Re: [Repeater-Builder] Re: Rolling Pipe Sound

[WA3GIN]

I have a wav (3Meg) file of the "rolling pipe" sound.  What is the best way to 
get it to those that want to listen to it?

73,
dave
wa3gin
  - Original Message - 
  From: Facility 406 DM09 
  To: Repeater-Builder@yahoogroups.com 
  Sent: Monday, December 07, 2009 9:39 PM
  Subject: Re: [Repeater-Builder] Re: Rolling Pipe Sound



  I don't think I've ever heard a "rolling pipe" sound over a repeater,
  although, once I had some interesting feedback from an SSB transmitter with
  FM receiver.

  Is there a good clean recording available?

Re: [Repeater-Builder] Re: Rolling Pipe Sound

[Mel Swanberg]

I recently located a very similar problem on a T-band public safety system, 
only in this case, it was two transmitters in a 28 channel 800 MHz trunker that 
were exactly 3 MHz apart that added that critical component to the mix. The end 
result was that every t-band repeater at that site would add it's own 
transmitter to the mix component, and would cause a feedback howl that could 
best be described as "a rolling pipe". 

Adding to the confusion in finding it, it would hit the various t-band channels 
in what seemed like a random fashion. It wasn't until later that I realized 
what was happening is, the combination of activity on any particular T-band 
receiver would cause it's associated transmitter to activate (obviously!), and 
if the two 800 MHz transmitters in question were active at that time, the 
howling noise would start up. If the other repeaters were quiet, they would 
STAY quiet. 

Cross coding the PL's between your own transmitter and receiver can help mask 
the symptom, because your own transmitter may end up providing the PL (or DPL, 
as the case may be) needed to open the receiver. Depending on where the mix is 
actually taking place, you may or may not be able to locate it and actually fix 
it. In that case, masking it becomes the necessary solution. 

In my case, the mix is pervasive throughout the site - including miles of rusty 
chain link fence. Removing the Angle Linear preamp eliminated the symptom, but 
only because, since the mix product is a pretty low level, it's making the 
receivers sensitive enough to hear what's always there.

Mel - WA6JBD 

--- On Mon, 12/7/09, larynl2  wrote:

> From: larynl2 
> Subject: [Repeater-Builder] Re: Rolling Pipe Sound
> To: Repeater-Builder@yahoogroups.com
> Date: Monday, December 7, 2009, 7:49 PM
> 
> Do you have two FM stations in your area that are separated
> by 600 kc.?  That will definitely do exactly what you
> describe.  We had it on our repeater.
> 
> I caught in one of your posts that your transmitter needs
> to be on for the problem to appear, so that's intermod
> causing your interference, not just a random carrier coming
> from a router or whatever device.
> 
> The problem here was caused by an FM station on 89.9 about
> a mile away, and another one on 89.3 roughly six miles away,
> plus our transmitter on 147.06.  A+B-C=D 147.06 + 89.9
> - 89.3 = 147.66.  The thing to watch for with FM
> broadcast intermod is the wide bandwidth of the intermod
> product.  There was no interference until BOTH stations
> were quiet -- no modulation.  Obviously, the instances
> of both being quiet simultaneously are quite random in
> length and occurrence, depending on the program material of
> each.  
> 
> I tracked the location of the mixing with the aid of a
> spectrum analyzer, which turned out to be safety cables
> threaded through the turnbuckles.
> 
> Laryn K8TVZ
> 
> 
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
>     repeater-builder-fullfeatu...@yahoogroups.com
> 
> 
> 


  

Re: [Repeater-Builder] Re: Rolling Pipe Sound

[Nate Duehr]

Nasssty.  Evil IM.  Nice find.

Nate WY0X

On Dec 7, 2009, at 8:49 PM, larynl2 wrote:

> 
> Do you have two FM stations in your area that are separated by 600 kc.? That 
> will definitely do exactly what you describe. We had it on our repeater.
> 
> I caught in one of your posts that your transmitter needs to be on for the 
> problem to appear, so that's intermod causing your interference, not just a 
> random carrier coming from a router or whatever device.
> 
> The problem here was caused by an FM station on 89.9 about a mile away, and 
> another one on 89.3 roughly six miles away, plus our transmitter on 147.06. 
> A+B-C=D 147.06 + 89.9 - 89.3 = 147.66. The thing to watch for with FM 
> broadcast intermod is the wide bandwidth of the intermod product. There was 
> no interference until BOTH stations were quiet -- no modulation. Obviously, 
> the instances of both being quiet simultaneously are quite random in length 
> and occurrence, depending on the program material of each. 
> 
> I tracked the location of the mixing with the aid of a spectrum analyzer, 
> which turned out to be safety cables threaded through the turnbuckles.
> 
> Laryn K8TVZ

Re: [Repeater-Builder] Re: Rolling Pipe Sound

[wd8chl]

larynl2 wrote:
> Do you have two FM stations in your area that are separated by 600
> kc.?  That will definitely do exactly what you describe.  We had it
> on our repeater.

Or AM. Or an AM station ON 600 kc also.

