At 6/30/2008 08:53, you wrote:
>The pad is only used during testing to isolate mismatch between the
>signal generator and spectrum analyzer and the device under test - not
>to be left in permanently. At WACOM it was standard practice to use a
>10 dB pad between the test equipment and the device un
At 6/30/2008 08:48, you wrote:
> > >This is why it is best to put about 1-2 db 50 ohm pad
> > between the duplexer
> > >and the receiver, to help keep the receive side at 50 ohm.
> >
> > And degrade my system sensitivity by that same amount? No thanks.
>
>Maybe I misunderstood - I thought he was s
> "Steve S. Bosshard (NU5D)" <[EMAIL PROTECTED]> wrote:
> No Skipp, deviation was not mentioned, but the frequency change is on
> the same magnitude as increasing transmitter deviation - a 12.5 khz
> shift in frequency. 73, Steve NU5D
OK, if you think they are the same... fine with me.
cheers
; From: Repeater-Builder@yahoogroups.com [mailto:Repeater-
> [EMAIL PROTECTED] On Behalf Of skipp025
> Sent: Monday, June 30, 2008 1:49 AM
> To: Repeater-Builder@yahoogroups.com
> Subject: [Repeater-Builder] Re: Frequency Change do I retune duplexer?
>
> Hi Paul,
>
> I g
The pad is only used during testing to isolate mismatch between the
signal generator and spectrum analyzer and the device under test - not
to be left in permanently. At WACOM it was standard practice to use a
10 dB pad between the test equipment and the device under test. This is
because it i
> >This is why it is best to put about 1-2 db 50 ohm pad
> between the duplexer
> >and the receiver, to help keep the receive side at 50 ohm.
>
> And degrade my system sensitivity by that same amount? No thanks.
Maybe I misunderstood - I thought he was suggesting using pads while tuning,
not du
No Skipp, deviation was not mentioned, but the frequency change is on
the same magnitude as increasing transmitter deviation - a 12.5 khz
shift in frequency. 73, Steve NU5D
skipp025 wrote:
>> "Steve S. Bosshard (NU5D)" <[EMAIL PROTECTED]> wrote:
>> I beg to differ on this one, most respectfull
> "Steve S. Bosshard (NU5D)" <[EMAIL PROTECTED]> wrote:
> I beg to differ on this one, most respectfully, but we are
> talking about the difference between running the transmitter
> at 2.5 Khz deviation vs 5.0 Khz, ie, 12.5 Khz occupied band
> width, vs, 25 khz occupied band width - does this me
> -Original Message-
> From: Repeater-Builder@yahoogroups.com
> [mailto:[EMAIL PROTECTED] On Behalf Of JOHN MACKEY
> Sent: Monday, June 30, 2008 1:58 AM
> To: Repeater-Builder@yahoogroups.com
> Subject: Re: [Repeater-Builder] Re: Frequency Change do I
> retune duplexer
At 6/29/2008 22:57, you wrote:
>This is why it is best to put about 1-2 db 50 ohm pad between the duplexer
>and the receiver, to help keep the receive side at 50 ohm.
And degrade my system sensitivity by that same amount? No thanks. The
duplexer simply has to be able to deal with the mismatch
I beg to differ on this one, most respectfully, but we are talking about
the difference between running the transmitter at 2.5 Khz deviation vs
5.0 Khz, ie, 12.5 Khz occupied band width, vs, 25 khz occupied band
width - does this mean a duplexer retune is needed when we switch from
narrow FM to
Hi Paul,
I go the other way where multiple Duplexer High-Q Series Cavities
have a deep sharp reject notch and a 12.5 KHz shift from F-center
results in a quite noticeable performance change.
cheers,
s.
> "Paul Plack" <[EMAIL PROTECTED]> wrote:
>
> The answer also needs to account for the
> > You've never taken a real close-in detailed look at the
> > notch of a high quality UHF cavity..?
> Maybe a dB or two at most.
I actually meant to write High Q UHF Cavity Duplexer Network. I
can clearly see more than a dB or two difference but maybe my
glasses are blurred again.
> I cla
From: skipp025
To: Repeater-Builder@yahoogroups.com
Sent: Sunday, June 29, 2008 10:24 PM
Subject: [Repeater-Builder] Re: Frequency Change do I retune duplexer?
> [EMAIL PROTECTED] wrote:
> I'm going to disagree here. Gary said he's only moving
> 12.5 kHz, &
This is why it is best to put about 1-2 db 50 ohm pad between the duplexer
and the receiver, to help keep the receive side at 50 ohm.
-- Original Message --
Received: Sun, 29 Jun 2008 10:35:15 PM PDT
From: [EMAIL PROTECTED]
SNIP
> Maybe a dB or two at most. I claim that once you take tha
At 6/29/2008 21:24, you wrote:
> > [EMAIL PROTECTED] wrote:
> > I'm going to disagree here. Gary said he's only moving
> > 12.5 kHz, & I've never seen any coaxial resonator in common
> > use (that means VHFLB cavities being used @ UHF don't count)
> > that has enough Q that 12.5 kHz is going to ma
> [EMAIL PROTECTED] wrote:
> I'm going to disagree here. Gary said he's only moving
> 12.5 kHz, & I've never seen any coaxial resonator in common
> use (that means VHFLB cavities being used @ UHF don't count)
> that has enough Q that 12.5 kHz is going to make a
> significant difference.
You'v
At 6/28/2008 23:30, you wrote:
>"need to be re-tuned?" Depends on who you are, where the
>equipment is, what type of duplexers you have and how they
>are set up.
>
>I can make a strong case for both yea or nay.
>
>One of the larger players in the choice to to re-adjust is
>the Q of the duplexer c
"need to be re-tuned?" Depends on who you are, where the
equipment is, what type of duplexers you have and how they
are set up.
I can make a strong case for both yea or nay.
One of the larger players in the choice to to re-adjust is
the Q of the duplexer cavities. Some of the really high-Q
> 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 ar
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
> 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 f
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?
12.5 Khz should not make any noticeable difference. Steve
garyp609 wrote:
> I have a TX/RX Vari-Notch duplexer. Would the same thing apply to no
> re-tuning?
>
TX/RX will be very close to that as it is the nature of
ganging 2 pass /reject cans on each side of a duplexer... 2 cans on
each side actually widens things out as compared to one, but 2 are
deeper passes and reject notches than one three cans gets
wider/deeper yet... 4 cans winds
I have a TX/RX Vari-Notch duplexer. Would the same thing apply to no
re-tuning?
--- In Repeater-Builder@yahoogroups.com, "Steve Bosshard (NU5D)"
<[EMAIL PROTECTED]> wrote:
>
> Most band pass / band reject will be plenty wide - I measured over
200
> Khz on a Wacom 678 that I use with 3 UHF clo
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