Re: [Repeater-Builder] Receiver for 6 meters

[wd8chl]

mickupi wrote:
> I need a good receiver for our 6 meter repeater. It is on
> 53.090/52.090. What would be a good radio to look for. Preferably
> crystal controlled and easy to tune. I am not completely ruling out
> programmable radios, it's just that they are not my preference. If you
> have something you would part with I might be a buyer.
> Thanks, Mick, KB4UPI

It seems the best choice is probably a Mastr II in the 42-50 MHz split. 
They take little if any conversion (for 52.09, they will probably not 
need it). Just be careful-they made 3 splits: 30-36, 36-42, and 42-50. 
The lower splits need considerable mods to go up to 6.

I like Micors, but the low band rx's take a bit of modding to go up to 6.

Re: [Repeater-Builder] Receiver for 6 meters

[Joe]

I built up a GE Mastr II Auxiliary Receiver for the 53.09Mhz N1PAH 
repeater in Pelham, Mass quite a few years ago.  It was originally a UHF 
receiver, but I swapped out the boards from a mobile lowband MastrII.  
This is a stand-alone receiver in it's own rack mountable tray, some 
come with a built-in AC power supply.  It has performed flawlessly since 
it's installation.


I have also used a MastrII receiver in my 6 meter repeater on 53.41 for 
many years now.  I never had a problem with it.  It's older technology, 
replacement boards are cheap, and you can actually see the components 
(no surface mount). 


73, Joe, K1ike


mickupi wrote:

I need a good receiver for our 6 meter repeater. It is on
53.090/52.090. What would be a good radio to look for. Preferably
crystal controlled and easy to tune. I am not completely ruling out
programmable radios, it's just that they are not my preference. If you
have something you would part with I might be a buyer.
Thanks, Mick, KB4UPI
  

RE: [Repeater-Builder] Receiver overload

[David Epley]

Muncie Indiana

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Joe
Sent: Thursday, November 22, 2007 9:32 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Receiver overload

 

Are you sure that 104.9 (WINN?) is the only FM station near your 
repeater? Looking at the data, it looks like 100.3 WYGB is possibly on 
the same tower. This is assuming that your repeater is in Columbus, IN.

73, Joe, K1ike

David Epley wrote:
>
> I have a repeater receiver overload problem I am trying to cure. The 
> repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast 
> station 100 yards away 104.9mhz. The repeater works fine at another 
> site. My transmitter is a Motorola Purc 5000 running 75 watts the 
> receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave 
> BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 
> different antennas on the tower. When I use a 900mhz dish antenna 
> pointed away from broadcast tower I only have 3 db degradation. I have 
> tried 3 different maxtrac receivers, added 2 more BpBr cavities in the 
> receiver side and used 3 pole filters in the receivers with no 
> improvement. Today I looked at the signal level getting to the 
> receiver at 104.9. To my surprise I was getting -8 dbm at the 
> receiver. I believe this level is overloading the front end of my 
> repeater. I was wondering if a stub cut for the broadcast frequency 
> would work. Any thoughts would be greatly appreciated.
>
> 
>
> 
>
> David Epley, N9CZV
>
> Winchester, Indiana
>
> 

 

Re: [Repeater-Builder] Receiver overload

[Joe]

Are you sure that 104.9 (WINN?) is the only FM station near your 
repeater?  Looking at the data, it looks like 100.3 WYGB is possibly on 
the same tower.  This is assuming that your repeater is in Columbus, IN.

73, Joe, K1ike

David Epley wrote:
>
> I have a repeater receiver overload problem I am trying to cure. The 
> repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast 
> station 100 yards away 104.9mhz. The repeater works fine at another 
> site. My transmitter is a Motorola Purc 5000 running 75 watts the 
> receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave 
> BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 
> different antennas on the tower. When I use a 900mhz dish antenna 
> pointed away from broadcast tower I only have 3 db degradation. I have 
> tried 3 different maxtrac receivers, added 2 more BpBr cavities in the 
> receiver side and used 3 pole filters in the receivers with no 
> improvement. Today I looked at the signal level getting to the 
> receiver at 104.9. To my surprise I was getting -8 dbm at the 
> receiver. I believe this level is overloading the front end of my 
> repeater. I was wondering if a stub cut for the broadcast frequency 
> would work. Any thoughts would be greatly appreciated.
>
>  
>
>  
>
> David Epley, N9CZV
>
> Winchester, Indiana
>
>  

Re: RE: RE: [Repeater-Builder] Receiver overload

[Ron Wright]

900 MHz is used for STLs.  Might consider looking at this as some image or 
other freq problem.  The STL is low power, but probably dish high gain antenna 
pointed directly to your site.

Too bad you cannot turn off the FM for a bit, but good way to loose your site.

73, ron, n9ee/r



>From: n9wys <[EMAIL PROTECTED]>
>Date: 2007/11/22 Thu AM 11:26:10 CST
>To: Repeater-Builder@yahoogroups.com
>Subject: RE: RE: [Repeater-Builder] Receiver overload

>  
>
>I was thinking that maybe yourinterference might be a harmonic of their uplink 
>freq…  Back tothinking some more.  ;-)
> 
>From: Repeater-Builder@yahoogroups.com On Behalf Of David Epley
>
>
>It is linked but there is only an STL linkreceiver at the site
> 
>From: Repeater-Builder@yahoogroups.com On Behalf Of n9wys
>Is the FM broadcast studio located at the transmitter site, or isit linked?  
>If the studio is remote to the transmitter, it could be aharmonic of the 
>studio uplink freq.  But now I:m shooting in the dark…
>Mark – N9WYS 


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

RE: RE: [Repeater-Builder] Receiver overload

[David Epley]

The conversion was done per the repeater builders page on maxtrac
conversions. I first used the standard 2 pole gigifilters you can for 900mhz
later replaced with  3 pole filters. This improved the site degradation by
about 5 db.  I remove the PA and install a female N connector on the back of
the maxtrac. I also pull the DC power connector from the PA and install it
on the back of the Maxtrac. I have one maxtrac that I installed in a 19"
rack extruded aluminum box with an N RF connector and all inputs\outputs
going thru feed thru caps. This showed no improvement. I do not believe I am
dealing with a signal on the input frequency but with a very high level of
RF energy at the receiver input that it is affecting the sensitivity of the
Receiver.

 

David N9CZV

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon
Sent: Thursday, November 22, 2007 12:59 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: [Repeater-Builder] Receiver overload

 

David,

This is definitely an interesting thread! I cannot think of a more suitable
topic to discuss in this forum.

You mentioned in your original post that you are using a converted 800 MHz
MaxTrac mobile radio as your 900 MHz receiver. Could you please elaborate a
bit on what you did in this conversion? Also, please advise what model
number of MaxTrac you began with. There may be some aspect of the
conversion that makes your receive radio especially vulnerable.

If you have already tried bandpass cavity filters on the receiver input,
with the radio inside a shielded box and all penetrations suitably filtered,
and not seen any reduction in desense, then the offending signal must be on
or very close to your desired receive frequency. That brings us back to a
spurious or harmonic signal being generated by the FM broadcast transmitter,
or perhaps there is an IM product being created between the FM station
carrier and another transmitter that has yet to be identified.

It may be instructive to use a good (i. e., well-shielded) spectrum analyzer
with a bandpass cavity on its input to filter out everything but signals
very close to your 900 MHz input frequency. This technique once helped me
track down a alarm system motion detector that was operating around 900 MHz.
Some spectrum analyzers are poorly shielded, and are practically useless
when immersed in a high-RF environment.

73, Eric Lemmon WB6FLY

-Original Message-
From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
[mailto:Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com] On Behalf Of David Epley
Sent: Thursday, November 22, 2007 9:17 AM
To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
Subject: RE: RE: [Repeater-Builder] Receiver overload

It is linked but there is only an STL link receiver at the site



From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
[mailto:Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com] On Behalf Of n9wys
Sent: Thursday, November 22, 2007 12:08 PM
To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
Subject: RE: RE: [Repeater-Builder] Receiver overload

Is the FM broadcast studio located at the transmitter site, or is it linked?
If the studio is remote to the transmitter, it could be a harmonic of the
studio uplink freq. But now I:m shooting in the dark.

Mark - N9WYS



From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com On Behalf Of David Epley

Analyzer was connected to the receiver port of the duplexers. The noise
floor looked good. The amount of degradation does not seem to change. There
are 900mhz pager transmitters on site but none are on full time and I do not
see any change as each one transmits. I can also have my transmitter turned
off and the degradation is still here.



From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com On Behalf Of Ron Wright

David,

Your problem might be harmonic related. Might do some calculator work. I can
see no muliple of 104.9 related to your 2 frequencies or IF related.

There are other 900 MHz stuff around. Would be good to get a spectrum
analyzer on your receiver port, but know spectrum analyzers are not easy to
come by.

Might be noise floor emissions from the FM station which could be on your
receiver input. Now this one would be a real problem.

73, ron, n9ee/r

>From: David Epley 
>Date: 2007/11/22 Thu AM 07:32:46 CST
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
<mailto:Repeater-Builder%40yahoogroups.com> 
>Subject: RE: [Repeater-Builder] Receiver overload> 
>
>I just tried a pair of Celwave 8 inch bandpass 

RE: RE: [Repeater-Builder] Receiver overload

[Eric Lemmon]

David,

This is definitely an interesting thread!  I cannot think of a more suitable
topic to discuss in this forum.

You mentioned in your original post that you are using a converted 800 MHz
MaxTrac mobile radio as your 900 MHz receiver.  Could you please elaborate a
bit on what you did in this conversion?  Also, please advise what model
number of MaxTrac you began with.  There may be some aspect of the
conversion that makes your receive radio especially vulnerable.

If you have already tried bandpass cavity filters on the receiver input,
with the radio inside a shielded box and all penetrations suitably filtered,
and not seen any reduction in desense, then the offending signal must be on
or very close to your desired receive frequency.  That brings us back to a
spurious or harmonic signal being generated by the FM broadcast transmitter,
or perhaps there is an IM product being created between the FM station
carrier and another transmitter that has yet to be identified.

It may be instructive to use a good (i. e., well-shielded) spectrum analyzer
with a bandpass cavity on its input to filter out everything but signals
very close to your 900 MHz input frequency.  This technique once helped me
track down a alarm system motion detector that was operating around 900 MHz.
Some spectrum analyzers are poorly shielded, and are practically useless
when immersed in a high-RF environment.

73, Eric Lemmon WB6FLY


-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of David Epley
Sent: Thursday, November 22, 2007 9:17 AM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: [Repeater-Builder] Receiver overload

It is linked but there is only an STL link receiver at the  site

 



From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of n9wys
Sent: Thursday, November 22, 2007 12:08 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: [Repeater-Builder] Receiver overload

 

Is the FM broadcast studio located at the transmitter site, or is it linked?
If the studio is remote to the transmitter, it could be a harmonic of the
studio uplink freq.  But now I:m shooting in the dark.

 

Mark - N9WYS

 



From: Repeater-Builder@yahoogroups.com On Behalf Of David Epley

Analyzer was connected to the receiver port of the duplexers. The noise
floor looked good. The amount of degradation does not seem to change. There
are 900mhz pager transmitters on site but none are on full time and I do not
see any change as each one transmits. I can also have my transmitter turned
off and the degradation is still here.

 



From: Repeater-Builder@yahoogroups.com On Behalf Of Ron Wright

David,

Your problem might be harmonic related. Might do some calculator work. I can
see no muliple of 104.9 related to your 2 frequencies or IF related.

There are other 900 MHz stuff around. Would be good to get a spectrum
analyzer on your receiver port, but know spectrum analyzers are not easy to
come by.

Might be noise floor emissions from the FM station which could be on your
receiver input. Now this one would be a real problem.

73, ron, n9ee/r

>From: David Epley 
>Date: 2007/11/22 Thu AM 07:32:46 CST
>To: Repeater-Builder@yahoogroups.com
<mailto:Repeater-Builder%40yahoogroups.com> 
>Subject: RE: [Repeater-Builder] Receiver overload> 
>
>I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable
improvement.
> 
> 
>David N9CZV
> 
>From: Repeater-Builder@yahoogroups.com
<mailto:Repeater-Builder%40yahoogroups.com>  On Behalf Of Jim Brown
> 
>David,try using one or two band pass only cavaties in
>the receive side instead of the BpBr type. The BpBr
>filters often do not discriminate against signals far
>off the pass frequency, and you may not be getting
>enough rejection out of your input cavities.
>
>73 - Jim W5ZIT
>
>--- David Epley wrote:
>
>> I have a repeater receiver overload problem I am
>> trying to cure. The
>> repeater is a 900mhz 927.7125/902.7125. There is an
>> FM broadcast station 100
>> yards away 104.9mhz. The repeater works fine at
>> another site. My transmitter
>> is a Motorola Purc 5000 running 75 watts the
>> receiver is a converted maxtrac
>> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
>> have 10 to 12 db
>> degradation when plugged into 3 different antennas
>> on the tower. When I use
>> a 900mhz dish antenna pointed away from broadcast
>> tower I only have 3 db
>> degradation. I have tried 3 different maxtrac
>> receivers, added 2 more BpBr
>> cavities in the receiver side and used 3 pole
>> filters in the receivers with
>> no improvement. Today I looked at the signal level
>> getting to the receiver
>> at 104.9. To my surprise I w

Re: [Repeater-Builder] Receiver overload

[Captainlance]

We had the same kind of troubles in NYC with Maxtracs, switched to Micor 
Spectra-Tac receivers and the problems went away. The Maxtrac is great for a 
mobile, or in a quiet location, but you need a "real" receiver with shielding, 
and a helical front end in high RF locations.
Lance N2HBA
  - Original Message - 
  From: Chuck Kelsey 
  To: Repeater-Builder@yahoogroups.com 
  Sent: Thursday, November 22, 2007 11:36 AM
  Subject: Re: [Repeater-Builder] Receiver overload


  I agree with Eric about the shielded enclosure especially. And be sure to 
  use a connector on the coax where it passes through the box. Just running 
  the coax through a hole in the box defeats all, most or some the shielding 
  of the box.

