbara that use folded
unipole.

CBS' KFWB shuts off IBOC at night
 

In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
...
In article ,
"David Eduardo" wrote:

Yeah. That's why I thought it would be more popular in central and
south America where expensive or difficult to install, due to
terrain, grounding systems requirements could be reduced.

Why would the terrain considerations, grounding requirements and such
be any different than in, say, Idaho or Wisconsin or Arizona or
Alabama?

They would not and since when is Idaho, Wisconsin, Arizona or Alabama
in south America?

I asked why South or Central America would have conditions of terrain,
grounding or cost any different than those states? I have no idea why you
think a unipole would be of any greater advantage there than in, say, Lake
City, FL? Why?

In a simple sentence; why would grounding be different than in the US.
Another: why would the terrain be different than in the US?

The pacific side of central America is similar to Florida but not the
west or south America. I don't understand why you are keying on central
or south America. I don't know why grounded towers are not used in most
place most of the time.

And why would it be more expensive to do in Central and South
America? I can see no logic in any of this set of statements.

Where did I say it was more expensive in SA?

You said that Latin America is "where (it is) expensive to install..." And
I do not see that it is expensive at all, and where a unipole would be less
expensive.

Ground systems are expensive to install. The grounded towers don't
eliminate them they just make them less critical.

The logic is why spend money you don't have to spend. The problem
looks to be reading comprehension.

Importing a unipole kit from the US (nobody makes them or uses them in Latin
America) and bringing in an experiienced installer would be much more
expensive than a simple to build and maintain series fed antenna. Every
nation in Latin America has a local tower fabricator and erector or two.

I don't understand where you are going with this. A grounded tower does
not eliminate the ground system it just makes for an easier to tune and
more broad band antenna. The antenna is easier to load properly.

A unipois also useful with a shorter than 1/4 wave tower because
the tuning network needed to tune out the capacitive reactance
often narrowbands the antenna (not the tower itself).

That my point. The shunt type coupling is more broadband.

Only for very short towers where a high capacitive reactance is
found. Otherwise, the bandwidth is much more the effect of the Q of
the ATU and the trandsmitter itself.

No.

You obviously have not measured may, if any, AM vertical radiators. Untill
they get very wide, like the old towers of the 20's and 30's which were
built like scaffolding, there is no appreciale benefit in width, and the
cost at any optimum point is prohibitative and likely will get no zoning
clearance. The problem with bandwidth can be solved by ATU design, and VSWR
reduced to less than 1.09 to 1 at 10 kHz with ease.

I haven't tuned any AM broadcasting towers but I have tuned higher
frequency antennas and I know theory and there are companies that build
kits I described to broaden the towers bandwidth as I described.

So for you to be right the theory as I understand it is wrong, I didn't
understand what was really happening in my past antenna tuning
experience and there are companies out there selling radio stations crap
for antenna modification kits.

So that said where do you think things went wrong?

Go back to Carl Smith's AM antenna and DA handbooks, Unless you find
a nice old Blaw Knox with a 24 foot center cross section, there is
not much gain except cost, maintenance, etc., in adding outriggers
insofar as broadbanding.

I don't have that book so I can't do that but general theory would
indicate otherwise and there are companies that offer tower kits to
improve bandwidth performance as I have described.

The purpose of a unipole is to allow the tower to be at ground potential so
we can get point to point and other antenna rentals without isocouplers. It
is also to compensate for bad grounds, like where a parking lot and shopping
center now sit on the ground system. Bandwidth is mostly enhanced below 1/4
wave, and the FCC only licences such towers under extreme circumstances...
very few towers under 90 degrees exist in the US. I've seen a bunch of
non-licensed stations, such as AFRTS facilities using them though.... 1040
at Ft. Brook used one to tune a roughly 75 foot tower and it did not sound
too dreadful, either. Rame, on 780, used one on a 50 foot tower, also.

The purpose you state may your reason to use a ground tower.

A well tuned tower of 1/4 wave has less than 1.08 to 1 vizwar. And,
except for test situations, a tower measurement is usually done at
-10, licenced frequency and +10 kHz. This is what is often asked for
by outside fabricators of ATUs.

