Re: [Repeater-Builder] Duplexer Loss Question

[Eric Lemmon]

Mathew,

A 1.5 dB insertion loss will result is an output that is 0.708 of the
input.  For 150 watts input, this would result in about 106 watts
output.  A lot of assumptions are made in arriving at this ballpark
figure!  First of all, your PA output into a 50 ohm resistive load is
not going to be the same when it is feeding a highly-reactive load such
as a duplexer cavity.  The presence of a ferrite isolator will affect
your readings.  The interconnecting cables, connectors, and (gasp!)
adapters will add additional attenuation.

One of the recurring topics on this list is the perceived or actual
mismatch between the transmitter PA output impedance and the duplexer's
input impedance.  This "dead horse" is forever going to rise from the
ashes and create dissension and discord among the ranks, so we can't
ignore it.  Suffice it to say that such a mismatch may be greatly
reduced by a careful selection of the interconnecting cable length,
which creates a sort of impedance transformer.  You may also use an
integral impedance matcher, sometimes called a "Z-matcher," to introduce
a compensating impedance and achieve an optimum power transfer.
Whichever method you choose, it's worth exploring.

73, Eric Lemmon WB6FLY

w9mwq wrote:

> I am curious with a set of TX-RX duplexers at 1.5 insertion loss,
> input power of 150 watts, what would be the power output?  Need to
> know, as I don't think they are tuned correctly, or something might
> be wrong here.
>
> Mathew
>
>
> Yahoo! Groups Links
>
>
>
>






 
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Re: [Repeater-Builder] Duplexer Loss Question

[Brent]

Hmm  I just  hooked up a set of cans over 
here, and  they were tuned for my freq used them b4 well 2 year a 
ago..
and I tested the antenna with 75watts direct from a 
radio and bird inline nothing else..
 
hooked up the duplexer and repeater (75w) and check 
the SWR was a crankin + 5:
so I checked the antenna again with the repeaters 
transmitter direct to the ant and it is 1.3:1 from 75-100w 
 
must be the im proper tuning, time for the r2600 to 
come out and play and tell me where the things are tuned at I hope.
Brent
 
 

  - Original Message - 
  From: 
  Captainlance 
  To: Repeater-Builder@yahoogroups.com 
  
  Sent: Tuesday, March 22, 2005 10:22 
  PM
  Subject: Re: [Repeater-Builder] Duplexer 
  Loss Question
  
  Check your transmitter for spurious signals... 
  much of your power might not be on the freq. you think it is...Also check the 
  reflected power at the TX port, this can be an indication if the cavities are 
  tuned correctly.  lance 
  
- Original Message - 
From: 
Mathew Quaife 

To: Repeater-Builder@yahoogroups.com 

Sent: Tuesday, March 22, 2005 9:58 
PM
Subject: Re: [Repeater-Builder] 
Duplexer Loss Question

Thanks Mike, well I wanted to make sure that I was not loosing the 
ability to do basic math, but for some reason I had the duplexers retuned 
and whenI dumped 200 watts into them, I got only 65 to 70 back out of 
them.  Trying to figure what when wrong in the process.
 
Mathew
Mike Morris WA6ILQ <[EMAIL PROTECTED]> wrote:
At 
  10:59 AM 3/22/05, you wrote:>I am curious with a set of TX-RX 
  duplexers at 1.5 insertion loss,>input power of 150 watts, what 
  would be the power output? Need to>know, as I don't think they are 
  tuned correctly, or something might>be wrong 
  here.>>MathewSee From that table 1.5 is 29.2%, so150 
  times 0.292 = 43.8150 less 43.8=106.2 wattsA few numbers worth 
  remembering:1db is about 20%1.5db is about 30% (actually 30% is 
  halfway between 1.5 and 1.6)3db is about 50%6db is about 
  75%10db is 90%20db is about 99%All of the above numbers are 
  close enough for field work, especiallywhen you factor in feedline and 
  connector loss.And 3db is double the power10db is 10 times the 
  power20db is 100 times the power.The big think is that you 
  hear the Yahoo! Groups Links<*> 
  To visit your group on the web, go 
  to:http://groups.yahoo.com/group/Repeater-Builder/<*> To 
  unsubscribe from this group, send an email 
  to:[EMAIL PROTECTED]<*> Your 
  use of Yahoo! Groups is subject 
  to:http://docs.yahoo.com/info/terms/


