Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[Mike Morris WA6ILQ]

At 10:50 PM 08/30/07, you wrote:
>At 12:25 AM 2007-08-31 -0400, you wrote:
>
>>Our local FD has been plagued by theives stealing the aluminum cans from
>>our can trailer.
>
>FWIW one ham club I know of have some kind of plug in cable connecting
>their building alarm system with the ARES/event trailer.   What kind of
>sensors and such I have no idea.
>
>Tony

One group for years used a 5-conductor twist-lock for 120vAC
(4 conductors - ground, neutral and two hot circuits) and the
extra conductor was attached to a relay in the building alarm
box.
The 120v kept the fridge cold, the battery up, the AC lighting
circuits hot. The alarm lead in the connector was just 120v fed
back from the trailer to the relay coil. When the AC went away,
the relay dropped out and the alarm circuit was activated by
the contacts opening.
There were a number of things that could drop that AC
voltage... a door opening, under or over temperature, and more.
The under/over temperature sensor was simply a standard dual
tipping mercury bulb air conditioning thermostat, one that had
both limits set a little further in the extremes than would be
considered comfortable (i.e. the low end switched on at about
38 degrees and the high end switched on at about 100 degrees).
Either one was considered a temperature alarm.

Since the connector was simply a large twist lock, and the cord
looked like a fat outdoor-grade AC cord, nobody had any inkling
that the cord had an alarm circuit in it as well as power

Just though I'd toss an idea out there...

Mike 

Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[Tony VE6MVP]

At 12:25 AM 2007-08-31 -0400, you wrote:


Our local FD has been plagued by theives stealing the aluminum cans from
our can trailer.


FWIW one ham club I know of have some kind of plug in cable connecting 
their building alarm system with the ARES/event trailer.   What kind of 
sensors and such I have no idea.


Tony

Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[MCH]

Our local FD has been plagued by theives stealing the aluminum cans from
our can trailer. It must be worth it. And the content of Heliax (no
matter what you call it) has to be higher than a thin walled can.

Joe M.

Ralph Mowery wrote:
> 
> --- DCFluX <[EMAIL PROTECTED]> wrote:
> 
> > Perhaps they should mark the jacket with 'Contains
> > no copper' to
> > deture cell site theft as well.
> >
> >
> 
> I think the price of aluminum is up enough also to
> make it worth while to scrap.  I have heard of reports
> of aluminum siding being ripped off.
> 
>   
> 
> Shape Yahoo! in your own image.  Join our Network Research Panel today!   
> http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7
> 
> 
> Yahoo! Groups Links
> 
> 
> 

Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[Eric Lemmon]

I just looked at the Andrew spec sheet for AVA5-50, which is the "Andrew
Virtual Air" replacement for LDF5-50, and the two cables appear to
identical.  The AVA5-50 has a copper tube inner conductor and a corrugated
copper outer conductor.  I suspect that the thickness of both inner and
outer conductors has been reduced, which accounts for the lighter weight,
but there is no aluminum involved.

It appears the "Heliax AL" is the aluminum version of Heliax LDF5-50.  As
Jesse pointed out, the smaller Heliax sizes such as LDF2 and LDF4 do use a
copper-clad solid aluminum center conductor.  Larger sizes have hollow
copper tubes as center conductors.

73, Eric Lemmon WB6FLY
 

-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Jesse Lloyd
Sent: Thursday, August 30, 2007 8:00 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Norton AntiSpam] Re: [Repeater-Builder] Wal Mart effect makes it
to the Communications Hard (feed)-Line industry

Isn't LDF a copper shield with an aluminum core that has copper coating on
it?

Jesse


On 8/30/07, Bob Dengler <[EMAIL PROTECTED]
 > wrote:

At 8/30/2007 03:45 PM, you wrote:
>The Wal Mart effect* makes it to the Communications Feed-Line
industry
>(*Global Economy)
>
>enjoy,
>s.
>
>[paste text]
>Building upon the market success of its two most significant cable
>products, Andrew Corporation has announced they will be
streamlining
>its long-running and market-leading HELIAX  product portfolio by
>discontinuing its LDF series cable and featuring alternative
products
>that offer higher value.
>
>Andrew will cease regular production of LDF5 and LDF7 series
coaxial
>cables on December 31, 2007 with equivalently sized HELIAX Andrew
>Virtual Air  (AVA ) and HELIAX AL aluminum series cables serving as
>direct replacements.

Under my previous site manager, aluminum hardline was banned from
the site.

Bob NO6B

Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[Jesse Lloyd]

Isn't LDF a copper shield with an aluminum core that has copper coating on
it?

Jesse

On 8/30/07, Bob Dengler <[EMAIL PROTECTED]> wrote:
>
>   At 8/30/2007 03:45 PM, you wrote:
> >The Wal Mart effect* makes it to the Communications Feed-Line industry
> >(*Global Economy)
> >
> >enjoy,
> >s.
> >
> >[paste text]
> >Building upon the market success of its two most significant cable
> >products, Andrew Corporation has announced they will be streamlining
> >its long-running and market-leading HELIAX� product portfolio by
> >discontinuing its LDF series cable and featuring alternative products
> >that offer higher value.
> >
> >Andrew will cease regular production of LDF5 and LDF7 series coaxial
> >cables on December 31, 2007 with equivalently sized HELIAX Andrew
> >Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as
> >direct replacements.
>
> Under my previous site manager, aluminum hardline was banned from the
> site.
>
> Bob NO6B
>
>  
>

RE: [Repeater-Builder] Duplexers

[Gary Schafer]

> -Original Message-
> From: Repeater-Builder@yahoogroups.com [mailto:Repeater-
> [EMAIL PROTECTED] On Behalf Of Bob Dengler
> Sent: Thursday, August 30, 2007 12:53 PM
> To: Repeater-Builder@yahoogroups.com
> Subject: RE: [Repeater-Builder] Duplexers
> 
> At 8/29/2007 06:40 PM, you wrote:
> 
> > > >If you have two watt meters and an antenna matching device you can
> put
> > > one
> > > >wattmeter between the transmitter and the matching device and tune it
> for
> > > >minimum reflected power on the first meter. Then with a second meter
> > > >between the tuner and the mismatched load you can see the second
> > > wattmeter
> > > >that is reading the reflected power. The second wattmeter will have a
> > > >higher forward power reading than the first due to the added re-
> reflected
> > > >power.
> > >
> > > This doesn't sound right either, as there should be no reflected power
> at
> > > the antenna if it's been matched further down the line.  The tuner
> would
> > > be
> > > adjusted so as to create a conjugate impedance of the antenna at the
> end
> > > of
> > > the feeding coax, thus eliminating the mismatch.
> > >
> > > My guess is that the higher power reading on the wattmeter is due to
> the
> > > weird impedances it's seeing on both its input & output.
> > >
> > > Bob NO6B
> > >
> >
> >Hi Bob,
> >
> >Please read again what I wrote. I am not sure that you are following how
> the
> >meters are in the circuit. Remember that whatever you do at the
> transmitter
> >end of a transmission line has no affect on what is going on in the line
> >itself. The only thing that will change the swr on the line is what you
> do
> >at the load.
> >
> >73
> >Gary  K4FMX
> 
> OK, after talking to a senior RF engineer at lunch here at work I think I
> understand what's going on.  The part that threw me was having the
> matching
> circuit in the middle of the feedline & the fact that any reflected power
> from the load MUST be totally re-reflected back by the matching circuit,
> otherwise there would be power reflected back to the TX, which by
> definition does not occur in this example.  Because of the multiple
> re-reflections between the matching circuit & load resulting in multiple
> waves back & forth within that coax section, typical single-wave thinking
> doesn't apply.
> 
> I guess it's a useful way to illustrate why coax gets lossier if you use a
> tuner far from the antenna.
> 
> Bob NO6B


Yes coax is lossier with reflected power on it. The part of the power that
gets reflected from the antenna back toward the transmitter gets attenuated
a second time by whatever lose the cable has to begin with. Then when that
portion of the power gets re-reflected at the transmitter end and is on its
way back to the antenna again it suffers attenuation a 3rd time by the coax
so all the re-reflected power does not make it back to the antenna. 
Then a portion of the re-reflected power gets reflected again back toward
the transmitter along with the new wave of power. This repeats itself again
and again adding to the loss but after a few round trips of bouncing up and
down the feed line most of it gets radiated and some has gotten attenuated
to a miniscule amount.
Of course this process is continuously repeated as power is constantly
applied from the transmitter.

But my reason for using the first wattmeter and the tuner was to have a
nearly perfect flat load on the transmitter so that one could see the true
power coming out of the transmitter. 
The second wattmeter after the tuner will then show the higher power which
would be the sum of the forward and re-reflected power so it could be seen
that reflected power does indeed get re-reflected at the transmitter (in
this case at the tuner)and makes its way back to the antenna.

In common applications with just a single wattmeter and no tuner involved
where there is reflected power on the line the wattmeter in the forward
position will show the forward power plus the re-reflected power. To find
power out of the transmitter you would subtract the reflected power shown in
the reverse position from the indicated forward power on the meter. This
works over a wide range of impedances with a bird wattmeter.