  Chuck
  WB2EDV

  - Original Message - 
  From: "Eric Lemmon" <[EMAIL PROTECTED]>
  To: 
  Sent: Thursday, November 22, 2007 11:10 AM
  Subject: RE: [Repeater-Builder] Receiver overload

  > David,
  >
  > My first move would be to add a bandpass cavity in front of the receiver.
  > All cabling between the receiver and the RX output of the duplexer should 
  > be
  > double-shielded, with proper connectors on each end- no adapters, and no
  > nickel-plated connectors. The mini-UHF connector going to the MaxTrac
  > should be the only exception, but it's okay if very tight.
  >
  > If that doesn't cure the problem, then enclose the receiver in a shielded
  > box, and bring the signal and power leads out through feedthrough
  > capacitors. The MaxTrac radio has a lot of plastic in its case, and is
  > susceptible to signal intrusion. The best shielded box to use is a 
  > die-cast
  > aluminum enclosure from Hammond.
  >
  > I have assumed that the FM transmitter carrier is pure, without harmonics 
  > or
  > spurious artifacts. If the FM transmitter is radiating on a frequency 
  > close
  > to your desired input frequency, the above fixes may not have any effect.
  >
  > 73, Eric Lemmon WB6FLY
  >
  > 


   

RE: RE: [Repeater-Builder] Receiver overload

[n9wys]

I was thinking that maybe your interference might be a harmonic of their
uplink freq.  Back to thinking some more.  ;-)

 

  _  

From: Repeater-Builder@yahoogroups.com On Behalf Of David Epley



It is linked but there is only an STL link receiver at the site

 

  _  

From: Repeater-Builder@yahoogroups.com On Behalf Of n9wys

Is the FM broadcast studio located at the transmitter site, or is it linked?
If the studio is remote to the transmitter, it could be a harmonic of the
studio uplink freq.  But now I:m shooting in the dark.

Mark - N9WYS 

RE: RE: [Repeater-Builder] Receiver overload

[David Epley]

It is linked but there is only an STL link receiver at the  site

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of n9wys
Sent: Thursday, November 22, 2007 12:08 PM
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: [Repeater-Builder] Receiver overload

 

Is the FM broadcast studio located at the transmitter site, or is it linked?
If the studio is remote to the transmitter, it could be a harmonic of the
studio uplink freq.  But now I:m shooting in the dark.

 

Mark - N9WYS

 

  _  

From: Repeater-Builder@yahoogroups.com On Behalf Of David Epley

Analyzer was connected to the receiver port of the duplexers. The noise
floor looked good. The amount of degradation does not seem to change. There
are 900mhz pager transmitters on site but none are on full time and I do not
see any change as each one transmits. I can also have my transmitter turned
off and the degradation is still here.

 

  _  

From: Repeater-Builder@yahoogroups.com On Behalf Of Ron Wright

David,

Your problem might be harmonic related. Might do some calculator work. I can
see no muliple of 104.9 related to your 2 frequencies or IF related.

There are other 900 MHz stuff around. Would be good to get a spectrum
analyzer on your receiver port, but know spectrum analyzers are not easy to
come by.

Might be noise floor emissions from the FM station which could be on your
receiver input. Now this one would be a real problem.

73, ron, n9ee/r

>From: David Epley 
>Date: 2007/11/22 Thu AM 07:32:46 CST
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload> 
>
>I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable
improvement.
> 
> 
>David N9CZV
> 
>From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com On Behalf Of Jim Brown
> 
>David,try using one or two band pass only cavaties in
>the receive side instead of the BpBr type. The BpBr
>filters often do not discriminate against signals far
>off the pass frequency, and you may not be getting
>enough rejection out of your input cavities.
>
>73 - Jim W5ZIT
>
>--- David Epley wrote:
>
>> I have a repeater receiver overload problem I am
>> trying to cure. The
>> repeater is a 900mhz 927.7125/902.7125. There is an
>> FM broadcast station 100
>> yards away 104.9mhz. The repeater works fine at
>> another site. My transmitter
>> is a Motorola Purc 5000 running 75 watts the
>> receiver is a converted maxtrac
>> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
>> have 10 to 12 db
>> degradation when plugged into 3 different antennas
>> on the tower. When I use
>> a 900mhz dish antenna pointed away from broadcast
>> tower I only have 3 db
>> degradation. I have tried 3 different maxtrac
>> receivers, added 2 more BpBr
>> cavities in the receiver side and used 3 pole
>> filters in the receivers with
>> no improvement. Today I looked at the signal level
>> getting to the receiver
>> at 104.9. To my surprise I was getting -8 dbm at the
>> receiver. I believe
>> this level is overloading the front end of my
>> repeater. I was wondering if a
>> stub cut for the broadcast frequency would work. Any
>> thoughts would be
>> greatly appreciated.
>> 
>> David Epley, N9CZV
>> Winchester, Indiana

 

RE: [Repeater-Builder] Receiver overload

[Eric Lemmon]

If you want to try constructing a stub filter to notch out the FM carrier,
look here:



73, Eric Lemmon WB6FLY
 

-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of David Epley
Sent: Thursday, November 22, 2007 8:42 AM
To: Repeater-Builder@yahoogroups.com
Subject: RE: [Repeater-Builder] Receiver overload

I have tried all the above. I even change out the mini UHF connector to an N
female when I use the maxtrac for repeater use. All cables are ¼ hardline.
When I use a 900mhz dish mounted at the same level as my primary antenna but
pointed away from the  FM Broadcast tower I have considerably less
degradation.

 



From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon
Sent: Thursday, November 22, 2007 11:10 AM
To: Repeater-Builder@yahoogroups.com
Subject: RE: [Repeater-Builder] Receiver overload

 

David,

My first move would be to add a bandpass cavity in front of the receiver.
All cabling between the receiver and the RX output of the duplexer should be
double-shielded, with proper connectors on each end- no adapters, and no
nickel-plated connectors. The mini-UHF connector going to the MaxTrac
should be the only exception, but it's okay if very tight.

If that doesn't cure the problem, then enclose the receiver in a shielded
box, and bring the signal and power leads out through feedthrough
capacitors. The MaxTrac radio has a lot of plastic in its case, and is
susceptible to signal intrusion. The best shielded box to use is a die-cast
aluminum enclosure from Hammond.

I have assumed that the FM transmitter carrier is pure, without harmonics or
spurious artifacts. If the FM transmitter is radiating on a frequency close
to your desired input frequency, the above fixes may not have any effect.

73, Eric Lemmon WB6FLY


-Original Message-
From: Repeater-Builder@yahoogroups.com
<mailto:Repeater-Builder%40yahoogroups.com> 
[mailto:Repeater-Builder@yahoogroups.com
<mailto:Repeater-Builder%40yahoogroups.com> ] On Behalf Of David Epley
Sent: Thursday, November 22, 2007 7:02 AM
To: Repeater-Builder@yahoogroups.com
<mailto:Repeater-Builder%40yahoogroups.com> 
Subject: RE: [Repeater-Builder] Receiver overload

The only transmitter that is on all the time is the FM broadcast My tx
plays no part in the noise



From: Repeater-Builder@yahoogroups.com
<mailto:Repeater-Builder%40yahoogroups.com> 
[mailto:Repeater-Builder@yahoogroups.com
<mailto:Repeater-Builder%40yahoogroups.com> ] On Behalf Of Joe
Sent: Thursday, November 22, 2007 9:55 AM
To: Repeater-Builder@yahoogroups.com
<mailto:Repeater-Builder%40yahoogroups.com> 
Subject: Re: [Repeater-Builder] Receiver overload

Can you give us a list of all the transmitters that are at/near the 
site? Ones that are on the air all the time such as the FM station. 
Does your transmitter have to be keyed to get the desense?

73, Joe, K1ike

David Epley wrote:
>
> I have a repeater receiver overload problem I am trying to cure. The 
> repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast 
> station 100 yards away 104.9mhz. The repeater works fine at another 
> site. My transmitter is a Motorola Purc 5000 running 75 watts the 
> receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave 
> BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 
> different antennas on the tower. When I use a 900mhz dish antenna 
> pointed away from broadcast tower I only have 3 db degradation. I have 
> tried 3 different maxtrac receivers, added 2 more BpBr cavities in the 
> receiver side and used 3 pole filters in the receivers with no 
> improvement. Today I looked at the signal level getting to the 
> receiver at 104.9. To my surprise I was getting -8 dbm at the 
> receiver. I believe this level is overloading the front end of my 
> repeater. I was wondering if a stub cut for the broadcast frequency 
> would work. Any thoughts would be greatly appreciated.
>
> 
>
> 
>
> David Epley, N9CZV
>
> Winchester, Indiana

 

RE: RE: [Repeater-Builder] Receiver overload

[n9wys]

Is the FM broadcast studio located at the transmitter site, or is it linked?
If the studio is remote to the transmitter, it could be a harmonic of the
studio uplink freq.  But now I:m shooting in the dark.

 

Mark - N9WYS

 

  _  

From: Repeater-Builder@yahoogroups.com On Behalf Of David Epley



Analyzer was connected to the receiver port of the duplexers. The noise
floor looked good. The amount of degradation does not seem to change. There
are 900mhz pager transmitters on site but none are on full time and I do not
see any change as each one transmits. I can also have my transmitter turned
off and the degradation is still here.

 

  _  

From: Repeater-Builder@yahoogroups.com On Behalf Of Ron Wright

David,

Your problem might be harmonic related. Might do some calculator work. I can
see no muliple of 104.9 related to your 2 frequencies or IF related.

There are other 900 MHz stuff around. Would be good to get a spectrum
analyzer on your receiver port, but know spectrum analyzers are not easy to
come by.

Might be noise floor emissions from the FM station which could be on your
receiver input. Now this one would be a real problem.

73, ron, n9ee/r

>From: David Epley 
>Date: 2007/11/22 Thu AM 07:32:46 CST
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload> 
>
>I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable
improvement.
> 
> 
>David N9CZV
> 
>From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com On Behalf Of Jim Brown
> 
>David,try using one or two band pass only cavaties in
>the receive side instead of the BpBr type. The BpBr
>filters often do not discriminate against signals far
>off the pass frequency, and you may not be getting
>enough rejection out of your input cavities.
>
>73 - Jim W5ZIT
>
>--- David Epley wrote:
>
>> I have a repeater receiver overload problem I am
>> trying to cure. The
>> repeater is a 900mhz 927.7125/902.7125. There is an
>> FM broadcast station 100
>> yards away 104.9mhz. The repeater works fine at
>> another site. My transmitter
>> is a Motorola Purc 5000 running 75 watts the
>> receiver is a converted maxtrac
>> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
>> have 10 to 12 db
>> degradation when plugged into 3 different antennas
>> on the tower. When I use
>> a 900mhz dish antenna pointed away from broadcast
>> tower I only have 3 db
>> degradation. I have tried 3 different maxtrac
>> receivers, added 2 more BpBr
>> cavities in the receiver side and used 3 pole
>> filters in the receivers with
>> no improvement. Today I looked at the signal level
>> getting to the receiver
>> at 104.9. To my surprise I was getting -8 dbm at the
>> receiver. I believe
>> this level is overloading the front end of my
>> repeater. I was wondering if a
>> stub cut for the broadcast frequency would work. Any
>> thoughts would be
>> greatly appreciated.
>> 
>> David Epley, N9CZV
>> Winchester, Indiana

RE: RE: [Repeater-Builder] Receiver overload

[David Epley]

Yes when broadcast goes off problem goes away

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright
Sent: Thursday, November 22, 2007 11:14 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: RE: [Repeater-Builder] Receiver overload

 

David,

Have we ask if you can verify the problem is the FM transmitter???

