[Repeater-Builder] Re: Frequency Change do I retune duplexer?

[skipp025]

> That is true for band pass filters but in the case of a 
> duplexer the filters are usually notch type (or pass/notch). 

In some but not all cases. I have a few shelves full of 
band-pass only mode duplexers and they have their very 
useful applications. 

> So the more notch type cans there are the wider the notch 
> will be at some given frequency. 

Not sure if I buy the above statement as in-stone fact. 

> Note that the pass response of a band pass / reject type 
> duplexer is very wide to start with.

Doesn't have to be... it directly depends on the Q of the 
cavities and how the duplexer is designed and set up. 

cheers,
s. 

RE: [Repeater-Builder] Re: Frequency Change do I retune duplexer?

[Gary Schafer]

That is true for band pass filters but in the case of a duplexer the filters
are usually notch type (or pass/notch). So the more notch type cans there
are the wider the notch will be at some given frequency. Think of it as an
upside down band pass response.

 

Note that the pass response of a band pass / reject type duplexer is very
wide to start with.

 

73

Gary  K4FMX

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Jim Brown
Sent: Friday, June 27, 2008 4:32 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Re: Frequency Change do I retune duplexer?

 


Doug, It has always been my experience that adding two or more cans in
series always narrows the bandpass, not widen it.  The first can will show a
given dB down at x frequency away from the center tune.  Adding the second
can will decrease the level by the sum of the two at the same x frequency
from the center tune.

The more bandpass cans you use in series, the narrower the bandpass.

73 - Jim  W5ZIT

--- On Fri, 6/27/08, Doug Bade <[EMAIL PROTECTED]> wrote:

From: Doug Bade <[EMAIL PROTECTED]>
Subject: Re: [Repeater-Builder] Re: Frequency Change do I retune duplexer?
To: Repeater-Builder@yahoogroups.com
Date: Friday, June 27, 2008, 11:22 AM

4 cans winds up in mhz wide as apposed to khz 
wide... ( as in an rx preselector, the more cans the wider it is)


Doug
KD8B

__ 


 

[Repeater-Builder] Re: Help! Duplexer setup = with two service monitors and a spectrum analyzer

[skipp025]

Hi Joel, 

There's going to be a lot of "if"s in this next text... 

If your service monitor will generate an RF Signal and 
allow an external modulation or sweep input (control). 

A lot of this depends on the range of external control available 
on your service monitor.  

You might be able to set up an external input source and 
sweep a service monitor generated signal. Just as a giggle test 
you might set up an external 10Hz audio input signal (like 
you're trying to input an external CTCSS Tone) and see how far 
and wide the service monitor will allow the external input to 
control the deviation. 

If the monitor sweeps enough with external control, you could 
possibly then connect the same external sweep signal to an external 
sweep or trigger input on your spec analyzer to sync the signals. 
It's not going to be a lot of sweep but it will be some x-value 
amount that you might deem usable or not. 

Wha'la... "a poor mans tracking generator".  I did the above 
trick many years ago to sweep some receiver circuits but that 
was 1984 and now I don't claim to be that old anymore. Plus I 
don't remember the specific details. Since then I've switched to 
Red Wine and all is much betta'

cheers, 
skipp 

> "Joel" <[EMAIL PROTECTED]> wrote:
> Skipp, thanks for responding.
> All I want is a setup for the equipment I listed (NOTE: NO TG 
> in none of the unit, the 2955/A will do duplex) that will 
> allow me to tune a duplexer, and the procedure.
> v44kai.Joel.

[Repeater-Builder] Re: Frequency Change do I retune duplexer?

[skipp025]

> It has always been my experience that adding two or more 
> cans in series always narrows the bandpass, not widen it.  

Depending on your perspective you can series stager tuned 
over-coupled band pass cavities to make a wider band-pass.

As in the case of a common receive pre-selector window filter. 

cheers, 
s. 

Re: [Repeater-Builder] Re: Frequency Change do I retune duplexer?

[Jim Brown]

Doug, It has always been my experience that adding two or more cans in series 
always narrows the bandpass, not widen it.  The first can will show a given dB 
down at x frequency away from the center tune.  Adding the second can will 
decrease the level by the sum of the two at the same x frequency from the 
center tune.

The more bandpass cans you use in series, the narrower the bandpass.

73 - Jim  W5ZIT

--- On Fri, 6/27/08, Doug Bade <[EMAIL PROTECTED]> wrote:
From: Doug Bade <[EMAIL PROTECTED]>
Subject: Re: [Repeater-Builder] Re: Frequency Change do I retune  duplexer?
To: Repeater-Builder@yahoogroups.com
Date: Friday, June 27, 2008, 11:22 AM











4 cans winds up in mhz wide as apposed to khz 

wide... ( as in an rx preselector, the more cans the wider it is)





Doug

KD8B

__

 

















  

[Repeater-Builder] W7AOR repeater system.

[Steve Kometz]

I downloaded the soft / firm / update / manual combination you suggested.
  It appears to be working.
  So, we plan to let it run and see what happens.
  Thanks for the help.
  Steve, N7KP.

Re: [Repeater-Builder] X500 Capacitors?

[Ken Arck]

At 11:56 AM 6/27/2008, rick wrote:

>Gabriel
>There are 2 capacitors in series marked 2C
>KCK
>Someone familliar with the markings can indicate the actual value.
>from an old diamond, x500, if I remember. It came in 3 sections.
>There is a photo in your@ hotmail box.