73
Gary  K4FMX
 

RE: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[Eric Lemmon]

Fred, et al:

The General Electric Datafile Bulletin 10003-1 is available for download
here:

 

These two files are also needed to perform the calculations:




73, Eric Lemmon WB6FLY


-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Fred Seamans
Sent: Thursday, August 30, 2007 6:11 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program
Available

To All Interested: I would invite you attention to a paper presented by
Kenneth Bullington, "Radio Propagation at Frequencies Above 30 Meagcycles"
in the October 1947 Proceedings of the I.R.E. - Waves and Electronics
Section. Most all radio propagation prediction methods over the years have
been based on the findings of his research for this paper.
A GE Mobile Radio Data File Bulletin (10003-1), "VHF and UHF Propagation",
was published in July 1962 for use by engineers and technicians for the
prediction of radio coverage. Along with this bulletin a hard paper/plastic
slide rule was manufactured by GE for its sales personnel to predict radio
coverage. Motorola sales people liked to get a hold of  it and use it also;
"Range and Signal Strength Calculator for 2 Way Radio".There was a second
version put together by GE in 1977; "Range and Transmitter Power
Calculator". 
If you can find them, either of these slide rules can give adequate results
with radio range calculations.
With the general usage of computers in the 1980's many propagation programs
appeared on the market, some use digitized USGA maps while others take a
more simplistic approach. You get what you pay for!
This Data File may be available on line, I am not sure if it is.
Fred W5VAY

Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[Bob Dengler]

At 8/30/2007 03:45 PM, you wrote:
>The Wal Mart effect* makes it to the Communications Feed-Line industry
>(*Global Economy)
>
>enjoy,
>s.
>
>[paste text]
>Building upon the market success of its two most significant cable
>products, Andrew Corporation has announced they will be streamlining
>its long-running and market-leading HELIAX� product portfolio by
>discontinuing its LDF series cable and featuring alternative products
>that offer higher value.
>
>Andrew will cease regular production of LDF5 and LDF7 series coaxial
>cables on December 31, 2007  with equivalently sized HELIAX Andrew
>Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as
>direct replacements.

Under my previous site manager, aluminum hardline was banned from the site.

Bob NO6B

RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers

[Gary Schafer]

I wonder what you were using to measure the impedance of the cable with
below .5 MHz?
Some cable especially rg59 types have copper clad steel center conductors.
If the copper clad is very thin low frequencies can penetrate the copper
clad and get into the steel where the loss can go up substantially. If you
are using that cable to transform an impedance the additional lose can make
the impedance transformation something other than expected. The impedance
will be closer to the characteristic impedance of the cable rather than the
expected transformation impedance.
But to have the characteristic impedance fall apart at .5 MHz would be a
mystery. 75 ohm cable is used extensively in video base band applications
where flat low frequency response is needed.

73
Gary  K4FMX

> -Original Message-
> From: Repeater-Builder@yahoogroups.com [mailto:Repeater-
> [EMAIL PROTECTED] On Behalf Of Ron Wright
> Sent: Thursday, August 30, 2007 10:48 AM
> To: Repeater-Builder@yahoogroups.com
> Subject: Re: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
> 
> Gary,
> 
> I've measured RG59 cable terminated into a 75 Ohm resistive load with a
> variable freq impedance meter.  We found the coax stopped being 75 Ohms
> below about 0.5 MHz. The cable manufacture also verified this.  Other
> engineers in our department knew of this as well.
> 
> We were designing security systems using video and the vertical and
> harizonal sync signals became very distored over long, 2500 ft. RG59
> cables and this was the major reason.  We had to design circuits that
> corrected this, but the cable had the problem.
> 
> I am sure different RG59 cables have different low freq bandwidths.  RG11
> would also be different as well as cable TV cable.
> 
> All coax has a lower and upper frequency range.  Since we deal with radio
> this is not much of a factor until one gets real low or GHz levels.
> 
> Coax also has the problem of a upper freq limit due to it's outer shield
> becomes large enough to act as wave guide.  One will see upper freq specs
> will be lower  the larger cable.
> 
> 73, ron, n9ee/r
> 
> 
> 
> >From: Gary Schafer <[EMAIL PROTECTED]>
> >Date: 2007/08/29 Wed PM 09:23:57 CDT
> >To: Repeater-Builder@yahoogroups.com
> >Subject: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers
> 
> 
> >As far as bandwidth goes,,, where do you get this .5 MHz for rg59 cable
> as a
> >lower limit?
> >
> >Open wire lines begin to radiate as frequency is increased to the point
> >where the line spacing becomes an appreciable portion of a wave length
> due
> >to the time it takes for propagation of fields between wires.
> >
> >73
> >Gary  K4FMX
> >
> 
> 
> Ron Wright, N9EE
> 727-376-6575
> MICRO COMPUTER CONCEPTS
> Owner 146.64 repeater Tampa Bay, FL
> No tone, all are welcome.
> 
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 

[Repeater-Builder] Contains No Copper!

[bbedoe]

 
 
Contains no copper 
 
I live just south of Orland Park, IL  (Andrew's old Corporate  office)  I had 
the opportunity a few years back to pick up some  LDF5.  While on the 
property I saw 2 - 30 yard dumpsters side by  side by one of the manufacturing 
buildings.  The 1 dumpster had all sizes  of scrap, bent, damaged heliax from 
1/4 
superflex to 3+ inch air cable. It was  ready to overflow, and no piece was 
larger than 6 ft.
 
The other 30 yard dumpster was almost full of pure scrap copper from  the 
manufacturing process.  The noon time sun made the dumpster look like  it was 
on 
fire from the shiny copper! 
 
Blinded by the light!  What a sight!
73 Brian, WD9HSY




Your kid  may be an Honor Student,
Your Kid may be a Great Athlete,
Your Kid may be  a Doctor or a Lawyer,
But My kid is in the US Air Force & plays  with ICBM's,  Inter Continental 
Ballistic Missiles, 

What was your Lat. and Long.  ?




** Get a sneak peek of the all-new AOL at 
http://discover.aol.com/memed/aolcom30tour

Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[Ralph Mowery]

--- DCFluX <[EMAIL PROTECTED]> wrote:

> Perhaps they should mark the jacket with 'Contains
> no copper' to
> deture cell site theft as well.
> 
>

I think the price of aluminum is up enough also to
make it worth while to scrap.  I have heard of reports
of aluminum siding being ripped off.



  

Shape Yahoo! in your own image.  Join our Network Research Panel today!   
http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7 

RE: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[Don KA9QJG]

I have had a 125 Ft. of Andrews
LDF 450 ½ in On My 444.75 Repeater for over 15 Yrs. it actually got
bent a little during a Move I put 3 Popsicle Sticks on it and Tape SWR
Is Still 1.1  ,  I just wonder if they Switch to alum if it will cause
some kind of reaction of Dissimilar Metals on the Connectors , Oh I
know what they will do Drop the price of the Coax and raise the Price
of special connectors .



Happy Repeater Building



Don KA9QJG

Re: Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[Ralph Mowery]

--- Ron Wright <[EMAIL PROTECTED]> wrote:

> Ralph,
> 
> I am sure the equation is 
> 
> Distance (in miles) = Square Root of (2 * height
> >> in feet)
>  
> not 
> 
> Distance (in miles) = Square Root (height in feet).
> 
> 

Then my refferance (ARRL Antenna Book 1974 version
page 11) must be wrong.  They give it as 1.415 * sqrt
height,  not 2 times the heigth.  You may be getting
the two times if you have two antennas at the same
height.   You have to use the formula two times, one
for each antenna and then add them together for the
total distance.  The 1.415 is a multiplier for radio
wave bending around the curve of the earth and may
need to be differant for differant kinds of earth.




   

Building a website is a piece of cake. Yahoo! Small Business gives you all the 
tools to get online.
http://smallbusiness.yahoo.com/webhosting 

Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[Nate Duehr]

skipp025 wrote:
> The Wal Mart effect* makes it to the Communications Feed-Line industry 
> (*Global Economy) 
> 
> enjoy,
> s. 
> 
> [paste text]
> Building upon the market success of its two most significant cable 
> products, Andrew Corporation has announced they will be streamlining 
> its long-running and market-leading HELIAX� product portfolio by 
> discontinuing its LDF series cable and featuring alternative products 
> that offer higher value.
> 
> Andrew will cease regular production of LDF5 and LDF7 series coaxial 
> cables on December 31, 2007  with equivalently sized HELIAX Andrew 
> Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as 
> direct replacements. 

Damn, I assume that the connectors aren't the same, then?

Our stash of LDF5 connectors is going to be worthless after a time... if 
that's the case.

G.

Thanks for the warning Skipp.

Nate WY0X

Re: [Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[DCFluX]

Perhaps they should mark the jacket with 'Contains no copper' to
deture cell site theft as well.

On 8/30/07, skipp025 <[EMAIL PROTECTED]> wrote:
> The Wal Mart effect* makes it to the Communications Feed-Line industry
> (*Global Economy)
>
> enjoy,
> s.
>
> [paste text]
> Building upon the market success of its two most significant cable
> products, Andrew Corporation has announced they will be streamlining
> its long-running and market-leading HELIAX� product portfolio by
> discontinuing its LDF series cable and featuring alternative products
> that offer higher value.
>
> Andrew will cease regular production of LDF5 and LDF7 series coaxial
> cables on December 31, 2007  with equivalently sized HELIAX Andrew
> Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as
> direct replacements.
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>

[Repeater-Builder] Wal Mart effect makes it to the Communications Hard (feed)-Line industry

[skipp025]

The Wal Mart effect* makes it to the Communications Feed-Line industry 
(*Global Economy) 

enjoy,
s. 

[paste text]
Building upon the market success of its two most significant cable 
products, Andrew Corporation has announced they will be streamlining 
its long-running and market-leading HELIAX� product portfolio by 
discontinuing its LDF series cable and featuring alternative products 
that offer higher value.

Andrew will cease regular production of LDF5 and LDF7 series coaxial 
cables on December 31, 2007  with equivalently sized HELIAX Andrew 
Virtual Air� (AVA�) and HELIAX AL aluminum series cables serving as 
direct replacements. 

RE: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers

[Gary Schafer]

Hi Ron,

Think about what goes on in power and RF transmission. Radiation is a
problem in power distribution just like it is in RF. Propagation down the
line is a concern in power distribution the same as RF. 
If you compare 160 meter transmitter/tuner L and C values to those of values
used at 2 meters there is a large difference there also. Power distribution
is just a lower frequency.
Standing waves on power distribution lines are just as important as those on
RF lines. Standing waves on power distribution produce hot spots in lines
just like RF does.
The only difference is the wave length is much longer at 60 Hz and you need
to travel a much greater distance to see the effects but the effect are the
same.

