KFI transmitter off the air
 

The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.

--
Telamon
Ventura, California

KFI transmitter off the air
 

In article
,
Telamon wrote:

The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.

Carrier came up. No audio though. S meter is not where it was before the
dropout. They still have problems to solve.

--
Telamon
Ventura, California

KFI transmitter off the air
 

In article
,
Telamon wrote:

In article
,
Telamon wrote:

The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.

Carrier came up. No audio though. S meter is not where it was before the
dropout. They still have problems to solve.

They are back on the air but signal strength is not what it was before
this event.

--
Telamon
Ventura, California

KFI transmitter off the air
 

On Oct 29, 11:29*pm, Telamon
wrote:
The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.

--
Telamon
Ventura, California

My cousin is an bcst engineer out there on the West coast. KFI had a
major transmitter failure
and is running on a backup xmiter with half power.

KFI transmitter off the air
 

In article
,
Wingdingaling6 wrote:

On Oct 29, 11:29*pm, Telamon
wrote:
The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.


My cousin is an bcst engineer out there on the West coast. KFI had a
major transmitter failure and is running on a backup xmiter with half
power.

Tonight's event was kind of weird. All of a sudden the voice peaks
sounded kind of fuzzy and then the carrier dropped out altogether.

They went from 10 over S9 to S7.

Got any idea when the new transmitter will be fixed?

--
Telamon
Ventura, California

KFI transmitter off the air
 

Telamon wrote:

In article
,
Wingdingaling6 wrote:

On Oct 29, 11:29 pm, Telamon
wrote:
The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.


My cousin is an bcst engineer out there on the West coast. KFI had a
major transmitter failure and is running on a backup xmiter with half
power.

Tonight's event was kind of weird. All of a sudden the voice peaks
sounded kind of fuzzy and then the carrier dropped out altogether.

They went from 10 over S9 to S7.

Got any idea when the new transmitter will be fixed?

Any idea when 'Eduardo' will stop transmitting?

KFI transmitter off the air
 

Wingdingaling6 wrote:
On Oct 29, 11:29 pm, Telamon
wrote:
The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.

--
Telamon
Ventura, California

My cousin is an bcst engineer out there on the West coast. KFI had a
major transmitter failure
and is running on a backup xmiter with half power.

25 KW into an 8th wave antenna is more like 20% power.

KFI transmitter off the air
 

David Eduardo wrote:

"Telamon" wrote in message
...

The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.


They are using the old Harris DX series, I believe. The new transmitter
had a catastrophic failure, and a new Nautel is apparently on rush order.

I thought they had an old Continental 317 (best damn AM transmitter ever).

KFI transmitter off the air
 

"Telamon" wrote in message
...

Tonight's event was kind of weird. All of a sudden the voice peaks
sounded kind of fuzzy and then the carrier dropped out altogether.

They went from 10 over S9 to S7.

Got any idea when the new transmitter will be fixed?


Supposedly the "new" transmitter, which they used at Montecito Hts also, had
"internal combustion" and is not coming back. KFI is awaiting a new Nautel
instead.

KFI transmitter off the air
 

"Dave" wrote in message
...
Wingdingaling6 wrote:
On Oct 29, 11:29 pm, Telamon
wrote:
The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.

--
Telamon
Ventura, California

My cousin is an bcst engineer out there on the West coast. KFI had a
major transmitter failure
and is running on a backup xmiter with half power.

25 KW into an 8th wave antenna is more like 20% power.

They are using a backup trasnsmitter, not the aux tower.

KFI transmitter off the air
 

"Dave" wrote in message
...
David Eduardo wrote:

"Telamon" wrote in message
...
The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.


They are using the old Harris DX series, I believe. The new transmitter
had a catastrophic failure, and a new Nautel is apparently on rush order.

I thought they had an old Continental 317 (best damn AM transmitter ever).

The Harris was the main, and the floor furnace the aux. I am told that the
new BE selfdestructed, and will be replaced with a Nautel (all into the new
tower) and the DX is the temporary main.

KFI transmitter off the air
 

On Oct 30, 6:37*am, Dave wrote:
Wingdingaling6 wrote:
On Oct 29, 11:29 pm, Telamon
wrote:
The 640 KFI transmitter just dropped out. Just before it dropped out
started sounding a little funny.