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Re: [Repeater-Builder] Duplexer Loss Question

[Captainlance]

Check your transmitter for spurious signals... much 
of your power might not be on the freq. you think it is...Also check the 
reflected power at the TX port, this can be an indication if the cavities are 
tuned correctly.  lance 

  - Original Message - 
  From: 
  Mathew Quaife 

  To: Repeater-Builder@yahoogroups.com 
  
  Sent: Tuesday, March 22, 2005 9:58 
  PM
  Subject: Re: [Repeater-Builder] Duplexer 
  Loss Question
  
  Thanks Mike, well I wanted to make sure that I was not loosing the 
  ability to do basic math, but for some reason I had the duplexers retuned and 
  whenI dumped 200 watts into them, I got only 65 to 70 back out of them.  
  Trying to figure what when wrong in the process.
   
  Mathew
  Mike Morris WA6ILQ <[EMAIL PROTECTED]> wrote:
  At 
10:59 AM 3/22/05, you wrote:>I am curious with a set of TX-RX 
duplexers at 1.5 insertion loss,>input power of 150 watts, what would 
be the power output? Need to>know, as I don't think they are tuned 
correctly, or something might>be wrong 
here.>>MathewSee From that table 1.5 is 29.2%, so150 times 
0.292 = 43.8150 less 43.8=106.2 wattsA few numbers worth 
remembering:1db is about 20%1.5db is about 30% (actually 30% is 
halfway between 1.5 and 1.6)3db is about 50%6db is about 75%10db 
is 90%20db is about 99%All of the above numbers are close enough for 
field work, especiallywhen you factor in feedline and connector 
loss.And 3db is double the power10db is 10 times the 
power20db is 100 times the power.The big think is that you hear 
the Yahoo! Groups Links<*> To 
visit your group on the web, go 
to:http://groups.yahoo.com/group/Repeater-Builder/<*> To 
unsubscribe from this group, send an email 
to:[EMAIL PROTECTED]<*> Your 
use of Yahoo! Groups is subject 
to:http://docs.yahoo.com/info/terms/
  
  
  Do you Yahoo!?Yahoo! Mail - 250MB free storage. Do 
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Re: [Repeater-Builder] Duplexer Loss Question

[Mathew Quaife]

Thanks Mike, well I wanted to make sure that I was not loosing the ability to do basic math, but for some reason I had the duplexers retuned and whenI dumped 200 watts into them, I got only 65 to 70 back out of them.  Trying to figure what when wrong in the process.
 
Mathew
Mike Morris WA6ILQ <[EMAIL PROTECTED]> wrote:
At 10:59 AM 3/22/05, you wrote:>I am curious with a set of TX-RX duplexers at 1.5 insertion loss,>input power of 150 watts, what would be the power output? Need to>know, as I don't think they are tuned correctly, or something might>be wrong here.>>MathewSee From that table 1.5 is 29.2%, so150 times 0.292 = 43.8150 less 43.8=106.2 wattsA few numbers worth remembering:1db is about 20%1.5db is about 30% (actually 30% is halfway between 1.5 and 1.6)3db is about 50%6db is about 75%10db is 90%20db is about 99%All of the above numbers are close enough for field work, especiallywhen you factor in feedline and connector loss.And 3db is double the power10db is 10 times the power20db is 100 times the power.The
 big think is that you hear the Yahoo! Groups Links<*> To visit your group on the web, go to:http://groups.yahoo.com/group/Repeater-Builder/<*> To unsubscribe from this group, send an email to:[EMAIL PROTECTED]<*> Your use of Yahoo! Groups is subject to:http://docs.yahoo.com/info/terms/
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Re: [Repeater-Builder] Duplexer Loss Question