73
Gary  K4FMX

> -Original Message-
> From: Repeater-Builder@yahoogroups.com [mailto:Repeater-
> [EMAIL PROTECTED] On Behalf Of Ron Wright
> Sent: Thursday, August 30, 2007 10:54 AM
> To: Repeater-Builder@yahoogroups.com
> Subject: Re: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers
> 
> Gary,
> 
> AC power line transmission theory is very different than RF.  In RF
> radiation and propagation down the line follows a much different science.
> Also in AC lines the load is continously changing and at 60 Hz it takes
> large Ls and Cs to make much difference.  AC power is more concerned with
> power factor than radiation.  This can lead to more voltage and current,
> at the same time, out than at the source.
> 
> There are some concerns of very long grid lines with transmission, but
> plays a much less factor than at RF.
> 
> 73, ron, n9ee/r
> 
> 
> 
> 
> >From: Gary Schafer <[EMAIL PROTECTED]>
> >Date: 2007/08/29 Wed PM 09:03:50 CDT
> >To: Repeater-Builder@yahoogroups.com
> >Subject: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers
> 
> >
> >Transmission line theory is transmission line theory. It doesn't matter
> what
> >the frequency is it all works the same. Power line transmission engineers
> >worry about the same things in power transmission as do RF engineers.
> Only
> >the wavelength is different.
> >
> >> IR drops in feed lines is much less than a factor than the
> LC/dielectric
> >> type losses.  Again frequency shows this.  100 W at 10 MHz and 1000 MHz
> >> will have radically different losses yet both have the same I and V and
> R.
> >>
> >
> >A feed line at 10 MHz has a totally different R loss than the same feed
> line
> >used at 1000 MHz. It does NOT have the same R at different frequencies.
> It
> >has the same "Z" (surge or characteristic impedance) at all frequencies
> but
> >not the same series resistance R.  The resistance increases because of
> skin
> >effect the higher the frequency is. This is where loss comes from.
> >
> >73
> >Gary  K4FMX
> >
> >> -Original Message-
> >> From: Repeater-Builder@yahoogroups.com [mailto:Repeater-
> >> [EMAIL PROTECTED] On Behalf Of Ron Wright
> >> Sent: Wednesday, August 29, 2007 9:32 AM
> >> To: Repeater-Builder@yahoogroups.com
> >> Subject: Re: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers
> >>
> >> Ralph,
> >>
> >> Transmission line theory for RF and AC power is totally different.  In
> AC
> >> power lines little is paid attention to as for transmission except for
> R
> >> losses and power factor.  Yes up the voltage/lower the current and the
> IR
> >> loss goes down.
> >>
> >> For RF this is totally different for the RF propergatesdown the line,
> not
> >> just passes as voltage and currents.  This is why feedlines have
> specific
> >> impedances and loads used.
> >>
> >> One can have any impedance of coax or twin feeds one wants...that is if
> >> you have the material and space for it.  One can get off the shelf 75
> Ohm
> >> twin lead.  Using 50 or 75 Ohm has more to do with stability especially
> at
> >> RF.
> >>
> >> IR drops in feedlines is much less than a factor than the LC/dielectric
> >> type losses.  Again frequency shows this.  100 W at 10 MHz and 1000 MHz
> >> will have radically different losses yet both have the same I and V and
> R.
> >>
> >> 73, ron, n9ee/r
> >>
> >>
> >>
> >>
> >> >From: Ralph Mowery <[EMAIL PROTECTED]>
> >> >Date: 2007/08/27 Mon AM 09:20:07 CDT
> >> >To: Repeater-Builder@yahoogroups.com
> >> >Subject: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers
> >>
> >> >
> >> >
> >> >--- Ron Wright <[EMAIL PROTECTED]> wrote:
> >> >
> >> >> Jesse,
> >> >>
> >> >> Then why do twin feeders have much less loss than
> >> >> coax???  Skin affect is even more of a factor there
> >> >> due to the differences in the area of the outer
> >> >> shield in coax vs the twin feeders wire.
> >> >>
> >> >> Maybe it is because of the larger C coupling in the
> >> >> coax due to the larger surface area of the shield.
> >> >> Coax has a lower R even with skin effect than twin
> >> >> line feeders.
> >> >>
> >> >> Skin affect is a factor, but a small one compared to
> >> >> the LC factor.
> >> >>
> >> >> 73, ron, n9ee/r
> >> >>
> >> >
> >> >It is not open wire or coax that determins the power
> >> >loss.  It is the 

Re: Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[Ron Wright]

Ralph,

I am sure the equation is 

Distance (in miles) = Square Root of (2 * height
>> in feet)
 
not 

Distance (in miles) = Square Root (height in feet).


>From: Ralph Mowery <[EMAIL PROTECTED]>
>Date: 2007/08/30 Thu PM 12:12:53 CDT
>To: Repeater-Builder@yahoogroups.com
>Subject: Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program 
>Available

>  
>
>--- Ron Wright <[EMAIL PROTECTED]> wrote:
>
>> 
>> 
>> >  
>> >
>> >On Aug 30, 2007, at 12:35 AM, ldgelectronics wrote:
>> >
>> >> As a quick and dirty method, the radio horizon
>> is:
>> >>
>> >> Distance (in miles) = Square Root of (2 * height
>> in feet).
>> >
>> 
>> This equation is ok, but for a perfect spheer.  Is a
>> good place to start.  Here in FL where max altitude
>> is about 330 ft ASL it works pretty well although
>> the lower the antenna the worse the actual coverage
>> results.  We have plenty of repeaters at 200 ft that
>> have noticably better coverage than 20 miles with a
>> mobile.
>> 
>> Also one has to take in account of the user's
>> station.   The equation is to the horizon so a user
>> with height over the horizon can also increase
>> coverage.
>> 
>> 73, ron, n9ee/r
>> 
>>
>The quick and dirty method at the top is not entirely
>correct.  For relative flat land the visual range to
>the horizon  in miles is the sqrt of the height in
>feet.  That is just for one station.  You have to do
>the same for the other station and add the results
>together.  Then there is a factor of about 1.2 to 1.5
>this distance has to be multiplied by for the radio
>horizon instead of the vusual horizon.
>
>For the repeater station antenna at 200 feet, it would
>be 14 miles to the horizon plus a mobile antenna of 5
>feet heigth to get 2.2 miles which would be 16.2
>miles.  Then multiply that by the radio wave bending
>factor of 1.2 to 1.5 to get 19.4 to 24.3 miles.  
>
>It does not take much of a rise in the road when the
>rest of the land is flat to get the mobile station up
>a few feet and this can add a lot to the range.  If
>the road goes up just 25 feet more the range will go
>up around 5 more miles.
>
>__
>Pinpoint customers who are looking for what you sell. 
>http://searchmarketing.yahoo.com/
>


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

Re: RE: [Repeater-Builder] Duplexers

[Ron Wright]

Bob,

It is better to have someone so one can set down and talk to.  This e-mail is 
great for bringing the world together, but face to face is much better except 
for most of the ugly Hams I hang out with.

The problem with a tuner is the feedline losses, but better than no tuner at 
all unless got resonant antennas.  On HF this is harder to do if one moves 
about.

Putting the tuner at the antenna is a solution, but then get into remote 
application.  Some tuners are automatic and tune whenever they see higher than 
say 1.5:1 SWR.

73, ron, n9ee/r



>From: Bob Dengler <[EMAIL PROTECTED]>
>Date: 2007/08/30 Thu PM 12:53:11 CDT
>To: Repeater-Builder@yahoogroups.com
>Subject: RE: [Repeater-Builder] Duplexers

>  

>
>OK, after talking to a senior RF engineer at lunch here at work I think I 
>understand what's going on.  The part that threw me was having the matching 
>circuit in the middle of the feedline & the fact that any reflected power 
>from the load MUST be totally re-reflected back by the matching circuit, 
>otherwise there would be power reflected back to the TX, which by 
>definition does not occur in this example.  Because of the multiple 
>re-reflections between the matching circuit & load resulting in multiple 
>waves back & forth within that coax section, typical single-wave thinking 
>doesn't apply.
>
>I guess it's a useful way to illustrate why coax gets lossier if you use a 
>tuner far from the antenna.
>
>Bob NO6B
>
>


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

[Repeater-Builder] Tuning Midland 70-1632B XTR moblie radio tuning to ham band

[hhzahnd]

We are looking to use a couple of Midland 70-1632B UHF radios to link 
to our tower location for interconnect of other repeaters.  Any one 
know the secret of getting them to go out of band and lock.  I have 
tried to retune the two pots to 1.5 volts but for some reason they do 
not want to stay.

Our received or input is on 443.725 and transmit or output is 448.725 
any ideas?

Thanks Herschel N9KPA

RE: [Repeater-Builder] Duplexers

[Bob Dengler]

At 8/29/2007 06:40 PM, you wrote:

> > >If you have two watt meters and an antenna matching device you can put
> > one
> > >wattmeter between the transmitter and the matching device and tune it for
> > >minimum reflected power on the first meter. Then with a second meter
> > >between the tuner and the mismatched load you can see the second
> > wattmeter
> > >that is reading the reflected power. The second wattmeter will have a
> > >higher forward power reading than the first due to the added re-reflected
> > >power.
> >
> > This doesn't sound right either, as there should be no reflected power at
> > the antenna if it's been matched further down the line.  The tuner would
> > be
> > adjusted so as to create a conjugate impedance of the antenna at the end
> > of
> > the feeding coax, thus eliminating the mismatch.
> >
> > My guess is that the higher power reading on the wattmeter is due to the
> > weird impedances it's seeing on both its input & output.
> >
> > Bob NO6B
> >
>
>Hi Bob,
>
>Please read again what I wrote. I am not sure that you are following how the
>meters are in the circuit. Remember that whatever you do at the transmitter
>end of a transmission line has no affect on what is going on in the line
>itself. The only thing that will change the swr on the line is what you do
>at the load.
>
>73
>Gary  K4FMX

OK, after talking to a senior RF engineer at lunch here at work I think I 
understand what's going on.  The part that threw me was having the matching 
circuit in the middle of the feedline & the fact that any reflected power 
from the load MUST be totally re-reflected back by the matching circuit, 
otherwise there would be power reflected back to the TX, which by 
definition does not occur in this example.  Because of the multiple 
re-reflections between the matching circuit & load resulting in multiple 
waves back & forth within that coax section, typical single-wave thinking 
doesn't apply.