It's only been on a few weeks now.

--
Telamon
Ventura, California

My cousin is an bcst engineer out there on the West coast. KFI had a
major transmitter failure
and is running on a backup xmiter with half power.

25 KW into an 8th wave antenna is more like 20% power.

Dead Air here for KFI on 640 kHz; but most of
the 'other' LA and SD AM-MW Radio Stations
were coming in very well.

~ RHF
Twain Harte, CA

KFI transmitter off the air
 

Telamon wrote:


KFI is having a lot of bad luck with transmitters and antennas.

So now that they have had two transmitters burn up anyone know why that
happened?


No excuse that I can think of. Broadcast engineering doesn't attract
the best and brightest any more. Other specialties pay a lot better.
People used to do it for love of the medium, but that's out the window
as the medium generally sucks.

KFI transmitter off the air
 

Telamon wrote:
In article ,
"Bob Campbell" wrote:

"Telamon" wrote in message
...
KFI is having a lot of bad luck with transmitters and antennas.

So now that they have had two transmitters burn up anyone know why that
happened?
Because they were broadcasting in HD?

rimshot

I suppose that is possible.

I was thinking more along the lines of the cooling system failed or a
HV component failed shorting out the final stage.


There are protections for both of those. However I must point out that
solid state transmitters have no B+.

KFI transmitter off the air
 

"Dave" wrote in message
...
Telamon wrote:


KFI is having a lot of bad luck with transmitters and antennas.

So now that they have had two transmitters burn up anyone know why that
happened?


No excuse that I can think of. Broadcast engineering doesn't attract the
best and brightest any more. Other specialties pay a lot better. People
used to do it for love of the medium, but that's out the window as the
medium generally sucks.

One transmitter burnt, and it has been commented that this is due to a
design issue since 2 others (there are not that many 50 kw installs in the
whole US) have gone the same way. The engineering at KFI is superb... but
it's the same thing as giving a lemon car to an Indy 500 driver... it will
still break down.

KFI transmitter off the air
 

"Telamon" wrote in message
...
In article ,

So what is the voltage out the finals on a solid state transmitter?


There are no finals. Just a bunch of combined modules. The Nautel 50 has 8
RF and 4 modulator power modules. There is no final stage.

KFI transmitter off the air
 

"David Eduardo" wrote in message
...

"Telamon" wrote in message
...
In article ,

So what is the voltage out the finals on a solid state transmitter?


There are no finals. Just a bunch of combined modules. The Nautel 50 has 8
RF and 4 modulator power modules. There is no final stage.

Ain't power MOSfet's a wunnerful thing?

KFI transmitter off the air
 

In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
...
In article ,

So what is the voltage out the finals on a solid state transmitter?


There are no finals. Just a bunch of combined modules. The Nautel 50 has 8
RF and 4 modulator power modules. There is no final stage.

Ok, Don't call the modules "finals" then but what is the output voltage
to the antenna? I would like to know what the RF current is as the
output is supposed to be 50KW.

You know the skin effect will concentrate all the current into the
conductor skin. I wanted to calculate the current density.

I wonder what the power loss is in the hardline from transmitter to
antenna?

I expect the parallel solid state design will have much lower voltage
and higher current than older tube designs. It would then follow that
transmitter destruction is more likely to result from connector problems
in a solid state transmitter where the higher voltage tube designs would
result from insulator breakdown or flashover.

--
Telamon
Ventura, California

KFI transmitter off the air
 

"Telamon" wrote in message
...


Ok, Don't call the modules "finals" then but what is the output voltage
to the antenna? I would like to know what the RF current is as the
output is supposed to be 50KW.

Almost all phasors or lines are50 or 52 ohms today.

You know the skin effect will concentrate all the current into the
conductor skin. I wanted to calculate the current density.

I wonder what the power loss is in the hardline from transmitter to
antenna?

The line manufacturers all have specs on loss as a function of frequency.

I expect the parallel solid state design will have much lower voltage
and higher current than older tube designs. It would then follow that
transmitter destruction is more likely to result from connector problems
in a solid state transmitter where the higher voltage tube designs would
result from insulator breakdown or flashover.

It all ends with a match to 50 ohm line at the output fitting on top of the
box.