73, ron, n9ee/r

>From: Eric Lemmon <[EMAIL PROTECTED] <mailto:wb6fly%40verizon.net> net>
>Date: 2007/11/22 Thu AM 10:10:19 CST
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload

> 
>David,
>
>My first move would be to add a bandpass cavity in front of the receiver.
>All cabling between the receiver and the RX output of the duplexer should
be
>double-shielded, with proper connectors on each end- no adapters, and no
>nickel-plated connectors. The mini-UHF connector going to the MaxTrac
>should be the only exception, but it's okay if very tight.
>
>If that doesn't cure the problem, then enclose the receiver in a shielded
>box, and bring the signal and power leads out through feedthrough
>capacitors. The MaxTrac radio has a lot of plastic in its case, and is
>susceptible to signal intrusion. The best shielded box to use is a die-cast
>aluminum enclosure from Hammond.
>
>I have assumed that the FM transmitter carrier is pure, without harmonics
or
>spurious artifacts. If the FM transmitter is radiating on a frequency close
>to your desired input frequency, the above fixes may not have any effect.
>
>73, Eric Lemmon WB6FLY
> 
>
>-Original Message-
>From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>[mailto:Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com] On Behalf Of David Epley
>Sent: Thursday, November 22, 2007 7:02 AM
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload
>
>The only transmitter that is on all the time is the FM broadcast My tx
>plays no part in the noise
>
>
>
>From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>[mailto:Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com] On Behalf Of Joe
>Sent: Thursday, November 22, 2007 9:55 AM
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>Subject: Re: [Repeater-Builder] Receiver overload
>
>Can you give us a list of all the transmitters that are at/near the 
>site? Ones that are on the air all the time such as the FM station. 
>Does your transmitter have to be keyed to get the desense?
>
>73, Joe, K1ike
>
>David Epley wrote:
>>
>> I have a repeater receiver overload problem I am trying to cure. The 
>> repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast 
>> station 100 yards away 104.9mhz. The repeater works fine at another 
>> site. My transmitter is a Motorola Purc 5000 running 75 watts the 
>> receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave 
>> BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 
>> different antennas on the tower. When I use a 900mhz dish antenna 
>> pointed away from broadcast tower I only have 3 db degradation. I have 
>> tried 3 different maxtrac receivers, added 2 more BpBr cavities in the 
>> receiver side and used 3 pole filters in the receivers with no 
>> improvement. Today I looked at the signal level getting to the 
>> receiver at 104.9. To my surprise I was getting -8 dbm at the 
>> receiver. I believe this level is overloading the front end of my 
>> repeater. I was wondering if a stub cut for the broadcast frequency 
>> would work. Any thoughts would be greatly appreciated.
>>
>> 
>>
>> 
>>
>> David Epley, N9CZV
>>
>> Winchester, Indiana
>
> 

Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

 

RE: [Repeater-Builder] Receiver overload

[David Epley]

I have tried all the above. I even change out the mini UHF connector to an N
female when I use the maxtrac for repeater use. All cables are ¼ hardline.
When I use a 900mhz dish mounted at the same level as my primary antenna but
pointed away from the  FM Broadcast tower I have considerably less
degradation.

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Eric Lemmon
Sent: Thursday, November 22, 2007 11:10 AM
To: Repeater-Builder@yahoogroups.com
Subject: RE: [Repeater-Builder] Receiver overload

 

David,

My first move would be to add a bandpass cavity in front of the receiver.
All cabling between the receiver and the RX output of the duplexer should be
double-shielded, with proper connectors on each end- no adapters, and no
nickel-plated connectors. The mini-UHF connector going to the MaxTrac
should be the only exception, but it's okay if very tight.

If that doesn't cure the problem, then enclose the receiver in a shielded
box, and bring the signal and power leads out through feedthrough
capacitors. The MaxTrac radio has a lot of plastic in its case, and is
susceptible to signal intrusion. The best shielded box to use is a die-cast
aluminum enclosure from Hammond.

I have assumed that the FM transmitter carrier is pure, without harmonics or
spurious artifacts. If the FM transmitter is radiating on a frequency close
to your desired input frequency, the above fixes may not have any effect.

73, Eric Lemmon WB6FLY


-Original Message-
From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
[mailto:Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com] On Behalf Of David Epley
Sent: Thursday, November 22, 2007 7:02 AM
To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
Subject: RE: [Repeater-Builder] Receiver overload

The only transmitter that is on all the time is the FM broadcast My tx
plays no part in the noise



From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
[mailto:Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com] On Behalf Of Joe
Sent: Thursday, November 22, 2007 9:55 AM
To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
Subject: Re: [Repeater-Builder] Receiver overload

Can you give us a list of all the transmitters that are at/near the 
site? Ones that are on the air all the time such as the FM station. 
Does your transmitter have to be keyed to get the desense?

73, Joe, K1ike

David Epley wrote:
>
> I have a repeater receiver overload problem I am trying to cure. The 
> repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast 
> station 100 yards away 104.9mhz. The repeater works fine at another 
> site. My transmitter is a Motorola Purc 5000 running 75 watts the 
> receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave 
> BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 
> different antennas on the tower. When I use a 900mhz dish antenna 
> pointed away from broadcast tower I only have 3 db degradation. I have 
> tried 3 different maxtrac receivers, added 2 more BpBr cavities in the 
> receiver side and used 3 pole filters in the receivers with no 
> improvement. Today I looked at the signal level getting to the 
> receiver at 104.9. To my surprise I was getting -8 dbm at the 
> receiver. I believe this level is overloading the front end of my 
> repeater. I was wondering if a stub cut for the broadcast frequency 
> would work. Any thoughts would be greatly appreciated.
>
> 
>
> 
>
> David Epley, N9CZV
>
> Winchester, Indiana

 

Re: [Repeater-Builder] Receiver overload

[Chuck Kelsey]

I agree with Eric about the shielded enclosure especially. And be sure to 
use a connector on the coax where it passes through the box. Just running 
the coax through a hole in the box defeats all, most or some the shielding 
of the box.

Chuck
WB2EDV



- Original Message - 
From: "Eric Lemmon" <[EMAIL PROTECTED]>
To: 
Sent: Thursday, November 22, 2007 11:10 AM
Subject: RE: [Repeater-Builder] Receiver overload


> David,
>
> My first move would be to add a bandpass cavity in front of the receiver.
> All cabling between the receiver and the RX output of the duplexer should 
> be
> double-shielded, with proper connectors on each end- no adapters, and no
> nickel-plated connectors.  The mini-UHF connector going to the MaxTrac
> should be the only exception, but it's okay if very tight.
>
> If that doesn't cure the problem, then enclose the receiver in a shielded
> box, and bring the signal and power leads out through feedthrough
> capacitors.  The MaxTrac radio has a lot of plastic in its case, and is
> susceptible to signal intrusion.  The best shielded box to use is a 
> die-cast
> aluminum enclosure from Hammond.
>
> I have assumed that the FM transmitter carrier is pure, without harmonics 
> or
> spurious artifacts.  If the FM transmitter is radiating on a frequency 
> close
> to your desired input frequency, the above fixes may not have any effect.
>
> 73, Eric Lemmon WB6FLY
>
> 

Re: RE: [Repeater-Builder] Receiver overload

[Ron Wright]

David,

Have we ask if you can verify the problem is the FM transmitter???

73, ron, n9ee/r




>From: Eric Lemmon <[EMAIL PROTECTED]>
>Date: 2007/11/22 Thu AM 10:10:19 CST
>To: Repeater-Builder@yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload

>  
>David,
>
>My first move would be to add a bandpass cavity in front of the receiver.
>All cabling between the receiver and the RX output of the duplexer should be
>double-shielded, with proper connectors on each end- no adapters, and no
>nickel-plated connectors.  The mini-UHF connector going to the MaxTrac
>should be the only exception, but it's okay if very tight.
>
>If that doesn't cure the problem, then enclose the receiver in a shielded
>box, and bring the signal and power leads out through feedthrough
>capacitors.  The MaxTrac radio has a lot of plastic in its case, and is
>susceptible to signal intrusion.  The best shielded box to use is a die-cast
>aluminum enclosure from Hammond.
>
>I have assumed that the FM transmitter carrier is pure, without harmonics or
>spurious artifacts.  If the FM transmitter is radiating on a frequency close
>to your desired input frequency, the above fixes may not have any effect.
>
>73, Eric Lemmon WB6FLY
> 
>
>-Original Message-
>From: Repeater-Builder@yahoogroups.com
>[mailto:[EMAIL PROTECTED] On Behalf Of David Epley
>Sent: Thursday, November 22, 2007 7:02 AM
>To: Repeater-Builder@yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload
>
>The only transmitter that is on all the time is the FM broadcast  My tx
>plays no part in the noise
>
>
>
>From: Repeater-Builder@yahoogroups.com
>[mailto:[EMAIL PROTECTED] On Behalf Of Joe
>Sent: Thursday, November 22, 2007 9:55 AM
>To: Repeater-Builder@yahoogroups.com
>Subject: Re: [Repeater-Builder] Receiver overload
>
>Can you give us a list of all the transmitters that are at/near the 
>site? Ones that are on the air all the time such as the FM station. 
>Does your transmitter have to be keyed to get the desense?
>
>73, Joe, K1ike
>
>David Epley wrote:
>>
>> I have a repeater receiver overload problem I am trying to cure. The 
>> repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast 
>> station 100 yards away 104.9mhz. The repeater works fine at another 
>> site. My transmitter is a Motorola Purc 5000 running 75 watts the 
>> receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave 
>> BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 
>> different antennas on the tower. When I use a 900mhz dish antenna 
>> pointed away from broadcast tower I only have 3 db degradation. I have 
>> tried 3 different maxtrac receivers, added 2 more BpBr cavities in the 
>> receiver side and used 3 pole filters in the receivers with no 
>> improvement. Today I looked at the signal level getting to the 
>> receiver at 104.9. To my surprise I was getting -8 dbm at the 
>> receiver. I believe this level is overloading the front end of my 
>> repeater. I was wondering if a stub cut for the broadcast frequency 
>> would work. Any thoughts would be greatly appreciated.
>>
>> 
>>
>> 
>>
>> David Epley, N9CZV
>>
>> Winchester, Indiana
>
>


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

RE: [Repeater-Builder] Receiver overload

[Eric Lemmon]

David,

My first move would be to add a bandpass cavity in front of the receiver.
All cabling between the receiver and the RX output of the duplexer should be
double-shielded, with proper connectors on each end- no adapters, and no
nickel-plated connectors.  The mini-UHF connector going to the MaxTrac
should be the only exception, but it's okay if very tight.

If that doesn't cure the problem, then enclose the receiver in a shielded
box, and bring the signal and power leads out through feedthrough
capacitors.  The MaxTrac radio has a lot of plastic in its case, and is
susceptible to signal intrusion.  The best shielded box to use is a die-cast
aluminum enclosure from Hammond.

I have assumed that the FM transmitter carrier is pure, without harmonics or
spurious artifacts.  If the FM transmitter is radiating on a frequency close
to your desired input frequency, the above fixes may not have any effect.

73, Eric Lemmon WB6FLY
 

-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of David Epley
Sent: Thursday, November 22, 2007 7:02 AM
To: Repeater-Builder@yahoogroups.com
Subject: RE: [Repeater-Builder] Receiver overload

The only transmitter that is on all the time is the FM broadcast  My tx
plays no part in the noise

 



From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Joe
Sent: Thursday, November 22, 2007 9:55 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Receiver overload

 

Can you give us a list of all the transmitters that are at/near the 
site? Ones that are on the air all the time such as the FM station. 
Does your transmitter have to be keyed to get the desense?

73, Joe, K1ike

David Epley wrote:
>
> I have a repeater receiver overload problem I am trying to cure. The 
> repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast 
> station 100 yards away 104.9mhz. The repeater works fine at another 
> site. My transmitter is a Motorola Purc 5000 running 75 watts the 
> receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave 
> BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 
> different antennas on the tower. When I use a 900mhz dish antenna 
> pointed away from broadcast tower I only have 3 db degradation. I have 
> tried 3 different maxtrac receivers, added 2 more BpBr cavities in the 
> receiver side and used 3 pole filters in the receivers with no 
> improvement. Today I looked at the signal level getting to the 
> receiver at 104.9. To my surprise I was getting -8 dbm at the 
> receiver. I believe this level is overloading the front end of my 
> repeater. I was wondering if a stub cut for the broadcast frequency 
> would work. Any thoughts would be greatly appreciated.
>
> 
>
> 
>
> David Epley, N9CZV
>
> Winchester, Indiana

RE: [Repeater-Builder] Receiver overload

[David Epley]

The only transmitter that is on all the time is the FM broadcast  My tx
plays no part in the noise

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Joe
Sent: Thursday, November 22, 2007 9:55 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Receiver overload

 

Can you give us a list of all the transmitters that are at/near the 
site? Ones that are on the air all the time such as the FM station. 
Does your transmitter have to be keyed to get the desense?

73, Joe, K1ike

David Epley wrote:
>
> I have a repeater receiver overload problem I am trying to cure. The 
> repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast 
> station 100 yards away 104.9mhz. The repeater works fine at another 
> site. My transmitter is a Motorola Purc 5000 running 75 watts the 
> receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave 
> BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 
> different antennas on the tower. When I use a 900mhz dish antenna 
> pointed away from broadcast tower I only have 3 db degradation. I have 
> tried 3 different maxtrac receivers, added 2 more BpBr cavities in the 
> receiver side and used 3 pole filters in the receivers with no 
> improvement. Today I looked at the signal level getting to the 
> receiver at 104.9. To my surprise I was getting -8 dbm at the 
> receiver. I believe this level is overloading the front end of my 
> repeater. I was wondering if a stub cut for the broadcast frequency 
> would work. Any thoughts would be greatly appreciated.
>
> 
>
> 
>
> David Epley, N9CZV
>
> Winchester, Indiana
>
> 

 

RE: RE: [Repeater-Builder] Receiver overload

[Joe Montierth]

An easy way to check for overload would be to install a HPF before the
RX, this would greatly cut down the 104.9 signal.

If you have a 2M/440 diplexer, like people use to split or combine
antennas, that would probably work, at least for a test to prove or
disprove this thought. Just connect antenna to the common port, and RX
to HPF port, terminating LPF (2M) port.

These things will usually have low insertion loss at 900, but 50+ dB of
rejection at 100MHz. Someone around there is likely to have one you can
borrow for a test.

