Gary,
Just a follow up to the preamp questions from last month.
Your advice was fantastic. We added attenuation right to the point
where the sensitivity started dropping off and it was perfect.
By putting in the attenuator, it actually increased the receive range
of the repeater by about 30%.
Had a good rain this evening. No change at all in the system.
Dwayne WD8OYG
> Sounds like you may have an antenna/loose hardware in near field of
antenna
> problem, which could also generate passive IMD. Does it get better
when
> it's raining?
>
> Bob NO6B
>
Had a good rain this evening. No change at all in the system.
Dwayne WD8OYG
> Sounds like you may have an antenna/loose hardware in near field of
antenna
> problem, which could also generate passive IMD. Does it get better
when
> it's raining?
>
> Bob NO6B
>
I have a ARR On My 440 And 220 Repeaters, No Problems Of course they are
both Motorola Micors thanks to this group . So that explains No Problems
You can tell I am biased.
Happy Repeater Building
Don KA9QJG
Guess I'm just lucky. I have used and use ARR preamps in all sorts of
situations with cavities and without, with many random pieces of feedline
and cabling, on bands from 29 to 470 mhz. and have never had an oscillation
problem. They have been very stable in my experience. (Of course, I never
h
Bob,
Great info. I'll check that too on the next trip.
For right now, we are using a stock GE pre with about 10 db gain and
no attenuators.
There has been enough great feedback from the group that will give me
several hours of testing on the next trip. There are all kinds of
things to try.
I
At 3/22/2007 09:34 AM, you wrote:
>Bob,
>
>How would we know if the preamp is nonlinear or not?
Only way to know for sure is to connect a spectrum analyzer to the output
of the preamp & look for anything greater than, say -15 dBm. The
advertised 1 dB gain compression point (P1dB) for these prea
Bob,
How would we know if the preamp is nonlinear or not?
> If the ARR preamp is nonlinear with a pass can ahead of it, it's
probably
> oscillating. I recommend replacing it with an Angle Linear preamp
> (http://www.anglelinear.com). Chip's preamps are guaranteed to be
> unconditionally
Never noticed. We're supposed to get some rain later, I'll check then.
> Sounds like you may have an antenna/loose hardware in near field of
antenna
> problem, which could also generate passive IMD. Does it get better
when
> it's raining?
>
> Bob NO6B
>
You mentioned that the site's noise floor is "pretty low".
Could you be more specific about that and how it was measured?
The usual method of determination of the site noise floor is to
measure the receiver's "effective sensitivity" using an RF coupler
such as the Microlab FXR or Bird devices t
peater-
> [EMAIL PROTECTED] On Behalf Of ldgelectronics
> Sent: Thursday, March 22, 2007 11:18 AM
> To: Repeater-Builder@yahoogroups.com
> Subject: [Repeater-Builder] Re: Preamp and attenuator
>
> Gary,
>
> That is very good information.
>
> We're going
At 3/21/2007 18:24, you wrote:
>Steve,
>
>It's on 2M, single Station Master antenna with about 400 feet of 7/8"
>feedline. The duplexer is a BP/BR followed by a band pass can, then
>the pre, then the radio side. All cables are RG-400.
>
>The radio is GE Exec II. The sensitivity without the pre is a
At 3/21/2007 20:46, you wrote:
>The "garbage" was pops, static, crackling on weak user signals. There
Sounds like you may have an antenna/loose hardware in near field of antenna
problem, which could also generate passive IMD. Does it get better when
it's raining?
Bob NO6B
Gary,
That is very good information.
We're going back up to the site today and will try that method.
>
> Hook your signal generator up to your system at the antenna port
and measure
> receiver sensitivity with and without the preamp. Then with the
preamp in
> circuit start adding attenuation
Gary,
Yes, Band Pass for the extra cans.
> Did you mean to say BP cans and not BP/BR for the extra cans?
> BP/BR cans provide little pass band attenuation.