KFI transmitter off the air
 

David Eduardo wrote:

"Dave" wrote in message
...
Telamon wrote:


KFI is having a lot of bad luck with transmitters and antennas.

So now that they have had two transmitters burn up anyone know why
that happened?


No excuse that I can think of. Broadcast engineering doesn't attract
the best and brightest any more. Other specialties pay a lot better.
People used to do it for love of the medium, but that's out the window
as the medium generally sucks.

One transmitter burnt, and it has been commented that this is due to a
design issue since 2 others (there are not that many 50 kw installs in
the whole US) have gone the same way. The engineering at KFI is
superb... but it's the same thing as giving a lemon car to an Indy 500
driver... it will still break down.

There's obviously a dumbass factor at work somewhere is this chain of
events. Somebody designed a HPA stage prone to catastrophic failure,
didn't they?

KFI transmitter off the air
 

Telamon wrote:
In article ,
Dave wrote:

Telamon wrote:
In article ,
"Bob Campbell" wrote:

"Telamon" wrote in message
.
..
KFI is having a lot of bad luck with transmitters and antennas.

So now that they have had two transmitters burn up anyone know why that
happened?
Because they were broadcasting in HD?

rimshot
I suppose that is possible.

I was thinking more along the lines of the cooling system failed or a
HV component failed shorting out the final stage.

There are protections for both of those. However I must point out that
solid state transmitters have no B+.

So what is the voltage out the finals on a solid state transmitter?


After the output matching network a little under 1,600 Volts.

KFI transmitter off the air
 

Telamon wrote:
In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
...
In article ,

So what is the voltage out the finals on a solid state transmitter?

There are no finals. Just a bunch of combined modules. The Nautel 50 has 8
RF and 4 modulator power modules. There is no final stage.

Ok, Don't call the modules "finals" then but what is the output voltage
to the antenna? I would like to know what the RF current is as the
output is supposed to be 50KW.

31 Amperes

KFI transmitter off the air
 

Billy Burpelson wrote:
Telamon wrote:

So what is the voltage out the finals on a solid state transmitter?

Do you mean the DC voltage on the collectors of the output transistors
or the RF voltage into the feed line?

Telamon wrote:

Ok, Don't call the modules "finals" then but what is the output
voltage to the antenna? I would like to know what the RF current is as
the output is supposed to be 50KW.

I'm surprised a smart person like you isn't familiar with Ohm's law...

To find the RF voltage for a 50 kW transmitter, assuming a 50 ohm
transmission line:

Simple Ohm's Law:

V= the square root of (RxW) (V=volts, W=watts, R=feed line impedance in
ohms...assume 50 ohms)

To find the current:

I= the square root of (W/R)

Sometimes you're just to, too, two clueless. :-)


This is even simpler:

http://www.sengpielaudio.com/calculator-ohm.htm

KFI transmitter off the air
 

Telamon wrote:
In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
...

I'll assume that there are 10 modules so each would put out about 3
amps. The outputs could be protected by limiting that source current and
there would also have to be a another protection against VSWR. Maybe a
temperature sensor on the output FET but that might be too slow.

So how do the separate modules work together? Do they all put out the
same voltage and current in phase through some kind of card backplane?

The principle manufacturers of solid state transmitters are Harris, BE, and
Nautel in the US/NA. Each as a website, and I believe there are both
functional diagrams and some white papers about design. I have never worked
inside a big ss transmitter so am of limited use in describing how they
work.

Thanks for answering my questions Eduardo. I'll check those sites out.

Can you tell me who makes the hardline between transmitter and antenna?

I'm just the curious sort. I have never really worked with RF power and
I just haven't though of the obvious answers to some of the questions I
have asked in the thread. In my work experience the RF power is 0 dBm
and less coming out of equipment like network analyzers and synthesizers.

I can tell you that there is a lot more to actually fabricating
electronics than the schematics can explain.

www.eriinc.com/pubs/Catalog07_168-171.pdf

Scroll down for specs at 0.64 MHz

KFI transmitter off the air
 

Telamon wrote:
In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
...
. :-)
You are such a retard. I was wondering what the line loss would be and I
am not familiar with the FCC rules. The 50Kw could be the max the
transmitter puts out or the input to the antenna or it could be based on
antenna field strength measurements.
There are several isssues here.