Re: [Repeater-Builder] Re: Rolling Pipe Sound

[Facility 406 DM09]

I don't think I've ever heard a "rolling pipe" sound over a repeater,
although, once I had some interesting feedback from an SSB transmitter with
FM receiver.

Is there a good clean recording available?

Kurt

RE: [Repeater-Builder] Re: Rolling Pipe Sound

[Eric Lemmon]

Scott,

One source is Telewave.  Here are the datasheets for the 5" and 8" bandpass
cavity filters:



With the 30% Amateur discount, the 5" cavity will cost you about $231 plus
shipping, and the 8" cavity is about $100 more.  Other sources are Comprod,
EMR, TX-RX, and Andrew.  Some brands may require purchase through a
distributor, such as Tessco, Hutton, or Talley.  Always ask about a Ham
discount when you are negotiating prices.  Depending upon the size of your
order, you may get 25% or 30%.

73, Eric Lemmon WB6FLY
 

-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:repeater-buil...@yahoogroups.com] On Behalf Of offtracks1
Sent: Monday, December 07, 2009 3:56 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Re: Rolling Pipe Sound

  

The router is right at 147.580 to almost 147.595. The repeater input is
147.600. So I plan to take that offline. All that cables are double shielded
with no adapters ect. I do not have anything between the isolator and the
duplexer.

Where is a good dealer for a 5" or 8" band pass for the receiver?

I may look at going with that for the first step as it is not very bad but a
bugger that pops up now and then.

Thanks for the help.

Scott 

--- In Repeater-Builder@yahoogroups.com
 , "Eric Lemmon" 
wrote:
>
> Scott,
> 
> A likely suspect is a carrier being emitted by a nearby computer or
> microprocessor. A few years ago, I was setting up a GR1225 repeater on a
> VHF channel, and I noticed that the receive indicator LED was lit
steadily.
> My spectrum analyzer revealed that there was a low-level but steady
carrier
> a few kHz off from my receive frequency. I then used my T-Hunt equipment
to
> pinpoint my desktop computer as the source. In the course of my
> investigation, I also found weak but benign carriers being emitted from my
> TV set, my idle microwave oven, and my programmable thermostat.
> 
> If it is an intermod problem, perhaps a DCI filter is far too wide to be
of
> much help. I'd strongly suggest putting a 5" or 8" bandpass cavity ahead
of
> the receiver- it is much sharper than the DCI product. Do you have a
second
> harmonic notch filter, or a low-pass filter, following the isolator? Are
> all of the jumper cables double-shielded, with proper connectors on each
> end- that is, no adapters or barrels?
> 
> 73, Eric Lemmon WB6FLY
> 
> 
> -Original Message-
> From: Repeater-Builder@yahoogroups.com
 
> [mailto:Repeater-Builder@yahoogroups.com
 ] On Behalf Of offtracks1
> Sent: Monday, December 07, 2009 12:49 PM
> To: Repeater-Builder@yahoogroups.com
 
> Subject: [Repeater-Builder] Rolling Pipe Sound
> 
> 
> 
> Thanks for all the post and for the web site and group.
> It's been very helpful to me as I have been setting up my system. 
> 
> My repeater system is a Kenwood TKR-750 K2, Telewave TPRD-1556 duplexer
set
> (6 cavities), A Telewave Isolator on the PA. Running 1/2" Heilax to a
Andrew
> DB224E antenna. This a repeater at my home as I am on a small hill. The
> antenna is about 40 feet vertical and 60 feet horizontally from the
> repeater/office. 
> 
> It works very well but I have had intermod issue that rears its head now
and
> then that sounds like rolling pipe or hollow sound. I am runing a PL on
both
> TX and RX. This sound opens up the receiver even. So my tx pl is getting
> back into the system. I have hunted down many noise makers in the office
> that could have been helping out. One was the Linksys router. I am going
to
> replace it anyway as it makes a ton of noise I found. Changing my network
> from 100 to 10 on the card speed also reduced the noise levels. 
> 
> Still I get the rolling pipe sound now and then and it leaves as fast as
it
> shows up. If I use my other antenna a Diamond F22 also fed with 1/2 Heliax
I
> also get the same result. I do use a preamp but it also seems to not
change
> with or without it. I have even ran it so the receive antenna is alone and
> the transmit is the other (split). I still get the rolling pipes now and
> then.
> 
> I do have a FM radio station on 92.1 about 4 miles from me that is known
to
> have a sloppy signal. Could it be that this is mixing with my system and
> creating this? 
> 
> Looking at getting a DCI Band pass filter on the receiver side but I am
not
> sure if that is just throwing more money at this project and not getting
> anywhere still.
> 
> Just wanted to see if anyone had some ideas?
> 
> Scott KB7DZR
>

Re: [Repeater-Builder] Re: Rolling Pipe Sound

[DCFluX]

Certain linksys routers may be able to take different the firmware.

http://www.dd-wrt.com/site/index

Of particular note is the ability to change the clock speed.

Also it has been my experience that the router isn't really the source of
the interference. Try switching the SMPS wall wart to one of the linear
variety.