>
> 73
> Gary K4FMX
>
> -Original Message-
> From: Repeater-Builder@yahoogroups.com [mailto:Repeater-
> [EMAIL PROTECTED] On Behalf Of ldgelectronics
> Sent: Wednesday, March 21, 2007 11:37 PM
> To: Repeater-Builder@yahoogroups.com
> Subject: [Repeater-Builder] Re: Preamp and attenuator
> > We've added a preamp to our local repeater and found that it
> > had too much gain. It started picking up lots of garbage.
I would ask if there is such a thing as "too much gain" but there
can be. Normally I would would not expect gain to be a problem in a
well designed - constructed syste
ary K4FMX
> -Original Message-
> From: Repeater-Builder@yahoogroups.com [mailto:Repeater-
> [EMAIL PROTECTED] On Behalf Of ldgelectronics
> Sent: Wednesday, March 21, 2007 9:32 PM
> To: Repeater-Builder@yahoogroups.com
> Subject: [Repeater-Builder] Re: Preamp and attenuator
&g
The "garbage" was pops, static, crackling on weak user signals. There
was also some intermod that would drop the receiver on all but the
strongest users.
The distant users were able to go farther, but the garbage noise made
it more difficult to actually use.
Dwayne Kincaid
WD8OYG
> Elaborate
Steve,
That's good info on tuning the BP can. I will put that info in the
file.
I'm pretty sure the duplexer is tuned properly. The four can BP/BR is
a Sinclair 202. It's got right at 1.5 db loss on each side with about
83 db of rejection on each.
There area also two Sinclair BP/BR cans. One
At 08:21 PM 3/21/2007, you wrote:
>Darn, I meant to put that in before. I have severaldifferent units. I'd
>like to use an ARR with 15 db gain (1 db NF), but we also have a couple
>of older Lunar with about 15 db gain and some stock GE units with about
>10 db. The Angle is on the list to try.
<-
Darn, I meant to put that in before. I have severaldifferent units. I'd
like to use an ARR with 15 db gain (1 db NF), but we also have a couple
of older Lunar with about 15 db gain and some stock GE units with about
10 db. The Angle is on the list to try.
One of the systems we just took out th
--- In Repeater-Builder@yahoogroups.com, "ldgelectronics"
<[EMAIL PROTECTED]> wrote:
>
> Hi all,
>
> We've added a preamp to our local repeater and found that it had too
> much gain. It started picking up lots of garbage.
Elaborate on the term . Intermod? Users from distant
repeaters? If in
I did mean coupling loops on the single band pass cavity and not the
duplexer. SB
On 3/21/07, Steve Bosshard (NU5D) <[EMAIL PROTECTED]> wrote:
Sounds like a nice setup Dwayne. I would make sure the duplexer is tuned
properly, maybe run an isolated TEE test just to be sure everything is OK.
Sounds like a nice setup Dwayne. I would make sure the duplexer is tuned
properly, maybe run an isolated TEE test just to be sure everything is OK.
Next I would rotate the coupling loops to increase insertion loss and make
the skirts steeper. What Wacom taught me to do was to take a cavity, hoo
At 06:31 PM 3/21/2007, you wrote:
>Ken, thanks for the input.
>
>So if I were to adjust the band pass can to have 3 db loss (it's at
>0.5 db right now) and steeper skirts, it would raise the noise figure
>about 2.5 db as well.
Ken, thanks for the input.
So if I were to adjust the band pass can to have 3 db loss (it's at
0.5 db right now) and steeper skirts, it would raise the noise figure
about 2.5 db as well.
That seemed like a good trick at first, but still raises the noise
figure.
Obviously lower noise figure is
Steve,
It's on 2M, single Station Master antenna with about 400 feet of 7/8"
feedline. The duplexer is a BP/BR followed by a band pass can, then
the pre, then the radio side. All cables are RG-400.
The radio is GE Exec II. The sensitivity without the pre is about
0.35 uV. The noise floor is pr
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