1. It's usually the licensed power into the antenna for non-directional
stations. So most new solid state transmitters deliver 10% to 20% more, so
that if the line loss is a couple of percent, the line is fed with the
licensed power plus line loss.

2. Directional systems feed the licensed power plus phasor loss to the
common point (input) of the directional phasor. So if phasor loss for a 50
kw station is 5 kw, then they feed the common point with 55 kw.

3. Some classes of AM service have a maximum field strength at a determined
distance. If the radiator is too efficient (a 5/8 wave or a Franklin) the
station may actually feed less than licensed power to the tower to
compensate for the radiation efficiency.

SNIP

The 5/8 wavelength antenna is a good one to use for local mobile
communications. I think that is because it has a good low to the horizon
lobe creating a better ground wave than a 1/4 wavelength antenna would
generate. That sound right to you or is there another reason?


That is correct. Most flamethrowers are electrically near 1/2 5/8
wave. Half wave antennas are harder to feed.

KFI transmitter off the air
 

In article ,
Dave wrote:

Telamon wrote:
In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
.
..

I'll assume that there are 10 modules so each would put out about 3
amps. The outputs could be protected by limiting that source current and
there would also have to be a another protection against VSWR. Maybe a
temperature sensor on the output FET but that might be too slow.

So how do the separate modules work together? Do they all put out the
same voltage and current in phase through some kind of card backplane?

The principle manufacturers of solid state transmitters are Harris, BE,
and
Nautel in the US/NA. Each as a website, and I believe there are both
functional diagrams and some white papers about design. I have never
worked
inside a big ss transmitter so am of limited use in describing how they
work.

Thanks for answering my questions Eduardo. I'll check those sites out.

Can you tell me who makes the hardline between transmitter and antenna?

I'm just the curious sort. I have never really worked with RF power and
I just haven't though of the obvious answers to some of the questions I
have asked in the thread. In my work experience the RF power is 0 dBm
and less coming out of equipment like network analyzers and synthesizers.

I can tell you that there is a lot more to actually fabricating
electronics than the schematics can explain.

www.eriinc.com/pubs/Catalog07_168-171.pdf

Scroll down for specs at 0.64 MHz

6 1/8 inch is what most radio stations use?

--
Telamon
Ventura, California

KFI transmitter off the air
 

"Telamon" wrote in message
...

6 1/8 inch is what most radio stations use?


Pretty common for FM and TV stations.. not so much for AM. IIRC, 1520 in
Portland used 3" Heliax for 50KW.

KFI transmitter off the air
 

In article ,
"Brenda Ann" wrote:

"Telamon" wrote in message
...

6 1/8 inch is what most radio stations use?


Pretty common for FM and TV stations.. not so much for AM. IIRC, 1520 in
Portland used 3" Heliax for 50KW.

Someone wrote that 50 ohm was standard. Why am I seeing 75 ohm
components then?

And while I'm back on the impedance subject I expect that tower
impedance can be much lower than 50 ohms so that why a matching network
is needed at the antenna?

--
Telamon
Ventura, California

KFI transmitter off the air
 

Telamon wrote:
In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
...

SNIP

Some time I need to find a time where our engineers can take you to Mt
Wilson. One of our sites is shared with multiple users, including several
TVs. You would have a lot of questions for the follks at that manned site.

SNIP

Now that would be an interesting field trip.

As long as you don't plan on having children...

KFI transmitter off the air
 

In article ,
Dave wrote:

Telamon wrote:
In article ,
"David Eduardo" wrote:

"Telamon" wrote in message
.
..

SNIP

Some time I need to find a time where our engineers can take you to Mt
Wilson. One of our sites is shared with multiple users, including several
TVs. You would have a lot of questions for the follks at that manned site.

SNIP

Now that would be an interesting field trip.

As long as you don't plan on having children...

I could wear lead lined depends.

It's just an hour or two of RF not as bad as holding a cell phone to
your head.

--
Telamon
Ventura, California

KFI transmitter off the air
 

In article ,
Billy Burpelson wrote:

Telamon wrote:

So what is the voltage out the finals on a solid state transmitter?
Do you mean the DC voltage on the collectors of the output transistors
or the RF voltage into the feed line?