I guess it's a useful way to illustrate why coax gets lossier if you use a 
tuner far from the antenna.

Bob NO6B

Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[Ralph Mowery]

--- Ron Wright <[EMAIL PROTECTED]> wrote:

> 
> 
> >  
> >
> >On Aug 30, 2007, at 12:35 AM, ldgelectronics wrote:
> >
> >> As a quick and dirty method, the radio horizon
> is:
> >>
> >> Distance (in miles) = Square Root of (2 * height
> in feet).
> >
> 
> This equation is ok, but for a perfect spheer.  Is a
> good place to start.  Here in FL where max altitude
> is about 330 ft ASL it works pretty well although
> the lower the antenna the worse the actual coverage
> results.  We have plenty of repeaters at 200 ft that
> have noticably better coverage than 20 miles with a
> mobile.
> 
> Also one has to take in account of the user's
> station.   The equation is to the horizon so a user
> with height over the horizon can also increase
> coverage.
> 
> 73, ron, n9ee/r
> 
>
The quick and dirty method at the top is not entirely
correct.  For relative flat land the visual range to
the horizon  in miles is the sqrt of the height in
feet.  That is just for one station.  You have to do
the same for the other station and add the results
together.  Then there is a factor of about 1.2 to 1.5
this distance has to be multiplied by for the radio
horizon instead of the vusual horizon.

For the repeater station antenna at 200 feet, it would
be 14 miles to the horizon plus a mobile antenna of 5
feet heigth to get 2.2 miles which would be 16.2
miles.  Then multiply that by the radio wave bending
factor of 1.2 to 1.5 to get 19.4 to 24.3 miles.  

It does not take much of a rise in the road when the
rest of the land is flat to get the mobile station up
a few feet and this can add a lot to the range.  If
the road goes up just 25 feet more the range will go
up around 5 more miles.


   

Pinpoint customers who are looking for what you sell. 
http://searchmarketing.yahoo.com/

[Repeater-Builder] Re: Repeater Range : Estimate Program Available

[ldgelectronics]

> >> As a quick and dirty method, the radio horizon (RH) is:
> >>
> >> Distance (in miles) = Square Root of (2 * height in feet).

> This equation is ok, but for a perfect spheer.  Is a good place to 
>start.  Here in FL where max altitude is about 330 ft ASL it works 
>pretty well although the lower the antenna the worse the actual 
>coverage results.  We have plenty of repeaters at 200 ft that have 
>noticably better coverage than 20 miles with a mobile.

 
I agree that it's not the perfect formula, but if someone is asking 
the question of how much power do I need, then they need to look at 
the height formula first to get them in the ball park. 

When it comes to range, nothing matters more than height. Doubling 
the height increases the range by about 50%. With power, you have to 
10 times the effective power to double the range (until the RH limit).

Since the original question was for flat terrain, the RH will be real 
close. HAAT = AGL.

Dwayne Kincaid
WD8OYG

RE: [Repeater-Builder] OT- Weather Radio Recall

[Peter Dakota Summerhawk]

On that topic I found that a pager works just as well:
http://www.iinc.com/ggcomm/pager.html
Been using one for quite a while now with good results.
Dakota Summerhawk
 
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of R. K. Brumback
Sent: Thursday, August 30, 2007 9:29 AM
To: Repeater-Builder@yahoogroups.com
Subject: RE: [Repeater-Builder] OT- Weather Radio Recall
 
Quote: "for between $30 and $150."
 
WOW!!  Consumer beware...huh
 
Randy
 
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of tgundo2003
Sent: Thursday, August 30, 2007 9:30 AM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] OT- Weather Radio Recall
 
This is a bit off-topic, but I thought it would be important to get 
the word out as life safety is involved...

Tom
W9SRV

NEWS from CPSC
U.S. Consumer Product Safety Commission
Office of Information and Public Affairs 
Washington, DC 20207 

FOR IMMEDIATE RELEASE
August 29, 2007
Release #07-292 

Firm's Recall Hotline: (800) 203-4921
CPSC Recall Hotline: (800) 638-2772
CPSC Media Contact: (301) 504-7908

Weather Radios Recalled by Oregon Scientific Due to Failure to 
Receive National Weather Service Alerts

WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in 
cooperation with the firm named below, today announced a voluntary 
recall of the following consumer product. Consumers should stop using 
recalled products immediately unless otherwise instructed. 

Name of Product: Oregon Scientific Weather Radios

Units: About 66,000

Manufacturer: Oregon Scientific Inc., of Tualatin, Ore.

Hazard: The radios could fail to receive National Weather Service 
alert signals in certain areas of the country. In the event of severe 
weather, this failure could put a consumer's life and property at 
risk.

Incidents/Injuries: None reported.

Description: This recall involves the following Weather Radios and 
Weather Stations:

NAME MODEL 
All Hazards Portable Weather Alert Radio WR103NX 
Portable Public Alert Radio WR108 
Public Alert Weather Station WRB308 
John Deere Public Alert Weather Station WRB308J 

No other models are included in this recall.

Sold at: Retail stores nationwide, including some electronics and 
sporting goods stores, online retailers and in catalogs from December 
2005 through June 2007 for between $30 and $150.

Manufactured in: China

Remedy: Consumers should not rely on the recalled weather radios to 
receive emergency information. Consumers should contact Oregon 
Scientific for instructions on returning the radio to receive a free 
replacement.

Consumer Contact: For additional information, contact Oregon 
Scientific at (800) 203-4921 between 8 a.m. and 5 p.m. PT Monday 
through Friday or visit the firm's Web site at 
www2.oregonscientific.com

To see this recall on CPSC's web site, including pictures of the 
recalled products, please go to:
http://www.cpsc.

gov/cpscpub/prerel/prhtml07/07292.html
 

No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.484 / Virus Database: 269.12.6 - Release Date: 8/24/2007
12:00 AM


No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.484 / Virus Database: 269.12.6 - Release Date: 8/24/2007
12:00 AM

Re: [Repeater-Builder] Re: Duplexer input and output power

[Ralph Mowery]

--- Joel <[EMAIL PROTECTED]> wrote:

> Ok Skipp, and Jesse,
> 
> So, I supposed that the specification of such,
> should be presented by the manufacturers of the
> said, and with the said, right!  Or there is a
> general concept for duplexers, as in both examples,
> .1 to 3dB Jesse, and Skipp input loss 15 to 35% 
> 
> And which will be more accurate to work from dB or
> %.
> 
> I always try to get a good balance when I'm tuning
> duplexers, most times I ended up taking a loss on
> the power for a better result on the receiver side,
> is this the best way to go?  Or it depends on your
> situation, whether or not the extra power would
> effect your  weakest signal!  (most times a final
> touch up is done at the repeater site, it always
> make me feel like a "perfectionist")
> 
> Sometimes I still depend on my ears, then take a
> look at the test gears, 99% of the time I go with my
> ears because the difference don't be much when the
> duplexers are setup to the test gear figures. 
> 
> So, is the figurers always the right thing to work
> with, or they are just guides for a Tech with a bad
> hearing?
> 
> v44kai.Joel.
>  

The percent and dB are the same thing.  They are just
the same numbers expressed in different ways.  Just as
distances can be expressed in miles, feet, meters, or
other units.  One is not more accurate , but some
units are easier to work with. Most of the time it is
easier to work with Db than percentages.  They will
just directly add or subtract.  You might state a
large distance in miles or kilometers instead of feet
or millimeters.  Neither is more accurate, just easier
to state something as 10.1 miles instead of 53328
feet. especially when extreme accuracy is not
required.

You should tune the duplexer for the best signal and
deepest notch.  You then take whatever loss you get. 
If it is too much you change the coupling loops in the
cans and try again.  While going from 1 db to 2 db of
power loss seems like a lot if you use a watt meter,
it is really not that much in the performance of a
system.  What will kill the system is the desense of
the receiver by the transmitter.  If you have to
detune a duplexer for less out of the transmitter to
eliminate the desense, you are doing something wrong
or the duplexer may not be up to the job to start
with.  Usually trying to use a 4 cavity duplexer to
separate a 600 kHz 2 meter repeater will not work with
transistor equipment, especially if the receiver is
very good.  It may work if everything is tuned just
right, but if it rains ,a bird lands on the antenna or
any other thing, it degrades enough to desense the
receiver.  

It is always best to touch up a duplexer hooked up to
the actual repeater and antenna system.  Almost no
system will be exec tally 50 ohms like the test setup.
 

If putting in 100 watts to most 2 meter duplexers
gives me about 70 watts out I am satisfied.  Depending
on the duplexer you may get less.  One 6 cavity
duplexer I have is set up for a high rejection of
about 120 db.  To get this I had to take a factory
rated loss of 3 db.  This only gives me 50 watts out. 
So anything between 50 and 75 watts out with 100 watts
in is only the differance in about a 2 db to 3 db loss
, or one dB of differance.   The db differance does
not seem to be much , but the actual power differance
does.  In actual use, the range will be almost the
same.  If you have a calibrated signal generator just
try to see if you can tell much by the quiting
differance of 1 dB.  


I do some weak signal work and 1 db may make the
differance in a contact, but that is for very weak
signals and not the casual usages most hams will be
using.



   

Pinpoint customers who are looking for what you sell. 
http://searchmarketing.yahoo.com/

RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers

[Mike Perryman]

  -Original Message-
  From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of 
Ron Wright
  Sent: Thursday, August 30, 2007 11:48 AM
  To: Repeater-Builder@yahoogroups.com
  Subject: Re: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers


  Gary,

  Coax also has the problem of a upper freq limit due to it's outer shield 
becomes large enough to act as wave guide. One will see upper freq specs will 
be lower the larger cable.