Joe

--- David Epley <[EMAIL PROTECTED]> wrote:

> Analyzer was connected to the receiver port of the duplexers. The
> noise
> floor looked good. The amount of degradation does not seem to change.
> There
> are 900mhz pager transmitters on site but none are on full time and I
> do not
> see any change as each one transmits. I can also have my transmitter
> turned
> off and the degradation is still here.
> 
>  
> 
>   _  
> 
> From: Repeater-Builder@yahoogroups.com
> [mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright
> Sent: Thursday, November 22, 2007 9:19 AM
> To: Repeater-Builder@yahoogroups.com
> Subject: Re: RE: [Repeater-Builder] Receiver overload
> 
>  
> 
> David,
> 
> Your problem might be harmonic related. Might do some calculator
> work. I can
> see no muliple of 104.9 related to your 2 frequencies or IF related.
> 
> There are other 900 MHz stuff around. Would be good to get a spectrum
> analyzer on your receiver port, but know spectrum analyzers are not
> easy to
> come by.
> 
> Might be noise floor emissions from the FM station which could be on
> your
> receiver input. Now this one would be a real problem.
> 
> 73, ron, n9ee/r
> 
> >From: David Epley <[EMAIL PROTECTED] <mailto:depley%40starband.net>
> net>
> >Date: 2007/11/22 Thu AM 07:32:46 CST
> >To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
> yahoogroups.com
> >Subject: RE: [Repeater-Builder] Receiver overload
> 
> > 
> >
> >I just tried a pair of Celwave 8 inch bandpass cavities with no
> noticeable
> improvement.
> > 
> > 
> >David N9CZV
> > 
> >From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
> yahoogroups.com [mailto:Repeater-Builder@
> <mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com] On
> Behalf Of
> Jim Brown
> >Sent: Thursday, November 22, 20076:13 AM
> >To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
> yahoogroups.com
> >Subject: Re: [Repeater-Builder]Receiver overload
> > 
> >David,try using one or two band pass only cavaties in
> >the receive side instead of the BpBr type. The BpBr
> >filters often do not discriminate against signals far
> >off the pass frequency, and you may not be getting
> >enough rejection out of your input cavities.
> >
> >73 - Jim W5ZIT
> >
> >--- David Epley <[EMAIL PROTECTED] <mailto:depley%40starband.net>
> net>wrote:
> >
> >> I have a repeater receiver overload problem I am
> >> trying to cure. The
> >> repeater is a 900mhz 927.7125/902.7125. There is an
> >> FM broadcast station 100
> >> yards away 104.9mhz. The repeater works fine at
> >> another site. My transmitter
> >> is a Motorola Purc 5000 running 75 watts the
> >> receiver is a converted maxtrac
> >> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
> >> have 10 to 12 db
> >> degradation when plugged into 3 different antennas
> >> on the tower. When I use
> >> a 900mhz dish antenna pointed away from broadcast
> >> tower I only have 3 db
> >> degradation. I have tried 3 different maxtrac
> >> receivers, added 2 more BpBr
> >> cavities in the receiver side and used 3 pole
> >> filters in the receivers with
> >> no improvement. Today I looked at the signal level
> >> getting to the receiver
> >> at 104.9. To my surprise I was getting -8 dbm at the
> >> receiver. I believe
> >> this level is overloading the front end of my
> >> repeater. I was wondering if a
> >> stub cut for the broadcast frequency would work. Any
> >> thoughts would be
> >> greatly appreciated.
> >> 
> >> 
> >> 
> >> 
> >> 
> >> David Epley, N9CZV
> >> 
> >> Winchester, Indiana
> >> 
> >> 
> >
> >__
> >Be a better pen pal. 
> >Text or chat with friends inside Yahoo! Mail. See how.
> http://overview.
> <http://overview.mail.yahoo.com/> mail.yahoo.com/
> > 
> 
> Ron Wright, N9EE
> 727-376-6575
> MICRO COMPUTER CONCEPTS
> Owner 146.64 repeater Tampa Bay, FL
> No tone, all are welcome.
> 
>  
> 
> 



  

Be a better sports nut!  Let your teams follow you 
with Yahoo Mobile. Try it now.  
http://mobile.yahoo.com/sports;_ylt=At9_qDKvtAbMuh1G1SQtBI7ntAcJ

Re: [Repeater-Builder] Receiver overload

[Mark Stennett]

I also share a site with an FM broadcaster. I use an all band notch 
filter from Microwave Filter Company on my receivers ahead of the 
preamp. Mine were custom made for 50 ohm input and output and are good 
for about -40 dB.

http://www.microwavefilter.com/



 >>> David Epley wrote:

>>> To my surprise I was getting -8 dbm at the
>>> receiver. I believe
>>> this level is overloading the front end of my
>>> repeater. I was wondering if a
>>> stub cut for the broadcast frequency would work. Any
>>> thoughts would be
>>> greatly appreciated.

Re: [Repeater-Builder] Receiver overload

[Joe]

Can you give us a list of all the transmitters that are at/near the 
site?  Ones that are on the air all the time such as the FM station.  
Does your transmitter have to be keyed to get the desense?

73, Joe, K1ike


David Epley wrote:
>
> I have a repeater receiver overload problem I am trying to cure. The 
> repeater is a 900mhz 927.7125/902.7125. There is an FM broadcast 
> station 100 yards away 104.9mhz. The repeater works fine at another 
> site. My transmitter is a Motorola Purc 5000 running 75 watts the 
> receiver is a converted maxtrac 800mhz radio. Duplexers are Telwave 
> BpBr 4 cavity. I have 10 to 12 db degradation when plugged into 3 
> different antennas on the tower. When I use a 900mhz dish antenna 
> pointed away from broadcast tower I only have 3 db degradation. I have 
> tried 3 different maxtrac receivers, added 2 more BpBr cavities in the 
> receiver side and used 3 pole filters in the receivers with no 
> improvement. Today I looked at the signal level getting to the 
> receiver at 104.9. To my surprise I was getting -8 dbm at the 
> receiver. I believe this level is overloading the front end of my 
> repeater. I was wondering if a stub cut for the broadcast frequency 
> would work. Any thoughts would be greatly appreciated.
>
>  
>
>  
>
> David Epley, N9CZV
>
> Winchester, Indiana
>
>  

RE: RE: [Repeater-Builder] Receiver overload

[David Epley]

Same antenna and feedline at both sites Decible 896-960mhz with 15/8
feedline.

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright
Sent: Thursday, November 22, 2007 9:22 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: RE: [Repeater-Builder] Receiver overload

 

David,

I assume the antenna system at the now location was different than the other
that worked.

What kind of feedline and antenna???

73, ron, n9ee/r

>From: David Epley <[EMAIL PROTECTED] <mailto:depley%40starband.net> net>
>Date: 2007/11/22 Thu AM 07:32:46 CST
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload

> 
>
>I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable
improvement.
> 
> 
>David N9CZV
> 
>From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com [mailto:Repeater-Builder@
<mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com] On Behalf Of
Jim Brown
>Sent: Thursday, November 22, 20076:13 AM
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>Subject: Re: [Repeater-Builder]Receiver overload
> 
>David,try using one or two band pass only cavaties in
>the receive side instead of the BpBr type. The BpBr
>filters often do not discriminate against signals far
>off the pass frequency, and you may not be getting
>enough rejection out of your input cavities.
>
>73 - Jim W5ZIT
>
>--- David Epley <[EMAIL PROTECTED] <mailto:depley%40starband.net> net>wrote:
>
>> I have a repeater receiver overload problem I am
>> trying to cure. The
>> repeater is a 900mhz 927.7125/902.7125. There is an
>> FM broadcast station 100
>> yards away 104.9mhz. The repeater works fine at
>> another site. My transmitter
>> is a Motorola Purc 5000 running 75 watts the
>> receiver is a converted maxtrac
>> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
>> have 10 to 12 db
>> degradation when plugged into 3 different antennas
>> on the tower. When I use
>> a 900mhz dish antenna pointed away from broadcast
>> tower I only have 3 db
>> degradation. I have tried 3 different maxtrac
>> receivers, added 2 more BpBr
>> cavities in the receiver side and used 3 pole
>> filters in the receivers with
>> no improvement. Today I looked at the signal level
>> getting to the receiver
>> at 104.9. To my surprise I was getting -8 dbm at the
>> receiver. I believe
>> this level is overloading the front end of my
>> repeater. I was wondering if a
>> stub cut for the broadcast frequency would work. Any
>> thoughts would be
>> greatly appreciated.
>> 
>> 
>> 
>> 
>> 
>> David Epley, N9CZV
>> 
>> Winchester, Indiana
>> 
>> 
>
>__
>Be a better pen pal. 
>Text or chat with friends inside Yahoo! Mail. See how. http://overview.
<http://overview.mail.yahoo.com/> mail.yahoo.com/
> 

Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

 

RE: RE: [Repeater-Builder] Receiver overload

[David Epley]

Analyzer was connected to the receiver port of the duplexers. The noise
floor looked good. The amount of degradation does not seem to change. There
are 900mhz pager transmitters on site but none are on full time and I do not
see any change as each one transmits. I can also have my transmitter turned
off and the degradation is still here.

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Ron Wright
Sent: Thursday, November 22, 2007 9:19 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: RE: [Repeater-Builder] Receiver overload

 

David,

Your problem might be harmonic related. Might do some calculator work. I can
see no muliple of 104.9 related to your 2 frequencies or IF related.

There are other 900 MHz stuff around. Would be good to get a spectrum
analyzer on your receiver port, but know spectrum analyzers are not easy to
come by.

Might be noise floor emissions from the FM station which could be on your
receiver input. Now this one would be a real problem.

73, ron, n9ee/r

>From: David Epley <[EMAIL PROTECTED] <mailto:depley%40starband.net> net>
>Date: 2007/11/22 Thu AM 07:32:46 CST
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload

> 
>
>I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable
improvement.
> 
> 
>David N9CZV
> 
>From: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com [mailto:Repeater-Builder@
<mailto:Repeater-Builder%40yahoogroups.com> yahoogroups.com] On Behalf Of
Jim Brown
>Sent: Thursday, November 22, 20076:13 AM
>To: Repeater-Builder@ <mailto:Repeater-Builder%40yahoogroups.com>
yahoogroups.com
>Subject: Re: [Repeater-Builder]Receiver overload
> 
>David,try using one or two band pass only cavaties in
>the receive side instead of the BpBr type. The BpBr
>filters often do not discriminate against signals far
>off the pass frequency, and you may not be getting
>enough rejection out of your input cavities.
>
>73 - Jim W5ZIT
>
>--- David Epley <[EMAIL PROTECTED] <mailto:depley%40starband.net> net>wrote:
>
>> I have a repeater receiver overload problem I am
>> trying to cure. The
>> repeater is a 900mhz 927.7125/902.7125. There is an
>> FM broadcast station 100
>> yards away 104.9mhz. The repeater works fine at
>> another site. My transmitter
>> is a Motorola Purc 5000 running 75 watts the
>> receiver is a converted maxtrac
>> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
>> have 10 to 12 db
>> degradation when plugged into 3 different antennas
>> on the tower. When I use
>> a 900mhz dish antenna pointed away from broadcast
>> tower I only have 3 db
>> degradation. I have tried 3 different maxtrac
>> receivers, added 2 more BpBr
>> cavities in the receiver side and used 3 pole
>> filters in the receivers with
>> no improvement. Today I looked at the signal level
>> getting to the receiver
>> at 104.9. To my surprise I was getting -8 dbm at the
>> receiver. I believe
>> this level is overloading the front end of my
>> repeater. I was wondering if a
>> stub cut for the broadcast frequency would work. Any
>> thoughts would be
>> greatly appreciated.
>> 
>> 
>> 
>> 
>> 
>> David Epley, N9CZV
>> 
>> Winchester, Indiana
>> 
>> 
>
>__
>Be a better pen pal. 
>Text or chat with friends inside Yahoo! Mail. See how. http://overview.
<http://overview.mail.yahoo.com/> mail.yahoo.com/
> 

Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

 

Re: RE: [Repeater-Builder] Receiver overload

[Ron Wright]

David,

I assume the antenna system at the now location was different than the other 
that worked.

What kind of feedline and antenna???

73, ron, n9ee/r




>From: David Epley <[EMAIL PROTECTED]>
>Date: 2007/11/22 Thu AM 07:32:46 CST
>To: Repeater-Builder@yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload

>  
>
>I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable 
>improvement.
> 
> 
>David  N9CZV
> 
>From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of 
>Jim Brown
>Sent: Thursday, November 22, 20076:13 AM
>To: Repeater-Builder@yahoogroups.com
>Subject: Re: [Repeater-Builder]Receiver overload
> 
>David,try using one or two band pass only cavaties in
>the receive side instead of the BpBr type. The BpBr
>filters often do not discriminate against signals far
>off the pass frequency, and you may not be getting
>enough rejection out of your input cavities.
>
>73 - Jim W5ZIT
>
>--- David Epley <[EMAIL PROTECTED]>wrote:
>
>> I have a repeater receiver overload problem I am
>> trying to cure. The
>> repeater is a 900mhz 927.7125/902.7125. There is an
>> FM broadcast station 100
>> yards away 104.9mhz. The repeater works fine at
>> another site. My transmitter
>> is a Motorola Purc 5000 running 75 watts the
>> receiver is a converted maxtrac
>> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
>> have 10 to 12 db
>> degradation when plugged into 3 different antennas
>> on the tower. When I use
>> a 900mhz dish antenna pointed away from broadcast
>> tower I only have 3 db
>> degradation. I have tried 3 different maxtrac
>> receivers, added 2 more BpBr
>> cavities in the receiver side and used 3 pole
>> filters in the receivers with
>> no improvement. Today I looked at the signal level
>> getting to the receiver
>> at 104.9. To my surprise I was getting -8 dbm at the
>> receiver. I believe
>> this level is overloading the front end of my
>> repeater. I was wondering if a
>> stub cut for the broadcast frequency would work. Any
>> thoughts would be
>> greatly appreciated.
>> 
>> 
>> 
>> 
>> 
>> David Epley, N9CZV
>> 
>> Winchester, Indiana
>> 
>> 
>
>__
>Be a better pen pal. 
>Text or chat with friends inside Yahoo! Mail. See how. 
>http://overview.mail.yahoo.com/
>


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

Re: RE: [Repeater-Builder] Receiver overload

[Ron Wright]

David,

Your problem might be harmonic related.  Might do some calculator work.  I can 
see no muliple of 104.9 related to your 2 frequencies or IF related.