On Mon, Dec 7, 2009 at 5:00 PM, WA3GIN  wrote:

>
>
> Just catchingup on this... yes the infamous rolling pipe sound.
>
> We had an issue with a link receiver that occassionaly would get hung-up in
> a loop, low audio but the correct PL.  We switched from PL to DCT on the
> links and that solved the problem.  We spent a year hunting for the source
> but no joy.
>
> Good Luck,
> dave
> WA3GIN
> W4AVA Trustee
>
>
> - Original Message -
> *From:* offtracks1 
> *To:* Repeater-Builder@yahoogroups.com
> *Sent:* Monday, December 07, 2009 5:25 PM
> *Subject:* [Repeater-Builder] Re: Rolling Pipe Sound
>
>
>
> No worries, the more info the better. Echoproducer is the Bees Knees if you
> are running echolink. It is one very impressive and free program. Peter has
> put a lot of work into it.
>
> Scott
>
> --- In Repeater-Builder@yahoogroups.com, Tony KT9AC  wrote:
>
>
>
> 

Re: [Repeater-Builder] Re: Rolling Pipe Sound

[WA3GIN]

Just catchingup on this... yes the infamous rolling pipe sound.  

We had an issue with a link receiver that occassionaly would get hung-up in a 
loop, low audio but the correct PL.  We switched from PL to DCT on the links 
and that solved the problem.  We spent a year hunting for the source but no joy.

Good Luck,
dave
WA3GIN
W4AVA Trustee

  - Original Message - 
  From: offtracks1 
  To: Repeater-Builder@yahoogroups.com 
  Sent: Monday, December 07, 2009 5:25 PM
  Subject: [Repeater-Builder] Re: Rolling Pipe Sound



  No worries, the more info the better. Echoproducer is the Bees Knees if you 
are running echolink. It is one very impressive and free program. Peter has put 
a lot of work into it.

  Scott

  --- In Repeater-Builder@yahoogroups.com, Tony KT9AC  wrote:

Re: [Repeater-Builder] Re: Rolling Pipe Sound

[Tony KT9AC]

Scott,
I also would second the "reverse repeater" theory. Years ago (many) we 
had a repeater in Western PA on 147.165 that would lock up with a 
Michigan repeater on 147.765 (both rightfully coordinated) and produce 
the "pipe" sound. In those days (1980s) everyone ran carrier squelch and 
we had some Lake Erie ducting once in a while.

Its up to you, but was just a quick workaround that I started doing. 
Funny thing is I can get the "growl" when the system ran DPL and 
conditions are right...but its not the repeater since another temporary 
system I put in did the same thing.

Sorry to hijack your note with my issue, but was hoping that there would 
be some commonality and we would both benefit. Thanks for the 
information on echoproducer, I might look into that.

Tony

offtracks1 wrote:
>
> Thanks for the quick reply
>
> The revers pair is a good point.
>
> I am in a remote area and did the full coordination but still we have 
> had some odd ducting here as I am close to 9K mountains and I am at 
> around 4K feet to start with.
>
> Tony I have not ran it without the tx pl. I have a few folks that like 
> that including myself as I drop the tone before the TX, the controller 
> is a ICS. But still for testing I may do that. I have echolink so I 
> hook it up at night to the Ireland conference and set the system to 
> listen only so I do not interfere with folks. Then with a program 
> called echoproducer I can log each time the system gets kerchunched. 
> sometimes its fine other times the log is big.
>
> Sorry I failed to put down its on 147.000 TX 147.600 RX.
>
> I have a repeater info page off of my weather station site.
>
> http://www.josephoregonweather.com/repeater.html 
> 
>
> --- In Repeater-Builder@yahoogroups.com 
> , Tony KT9AC  wrote:
> >
> > Scott,
> > You are not alone in this!! I too have been fighting a problem almost
> > exactly like this - I've tried different PL tones on RX and TX and that
> > seemed to keep it from "self-oscillating". Seems to happen more when 
> the
> > weather is dry and I describe it as a "growl" sound. Happening on a
> > MSF5000 at a commercial site. We too have numerous broadcast towers
> > within 2 miles, and lots of Cellular/PCS antennas around. Mine is on
> > UHF, yours appears to be high-band VHF (from the TKR-750 K2 note).
> >
> > I'm still working on a resolution, but again for now try either split
> > tone or remove PL from the transmitter (CSQ). It would keep the 
> repeater
> > keyed up for several seconds, then drop signal and come back again (as
> > long as the tail remained with PL output). I've also shortened the hang
> > timer to 3 seconds to help. It wouldn't bring up the system unless
> > someone kerchunked it, then it started.
> >
> > Tony, KT9AC
> >
>
> 






Yahoo! Groups Links

<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/Repeater-Builder/

<*> Your email settings:
Individual Email | Traditional

<*> To change settings online go to:
http://groups.yahoo.com/group/Repeater-Builder/join
(Yahoo! ID required)

<*> To change settings via email:
repeater-builder-dig...@yahoogroups.com 
repeater-builder-fullfeatu...@yahoogroups.com

<*> To unsubscribe from this group, send an email to:
repeater-builder-unsubscr...@yahoogroups.com

<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/