Telamon wrote:

Ok, Don't call the modules "finals" then but what is the output voltage
to the antenna? I would like to know what the RF current is as the
output is supposed to be 50KW.
I'm surprised a smart person like you isn't familiar with Ohm's law...

To find the RF voltage for a 50 kW transmitter, assuming a 50 ohm
transmission line:

Simple Ohm's Law:

V= the square root of (RxW) (V=volts, W=watts, R=feed line impedance in
ohms...assume 50 ohms)

To find the current:

I= the square root of (W/R)

Sometimes you're just to, too, two clueless. :-)


Telamon wrote:

You are such a retard. I was wondering what the line loss would be

Try again. You were NOT asking about the "line loss".

and I
am not familiar with the FCC rules.

Well, then could we say YOU are clueless?

The 50Kw could be the max the
transmitter puts out or the input to the antenna or it could be based on
antenna field strength measurements.

Again, could we say YOU are clueless?

And also the 50 ohms impedance would be another assumption on my part
but since a clueless wonder such as yourself generally proceeds on
unfounded assumptions you will not understand this.

You admit *YOU* know *NOTHING* about the power or impedance and yet you
accuse others of being "clueless".

Can you see the irony here? Or are you to, too, two clueless to get it?

KFI transmitter off the air
 

Telamon wrote:
In article ,
"Brenda Ann" wrote:

"Telamon" wrote in
message
...

6 1/8 inch is what most radio stations use?

Pretty common for FM and TV stations.. not so much for AM. IIRC, 1520
in Portland used 3" Heliax for 50KW.

Someone wrote that 50 ohm was standard. Why am I seeing 75 ohm
components then?

Dave wrote:

75 Ohm has lower loss for long runs, but requires extra matching
sections, usually at both ends.

Sorry to rain on your parade...but to follow your own (lack of) logic:

The "extra matching sections" you talk about (at each end) would add
*more* loss than you would gain by using your -supposedly- lower loss 75
ohm cable.

Also, 75 ohm cable does not inherently have less (or more) loss than 50
ohm cable. *Loss* is dependent on the dielectric used, the materials
used and the construction (size) of the cable, no matter what the impedance.

Finally, AFAIK, 50 ohms has been traditionally used for AM/FM/SW
transmitters while 75 ohms is used for CATV distribution.

KFI transmitter off the air
 

In article ,
Billy Burpelson wrote:

In article ,
Billy Burpelson wrote:

Telamon wrote:

So what is the voltage out the finals on a solid state transmitter?
Do you mean the DC voltage on the collectors of the output transistors
or the RF voltage into the feed line?

Telamon wrote:

Ok, Don't call the modules "finals" then but what is the output voltage
to the antenna? I would like to know what the RF current is as the
output is supposed to be 50KW.
I'm surprised a smart person like you isn't familiar with Ohm's law...

To find the RF voltage for a 50 kW transmitter, assuming a 50 ohm
transmission line:

Simple Ohm's Law:

V= the square root of (RxW) (V=volts, W=watts, R=feed line impedance in
ohms...assume 50 ohms)

To find the current:

I= the square root of (W/R)

Sometimes you're just to, too, two clueless. :-)


Telamon wrote:

You are such a retard. I was wondering what the line loss would be

Try again. You were NOT asking about the "line loss".

SNIP

Excuse me 'tard boy. I just happen to know what I was after here. Your
cluelessness is not my problem.

--
Telamon
Ventura, California

KFI transmitter off the air
 

In article ,
Billy Burpelson wrote:

Telamon wrote:
In article ,
"Brenda Ann" wrote:

"Telamon" wrote in
message

...

6 1/8 inch is what most radio stations use?

Pretty common for FM and TV stations.. not so much for AM. IIRC, 1520
in Portland used 3" Heliax for 50KW.

Someone wrote that 50 ohm was standard. Why am I seeing 75 ohm
components then?

Dave wrote:

75 Ohm has lower loss for long runs, but requires extra matching
sections, usually at both ends.

Sorry to rain on your parade...but to follow your own (lack of) logic:

The "extra matching sections" you talk about (at each end) would add
*more* loss than you would gain by using your -supposedly- lower loss 75
ohm cable.