There are other 900 MHz stuff around.  Would be good to get a spectrum analyzer 
on your receiver port, but know spectrum analyzers are not easy to come by.

Might be noise floor emissions from the FM station which could be on your 
receiver input.  Now this one would be a real problem.

73, ron, n9ee/r



>From: David Epley <[EMAIL PROTECTED]>
>Date: 2007/11/22 Thu AM 07:32:46 CST
>To: Repeater-Builder@yahoogroups.com
>Subject: RE: [Repeater-Builder] Receiver overload

>  
>
>I just tried a pair of Celwave 8 inch bandpass cavities with no noticeable 
>improvement.
> 
> 
>David  N9CZV
> 
>From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of 
>Jim Brown
>Sent: Thursday, November 22, 20076:13 AM
>To: Repeater-Builder@yahoogroups.com
>Subject: Re: [Repeater-Builder]Receiver overload
> 
>David,try using one or two band pass only cavaties in
>the receive side instead of the BpBr type. The BpBr
>filters often do not discriminate against signals far
>off the pass frequency, and you may not be getting
>enough rejection out of your input cavities.
>
>73 - Jim W5ZIT
>
>--- David Epley <[EMAIL PROTECTED]>wrote:
>
>> I have a repeater receiver overload problem I am
>> trying to cure. The
>> repeater is a 900mhz 927.7125/902.7125. There is an
>> FM broadcast station 100
>> yards away 104.9mhz. The repeater works fine at
>> another site. My transmitter
>> is a Motorola Purc 5000 running 75 watts the
>> receiver is a converted maxtrac
>> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
>> have 10 to 12 db
>> degradation when plugged into 3 different antennas
>> on the tower. When I use
>> a 900mhz dish antenna pointed away from broadcast
>> tower I only have 3 db
>> degradation. I have tried 3 different maxtrac
>> receivers, added 2 more BpBr
>> cavities in the receiver side and used 3 pole
>> filters in the receivers with
>> no improvement. Today I looked at the signal level
>> getting to the receiver
>> at 104.9. To my surprise I was getting -8 dbm at the
>> receiver. I believe
>> this level is overloading the front end of my
>> repeater. I was wondering if a
>> stub cut for the broadcast frequency would work. Any
>> thoughts would be
>> greatly appreciated.
>> 
>> 
>> 
>> 
>> 
>> David Epley, N9CZV
>> 
>> Winchester, Indiana
>> 
>> 
>
>__
>Be a better pen pal. 
>Text or chat with friends inside Yahoo! Mail. See how. 
>http://overview.mail.yahoo.com/
>


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

RE: [Repeater-Builder] Receiver overload

[David Epley]

I just tried a pair of Celwave 8 inch band pass cavities with no noticeable
improvement.

 

 

David  N9CZV

 

  _  

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Jim Brown
Sent: Thursday, November 22, 2007 6:13 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Receiver overload

 

David, try using one or two band pass only cavaties in
the receive side instead of the BpBr type. The BpBr
filters often do not discriminate against signals far
off the pass frequency, and you may not be getting
enough rejection out of your input cavities.

73 - Jim W5ZIT

--- David Epley <[EMAIL PROTECTED] <mailto:depley%40starband.net> net> wrote:

> I have a repeater receiver overload problem I am
> trying to cure. The
> repeater is a 900mhz 927.7125/902.7125. There is an
> FM broadcast station 100
> yards away 104.9mhz. The repeater works fine at
> another site. My transmitter
> is a Motorola Purc 5000 running 75 watts the
> receiver is a converted maxtrac
> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
> have 10 to 12 db
> degradation when plugged into 3 different antennas
> on the tower. When I use
> a 900mhz dish antenna pointed away from broadcast
> tower I only have 3 db
> degradation. I have tried 3 different maxtrac
> receivers, added 2 more BpBr
> cavities in the receiver side and used 3 pole
> filters in the receivers with
> no improvement. Today I looked at the signal level
> getting to the receiver
> at 104.9. To my surprise I was getting -8 dbm at the
> receiver. I believe
> this level is overloading the front end of my
> repeater. I was wondering if a
> stub cut for the broadcast frequency would work. Any
> thoughts would be
> greatly appreciated.
> 
> 
> 
> 
> 
> David Epley, N9CZV
> 
> Winchester, Indiana
> 
> 

__
Be a better pen pal. 
Text or chat with friends inside Yahoo! Mail. See how. http://overview.
<http://overview.mail.yahoo.com/> mail.yahoo.com/

 

Re: [Repeater-Builder] Receiver overload

[Ron Wright]

David,

As suggested in another post a bandpass cavity might be in order.

You idea of a stub, open ended 1/4 wavelength coax, will probably help.  Just 
have to make sure it don't affect your 900 MHz signal, but would be cheap thing 
to try.

I have 2 m repeater antenna about 100 ft vertically from 2 100 kW ERP, 40 kW 
RF, FM stations.  I have no problem and bet if I sampled on my antenna I would 
have enormous level from them.

If over load from the FM carrier it should be simple to solve.

73, ron, n9ee/r



>From: David Epley <[EMAIL PROTECTED]>
>Date: 2007/11/21 Wed PM 10:03:29 CST
>To: Repeater-Builder@yahoogroups.com
>Subject: [Repeater-Builder] Receiver overload

>  
>
>I have a repeaterreceiver overload problem I am trying to cure. The repeater 
>is a 900mhz927.7125/902.7125. There is an FM broadcast station 100 yards away 
>104.9mhz.The repeater works fine at another site. My transmitter is a Motorola 
>Purc 5000running 75 watts the receiver is a converted maxtrac 800mhz radio. 
>Duplexersare Telwave BpBr 4 cavity. I have 10 to 12 db degradation when 
>plugged into 3different antennas on the tower. When I use a 900mhz dish 
>antenna pointed awayfrom broadcast tower I only have 3 db degradation. I have 
>tried 3 different maxtracreceivers, added 2 more BpBr cavities in the receiver 
>side and used 3 polefilters in the receivers with no improvement. Today I 
>looked at the signallevel getting to the receiver at 104.9. To my surprise I 
>was getting -8 dbm atthe receiver. I believe this level is overloading the 
>front end of my repeater.I was wondering if a stub cut for the broadcast 
>frequency would work. Anythoughts would be greatly appreciated.
> 
> 
>David Epley, N9CZV
>Winchester, Indiana


Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.

Re: [Repeater-Builder] Receiver overload

[Jim Brown]

David, try using one or two band pass only cavaties in
the receive side instead of the BpBr type.  The BpBr
filters often do not discriminate against signals far
off the pass frequency, and you may not be getting
enough rejection out of your input cavities.

73 - Jim  W5ZIT

--- David Epley <[EMAIL PROTECTED]> wrote:

> I have a repeater receiver overload problem I am
> trying to cure. The
> repeater is a 900mhz 927.7125/902.7125. There is an
> FM broadcast station 100
> yards away 104.9mhz. The repeater works fine at
> another site. My transmitter
> is a Motorola Purc 5000 running 75 watts the
> receiver is a converted maxtrac
> 800mhz radio. Duplexers are Telwave BpBr 4 cavity. I
> have 10 to 12 db
> degradation when plugged into 3 different antennas
> on the tower. When I use
> a 900mhz dish antenna pointed away from broadcast
> tower I only have 3 db
> degradation. I have tried 3 different maxtrac
> receivers, added 2 more BpBr
> cavities in the receiver side and used 3 pole
> filters in the receivers with
> no improvement. Today I looked at the signal level
> getting to the receiver
> at 104.9. To my surprise I was getting -8 dbm at the
> receiver. I believe
> this level is overloading the front end of my
> repeater. I was wondering if a
> stub cut for the broadcast frequency would work. Any
> thoughts would be
> greatly appreciated.
> 
>  
> 
>  
> 
> David Epley, N9CZV
> 
> Winchester, Indiana
> 
> 



  

Be a better pen pal. 
Text or chat with friends inside Yahoo! Mail. See how.  
http://overview.mail.yahoo.com/

Re: [Repeater-Builder] Receiver Measurements

[no6b]

At 2/11/2007 16:25, you wrote:

>This discussion about preamps and matching is interesting.
>
>So, what about the return loss of  receivers, you know, the
>ones we all know and love like Mastr II, Micor, UHF, VHF.  Has anyone
>done measurements on these receivers, and how those measurements might
>change with adjustments in helical tuning?
>
>Laryn K8TVZ

W.r.t. receivers with relatively high intrinsic noise figures, tuning for 
best match should yield the lowest noise figure since the high NF is 
usually due to lossy filtering ahead of the 1st active device.

Bob NO6B

RE: [Repeater-Builder] Receiver crystal filter

[Mike Morris WA6ILQ]

Make sure that you have the signal level to use a crystal filter. Some can be
as low as 2db insertion loss, others can be as high as 10db.

At 11:44 AM 11/24/06, you wrote:
>John,
>
>Front-end crystal filters are generally available only up to 200 MHz or
>thereabouts, so you may not find a supplier of such a filter for the 70cm
>band.  Here is one of several sources of crystal filters:
>
>http://www.mtronpti.com/products/index.php?id=65
>
>73, Eric Lemmon WB6FLY
>
>
>-Original Message-
>From: Repeater-Builder@yahoogroups.com
>[mailto:[EMAIL PROTECTED] On Behalf Of johnmichaelwelton
>Sent: Sunday, November 19, 2006 1:19 PM
>To: Repeater-Builder@yahoogroups.com
>Subject: [Repeater-Builder] Receiver crystal filter
>
>Any recommendations for a receiver crystal filter for 2M or 440 repeater
>application?
>
>Thanks, John/N4SJW
>
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>

RE: [Repeater-Builder] Receiver crystal filter

[Eric Lemmon]

John,

Front-end crystal filters are generally available only up to 200 MHz or
thereabouts, so you may not find a supplier of such a filter for the 70cm
band.  Here is one of several sources of crystal filters:

http://www.mtronpti.com/products/index.php?id=65

73, Eric Lemmon WB6FLY


-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of johnmichaelwelton
Sent: Sunday, November 19, 2006 1:19 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Receiver crystal filter

Any recommendations for a receiver crystal filter for 2M or 440 repeater
application?

Thanks, John/N4SJW
 

Re: [Repeater-Builder] Receiver crystal filter

[Glenn Little WB4UIV]

What bandwidth? What insertion loss?

A 150 MHz xtal filter with 6 KHz BW has about 11.5 dB insertion loss.

A 140 MHz xtal filter with 40 KHz BW has about 5 dB insertion loss.

See 

73
Glenn
WB4UIV

At 04:19 PM 11/19/06, you wrote:
>Any recommendations for a receiver crystal filter for 2M or 440
>repeater application?
>
>Thanks, John/N4SJW
>
>
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>

RE: [Repeater-Builder] receiver

[n . mckie]

  Well, first off ... we will need the make and model number 
 of 'that' receiver you are going to use ... 

  Neil - WA6KLA 

 Original Message 
From: [EMAIL PROTECTED]
To: Repeater-Builder@yahoogroups.com
Subject: RE: [Repeater-Builder] receiver
Date: Tue, 23 May 2006 20:25:55 -0400

>I need to hook up a non Motorola receiver to a micor repeater I am
>going 
>to remove the original and want to use the Motorola hang trimmer card
> 
>and timeout timer card need to know were to hook up cos and audio in 
> 
>440 band
>
>
>
>Any help  please
>73
>merrill
>KG4IDD
>
>
>
>
>
>
> 
>Yahoo! Groups Links
>
>
>
> 
>
>






 
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:
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Re: [Repeater-Builder] receiver

[Ken Arck]

At 08:25 PM 5/23/2006 -0400, you wrote:
>I need to hook up a non Motorola receiver to a micor repeater I am going 
>to remove the original..

<--Why are you doing that?

Ken
--
President and CTO - Arcom Communications
Makers of the world famous RC210 Repeater Controller and accessories.
http://www.ah6le.net/arcom/index.html
Authorized Dealers for Kenwood and Telewave and
we offer complete repeater packages!
AH6LE/R - IRLP Node 3000
http://www.irlp.net




 
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/
 

Re: [Repeater-Builder] Receiver Tuning

[Doug Bade]

In a Mastr II if everything is correct, you should perceive no 
difference from [EMAIL PROTECTED] to [EMAIL PROTECTED] I suspect the IF 
alignment 
is off. You do not need a sinnader to check this. Most Mastr II are 
11.2 mhz IF , some are 9.4 Close couple a strong 5kz deviation 
1khz tone at 11.2 Mhz in the IF housing and watch the audio with a 
scope at vol hi.. If it is flat topping on one side or the other, it 
is misalligned, if the sine wave is slanted it is misalligned...