Again that is not my understanding of tower VSWR. The levels at 5, 10,
and 15 KHz are much higher than you indicate, which requires mitigation
efforts.

The ATU will generally create a 52 ohm match at carrier, and j 0. At plus
or minus 10 kHz, we would look for well under 1.1 to 1 VSWR with a good ATU.
They can be designed to give even less than that, but considering the amount
of entergy under NRSC at 10 kHz is minimal, that is often good enough.

The ATU can not improve the tower bandwidth. The ATU can only make it
worse.

A mismatch is generally considered to be a mismatch of impedance
output of the ATU with the tower itself at the fundamental. Since the
audio is brick-walled right under 10 kHz, there should be little or
no excursions beyond +/- 10 kHz.

For analog +/- 10 KHz sounds reasonable but it looks like IBOC is
going past that number. The testing recommendation I read suggests
testing to +/- 15 KHz.

The stations for which AM HD is even appropriate are major stations in each
market only... and most of these have nicely designed antennas. The very
directional stations are going to have more problems in the phasor than in
the ATU and tower. Phasors have to be a compromise of tunability (High Q)
and bandwidth... so the bottleneck is in the phasor, the rest of the system
being infinitely more tolerant.

Not for the last 40 years or so. High Q was much more common pre-60's
when AMs mostly ran network showsthat came over 5 kHz lines from very
far away. When music took over AM, stations wanted better bandwidth.

I don't see how that can be improved. Series feeding the tower will
require a fairly high Q network that is inherently narrow band
compared to a shunt feed method.

The kind of network and the network design can make a pretty decent
broadbanding within licensed bandwith possible. In any case, you are not
going to get a shunt fed tower in the US, and you are not going to get shunt
fed directionals anywhere.

The ATU's and antenna networks do not improve antenna bandwidth.

Since true shunts are no longer licensed, this point is moot. Most US
AMs, for economy, zoning, FAA, etc. use quarter wave series fed
towers. Since a huge percentage are directional, there are very, very
few Unipole directionals, so in that area series fed is the only way
to go.

I don't see where you keep on this tack about Unipoles as they can just
as easily be part of a directional network.

Shunt fed towers tend to have slight directionality, and unipoles have
enormous mechanical instability, making adjusting a unipole directional and
meeting licensing requirements something that might not even be possible.
And the cost of readjusting as the outriggers move about and the wires
strech and age would be huge... most station engineers do not adjust their
own directionals... a consulting engineer does, at great cost.

I don't see where a Unipole would present a problem in a directional
network.

See above. Mechanical stability is the first issue.

1. I was posting about grounded towers not Uniploes.
2. Grounded tower are more stable that isolated ones.
3. I don't where a Unipole would be more of a mechanical design problem
over an isolated tower.

An ATU is not necessary if the tower is 52 ohms and not reactive,
found around about 100 to 110 degrees in electrical height.

The ATU is a matching circuit, to make the coax "see" 52 ohms (or
some other impedance) when, in fact, the tower is not of that
impedance. In some senses, a top hat or top loading does the same
thing... it makes the tower change the apparent electrical height.
You are trying to complicate something that is relatively simple...
cancelling the reactance and matching impedance.

That's fine if the coax and transmitter output impedance is 52 ohms. I
didn't realize I was making it more complicated I was just trying to
explain the dynamics of tuning the tower.

How many towers have you tuned?

AM broadcast towers zero. I have tuned many other types of antennas and
RF circuits. AM towers tune like any other antenna of its type.

An ATU is usually necessary.

Always unless there is a perfect match. I chatted with some engineers who
are into this sort of thing, and we came up with one station in the west,
the 1590 in the Victor Valley about two decades ago... it has since moved
and has a doghouse at the tower base, now.

Many amateur radio operators don't understand the necessity of tuning
the antenna at the antenna and not in the shack. Usually this is done
for convenience though.

That is not why the very few cases of transmitter damage have
occured. Most transmitters will simply shut down over reactive or
mismatched loads. The issues reported (and one that took out 80% of
the power modules at KTNQ) had to do with the control interface of
the HD exciter and the analog transmitter.... a design defect in
non-rf and non-af circuitry.