  73, ron, n9ee/r

  Recent Activity
a..  14New Members
b..  3New Files
  Visit Your Group 
  Share Photos
  Put your favorite

  photos and

  more online.

  Yoga Resources
  on Yahoo! Groups

  Take the stress

  out of your life.

  Endurance Zone
  on Yahoo! Groups

  Communities about

  higher endurance.
  .
   Yep, try 2.4ghz ATV using 1-7/8" heliax...  not a happy combo..  LOL!
   73 
  Mike Perryman 
  www.k5jmp.us 

   

Re: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers

[Ron Wright]

Gary,

I've measured RG59 cable terminated into a 75 Ohm resistive load with a 
variable freq impedance meter.  We found the coax stopped being 75 Ohms below 
about 0.5 MHz. The cable manufacture also verified this.  Other engineers in 
our department knew of this as well.

We were designing security systems using video and the vertical and harizonal 
sync signals became very distored over long, 2500 ft. RG59 cables and this was 
the major reason.  We had to design circuits that corrected this, but the cable 
had the problem.

I am sure different RG59 cables have different low freq bandwidths.  RG11 would 
also be different as well as cable TV cable.

All coax has a lower and upper frequency range.  Since we deal with radio this 
is not much of a factor until one gets real low or GHz levels.

Coax also has the problem of a upper freq limit due to it's outer shield 
becomes large enough to act as wave guide.  One will see upper freq specs will 
be lower  the larger cable.

73, ron, n9ee/r



>From: Gary Schafer <[EMAIL PROTECTED]>
>Date: 2007/08/29 Wed PM 09:23:57 CDT
>To: Repeater-Builder@yahoogroups.com
>Subject: RE: RE: Re: Re: RE: [Repeater-Builder] Re: Duplexers


>As far as bandwidth goes,,, where do you get this .5 MHz for rg59 cable as a
>lower limit?
>
>Open wire lines begin to radiate as frequency is increased to the point
>where the line spacing becomes an appreciable portion of a wave length due
>to the time it takes for propagation of fields between wires.
>
>73
>Gary  K4FMX
>


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

[Repeater-Builder] Re: Duplexer input and output power

[skipp025]

Telewave once told me their TPRD 4 bottle 5 inch duplexer insertion 
loss per side... target value is about 1.2 to 1.5 dB per side, which 
works out to about 35 watts output with 50 watts input. One can 
often see those figures in play out in the real world. 

Work with what ever value best describes what idea you want to 
convey. Percentage is not one normally seen as a technical value 
but most of the generic world understands it. 

cheers, 
skipp 

> "Joel" <[EMAIL PROTECTED]> wrote:
>
> Ok Skipp, and Jesse,
> 
> So, I supposed that the specification of such, should be presented
by the manufacturers of the said, and with the said, right!  Or there
is a general concept for duplexers, as in both examples, .1 to 3dB
Jesse, and Skipp input loss 15 to 35% 
> 
> And which will be more accurate to work from dB or %.
> 
> I always try to get a good balance when I'm tuning duplexers, most
times I ended up taking a loss on the power for a better result on the
receiver side, is this the best way to go?  Or it depends on your
situation, whether or not the extra power would effect your  weakest
signal!  (most times a final touch up is done at the repeater site, it
always make me feel like a "perfectionist")
> 
> Sometimes I still depend on my ears, then take a look at the test
gears, 99% of the time I go with my ears because the difference don't
be much when the duplexers are setup to the test gear figures. 
> 
> So, is the figurers always the right thing to work with, or they are
just guides for a Tech with a bad hearing?
> 
> v44kai.Joel.
>  
>   - Original Message - 
>   Fom: Jesse Lloyd 
>   To: Repeater-Builder@yahoogroups.com 
>   Sent: Wednesday, August 29, 2007 12:54 PM
>   Subject: Re: [Repeater-Builder] Re: Duplexer input and output power
> 
> 
>   Ya, duplexers will have insertion loss.  Typically you get more
insertion loss with more rejection, so its a balancing act.
> 
>   Insertion loss can range from .1 dB (very good) to 3 dB.
> 
>   Typically if I can get a duplexer to less than a dB I'm happy.
> 
>   Insertion loss (dB) = 10 log ( PIN / POUT )
> 
>   So Pout = Pin x 10^(Insertion Loss/10)
> 
>   So for 50 Watts:
> 
>   .1 dB = 48.9 Watts
>   .3 = 46.7
>   .5 = 44.6
>   .8 = 41.6
>   1 = 39.7
>   1.2 = 37.9
>   1.5 = 35.4
>   2 = 31.5
>   2.5 = 28.1
>   3 = 25
> 
>   Jesse
> 
> 
> 
>   On 8/29/07, skipp025 <[EMAIL PROTECTED]> wrote: 
> Hi Joel, 
> 
> In the real world it depends on the duplexer type, size, quality,
> operation and setup values, which may be fixed or adjustable. 
> 
> Just throwing out a generic rule of thumb... you will find many 
> duplexers lose about 15% to 35% of the input power. One would hope 
> for near zero loss but that will never happen. 
> 
> A common quality duplexer has adjustable probes or coax ports (the 
> name used is based on the duplexer type), which often trade what we 
> generic call insertion loss for increased performance. 
> 
> Loss through a duplexer is not always a linear graph of power in 
> vs power out. 
> 
> Just to put something out... be happy if a properly setup and 
> working duplexer delivers 75% to maybe 95% of the input power. 
> Be grateful if you receive better than 85% of the rated power. 
> A really "tight" duplexer might eat as much as 35% to 40% of 
> your input power and there are much worse possible examples. 
> 
> cheers,
> s. 
> 
> > "Joel"  wrote:
> > Is there a table or formula or ratio for power input to a
duplexer, 
> > to the resulting output power of the said? For instance, if I put 
> > 10, 20, 50, 100 watts to the input, what should be the output,
with 
> > a 50 Ohms at the load?
> > 
> > example 10,20, 50, 100 watts in = x output @ 50 Ohms. "BASED 
> > ON A PROPERLY TUNED DUPLEXER"
> > 
> > I think someone had a short for-instance on this, can't find it, 
> > and will like some insight on this.
> > v44kai.Joel.
> 
> 
> 
> 
>
> 
> 
>
--
> 
> 
>   No virus found in this incoming message.
>   Checked by AVG Free Edition. 
>   Version: 7.5.484 / Virus Database: 269.12.10/977 - Release Date:
8/28/2007 4:29 PM
>

Re: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers

[Ron Wright]

Gary,

AC power line transmission theory is very different than RF.  In RF radiation 
and propagation down the line follows a much different science.  Also in AC 
lines the load is continously changing and at 60 Hz it takes large Ls and Cs to 
make much difference.  AC power is more concerned with power factor than 
radiation.  This can lead to more voltage and current, at the same time, out 
than at the source.

There are some concerns of very long grid lines with transmission, but plays a 
much less factor than at RF.

73, ron, n9ee/r




>From: Gary Schafer <[EMAIL PROTECTED]>
>Date: 2007/08/29 Wed PM 09:03:50 CDT
>To: Repeater-Builder@yahoogroups.com
>Subject: RE: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers

>  
>Transmission line theory is transmission line theory. It doesn't matter what
>the frequency is it all works the same. Power line transmission engineers
>worry about the same things in power transmission as do RF engineers. Only
>the wavelength is different.
>
>> IR drops in feed lines is much less than a factor than the LC/dielectric
>> type losses.  Again frequency shows this.  100 W at 10 MHz and 1000 MHz
>> will have radically different losses yet both have the same I and V and R.
>>
>
>A feed line at 10 MHz has a totally different R loss than the same feed line
>used at 1000 MHz. It does NOT have the same R at different frequencies.  It
>has the same "Z" (surge or characteristic impedance) at all frequencies but
>not the same series resistance R.  The resistance increases because of skin
>effect the higher the frequency is. This is where loss comes from.
>
>73
>Gary  K4FMX
>
>> -Original Message-
>> From: Repeater-Builder@yahoogroups.com [mailto:Repeater-
>> [EMAIL PROTECTED] On Behalf Of Ron Wright
>> Sent: Wednesday, August 29, 2007 9:32 AM
>> To: Repeater-Builder@yahoogroups.com
>> Subject: Re: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers
>> 
>> Ralph,
>> 
>> Transmission line theory for RF and AC power is totally different.  In AC
>> power lines little is paid attention to as for transmission except for R
>> losses and power factor.  Yes up the voltage/lower the current and the IR
>> loss goes down.
>> 
>> For RF this is totally different for the RF propergatesdown the line, not
>> just passes as voltage and currents.  This is why feedlines have specific
>> impedances and loads used.
>> 
>> One can have any impedance of coax or twin feeds one wants...that is if
>> you have the material and space for it.  One can get off the shelf 75 Ohm
>> twin lead.  Using 50 or 75 Ohm has more to do with stability especially at
>> RF.
>> 
>> IR drops in feedlines is much less than a factor than the LC/dielectric
>> type losses.  Again frequency shows this.  100 W at 10 MHz and 1000 MHz
>> will have radically different losses yet both have the same I and V and R.
>> 
>> 73, ron, n9ee/r
>> 
>> 
>> 
>> 
>> >From: Ralph Mowery <[EMAIL PROTECTED]>
>> >Date: 2007/08/27 Mon AM 09:20:07 CDT
>> >To: Repeater-Builder@yahoogroups.com
>> >Subject: Re: Re: Re: RE: [Repeater-Builder] Re: Duplexers
>> 
>> >
>> >
>> >--- Ron Wright <[EMAIL PROTECTED]> wrote:
>> >
>> >> Jesse,
>> >>
>> >> Then why do twin feeders have much less loss than
>> >> coax???  Skin affect is even more of a factor there
>> >> due to the differences in the area of the outer
>> >> shield in coax vs the twin feeders wire.
>> >>
>> >> Maybe it is because of the larger C coupling in the
>> >> coax due to the larger surface area of the shield.
>> >> Coax has a lower R even with skin effect than twin
>> >> line feeders.
>> >>
>> >> Skin affect is a factor, but a small one compared to
>> >> the LC factor.
>> >>
>> >> 73, ron, n9ee/r
>> >>
>> >
>> >It is not open wire or coax that determins the power
>> >loss.  It is the impedance of the line and the size of
>> >the conductors for frequencies up to 1000 Mhz or so.
>> >
>> >To transfer 1000 watts of power , the voltage will be
>> >higher and the current lower in most prectical open
>> >wire lines.  That is because the impedance will be
>> >around 300 to 600 ohms.   Coax is usually 50 or 70
>> >ohms.  To get 1000 watts of power through that
>> >impedance line it requires less voltage and more
>> >current.
>> >
>> >This is the principal of regular 60 hz power line
>> >transmission.  Up the voltage to a few hundred
>> >thousand volts and the current will go down.  This
>> >lowers the losses.
>> >
>> >I don't care to take time to do the calculations, but
>> >if you take some small guage wire (say # 20)  and
>> >space it close to make about 200 ohms line and figuer
>> >the loss, it may be higher than some 1 inch or even
>> >1/2 inch hardline.
>> >
>> >At frequencies below around 1000 Mhz the major loss is
>> >the IsqR loss in all lines.  Radiation is a very small
>> >part.  In coax there is a point in which the current
>> >on the shield is not flowing but jumping from point to
>> >point where the shield wires cross. This causes some
>> >resistance.  That is partly why the fo

RE: [Repeater-Builder] OT- Weather Radio Recall

[R. K. Brumback]

Quote: “for between $30 and $150.”