Decrease the rf signal and see if it stays clean down into the 
noise... Obvious distortion will be visible if it is mis tuned..
Assuming the IF is correctly aligned the next likely culprit is the 
rx is off freqThe CORRECT procedure is to set the absolute rx 
freq is to measure the IF injection freq by sticking a probe into the 
mixer area and reading the LO which should be Operating freq -11.2 
mhz ( or 9.4 ).When this is set this way, assuming you can 
generate the proper input on the operating freq, the absolute 
difference is the IF freq which should be processed into symmetrical 
audio at vol hi.

An absolute test to see if the IF is aligned properly is to set the 
freq this way, then inject the operating frq into the rx and monitor 
the vol hi with a scope, if ANY flat topping or unsymetrical image is 
viewed, the IF is misaligned or maybe bad IF xtals

The problem is over time folks mess with the IF and get it 
mis-centered and the only way to correct for this is to change the 
injection freq to compensate..this works to a point until you run 
into the rails of the IF crystal filters which do not moveThe 
proper procedure is to align the rx around a know proper injection 
freq. This is actually the only finite measurable part as the rest is 
all interpretation by ear or by sinnader...( or a scope ).

The Mastr II rx under normal properly tune circumstances should be 
flattening off symmetrically at just above 5khz deviationby 7 is 
should be all but square waves... They key is this should be visibly 
symmetrical as you increase the signal while viewing vol hi on a scope

Vol HI actually does exhibit some distortion normally as it is after 
some filtering.. Any sloping of the sine wave indicates alignment 
issues in the IF...

Doug
KD8B



At 12:44 PM 3/4/2006, you wrote:

>I've noticed that I can get a lot better sensitivity on my receivers if
>the source I'm measuring against is either unmodulated, or I set the
>deviation to 1 or 2 kHz. When I get up to 3-5 kHz deviation, the
>apparent sensitivity of the receiver is significantly less.
>
>I notice this on many systems, where a weak station will be "in" until
>they talk a little louder, then they drop out.
>
>Is there a tuning method I can use to minimize this effect?
>
>
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>






 
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Re: [Repeater-Builder] Receiver Tuning

[Steve]

Hi

This is true, part of the problem maybe it is limiting
due to say being a 12.5Kc and the mobiles are
over deviating, ie, peaking at over 3kc/s or so.
Just a thought.

73

Steve
- Original Message - 
From: "Ralph Mowery" <[EMAIL PROTECTED]>
To: 
Sent: Saturday, March 04, 2006 9:09 PM
Subject: Re: [Repeater-Builder] Receiver Tuning


> 
> 
> --- Steve <[EMAIL PROTECTED]> wrote:
> 
> > Hi
> > 
> > on the rx discriminator is ther a test point ?.
> > You may have to connect a test meter and from a
> > signal generator input a
> > fairly heafty signal and tune the discriminator for
> > either zero or center
> > balance.
> > As a matter of interest what is the rx 25kc or 12.5
> > if 25 then peak dev is +/- 5Kc/s and 12.5 is 2.5Kc/s
> > 
> > 73
> > 
> > Steve
> > 
> Only problem is that many of the receivers now do not
> have a true discriminator that you can tune for a zero
> center.  They use other types of circuits to convert
> the RF to audio. 
> YOu may be able to use an oscilliscope to determin the
> best recovered audio or in some cases an ac voltmeter
> to get the maximum voltage.
> 
> 
> 
> __
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> 
> 
> 
>  
> Yahoo! Groups Links
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> 
> 
>  
> 
> 
> 
> 
> 
> -- 
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> 




 
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Re: [Repeater-Builder] Receiver Tuning

[Ralph Mowery]

--- Steve <[EMAIL PROTECTED]> wrote:

> Hi
> 
> on the rx discriminator is ther a test point ?.
> You may have to connect a test meter and from a
> signal generator input a
> fairly heafty signal and tune the discriminator for
> either zero or center
> balance.
> As a matter of interest what is the rx 25kc or 12.5
> if 25 then peak dev is +/- 5Kc/s and 12.5 is 2.5Kc/s
> 
> 73
> 
> Steve
> 
Only problem is that many of the receivers now do not
have a true discriminator that you can tune for a zero
center.  They use other types of circuits to convert
the RF to audio. 
YOu may be able to use an oscilliscope to determin the
best recovered audio or in some cases an ac voltmeter
to get the maximum voltage.



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Re: [Repeater-Builder] Receiver Tuning

[Steve]

Hi

on the rx discriminator is ther a test point ?.
You may have to connect a test meter and from a signal generator input a
fairly heafty signal and tune the discriminator for either zero or center
balance.
As a matter of interest what is the rx 25kc or 12.5
if 25 then peak dev is +/- 5Kc/s and 12.5 is 2.5Kc/s

73

Steve

- Original Message -
From: "Dave VanHorn" <[EMAIL PROTECTED]>
To: 
Sent: Saturday, March 04, 2006 5:44 PM
Subject: [Repeater-Builder] Receiver Tuning


>
> I've noticed that I can get a lot better sensitivity on my receivers if
> the source I'm measuring against is either unmodulated, or I set the
> deviation to 1 or 2 kHz. When I get up to 3-5 kHz deviation, the
> apparent sensitivity of the receiver is significantly less.
>
> I notice this on many systems, where a weak station will be "in" until
> they talk a little louder, then they drop out.
>
> Is there a tuning method I can use to minimize this effect?
>
>
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.375 / Virus Database: 268.1.2/274 - Release Date: 03/03/06
>
>




 
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RE: [Repeater-Builder] Receiver Tuning

[Eric Lemmon]

Dave,

Depending upon the symmetry of the IF and detector component responses,
there will be a difference in the apparent sensitivity with different
deviation levels.  The operative word is "apparent."  If you intend to use
the receiver for FM voice which averages about 3 kHz deviation, then you
should use the EIA standard method of tuning to 12 dB SINAD with 3.0 kHz
deviation of a 1 kHz tone.  If you optimize the tuning on an unmodulated
test signal, then the receiver's sensitivity to voice modulation will likely
be poorer than it would be if tuned with a modulated signal.

73, Eric Lemmon WB6FLY


-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Dave VanHorn
Sent: Saturday, March 04, 2006 9:45 AM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Receiver Tuning


I've noticed that I can get a lot better sensitivity on my receivers if 
the source I'm measuring against is either unmodulated, or I set the 
deviation to 1 or 2 kHz. When I get up to 3-5 kHz deviation, the 
apparent sensitivity of the receiver is significantly less.  

I notice this on many systems, where a weak station will be "in" until 
they talk a little louder, then they drop out.

Is there a tuning method I can use to minimize this effect?








 
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Re: [Repeater-Builder] Receiver Tuning

[Bob M.]

I thought that's the whole idea behind the SINAD
measurement method, and why it's "so much better" than
the 20dB quieting method.

I figure this reply will elicit all sorts of opinion,
so I'll just sit back and let it fly. We're due for a
heated discussion.

Bob M.
==
--- Dave VanHorn <[EMAIL PROTECTED]> wrote:

> 
> I've noticed that I can get a lot better sensitivity
> on my receivers if 
> the source I'm measuring against is either
> unmodulated, or I set the 
> deviation to 1 or 2 kHz. When I get up to 3-5 kHz
> deviation, the 
> apparent sensitivity of the receiver is
> significantly less.  
> 
> I notice this on many systems, where a weak station
> will be "in" until 
> they talk a little louder, then they drop out.
> 
> Is there a tuning method I can use to minimize this
> effect?

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RE: [Repeater-Builder]Receiver ant splitter

[Clarke, Tom VX-20 OPS]

Recently someone was looking for a splitter to operate several UHF rxs from one 
antenna.  I stumbled upon a DB products 4 port divider (400-512MHz) in a recent 
garage cleanup spree.  I don't have the model number handy, but if you are 
interested I can look at it tonight and send an email.  Includes a couple of 50 
ohm terminations.  $25 shipped.

Other gems: 

An 8 port splitter which is equipped with a preamp ahead. $ 25 shipped.

Also available is a 2 port Tx UHF combiner by DB.  Currently tuned to 419 MHz.  
Contains 2 cavities, 2 circulators and 2 dummy loads all in a 19 inch rack 
panel with N connectors. $100 obo.

73 de Tom/W4OKW




 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Jim B.]

Mike WA6ILQ wrote:

> I like the idea but I'd use a parked mobile instead.  HT's are hand held 
> and can
> be moved which will change the signal level, plus they pull 3/4 to 1amp from
> the batteries and can suck them down, which also changes the signal level.
> The use of a parked mobile - set to the lowest power level it can do - 
> eliminates
> both factors from the equation.
> 
> Mike WA6ILQ
> 

I use my Kenwood G-71 at what they call 'extra-low' power-about 60-75mW, 
with no antenna. At that power level, reflected power isn't likely to do 
much damage, since there's probably that much or more with the duck on 
high power. But yes, you do have a problem with movement with a handheld.

-- 
Jim Barbour
WD8CHL





 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Mathew Quaife]

Will give that a try tomorrow and see if it is the same and take it from
there.  I'm almost betting it is the Handhelds with the elevated pl tone
output.  Going to have to give another stab at making an iso tee to work
with.  Thanks for the input.  Will let you know how it comes out.

Mathew


> You want the user to be a bit noisy when you do that test. If you then
turn
> your repeater TX on and nothing changes, you don't have desense.
>
> Chuck
> WB2EDV
>
>
>
> - Original Message -
> From: "Mathew Quaife" <[EMAIL PROTECTED]>
> To: 
> Sent: Monday, July 26, 2004 10:48 PM
> Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through
> Duplexer
>
>
> > That I can do, I have another antenna that is up that I can hook to the
> SM.
> > From what I can tell I am not getting any desence, as I did have one
> > operator about 25 miles away, listening through the receiver ouput, I
> could
> > here him just fine and that was with the repeat mode turned off.  He
would
> > talk, and I would key up the transmitter, nothing would change.  I'm
> leading
> > it back to the PL area, as was mentioned, I think it is killing the PL
as
> > they talk.  I just want to make sure the duplexer is tuned up properly
and
> > all is working there.  If its the PL, and is coming from the handie
> talkie,
> > not much I can do there.
> >
> >
> > > Mathew,
> > >
> > >
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>





 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Chuck Kelsey]

You want the user to be a bit noisy when you do that test. If you then turn
your repeater TX on and nothing changes, you don't have desense.

Chuck
WB2EDV



- Original Message - 
From: "Mathew Quaife" <[EMAIL PROTECTED]>
To: 
Sent: Monday, July 26, 2004 10:48 PM
Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through
Duplexer


> That I can do, I have another antenna that is up that I can hook to the
SM.
> From what I can tell I am not getting any desence, as I did have one
> operator about 25 miles away, listening through the receiver ouput, I
could
> here him just fine and that was with the repeat mode turned off.  He would
> talk, and I would key up the transmitter, nothing would change.  I'm
leading
> it back to the PL area, as was mentioned, I think it is killing the PL as
> they talk.  I just want to make sure the duplexer is tuned up properly and
> all is working there.  If its the PL, and is coming from the handie
talkie,
> not much I can do there.
>
>
> > Mathew,
> >
> >






 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Mathew Quaife]

That I can do, I have another antenna that is up that I can hook to the SM.
>From what I can tell I am not getting any desence, as I did have one
operator about 25 miles away, listening through the receiver ouput, I could
here him just fine and that was with the repeat mode turned off.  He would
talk, and I would key up the transmitter, nothing would change.  I'm leading
it back to the PL area, as was mentioned, I think it is killing the PL as
they talk.  I just want to make sure the duplexer is tuned up properly and
all is working there.  If its the PL, and is coming from the handie talkie,
not much I can do there.


> Mathew,
>
> No, you should not disturb any of the hookups between your duplexer and
> antenna, transmitter, or receiver.  What I meant by a "separate antenna"
> is one connected to the output of your service monitor, and which
> radiates a signal that is picked up by your repeater antenna.
>
> This method will prove or disprove whether desense is caused by your own
> transmitter.  It will also enable you to determine if desense is being
> caused by a nearby transmitter on a different frequency, if the SINAD
> reading suddenly drops while your repeater transmitter is disabled.  If
> this happens, you can use a spectrum analyzer to sweep the band several
> MHz each side of your receiver frequency and note what carriers are
> present at the same time your SINAD drops.  As I noted in a previous
> posting, a bandpass filter may be needed to eliminate desense caused by
> a nearby transmitter.
>
> 73, Eric Lemmon WB6FLY
>
> Mathew Quaife wrote:
> >
> > Could I get by using a separate antenna to test for desense?  Say
leaving
> > the antenna for the receiver through the duplexer and hooking the
> > transmitter up to another antenna, would that work the same to test for
> > desense.  I tried to make an iso-tee, did not have real good luck with
it,
> > but then as far as a machinist, I have no luck at that, hihi
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>





 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Mathew Quaife]

Actually the repeater is here at my home qth, only other transmitter is a
460 commercial repeater about 2 miles away, do don't think I am getting any
problems from that one.