Wow, I guess the engineering of the IBOC working group really sucks. I
figured something in the way of the application in the field is what
would bring things down. This is far worse that I imagined.

iBiquity does not design exciters. In this case, the HD exciter was built by
one of the big three transmitter companies, and it had a "design mismatch"
(read "flaw") when mated to one particular transmitter which they did not
even manufacture. It's the price stations pay for being early on the
curve... which is usual in major markets because, problem and all, such
stations have at least one backup transmitter, and many have two.

Or, in today's transmitters, it does neither. It detects VSWR and
shuts off.

And all my equipment has fuses or circuit breakers but I usually apply
effort toward making sure they are not used.

In the case of transmitters, the control circuit performs system shutdown or
power reduction to protect itself without fuses or circuit breakers; a high
VSWR might cause a transmitter to progressively fall back to half power,
half again, and so on until it can operate... or it shuts off.

You may be looking at this a little to simplistically. I don't know what
the response time of the transmitter fallback circuitry is and I don't
know when the transmitter modules failed. Did they fail at the turn on
of the IBOC exciter? Did they fail after a while? I don't know the
details.

The fact is you have said that shunt feeding is common in Latin
America where it is highly uncommon and always has been. You made
statements about costs, land and towers in Latin America that make it
sound like you think we are talking about another planet, not the
same Hemisphere. In fact, the conditions and terrain in South Florida
are more difficult and hostile than in most places in Latin America.

I don't see the need to be so defensive about what I posted. I made it
clear it was an assumption and explained my logic for those
assumptions. The reasoning was technical and there is no need to try to
make it into something else.

In that case, I do apologize. I may have mistakenly thought you were one of
the multitude that thinks that all of Latin America consists of terrain that
can only be found in an Indiana Jones movie; the fact is that the land
anywhere there is comparable to some place in the US. Towers tend to cost
less, as they are locally fabricated and the labor costs are lower; ATUs and
such can be made from off the shelf caps and coils you can wind from
automotive AC tubing if the need arises.

From what I have seen the coils don't look to hard to fabricate out of
tubing but you have to buy the high voltage vacuum capacitors. The
connections look like hardware store nuts and bolts would do most of the
time. You would most likely need to buy sense transformers for the
metering.

--
Telamon
Ventura, California

CBS' KFWB shuts off IBOC at night
 

In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
...
In article ,
"Brenda Ann" wrote:

"Telamon" wrote in message
.
..

I would say bandwidth. Large aspect ratio antenna elements have a
narrow
band of resonance. It seems to me that there are some companies out
there that have tower kits that run 3 to 4 wires on spreaders so the
electrical diameter of the tower is increased. This will allow the
tower
to have lower VSWR over the +/-15KHz required.

I've been in on installing one of those kits.. lot of fun when you have
the
backup tower for the station only a few dozens of yards away.. you don't
want to forget to connect that ground in at least two places on the way
down
the tower.. :)

That's great. Tell us how it works out when you tune it up.

In about 1989, we put a unipole on WDSR 1340 in Lake City, FL. The tower was
actually over 90 degrees, but the base was nearly 100 feet offshore in the
lake (thus the city name). The brackish water had pretty much dissolved the
ground system after some 40 years, and we put down a large ground mesh in
the water around the tower, and put a unipole on. The folks form Tennessee
came down, and they supervised the rigger. they strapped the tower base
plate to ground with three 2" copper straps, and use experience, the known
impedance of the tower and the rigger to find a connect point. They were
close enough that only two minor moves of less than a meter fund the right
match, and the station was back on the air.

The unipole did increase coverage, in an area where ground conductivity is
horrible. We did not notice any audio change, good or bad. The only long
term bad thing is that the outriggers had to be retensioned a bit, and in
major storms flying objects could break the wires or dislodge the fiberglass
yardarms that held them away from the tower, and on one occasion breaking
the critters off at the tower mount. I would not want one in a hurricane
prone region, as it would fly off the tower at the first impact of airborne
aluminum siding or trash cans.

That's a good point. I didn't think about flying objects breaking the
tower wires on the extenders. Every engineering solution has its down
side.

--
Telamon
Ventura, California