 

WOW!!  Consumer beware………huh

 

Randy

 

-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of tgundo2003
Sent: Thursday, August 30, 2007 9:30 AM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] OT- Weather Radio Recall

 

This is a bit off-topic, but I thought it would be important to get 
the word out as life safety is involved...

Tom
W9SRV

NEWS from CPSC
U.S. Consumer Product Safety Commission
Office of Information and Public Affairs 
Washington, DC 20207 

FOR IMMEDIATE RELEASE
August 29, 2007
Release #07-292 

Firm's Recall Hotline: (800) 203-4921
CPSC Recall Hotline: (800) 638-2772
CPSC Media Contact: (301) 504-7908

Weather Radios Recalled by Oregon Scientific Due to Failure to 
Receive National Weather Service Alerts

WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in 
cooperation with the firm named below, today announced a voluntary 
recall of the following consumer product. Consumers should stop using 
recalled products immediately unless otherwise instructed. 

Name of Product: Oregon Scientific Weather Radios

Units: About 66,000

Manufacturer: Oregon Scientific Inc., of Tualatin, Ore.

Hazard: The radios could fail to receive National Weather Service 
alert signals in certain areas of the country. In the event of severe 
weather, this failure could put a consumer's life and property at 
risk.

Incidents/Injuries: None reported.

Description: This recall involves the following Weather Radios and 
Weather Stations:

NAME MODEL 
All Hazards Portable Weather Alert Radio WR103NX 
Portable Public Alert Radio WR108 
Public Alert Weather Station WRB308 
John Deere Public Alert Weather Station WRB308J 

No other models are included in this recall.

Sold at: Retail stores nationwide, including some electronics and 
sporting goods stores, online retailers and in catalogs from December 
2005 through June 2007 for between $30 and $150.

Manufactured in: China

Remedy: Consumers should not rely on the recalled weather radios to 
receive emergency information. Consumers should contact Oregon 
Scientific for instructions on returning the radio to receive a free 
replacement.

Consumer Contact: For additional information, contact Oregon 
Scientific at (800) 203-4921 between 8 a.m. and 5 p.m. PT Monday 
through Friday or visit the firm's Web site at 
www2.oregonscientif-ic.com

To see this recall on CPSC's web site, including pictures of the 
recalled products, please go to:
HYPERLINK
"http://www.cpsc.gov/cpscpub/prerel/prhtml07/07292.html"http://www.cpsc.-gov
/cpscpub/-prerel/prhtml07/-07292.html

 


No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.484 / Virus Database: 269.12.6 - Release Date: 8/24/2007 12:00
AM



No virus found in this outgoing message.
Checked by AVG Free Edition. 
Version: 7.5.484 / Virus Database: 269.12.6 - Release Date: 8/24/2007 12:00
AM
 

Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[Ron Wright]

>  
>
>On Aug 30, 2007, at 12:35 AM, ldgelectronics wrote:
>
>> As a quick and dirty method, the radio horizon is:
>>
>> Distance (in miles) = Square Root of (2 * height in feet).
>

This equation is ok, but for a perfect spheer.  Is a good place to start.  Here 
in FL where max altitude is about 330 ft ASL it works pretty well although the 
lower the antenna the worse the actual coverage results.  We have plenty of 
repeaters at 200 ft that have noticably better coverage than 20 miles with a 
mobile.

Also one has to take in account of the user's station.   The equation is to the 
horizon so a user with height over the horizon can also increase coverage.

73, ron, n9ee/r



Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

Re: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[Ron Wright]

Nate,

Totally aggree with you. HAAT, true HAAT, is the real factor.  Coverage of a 
repeater is determined by HAAT.

I've been told by a repeater owner and users a repeater is say 850 ft high.  
Turns out they were giving referenced to ASL and the ground ASL was 800 ft, hi. 
 Kinda down the same lines as one stating when they are monitoring a repeater a 
user will turn their beam in the direction of a users location.

73, ron, n9ee/r




>From: Nate Duehr <[EMAIL PROTECTED]>
>Date: 2007/08/30 Thu AM 03:44:32 CDT
>To: Repeater-Builder@yahoogroups.com
>Subject: Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

>  
>
>On Aug 30, 2007, at 1:20 AM, MCH wrote:
>
>> Height = elevation AMSL of the antenna, HAAT, or AGL (which would make
>> no sense)?
>
>I assumed HAAT for my calculations and that number seemed to be the  
>most sane, after trying a few.  But I think the resulting number is  
>generous for a badly-built repeater, and too small for a well-built one.
>
>--
>Nate Duehr, WY0X
>[EMAIL PROTECTED]
>
>


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

Re: Re: [Repeater-Builder] Re: Duplexer input and output power

[Ron Wright]

Joel,

I aggree the major is the equipment working.  If it aint broke don't fix it.

Test gear measurments allow determining the source of a problem if there is a 
problem.  If your ears say it aint working what is not working and in this case 
might not be the duplexer.  Yes the test gear measurements do make a big 
difference.

In a repeater there is so much that has to work.

73, ron, n9ee/r

ps: with the start of this discussion has anyone said what type, model, etc of 
duplexer it is???  Might be a clue.




>From: Joel <[EMAIL PROTECTED]>
>Date: 2007/08/29 Wed PM 03:49:32 CDT
>To: Repeater-Builder@yahoogroups.com
>Subject: Re: [Repeater-Builder] Re: Duplexer input and output power

>  
>Ok Skipp, and Jesse, So, I supposed that the specification of such, should be 
>presented by the manufacturers of the said, and with the said, right!  Or 
>there is a general concept for duplexers, as in both examples, .1 to 3dB 
>Jesse, and Skipp input loss 15 to 35%  And which will be more accurate to work 
>from dB or %. I always try to get a good balance when I'm tuning duplexers, 
>most times I ended up taking a loss on the power for a better result on the 
>receiver side, is this the best way to go?  Or it depends on your situation, 
>whether or not the extra power would effect your  weakest signal!  (most times 
>a final touch up is done at the repeater site, it always make me feel like a 
>"perfectionist") Sometimes I still depend on my ears, then take a look at the 
>test gears, 99% of the time I go with my ears because the difference don't be 
>much when the duplexers are setup to the test gear figures.  So, is the 
>figurers always the right thing to work with, or they are just guides for a 
>Tech with a bad hearing? v44kai.Joel.   - Original Message -   
>Fom:  Jesse Lloyd  To: Repeater-Builder@yahoogroups.comSent: Wednesday, 
>August 29, 2007 12:54   PM  Subject: Re: [Repeater-Builder] Re:   Duplexer 
>input and output power  
>Ya, duplexers will have insertion loss.  Typically you get   more insertion 
>loss with more rejection, so its a balancing   act.
>
>Insertion loss can range from .1 dB (very good) to 3   dB.
>
>Typically if I can get a duplexer to less than a dB I'm   happy.
>
>Insertion loss (dB) = 10 log ( PIN /   POUT )
>
>So Pout = Pin x 10^(Insertion   Loss/10)
>
>So for 50 Watts:
>
>.1 dB = 48.9 Watts
>.3 = 46.7
>.5   = 44.6
>.8 = 41.6
>1 = 39.7
>1.2 = 37.9
>1.5 = 35.4
>2 = 31.5
>2.5   = 28.1
>3 = 25
>
>Jesse
>
>
>  On 8/29/07, skipp025 <[EMAIL PROTECTED]> wrote:  
>Hi Joel, 
>
>In the real world it depends on the duplexer type, size, quality,
>operation and setup values, which may be fixed or adjustable. 
>
>Just throwing out a generic rule of thumb... you will find many 
>duplexers lose about 15% to 35% of the input power. One would hope 
>for near zero loss but that will never happen. 
>
>A common quality duplexer has adjustable probes or coax ports (the 
>name used is based on the duplexer type), which often trade what we 
>generic call insertion loss for increased performance. 
>
>Loss through a duplexer is not always a linear graph of power in 
>vs power out. 
>
>Just to put something out... be happy if a properly setup and 
>working duplexer delivers 75% to maybe 95% of the input power. 
>Be grateful if you receive better than 85% of the rated power. 
>A really "tight" duplexer might eat as much as 35% to 40% of 
>your input power and there are much worse possible examples. 
>
>cheers,
>s. 
>
>> "Joel"<[EMAIL PROTECTED]> wrote:
>> Is there a table or formula or ratio for power input to a duplexer, 
>> to the resulting output power of the said? For instance, if I put 
>> 10, 20, 50, 100 watts to the input, what should be the output, with 
>> a 50 Ohms at the load?
>> 
>> example 10,20, 50, 100 watts in = x output @ 50 Ohms. "BASED 
>> ON A PROPERLY TUNED DUPLEXER"
>> 
>> I think someone had a short for-instance on this, can't find it, 
>> and will like some insight on this.
>> v44kai.Joel.
>
>
>  
>
>No virus found in this incoming message.
>Checked by AVG Free   Edition. 
>Version: 7.5.484 / Virus Database: 269.12.10/977 - Release Date:   8/28/2007 
>4:29 PM
>


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

Re: [Repeater-Builder] OT- Weather Radio Recall

[Mike]

Thanks!!