Mathew

- Original Message -
From: "Mike WA6ILQ" <[EMAIL PROTECTED]>
To: 
Sent: Monday, July 26, 2004 7:33 PM
Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through
Duplexer


> Forgot to mention one thing - you don't even need to visit the site
> if the repeater has an autopatch (or even a remote base that is on
> a different band) you can listen to the RX via the patch or remote
> and let the main channel TX time out.  If the quieting level in the
> RX goes up exactly when the TX drops off that indicates a problem.
>
> Mike WA6ILQ
>
> At 07:14 PM 7/26/04, you wrote:
>
> >I like the idea but I'd use a parked mobile instead.  HT's are hand held
> >and can
> >be moved which will change the signal level, plus they pull 3/4 to 1amp
from
> >the batteries and can suck them down, which also changes the signal
level.
> >The use of a parked mobile - set to the lowest power level it can do -
> >eliminates
> >both factors from the equation.
> >
> >Mike WA6ILQ
> >
> >At 06:57 PM 7/26/04, you wrote:
> >
> > >Here's one simple test. Have someone with an HT get into a noisy
location,
> > >then disable your repeater transmitter while listening on the local
speaker.
> > >If all of a sudden the HT becomes full quieting, you've got a desense
> > >problem.
> > >
> > >Chuck
> > >WB2EDV
> > >
> > >
> > >
> > >- Original Message -
> > >From: "w9mwq" <[EMAIL PROTECTED]>
> > >To: 
> > >Sent: Monday, July 26, 2004 8:01 PM
> > >Subject: [Repeater-Builder] Receiver Sensitivity Testing Through
Duplexer
> > >
> > >
> > > > I need a little advise here.  I want to test my repeater's
> > > > sensitivity through the duplexer's while the transmitter is keyed
> > > > up, into my Cushman Service Monitor.  What is the best method of
> > > > doing this?  Do I need an isolator of some sort, or will the service
> > > > monitor handle both the incoming power and the outgoing signal
> > > > generator?  It's a Cushman 6030 by the way.  The repeater is working
> > > > excellent for the most part.  The problem that I am having is on
> > > > weak signals, the audio is being chopped out, almost like the PL
> > > > deck is shutting down.  On the bench, the receiver is at about .25
> > > > microvolts sensitivity at 12 DB Sinad.  Audio out of the transmitter
> > > > is about 4KHz wide, and clean at 100 watts.  Any suggestions.
> > > > Handhelds are able to get in from about 4 miles away, mobiles have
> > > > no troubles at 30 miles away.  The antenna is only up at 60' right
> > > > now, fed with 120' of 7/8" Andrews hardline.  But it seems the
> > > > handhelds are the one's having the problems, and their signal is not
> > > > really that bad.  Help please.
> > > >
> > > > Mathew
> > > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >Yahoo! Groups Links
> > >
> > >
> > >
> > >
> >
> >
> >
> >
> >
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>





 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Eric Lemmon]

Mathew,

No, you should not disturb any of the hookups between your duplexer and
antenna, transmitter, or receiver.  What I meant by a "separate antenna"
is one connected to the output of your service monitor, and which
radiates a signal that is picked up by your repeater antenna.

This method will prove or disprove whether desense is caused by your own
transmitter.  It will also enable you to determine if desense is being
caused by a nearby transmitter on a different frequency, if the SINAD
reading suddenly drops while your repeater transmitter is disabled.  If
this happens, you can use a spectrum analyzer to sweep the band several
MHz each side of your receiver frequency and note what carriers are
present at the same time your SINAD drops.  As I noted in a previous
posting, a bandpass filter may be needed to eliminate desense caused by
a nearby transmitter.

73, Eric Lemmon WB6FLY

Mathew Quaife wrote:
> 
> Could I get by using a separate antenna to test for desense?  Say leaving
> the antenna for the receiver through the duplexer and hooking the
> transmitter up to another antenna, would that work the same to test for
> desense.  I tried to make an iso-tee, did not have real good luck with it,
> but then as far as a machinist, I have no luck at that, hihi




 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Mike WA6ILQ]

Forgot to mention one thing - you don't even need to visit the site
if the repeater has an autopatch (or even a remote base that is on
a different band) you can listen to the RX via the patch or remote
and let the main channel TX time out.  If the quieting level in the
RX goes up exactly when the TX drops off that indicates a problem.

Mike WA6ILQ

At 07:14 PM 7/26/04, you wrote:

>I like the idea but I'd use a parked mobile instead.  HT's are hand held
>and can
>be moved which will change the signal level, plus they pull 3/4 to 1amp from
>the batteries and can suck them down, which also changes the signal level.
>The use of a parked mobile - set to the lowest power level it can do -
>eliminates
>both factors from the equation.
>
>Mike WA6ILQ
>
>At 06:57 PM 7/26/04, you wrote:
>
> >Here's one simple test. Have someone with an HT get into a noisy location,
> >then disable your repeater transmitter while listening on the local speaker.
> >If all of a sudden the HT becomes full quieting, you've got a desense
> >problem.
> >
> >Chuck
> >WB2EDV
> >
> >
> >
> >- Original Message -
> >From: "w9mwq" <[EMAIL PROTECTED]>
> >To: 
> >Sent: Monday, July 26, 2004 8:01 PM
> >Subject: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
> >
> >
> > > I need a little advise here.  I want to test my repeater's
> > > sensitivity through the duplexer's while the transmitter is keyed
> > > up, into my Cushman Service Monitor.  What is the best method of
> > > doing this?  Do I need an isolator of some sort, or will the service
> > > monitor handle both the incoming power and the outgoing signal
> > > generator?  It's a Cushman 6030 by the way.  The repeater is working
> > > excellent for the most part.  The problem that I am having is on
> > > weak signals, the audio is being chopped out, almost like the PL
> > > deck is shutting down.  On the bench, the receiver is at about .25
> > > microvolts sensitivity at 12 DB Sinad.  Audio out of the transmitter
> > > is about 4KHz wide, and clean at 100 watts.  Any suggestions.
> > > Handhelds are able to get in from about 4 miles away, mobiles have
> > > no troubles at 30 miles away.  The antenna is only up at 60' right
> > > now, fed with 120' of 7/8" Andrews hardline.  But it seems the
> > > handhelds are the one's having the problems, and their signal is not
> > > really that bad.  Help please.
> > >
> > > Mathew
> > >
> >
> >
> >
> >
> >
> >
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>





 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Mathew Quaife]

Ok, looks like I need to get the Iso-tee made then.

Mathew

- Original Message -
From: "Chuck Kelsey" <[EMAIL PROTECTED]>
To: 
Sent: Monday, July 26, 2004 7:25 PM
Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through
Duplexer


> No.
>
>
>
> - Original Message -
> From: "Mathew Quaife" <[EMAIL PROTECTED]>
> To: 
> Sent: Monday, July 26, 2004 10:17 PM
> Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through
> Duplexer
>
>
> > Could I get by using a seperate antenna to test for desense?  Say
leaving
> > the antenna for the receiver through the duplexer and hooking the
> > transmitter up to another antenna, would that work the same to test for
> > desense.  I tried to make an iso-tee, did not heave real good luck with
> it,
> > but then as far as a machinest, I have to luck at that, hihi
> >
> > Mathew
> >
> > - Original Message -
> > From: "Eric Lemmon" <[EMAIL PROTECTED]>
> > To: 
> > Sent: Monday, July 26, 2004 6:09 PM
> > Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through
> > Duplexer
> >
> >
> > > Mathew,
> > >
> > > There may be more than one problem to consider.  It is wise to check
for
> > > desense, but also be aware that some amateur-grade handhelds are
> > > notorious for excessive PL deviation.  Alincos are the worst, in my
> > > opinion.  My DJ-S11T had 1400 Hz of PL deviation out of the box, when
> > > 400-700 Hz is ideal.  When a commercial-grade repeater (MICOR, GE,
etc.)
> > > receives an input from a user with excessive PL deviation, the user's
> > > voice may over-deviate the carrier, causing the PL to be clipped.
When
> > > this happens on a PL-required repeater, the repeater shuts down on
voice
> > > peaks.  Of course, this symptom is made much worse when the voice
> > > deviation is too high, as well.  One way to check this is to use a
> > > commercial-grade handheld radio to check for the same symptoms.
> > >
> > > To check for desense, you can use an "iso-tee" to inject a low-level
> > > signal into the antenna feedline at the receiver frequency, while
> > > monitoring the receiver audio at 12 dB SINAD with the repeater
> > > disabled.  Then enable the repeater so that the transmitter turns on.
> > > The SINAD reading should drop no more than 1 dB.  Some service
monitors
> > > will change modes when RF is detected, so you may want to use a
separate
> > > antenna, instead of the iso-tee, to get the test signal into the
> > > receiver.
> > >
> > > If your repeater is at a site with other transmitters, you may need to
> > > add some bandpass-only (NOT pass/notch) cavities between the duplexer
> > > and the receiver input.  As has been noted many times on this list, a
> > > pass/notch or "BpBr" duplexer has almost no bandpass selectivity, and
a
> > > nearby transmitter many MHz away can easily cause desense in your
> > > receiver if not filtered out with a dedicated bandpass cavity.
> > >
> > > 73, Eric Lemmon WB6FLY
> > >
> > > w9mwq wrote:
> > > >
> > > > I need a little advice here.  I want to test my repeater's
sensitivity
> > through the duplexer, while the transmitter is keyed up, into my Cushman
> > Service Monitor.  What is the best method of doing this?  Do I need an
> > isolator of some sort, or will the service monitor handle both the
> incoming
> > power and the outgoing signal
> > > > generator?  It's a Cushman 6030 by the way.  The repeater is working
> > excellent for the most part.  The problem that I am having is on weak
> > signals, the audio is being chopped out, almost like the PL deck is
> shutting
> > down.  On the bench, the receiver is at about .25 microvolts sensitivity
> at
> > 12 dB Sinad.  Audio out of the transmitter
> > > > is about 4 kHz wide, and clean at 100 watts.  Any suggestions?
> > Handhelds are able to get in from about 4 miles away, mobiles have no
> > troubles at 30 miles away.  The antenna is only up at 60' right now, fed
> > with 120' of 7/8" Andrews hardline.  But it seems the handhelds are the
> ones
> > having the problems, and their signal is not really that bad.  Help
> please.
> > >
> > >
> > >
> > >
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
>
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>





 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Chuck Kelsey]

No.



- Original Message - 
From: "Mathew Quaife" <[EMAIL PROTECTED]>
To: 
Sent: Monday, July 26, 2004 10:17 PM
Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through
Duplexer


> Could I get by using a seperate antenna to test for desense?  Say leaving
> the antenna for the receiver through the duplexer and hooking the
> transmitter up to another antenna, would that work the same to test for
> desense.  I tried to make an iso-tee, did not heave real good luck with
it,
> but then as far as a machinest, I have to luck at that, hihi
>
> Mathew
>
> - Original Message -
> From: "Eric Lemmon" <[EMAIL PROTECTED]>
> To: 
> Sent: Monday, July 26, 2004 6:09 PM
> Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through
> Duplexer
>
>
> > Mathew,
> >
> > There may be more than one problem to consider.  It is wise to check for
> > desense, but also be aware that some amateur-grade handhelds are
> > notorious for excessive PL deviation.  Alincos are the worst, in my
> > opinion.  My DJ-S11T had 1400 Hz of PL deviation out of the box, when
> > 400-700 Hz is ideal.  When a commercial-grade repeater (MICOR, GE, etc.)
> > receives an input from a user with excessive PL deviation, the user's
> > voice may over-deviate the carrier, causing the PL to be clipped.  When
> > this happens on a PL-required repeater, the repeater shuts down on voice
> > peaks.  Of course, this symptom is made much worse when the voice
> > deviation is too high, as well.  One way to check this is to use a
> > commercial-grade handheld radio to check for the same symptoms.
> >
> > To check for desense, you can use an "iso-tee" to inject a low-level
> > signal into the antenna feedline at the receiver frequency, while
> > monitoring the receiver audio at 12 dB SINAD with the repeater
> > disabled.  Then enable the repeater so that the transmitter turns on.
> > The SINAD reading should drop no more than 1 dB.  Some service monitors
> > will change modes when RF is detected, so you may want to use a separate
> > antenna, instead of the iso-tee, to get the test signal into the
> > receiver.
> >
> > If your repeater is at a site with other transmitters, you may need to
> > add some bandpass-only (NOT pass/notch) cavities between the duplexer
> > and the receiver input.  As has been noted many times on this list, a
> > pass/notch or "BpBr" duplexer has almost no bandpass selectivity, and a
> > nearby transmitter many MHz away can easily cause desense in your
> > receiver if not filtered out with a dedicated bandpass cavity.
> >
> > 73, Eric Lemmon WB6FLY
> >
> > w9mwq wrote:
> > >
> > > I need a little advice here.  I want to test my repeater's sensitivity
> through the duplexer, while the transmitter is keyed up, into my Cushman
> Service Monitor.  What is the best method of doing this?  Do I need an
> isolator of some sort, or will the service monitor handle both the
incoming
> power and the outgoing signal
> > > generator?  It's a Cushman 6030 by the way.  The repeater is working
> excellent for the most part.  The problem that I am having is on weak
> signals, the audio is being chopped out, almost like the PL deck is
shutting
> down.  On the bench, the receiver is at about .25 microvolts sensitivity
at
> 12 dB Sinad.  Audio out of the transmitter
> > > is about 4 kHz wide, and clean at 100 watts.  Any suggestions?
> Handhelds are able to get in from about 4 miles away, mobiles have no
> troubles at 30 miles away.  The antenna is only up at 60' right now, fed
> with 120' of 7/8" Andrews hardline.  But it seems the handhelds are the
ones
> having the problems, and their signal is not really that bad.  Help
please.
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>






 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Mathew Quaife]

Very true indeed.  I'm thinking it may be a combination of two things.
First the handhelds are clipping the PL, I have a commercial Vertex HT, and
it does not do it with that, but then I have mine turned down to about 400
Hertz.  I'm sure the duplexers were tuned properly, as they were done by a
service shop before being shipped, they are TXRX.

