Jeff's excellent dissertation on adding attenuators ahead and behind
preamps has been added to the following page:
http://www.repeater-builder.com/rbtip/preamps.html
Kevin Custer
Not trying to be a smart A$$, but why would you put a preamp in line and then an attenuator?
Alexander,
That is a good start. Now you have some more work to do
(sorry I didn't have a chance to comment before your trip
to the site!)
With the preamp OUT and repeater transmitter DISABLED, get
someone to give you a weak signal (something that is far
from full quieting). Now put the
>
> Not trying to be a smart A$$,
> but why would you put a preamp in line and then an attenuator?
To prevent receiver overload.
If the noise level received by the antenna is sufficiently high (i.e. higher
than the natural thermal noise floor of the receiver/preamp), an attenuator
ahead of the p
Alexander,
Not trying to be a smart A$$,
but why would you put a preamp in line and then an attenuator?
Kind of defeats the purpose of the preamp.
What make of preamp are you using and how much gain does it have? Might
want to try one with a lot less gain,
I think I saw a couple postings stating
At 01:34 PM 5/23/05, you wrote:
>Hey Guys,
> Well few of us played with the repeater today. We took the preamp
>out of line and then did the "desense test". We shut the transmitter
>of, opened the squelch and listened to a weak station on input of the
>repeater, when the transmitter was enab
Hey Guys,
Well few of us played with the repeater today. We took the preamp
out of line and then did the "desense test". We shut the transmitter
of, opened the squelch and listened to a weak station on input of the
repeater, when the transmitter was enabled I was the only one to
notice any des
to:[EMAIL PROTECTED] Behalf Of DCFluX
>Sent: Saturday, May 21, 2005 7:17 PM
>To: Repeater-Builder@yahoogroups.com
>Subject: Re: RE : Re: [Repeater-Builder] Poor Repeater RX
>
>
>Don't you mean, kiloCycles?
>
>On 5/21/05, Kevin K. Custer <[EMAIL PROTECTED]> wrote:
&
At 11:32 PM 5/21/05, DCFluX wrote:
>I've got a kiloCycle to kiloHertz conversion table you can study.
LOL! Did that come with one for uuf to pf also?
Roger Grady K9OPO
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/Repeater-Builder/
<*>
t; Richard, N7TGB
> >>
> >>
> >> -Original Message-
> >> From: Repeater-Builder@yahoogroups.com
> >> [mailto:[EMAIL PROTECTED] Behalf Of DCFluX
> >> Sent: Saturday, May 21, 2005 7:17 PM
> >> To: Repeater-Builder@yahoogroups.com
>
: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] Behalf Of Joe Jarrett
Sent: Sunday, May 22, 2005 5:47 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Poor Repeater RX
This has to be OT for this group but the proper conversion would be:
KiloCycles per Second
--Original Message-
>> From: Repeater-Builder@yahoogroups.com
>> [mailto:[EMAIL PROTECTED] Behalf Of DCFluX
>> Sent: Saturday, May 21, 2005 7:17 PM
>> To: Repeater-Builder@yahoogroups.com
>> Subject: Re: RE : Re: [Repeater-Builder] Poor Repea
PROTECTED] Behalf Of DCFluX
> Sent: Saturday, May 21, 2005 7:17 PM
> To: Repeater-Builder@yahoogroups.com
> Subject: Re: RE : Re: [Repeater-Builder] Poor Repeater RX
>
>
> Don't you mean, kiloCycles?
>
> On 5/21/05, Kevin K. Custer <[EMAIL PROTECTED]> wrote:
>
KiloHertz is the correct term!
Richard, N7TGB
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] Behalf Of DCFluX
Sent: Saturday, May 21, 2005 7:17 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: RE : Re: [Repeater-Builder] Poor Repeater RX
Don&#
>Cc :
> >Subject : RE : Re: [Repeater-Builder] Poor Repeater RX
> >
> >Alexander,
> >
> >The
> >Sinclair Q-202G duplexer can barely make 85 dB when tuned on a network
> >analyzer, so that's the major part of your desense problem. It's only
>--- Original Message --->From: Eric Lemmon[mailto:[EMAIL PROTECTED]>Sent: 5/21/2005 4:05:15 PM>To : Repeater-Builder@yahoogroups.com>Cc : >Subject : RE : Re: [Repeater-Builder] Poor Repeater RX> >Alexander,>>The>Sinclair Q-202G du
Alexander,
I ran your system's numbers through CommShop to see what kind of isolation
your duplexer must have to show no desense, and I came up with 92 dB. The
Sinclair Q-202G duplexer can barely make 85 dB when tuned on a network
analyzer, so that's the major part of your desense problem. It's
Easy Fix,
Get better duplexers, TX/RX are a good start.
Takes mansize cans to support a preamp. TX/RX duplexers will provide the
channel separation you will need for a preamp,
but you still need a selective receiver to go with it. I believe the
Mitrek has the selectivity you need.
Also while I'm
Is the preamp in a shielded box?
Is the power to the preamp via a feedthrough capacitor?
How does the repeater perform without the preamp?
What does the transmitter look like on a spectrum analyzer?
How does the repeater work with a simple 1/4 wavelength vertical?
Is all of the cable going into the
: "Alexander Tubonjic" <[EMAIL PROTECTED]>
To:
Sent: Friday, May 20, 2005 10:18 PM
Subject: [Repeater-Builder] Poor Repeater RX
> Hello,
> Well here is one that cant be figured out locally, thought I would
> throw it to the experts. My high school radio club has recently
Hello,
Well here is one that cant be figured out locally, thought I would
throw it to the experts. My high school radio club has recently made a
few upgrades to our VHF repeater. We replaced the Ringo Ranger antenna
with a Comet GP-9 Antenna, replaced the 9913 coax with Andrews 1/2''
Heliax, and
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