[Mathew Quaife]

Thanks, this is what I came up with, not I can say something is wrong.  I put 200 in and get 65 to 70 watts out.  Now to figure out why.  These were tuned for me, I was not there when they was tuned, so I am not sure what was done.  They were moved from 156.925/325 to 154.410/810.  And no, I am not leaving it at 200 watts.  I've checked the power out with a watt meter and a dummy load, changed cables, etc.same results.
 
Mathew
Kevin Custer <[EMAIL PROTECTED]> wrote:
1.5 dB is 29%. Take 150, less 29%, and you get 106.5 watts.Kevinw9mwq wrote:>I am curious with a set of TX-RX duplexers at 1.5 insertion loss, >input power of 150 watts, what would be the power output? Need to >know, as I don't think they are tuned correctly, or something might >be wrong here. >Yahoo! Groups Links<*> To visit your group on the web, go to:http://groups.yahoo.com/group/Repeater-Builder/<*> To unsubscribe from this group, send an email to:[EMAIL PROTECTED]<*> Your use of Yahoo! Groups is subject to:http://docs.yahoo.com/info/terms/__Do You Yahoo!?Tired of spam?  Yahoo! Mail has the best spam protection around
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Re: [Repeater-Builder] Duplexer Loss Question

[Mike Morris WA6ILQ]

At 10:59 AM 3/22/05, you wrote:

>I am curious with a set of TX-RX duplexers at 1.5 insertion loss,
>input power of 150 watts, what would be the power output?  Need to
>know, as I don't think they are tuned correctly, or something might
>be wrong here.
>
>Mathew

See 

 From that table 1.5 is 29.2%, so
150 times 0.292 = 43.8
150 less 43.8=106.2 watts

A few numbers worth remembering:
1db is about 20%
1.5db is about 30% (actually 30% is halfway between 1.5 and 1.6)
3db is about 50%
6db is about 75%
10db is 90%
20db is about 99%
All of the above numbers are close enough for field work, especially
when you factor in feedline and connector loss.

And 3db is double the power
10db is 10 times the power
20db is 100 times the power.

The big think is that you hear the  





 
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Re: [Repeater-Builder] Duplexer Loss Question

[Gary Hoff]

db = 10 Log(P-out / P in)   According to my slide rule, P out / P in would 
be about .707 for  1.5 db   .707 X 150  =  106 watts
Somebody correct me if I'm wrong.
Gary - K7NEY
- Original Message - 
From: "w9mwq" <[EMAIL PROTECTED]>
To: 
Sent: Tuesday, March 22, 2005 11:59 AM
Subject: [Repeater-Builder] Duplexer Loss Question


>
>
> I am curious with a set of TX-RX duplexers at 1.5 insertion loss,
> input power of 150 watts, what would be the power output?  Need to
> know, as I don't think they are tuned correctly, or something might
> be wrong here.
>
> Mathew
>
>
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
> 





 
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Re: [Repeater-Builder] Duplexer Loss Question

[Kevin Custer]

1.5 dB is 29%.  Take 150, less 29%, and you get 106.5 watts.

Kevin

w9mwq wrote:

>I am curious with a set of TX-RX duplexers at 1.5 insertion loss, 
>input power of 150 watts, what would be the power output?  Need to 
>know, as I don't think they are tuned correctly, or something might 
>be wrong here. 
>





 
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[Repeater-Builder] Duplexer Loss Question

[w9mwq]

I am curious with a set of TX-RX duplexers at 1.5 insertion loss, 
input power of 150 watts, what would be the power output?  Need to 
know, as I don't think they are tuned correctly, or something might 
be wrong here. 

Mathew








 
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