Mathew


> I like the idea but I'd use a parked mobile instead.  HT's are hand held
> and can
> be moved which will change the signal level, plus they pull 3/4 to 1amp
from
> the batteries and can suck them down, which also changes the signal level.
> The use of a parked mobile - set to the lowest power level it can do -
> eliminates
> both factors from the equation.
>
> Mike WA6ILQ
>
> At 06:57 PM 7/26/04, you wrote:
>
> >Here's one simple test. Have someone with an HT get into a noisy
location,
> >then disable your repeater transmitter while listening on the local
speaker.
> >If all of a sudden the HT becomes full quieting, you've got a desense
> >problem.
> >
> >Chuck
> >WB2EDV
> >
> >
> >
> >- Original Message -
> >From: "w9mwq" <[EMAIL PROTECTED]>
> >To: 
> >Sent: Monday, July 26, 2004 8:01 PM
> >Subject: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
> >
> >
> > > I need a little advise here.  I want to test my repeater's
> > > sensitivity through the duplexer's while the transmitter is keyed
> > > up, into my Cushman Service Monitor.  What is the best method of
> > > doing this?  Do I need an isolator of some sort, or will the service
> > > monitor handle both the incoming power and the outgoing signal
> > > generator?  It's a Cushman 6030 by the way.  The repeater is working
> > > excellent for the most part.  The problem that I am having is on
> > > weak signals, the audio is being chopped out, almost like the PL
> > > deck is shutting down.  On the bench, the receiver is at about .25
> > > microvolts sensitivity at 12 DB Sinad.  Audio out of the transmitter
> > > is about 4KHz wide, and clean at 100 watts.  Any suggestions.
> > > Handhelds are able to get in from about 4 miles away, mobiles have
> > > no troubles at 30 miles away.  The antenna is only up at 60' right
> > > now, fed with 120' of 7/8" Andrews hardline.  But it seems the
> > > handhelds are the one's having the problems, and their signal is not
> > > really that bad.  Help please.
> > >
> > > Mathew
> > >
> >
> >
> >
> >
> >
> >
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>





 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Mathew Quaife]

Could I get by using a seperate antenna to test for desense?  Say leaving
the antenna for the receiver through the duplexer and hooking the
transmitter up to another antenna, would that work the same to test for
desense.  I tried to make an iso-tee, did not heave real good luck with it,
but then as far as a machinest, I have to luck at that, hihi

Mathew

- Original Message -
From: "Eric Lemmon" <[EMAIL PROTECTED]>
To: 
Sent: Monday, July 26, 2004 6:09 PM
Subject: Re: [Repeater-Builder] Receiver Sensitivity Testing Through
Duplexer


> Mathew,
>
> There may be more than one problem to consider.  It is wise to check for
> desense, but also be aware that some amateur-grade handhelds are
> notorious for excessive PL deviation.  Alincos are the worst, in my
> opinion.  My DJ-S11T had 1400 Hz of PL deviation out of the box, when
> 400-700 Hz is ideal.  When a commercial-grade repeater (MICOR, GE, etc.)
> receives an input from a user with excessive PL deviation, the user's
> voice may over-deviate the carrier, causing the PL to be clipped.  When
> this happens on a PL-required repeater, the repeater shuts down on voice
> peaks.  Of course, this symptom is made much worse when the voice
> deviation is too high, as well.  One way to check this is to use a
> commercial-grade handheld radio to check for the same symptoms.
>
> To check for desense, you can use an "iso-tee" to inject a low-level
> signal into the antenna feedline at the receiver frequency, while
> monitoring the receiver audio at 12 dB SINAD with the repeater
> disabled.  Then enable the repeater so that the transmitter turns on.
> The SINAD reading should drop no more than 1 dB.  Some service monitors
> will change modes when RF is detected, so you may want to use a separate
> antenna, instead of the iso-tee, to get the test signal into the
> receiver.
>
> If your repeater is at a site with other transmitters, you may need to
> add some bandpass-only (NOT pass/notch) cavities between the duplexer
> and the receiver input.  As has been noted many times on this list, a
> pass/notch or "BpBr" duplexer has almost no bandpass selectivity, and a
> nearby transmitter many MHz away can easily cause desense in your
> receiver if not filtered out with a dedicated bandpass cavity.
>
> 73, Eric Lemmon WB6FLY
>
> w9mwq wrote:
> >
> > I need a little advice here.  I want to test my repeater's sensitivity
through the duplexer, while the transmitter is keyed up, into my Cushman
Service Monitor.  What is the best method of doing this?  Do I need an
isolator of some sort, or will the service monitor handle both the incoming
power and the outgoing signal
> > generator?  It's a Cushman 6030 by the way.  The repeater is working
excellent for the most part.  The problem that I am having is on weak
signals, the audio is being chopped out, almost like the PL deck is shutting
down.  On the bench, the receiver is at about .25 microvolts sensitivity at
12 dB Sinad.  Audio out of the transmitter
> > is about 4 kHz wide, and clean at 100 watts.  Any suggestions?
Handhelds are able to get in from about 4 miles away, mobiles have no
troubles at 30 miles away.  The antenna is only up at 60' right now, fed
with 120' of 7/8" Andrews hardline.  But it seems the handhelds are the ones
having the problems, and their signal is not really that bad.  Help please.
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>





 
Yahoo! Groups Links

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http://groups.yahoo.com/group/Repeater-Builder/

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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Mike WA6ILQ]

I like the idea but I'd use a parked mobile instead.  HT's are hand held 
and can
be moved which will change the signal level, plus they pull 3/4 to 1amp from
the batteries and can suck them down, which also changes the signal level.
The use of a parked mobile - set to the lowest power level it can do - 
eliminates
both factors from the equation.

Mike WA6ILQ

At 06:57 PM 7/26/04, you wrote:

>Here's one simple test. Have someone with an HT get into a noisy location,
>then disable your repeater transmitter while listening on the local speaker.
>If all of a sudden the HT becomes full quieting, you've got a desense
>problem.
>
>Chuck
>WB2EDV
>
>
>
>- Original Message -
>From: "w9mwq" <[EMAIL PROTECTED]>
>To: 
>Sent: Monday, July 26, 2004 8:01 PM
>Subject: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer
>
>
> > I need a little advise here.  I want to test my repeater's
> > sensitivity through the duplexer's while the transmitter is keyed
> > up, into my Cushman Service Monitor.  What is the best method of
> > doing this?  Do I need an isolator of some sort, or will the service
> > monitor handle both the incoming power and the outgoing signal
> > generator?  It's a Cushman 6030 by the way.  The repeater is working
> > excellent for the most part.  The problem that I am having is on
> > weak signals, the audio is being chopped out, almost like the PL
> > deck is shutting down.  On the bench, the receiver is at about .25
> > microvolts sensitivity at 12 DB Sinad.  Audio out of the transmitter
> > is about 4KHz wide, and clean at 100 watts.  Any suggestions.
> > Handhelds are able to get in from about 4 miles away, mobiles have
> > no troubles at 30 miles away.  The antenna is only up at 60' right
> > now, fed with 120' of 7/8" Andrews hardline.  But it seems the
> > handhelds are the one's having the problems, and their signal is not
> > really that bad.  Help please.
> >
> > Mathew
> >
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>
>





 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Chuck Kelsey]

Here's one simple test. Have someone with an HT get into a noisy location,
then disable your repeater transmitter while listening on the local speaker.
If all of a sudden the HT becomes full quieting, you've got a desense
problem.

Chuck
WB2EDV



- Original Message - 
From: "w9mwq" <[EMAIL PROTECTED]>
To: 
Sent: Monday, July 26, 2004 8:01 PM
Subject: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer


> I need a little advise here.  I want to test my repeater's
> sensitivity through the duplexer's while the transmitter is keyed
> up, into my Cushman Service Monitor.  What is the best method of
> doing this?  Do I need an isolator of some sort, or will the service
> monitor handle both the incoming power and the outgoing signal
> generator?  It's a Cushman 6030 by the way.  The repeater is working
> excellent for the most part.  The problem that I am having is on
> weak signals, the audio is being chopped out, almost like the PL
> deck is shutting down.  On the bench, the receiver is at about .25
> microvolts sensitivity at 12 DB Sinad.  Audio out of the transmitter
> is about 4KHz wide, and clean at 100 watts.  Any suggestions.
> Handhelds are able to get in from about 4 miles away, mobiles have
> no troubles at 30 miles away.  The antenna is only up at 60' right
> now, fed with 120' of 7/8" Andrews hardline.  But it seems the
> handhelds are the one's having the problems, and their signal is not
> really that bad.  Help please.
>
> Mathew
>






 
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Re: [Repeater-Builder] Receiver Sensitivity Testing Through Duplexer

[Eric Lemmon]

Mathew,

There may be more than one problem to consider.  It is wise to check for
desense, but also be aware that some amateur-grade handhelds are
notorious for excessive PL deviation.  Alincos are the worst, in my
opinion.  My DJ-S11T had 1400 Hz of PL deviation out of the box, when
400-700 Hz is ideal.  When a commercial-grade repeater (MICOR, GE, etc.)
receives an input from a user with excessive PL deviation, the user's
voice may over-deviate the carrier, causing the PL to be clipped.  When
this happens on a PL-required repeater, the repeater shuts down on voice
peaks.  Of course, this symptom is made much worse when the voice
deviation is too high, as well.  One way to check this is to use a
commercial-grade handheld radio to check for the same symptoms.

To check for desense, you can use an "iso-tee" to inject a low-level
signal into the antenna feedline at the receiver frequency, while
monitoring the receiver audio at 12 dB SINAD with the repeater
disabled.  Then enable the repeater so that the transmitter turns on. 
The SINAD reading should drop no more than 1 dB.  Some service monitors
will change modes when RF is detected, so you may want to use a separate
antenna, instead of the iso-tee, to get the test signal into the
receiver.

If your repeater is at a site with other transmitters, you may need to
add some bandpass-only (NOT pass/notch) cavities between the duplexer
and the receiver input.  As has been noted many times on this list, a
pass/notch or "BpBr" duplexer has almost no bandpass selectivity, and a
nearby transmitter many MHz away can easily cause desense in your
receiver if not filtered out with a dedicated bandpass cavity.

73, Eric Lemmon WB6FLY

w9mwq wrote:
> 
> I need a little advice here.  I want to test my repeater's sensitivity 
> through the duplexer, while the transmitter is keyed up, into my Cushman 
> Service Monitor.  What is the best method of doing this?  Do I need an 
> isolator of some sort, or will the service monitor handle both the incoming 
> power and the outgoing signal
> generator?  It's a Cushman 6030 by the way.  The repeater is working 
> excellent for the most part.  The problem that I am having is on weak 
> signals, the audio is being chopped out, almost like the PL deck is shutting 
> down.  On the bench, the receiver is at about .25 microvolts sensitivity at 
> 12 dB Sinad.  Audio out of the transmitter
> is about 4 kHz wide, and clean at 100 watts.  Any suggestions?  Handhelds are 
> able to get in from about 4 miles away, mobiles have no troubles at 30 miles 
> away.  The antenna is only up at 60' right now, fed with 120' of 7/8" Andrews 
> hardline.  But it seems the handhelds are the ones having the problems, and 
> their signal is not really that bad.  Help please.




 
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RE: [Repeater-Builder] Receiver Sensitivity

[Joe LaGanga]

It is receiver "A"

Thank you
Joe
 

I find television very educating. Every time somebody turns on the set, I go
into the other room and read a book.

-- Groucho Marx, 1890-1977 

-Original Message-
From: dy3lmk143_13mhz [mailto:[EMAIL PROTECTED] 
Sent: Monday, April 19, 2004 8:05 AM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Receiver Sensitivity

If I have two receivers A and B. Receiver A has a sensitivity of 
0.25uV for a 12dB SINAD and Receiver B has a 0.35uV, which has a 
better sensitivity? is it Receiver A?





 
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Re: [Repeater-Builder] Receiver Sensitivity

[Eric Lemmon]

If the value for Receiver B is also based upon a 12dB SINAD, yes,
Receiver A is more sensitive.  Expressed another way, Receiver B
requires 40% more signal than Receiver A to achieve the same degree of
quieting.  Even so, a value of 0.35uV for 12dB SINAD is satisfactory for
most applications.

73, Eric Lemmon WB6FLY

dy3lmk143_13mhz wrote:
> 
> If I have two receivers A and B. Receiver A has a sensitivity of
> 0.25uV for a 12dB SINAD and Receiver B has a 0.35uV, which has a
> better sensitivity? is it Receiver A?
> 
> 
> Yahoo! Groups Links
> 
> 
> 
>




 
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Re: [Repeater-Builder] Receiver Sensitivity

[Tedd Doda]

On Mon, 19 Apr 2004 12:05:19 -, dy3lmk143_13mhz wrote:

>is it Receiver A?

If they were both measured at 12dB Sinad, yes.

The lower the number means that it takes less
signal to achieve the required spec (12dB Sinad)



Tedd Doda, VE3TJD

Lazer Audio and Electronics
Baden, Ontario, Canada







 
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