On 8/30/07, tgundo2003 <[EMAIL PROTECTED]> wrote:
>
>   This is a bit off-topic, but I thought it would be important to get
> the word out as life safety is involved...
>
> Tom
> W9SRV
>
> NEWS from CPSC
> U.S. Consumer Product Safety Commission
> Office of Information and Public Affairs
> Washington, DC 20207
>
> FOR IMMEDIATE RELEASE
> August 29, 2007
> Release #07-292
>
> Firm's Recall Hotline: (800) 203-4921
> CPSC Recall Hotline: (800) 638-2772
> CPSC Media Contact: (301) 504-7908
>
> Weather Radios Recalled by Oregon Scientific Due to Failure to
> Receive National Weather Service Alerts
>
> WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in
> cooperation with the firm named below, today announced a voluntary
> recall of the following consumer product. Consumers should stop using
> recalled products immediately unless otherwise instructed.
>
> Name of Product: Oregon Scientific Weather Radios
>
> Units: About 66,000
>
> Manufacturer: Oregon Scientific Inc., of Tualatin, Ore.
>
> Hazard: The radios could fail to receive National Weather Service
> alert signals in certain areas of the country. In the event of severe
> weather, this failure could put a consumer's life and property at
> risk.
>
> Incidents/Injuries: None reported.
>
> Description: This recall involves the following Weather Radios and
> Weather Stations:
>
> NAME MODEL
> All Hazards Portable Weather Alert Radio WR103NX
> Portable Public Alert Radio WR108
> Public Alert Weather Station WRB308
> John Deere Public Alert Weather Station WRB308J
>
> No other models are included in this recall.
>
> Sold at: Retail stores nationwide, including some electronics and
> sporting goods stores, online retailers and in catalogs from December
> 2005 through June 2007 for between $30 and $150.
>
> Manufactured in: China
>
> Remedy: Consumers should not rely on the recalled weather radios to
> receive emergency information. Consumers should contact Oregon
> Scientific for instructions on returning the radio to receive a free
> replacement.
>
> Consumer Contact: For additional information, contact Oregon
> Scientific at (800) 203-4921 between 8 a.m. and 5 p.m. PT Monday
> through Friday or visit the firm's Web site at
> www2.oregonscientific.com
>
> To see this recall on CPSC's web site, including pictures of the
> recalled products, please go to:
> http://www.cpsc.gov/cpscpub/prerel/prhtml07/07292.html
>
> 
>

Re: [Repeater-Builder] Re: Duplexer input and output power

[Joel]

Ok Skipp, and Jesse,

So, I supposed that the specification of such, should be presented by the 
manufacturers of the said, and with the said, right!  Or there is a general 
concept for duplexers, as in both examples, .1 to 3dB Jesse, and Skipp input 
loss 15 to 35% 

And which will be more accurate to work from dB or %.

I always try to get a good balance when I'm tuning duplexers, most times I 
ended up taking a loss on the power for a better result on the receiver side, 
is this the best way to go?  Or it depends on your situation, whether or not 
the extra power would effect your  weakest signal!  (most times a final touch 
up is done at the repeater site, it always make me feel like a "perfectionist")

Sometimes I still depend on my ears, then take a look at the test gears, 99% of 
the time I go with my ears because the difference don't be much when the 
duplexers are setup to the test gear figures. 

So, is the figurers always the right thing to work with, or they are just 
guides for a Tech with a bad hearing?

v44kai.Joel.
 
  - Original Message - 
  Fom: Jesse Lloyd 
  To: Repeater-Builder@yahoogroups.com 
  Sent: Wednesday, August 29, 2007 12:54 PM
  Subject: Re: [Repeater-Builder] Re: Duplexer input and output power


  Ya, duplexers will have insertion loss.  Typically you get more insertion 
loss with more rejection, so its a balancing act.

  Insertion loss can range from .1 dB (very good) to 3 dB.

  Typically if I can get a duplexer to less than a dB I'm happy.

  Insertion loss (dB) = 10 log ( PIN / POUT )

  So Pout = Pin x 10^(Insertion Loss/10)

  So for 50 Watts:

  .1 dB = 48.9 Watts
  .3 = 46.7
  .5 = 44.6
  .8 = 41.6
  1 = 39.7
  1.2 = 37.9
  1.5 = 35.4
  2 = 31.5
  2.5 = 28.1
  3 = 25

  Jesse



  On 8/29/07, skipp025 <[EMAIL PROTECTED]> wrote: 
Hi Joel, 

In the real world it depends on the duplexer type, size, quality,
operation and setup values, which may be fixed or adjustable. 

Just throwing out a generic rule of thumb... you will find many 
duplexers lose about 15% to 35% of the input power. One would hope 
for near zero loss but that will never happen. 

A common quality duplexer has adjustable probes or coax ports (the 
name used is based on the duplexer type), which often trade what we 
generic call insertion loss for increased performance. 

Loss through a duplexer is not always a linear graph of power in 
vs power out. 

Just to put something out... be happy if a properly setup and 
working duplexer delivers 75% to maybe 95% of the input power. 
Be grateful if you receive better than 85% of the rated power. 
A really "tight" duplexer might eat as much as 35% to 40% of 
your input power and there are much worse possible examples. 

cheers,
s. 

> "Joel" <[EMAIL PROTECTED]> wrote:
> Is there a table or formula or ratio for power input to a duplexer, 
> to the resulting output power of the said? For instance, if I put 
> 10, 20, 50, 100 watts to the input, what should be the output, with 
> a 50 Ohms at the load?
> 
> example 10,20, 50, 100 watts in = x output @ 50 Ohms. "BASED 
> ON A PROPERLY TUNED DUPLEXER"
> 
> I think someone had a short for-instance on this, can't find it, 
> and will like some insight on this.
> v44kai.Joel.




   


--


  No virus found in this incoming message.
  Checked by AVG Free Edition. 
  Version: 7.5.484 / Virus Database: 269.12.10/977 - Release Date: 8/28/2007 
4:29 PM

Re: [Repeater-Builder] OT- Weather Radio Recall

[Jim]

tgundo2003 wrote:
> This is a bit off-topic, but I thought it would be important to get 
> the word out as life safety is involved...
> 
> Tom
> W9SRV
 >
> Firm's Recall Hotline: (800) 203-4921
> CPSC Recall Hotline: (800) 638-2772
> CPSC Media Contact: (301) 504-7908
> 
> Weather Radios Recalled by Oregon Scientific Due to Failure to 
> Receive National Weather Service Alerts

I've never cared for Oregon Scientific-they're the ones that put all 
those "wireless" weather stations in the middle of the 433 MHz ham 
band-and are getting away with it!

My father tells me that 430-440 is totally useless at his house in rural 
  N. AZ because of all the "unlicensed wireless" junk.


> Manufactured in: China
> 

Why does that NOT surprise me?

-- 
Jim Barbour
WD8CHL

Re: [Repeater-Builder] Re: subaudibe tones..

[Jim]

MCH wrote:
> Which results in OH 'claiming' 30 of the 32 (or 38) available tones.
> 
> That leaves 2 or 8 tones for everyone else. Not a particularly fair or
> reasonable plan.
> 
> Joe M.


??

-- 
Jim Barbour
WD8CHL

[Repeater-Builder] OT- Weather Radio Recall

[tgundo2003]

This is a bit off-topic, but I thought it would be important to get 
the word out as life safety is involved...

Tom
W9SRV

NEWS from CPSC
U.S. Consumer Product Safety Commission
Office of Information and Public Affairs 
Washington, DC 20207 

FOR IMMEDIATE RELEASE
August 29, 2007
Release #07-292 

Firm's Recall Hotline: (800) 203-4921
CPSC Recall Hotline: (800) 638-2772
CPSC Media Contact: (301) 504-7908

Weather Radios Recalled by Oregon Scientific Due to Failure to 
Receive National Weather Service Alerts

WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in 
cooperation with the firm named below, today announced a voluntary 
recall of the following consumer product. Consumers should stop using 
recalled products immediately unless otherwise instructed. 

Name of Product: Oregon Scientific Weather Radios

Units: About 66,000

Manufacturer: Oregon Scientific Inc., of Tualatin, Ore.

Hazard: The radios could fail to receive National Weather Service 
alert signals in certain areas of the country. In the event of severe 
weather, this failure could put a consumer's life and property at 
risk.

Incidents/Injuries: None reported.

Description: This recall involves the following Weather Radios and 
Weather Stations:

NAME MODEL 
All Hazards Portable Weather Alert Radio WR103NX 
Portable Public Alert Radio WR108 
Public Alert Weather Station WRB308 
John Deere Public Alert Weather Station WRB308J 

No other models are included in this recall.

Sold at: Retail stores nationwide, including some electronics and 
sporting goods stores, online retailers and in catalogs from December 
2005 through June 2007 for between $30 and $150.

Manufactured in: China

Remedy: Consumers should not rely on the recalled weather radios to 
receive emergency information. Consumers should contact Oregon 
Scientific for instructions on returning the radio to receive a free 
replacement.