Also, 75 ohm cable does not inherently have less (or more) loss than 50
ohm cable. *Loss* is dependent on the dielectric used, the materials
used and the construction (size) of the cable, no matter what the impedance.

Finally, AFAIK, 50 ohms has been traditionally used for AM/FM/SW
transmitters while 75 ohms is used for CATV distribution.

I'm inclined to agree with you on this but seeing how you are clueless
99.999% of the time I'll have to think and research this a little more.

Maybe you could supply a little logic behind this view?

--
Telamon
Ventura, California

KFI transmitter off the air
 

On Nov 2, 4:12*pm, Dave wrote:
Telamon wrote:

I would think that this argument would be about which would be easier
to make, use, or construct for a low loss transmission line 50 or 75
ohms.

- Argument?
-*If you want to argue about cables ad infinitum
- I suggest rec.radio.amateur.antenna

Dave D'Oh! so Political Off-Topic is OK

but something remotely related to Shortwave Radio
like technology should be taken elsewhere.

ok i get it 'not' ~ RHF

KFI transmitter off the air
 

Telamon wrote:

In article ,
Dave wrote:


Telamon wrote:


I would think that this argument would be about which would be easier
to make, use, or construct for a low loss transmission line 50 or 75
ohms.


Argument?


The argument would be between you and Ian.


If you want to argue about cables ad infinitum I suggest
rec.radio.amateur.antenna


No thanks that news group blows.

As if this group doesn't? Hardly any of the valued contributors from
years past bother to post here anymore. They moved on to groups with
moderators that don't allow the kind of BS that goes on here.

KFI transmitter off the air
 

RHF wrote:
On Nov 2, 4:12 pm, Dave wrote:
Telamon wrote:

I would think that this argument would be about which would be easier
to make, use, or construct for a low loss transmission line 50 or 75
ohms.
- Argument?
- If you want to argue about cables ad infinitum
- I suggest rec.radio.amateur.antenna

Dave D'Oh! so Political Off-Topic is OK

but something remotely related to Shortwave Radio
like technology should be taken elsewhere.

ok i get it 'not' ~ RHF
.

If you want to center feed a dipole, go for the 75 Ohm.

KFI transmitter off the air
 

On Mon, 03 Nov 2008 16:10:01 -0500, Billy Burpelson wrote:
..

However, the thread seems clearly titled " KFI transmitter off the
air" and I doubt your statement above ( center feeding a dipole) is
implying that KFI is using a dipole.

Please 'splain.

It depends on your meaning of dipole. Read the thread all the way back,
and you'll see what I mean by bull****.

KFI transmitter off the air
 

In article ,
factcheck wrote:

Telamon wrote:

In article ,
Dave wrote:


Telamon wrote:


I would think that this argument would be about which would be easier
to make, use, or construct for a low loss transmission line 50 or 75
ohms.


Argument?


The argument would be between you and Ian.


If you want to argue about cables ad infinitum I suggest
rec.radio.amateur.antenna


No thanks that news group blows.

As if this group doesn't? Hardly any of the valued contributors from
years past bother to post here anymore. They moved on to groups with
moderators that don't allow the kind of BS that goes on here.

That news group is way worse than this one. The regulars in that news
group are all like Billy Boy. I'm thankful we just have one of those
here.

--
Telamon
Ventura, California

KFI transmitter off the air
 

In article ,
Billy Burpelson wrote:

Dave wrote:

If you want to center feed a dipole, go for the 75 Ohm.

As far as it goes, you are correct in that the nominal impedance of a
half-wave, center fed dipole is around 72 Ohms only at its resonant
frequency.

So yes, you would have a good match between the feed line and the
antenna, BUT...(and there is usually a but)...

...all you are doing is moving the mismatch of the 75 ohm feed line to
the back of the transceiver, as all rigs made in the last 20 years or so
have a fixed, nominal 50 Ohm input/output.

So, would you like your mismatch at the back of your transceiver or at
the antenna? In -either- case (50 or 75 ohm line), you will still have a
nominal 1.44: 1 SWR at the resonant frequency. If you are at any other
frequency than resonance, all bets are off, no matter what impedance
coax you use.

He could use a broadband UNUN at the back of the receiver Mr. Clueless.

--
Telamon
Ventura, California