Consumer Contact: For additional information, contact Oregon 
Scientific at (800) 203-4921 between 8 a.m. and 5 p.m. PT Monday 
through Friday or visit the firm's Web site at 
www2.oregonscientific.com

To see this recall on CPSC's web site, including pictures of the 
recalled products, please go to:
http://www.cpsc.gov/cpscpub/prerel/prhtml07/07292.html

Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[Fred Seamans]

To All Interested: I would invite you attention to a paper presented by Kenneth 
Bullington, "Radio Propagation at Frequencies Above 30 Meagcycles" in the 
October 1947 Proceedings of the I.R.E. - Waves and Electronics Section. Most 
all radio propagation prediction methods over the years have been based on the 
findings of his research for this paper.
A GE Mobile Radio Data File Bulletin (10003-1), "VHF and UHF Propagation", was 
published in July 1962 for use by engineers and technicians for the prediction 
of radio coverage. Along with this bulletin a hard paper/plastic slide rule was 
manufactured by GE for its sales personnel to predict radio coverage. Motorola 
sales people liked to get a hold of  it and use it also; "Range and Signal 
Strength Calculator for 2 Way Radio".There was a second version put together by 
GE in 1977; "Range and Transmitter Power Calculator". 
If you can find them, either of these slide rules can give adequate results 
with radio range calculations.
With the general usage of computers in the 1980's many propagation programs 
appeared on the market, some use digitized USGA maps while others take a more 
simplistic approach. You get what you pay for!
This Data File may be available on line, I am not sure if it is.
Fred W5VAY

  - Original Message - 
  From: ldgelectronics 
  To: Repeater-Builder@yahoogroups.com 
  Sent: Thursday, August 30, 2007 1:35 AM
  Subject: [Repeater-Builder] Re: Repeater Range : Estimate Program Available


  As a quick and dirty method, the radio horizon is:

  Distance (in miles) = Square Root of (2 * height in feet).

  Power and frequency do not really play that much into it. This has 
  been mentioned in many stories of a repeater running just on the 
  exciter and not many noticed. Once you get past the radio horizon, 
  you cannot practically increase the power to get more distance.

  So a radio transmitting with an antenna on a 200 foot tower will give 
  about 20 miles of coverage. 

  VHF goes a little farther than UHF, but it's not by a lot. 

  RadioMobile does a great job of factoring in many other things like 
  TX power, RX sensitivity, frequency, coax and duplexer losses and 
  some antenna modeling. After the learning curve, you can closely 
  approximate typical systems with ease.

  Dwayne Kincaid
  WD8OYG

  > Ya I use it at work too. Its better than at least 1/2 of the 
  commercial
  > products available. Quite amazing considering a Ham out of Quebec
  > programmed it.
  > 
  > Jesse
  > 
  > 
  > 
  > On 8/29/07, Nate Duehr <[EMAIL PROTECTED]> wrote:
  > >
  > > skipp025 wrote:
  > > > OK Groovy Guys and Gals,
  > > >
  > > > Is there a simple rule of thumb radio range versus frequency
  > > > and power level type computer program/software on the web? Maybe
  > > > some software that also considers generic repeater operation 
  from
  > > > x-height agl with input frequency and power values.
  > > >
  > > > My friend doesn't need or really want a program with involved
  > > > graphics or Lat Long issues. Most of his Ham Radio work is
  > > > actually FM Simplex on flat ground and he's really interested
  > > > in using the program for both VHF High and Low Bands as a
  > > > very rough estimate of expected operational range (on flat
  > > > ground) in miles.
  > > >
  > > > Your turn...
  > > >
  > > > Thanks in advance...
  > > >
  > > > skipp
  > >
  > > Even though he doesn't need it, I think spending the effort to 
  learn how
  > > to drive RadioMobile is time well spent, if you're into looking at
  > > paths, coverage, etc.
  > >
  > > For a free program, it's really not bad at all. And it'd give him
  > > something to "grow into" after he mastered the basics.
  > >
  > > Nate WY0X
  > > 
  > >
  >



   

Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[Nate Duehr]

On Aug 30, 2007, at 1:20 AM, MCH wrote:

> Height = elevation AMSL of the antenna, HAAT, or AGL (which would make
> no sense)?

I assumed HAAT for my calculations and that number seemed to be the  
most sane, after trying a few.  But I think the resulting number is  
generous for a badly-built repeater, and too small for a well-built one.

--
Nate Duehr, WY0X
[EMAIL PROTECTED]

Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[Nate Duehr]

On Aug 30, 2007, at 12:35 AM, ldgelectronics wrote:

> As a quick and dirty method, the radio horizon is:
>
> Distance (in miles) = Square Root of (2 * height in feet).

It's a rule of thumb, but isn't nearly as accurate as doing the real  
engineering on a system.

> Power and frequency do not really play that much into it. This has
> been mentioned in many stories of a repeater running just on the
> exciter and not many noticed. Once you get past the radio horizon,
> you cannot practically increase the power to get more distance.

Humbug.  Please tell all the VUCC holders at VHF and up that, and see  
if they laugh pretty hard.  You can't just increase transmitter  
power, though -- you have to increase the overall gain of the system  
on both transmit and receive.  The biggest bang for the buck in dB?   
The antenna system.  Ask any Moonbounce specialist, or satellite  
chaser.  They'll tell you the same thing.  Ever seen the size/effort  
involved in a 2m EME array for CW?

> So a radio transmitting with an antenna on a 200 foot tower will give
> about 20 miles of coverage.

With an average gain antenna, average feedline, and average power  
levels on both ends.

> VHF goes a little farther than UHF, but it's not by a lot.

Only part of the story.  Try 220 MHz.  It'll out-perform VHF by a  
large margin, in most cases.  Why?  Noise floor is lower in densely  
populated areas.  (This won't hold as true out in the sticks.)

> RadioMobile does a great job of factoring in many other things like
> TX power, RX sensitivity, frequency, coax and duplexer losses and
> some antenna modeling. After the learning curve, you can closely
> approximate typical systems with ease.

Yes!  That's real engineering.

The problem is... most people think that the rule of thumb is some  
kind of law, and don't bother doing the real calculations.  Will this  
low-loss coax help my system?  Will a bigger antenna or one with more  
directional characteristics help?

Additionally, between 2m and UHF, most people run MUCH higher gain  
antennas, because they fit in the same physical space.  One's UHF  
station can out-perform one's VHF station by a mile (no pun intended)  
if it has similarly sized antennas.

I think rules-of-thumb in most things are great AFTER you "do the  
math" and know what their limitations are.  If you haven't done that,  
they're a crutch and/or worse, a perceived limitation that really  
isn't there.

A mediocre repeater, not tuned/optimized on a relatively low gain  
antenna with average system losses (cheap feedline, smaller antenna)  
out here on a mountain top (5000' HAAT) will perform approximately to  
your rule of thumb.  A repeater with excellent receiver sensitivity  
by adding a good low-noise pre-amp (GaAsFET or PHEMT), very low loss  
feedline (7/8" hardline or better), and a relatively high gain  
antenna (perhaps with slight down-tilt) will perform FLAWLESSLY at  
your rule-of-thumb radio horizon and be useable for another 25-50  
miles beyond that.  Especially if the mobile user is also blessed  
with a better than average gain antenna with a nice pattern as close  
to the horizon as possible!  Give that mobile an optimized yagi, and  
they'll be working the repeater far into the next state out here, and  
our states aren't very small!

http://www.repeater-builder.com/antenna/3db.html  <- A good article  
on the topic and the trade-offs for a repeater.

Many people simply won't take the time, expense, and effort to do  
that level of engineering work on a repeater -- or a home station.   
But those that will, are rewarded with communications capability far  
beyond where the rule-of-thumb says it shouldn't work anymore.

Like I mentioned above, the VUCC roles tell the tail.  Never limit  
the new guy's imagination with a rule-of-thumb.  Show them the TOP  
operator's achievements and tell 'em it's attainable by anyone with  
enough time, resources, and patient application of ALL the radio  
theory they can learn.  Apply what those guys know to your repeaters  
and it'll make a significant improvement in performance, at the edges.

ALWAYS recommend that anyone upgrading a station or building a  
repeater put their maximum effort into the antenna and antenna  
system.  As my first Elmer used to say, "The antenna makes the radio."

--
Nate Duehr, WY0X
[EMAIL PROTECTED]

Re: [Repeater-Builder] Re: Repeater Range : Estimate Program Available

[MCH]

Height = elevation AMSL of the antenna, HAAT, or AGL (which would make
no sense)?

Joe M.

ldgelectronics wrote:
> 
> As a quick and dirty method, the radio horizon is:
> 
> Distance (in miles) = Square Root of (2 * height in feet).

Re: [Repeater-Builder] Re: [AR902Mhz & Repeater-Builder] PURC 5000 questions

[JOHN MACKEY]

Correct!

There is a rule for FCC Commercial radio type acceptance that
radios can not be front panel programmed.

-- Original Message --
Received: Wed, 29 Aug 2007 07:33:03 PM CDT
From: "Bob M." <[EMAIL PROTECTED]>
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Re: [AR902Mhz & Repeater-Builder] PURC 5000
questions

> There's probably some FCC rule that prohibits
> commercial stuff from being front-panel programmable
> by other than the manufacturer or a radio technician.
> Nucleus paging transmitters have a DIP switch inside
> that disables frequency programming. Some radios
> require a special dongle to be attached to allow freqs
> to be entered. So I figured that the PURC is no
> different and while it's capable of being programmed,
> there's a mechanism in place to inhibit it to all but
> those who should know what they're doing.
> 
> Bob M.
> ==
> --- Jim <[EMAIL PROTECTED]> wrote:
> 
> > Bob M. wrote:
> > 
> > > A third has an actual numeric keypad on the front
> > > panel, but it's usually locked so it can't easily
> > be
> > > changed. Either a password or flipping a DIP
> > switch
> > > inside the unit would be necessary to allow
> > frequency
> > > programming.
> > > 
> > 
> > The default password is 5000, and I have yet to see
> > one where it had 
> > been changed.
> > But yes, I remember there is a dip switch or push-on
> > jumper  that can 
> > disable the keypad.
> > 
> > -- 
> > Jim Barbour
> > WD8CHL
> 
> 
>  

> Park yourself in front of a world of choices in alternative vehicles. Visit
the Yahoo! Auto Green Center.
> http://autos.yahoo.com/green_center/ 
>