Re: [Repeater-Builder] Simplest Radio to mod for a 1.25m repeater....

[Nate Duehr]

On Jul 28, 2008, at 9:11 AM, lou_c1357 wrote:

> Also what about duplexers??  I have not seen any for the 1.25m band,
> but I may not be loking hard enough...

They pop up from time to time.  My "steal of the year" last year was a  
beautiful never-used four-can Sinclair set with the larger higher-Q  
cans... $300.   Very nice!

(I'd been watching for a good quality duplexer for 2 years for 220 at  
that point in time, and couldn't believe no one bid against me for  
them.  Sometimes, you just get lucky.  Then there were 220 cans all  
over eBay for a year after that.  They come and go...)

--
Nate Duehr, WY0X
[EMAIL PROTECTED]

Re: [Repeater-Builder] Re: Feedback Problem

[no6b]

At 7/31/2008 11:41, you wrote:

>I don't think they are your problem, at 15 miles and with this pattern 
>(scroll down on page)
>
>http://www.fccinfo.com/CMDProEngine.php?sCurrentService=AM&tabSearchType=Appl&sAppIDNumber=594312&sHours=D
>

Looks to me like his repeater site is just inside the main lobe.

Bob NO6B

Re: [Repeater-Builder] Re: Feedback Problem

[no6b]

At 7/31/2008 10:38, you wrote:

> > If you've got the patience... drop the transmitter down to
> > the exciter only power and see if you can reproduce the
> > problem at any time.
> >
> > Do you have a circulator on the power amplifier's output?
>
>I have taken the amplifier out of line and had the same results. I've
>also taken the duplexer out completely, and run the RX on the top
>antenna, and TX on the bottom. I thought for a while that this solved
>the problem, but it ended coming back eventually. There was quite a
>bit of desense in this configuration obviously, so the feedback
>probably just wasn't strong enough to overcome it, for a while.

I was thinking that this configuration might help, as I've seen moving to 
separate TX & RX antennas solve other 3rd party mix problems.  The key is 
to separate the TX & RX near fields as much as possible so that any 3rd 
party mix will be more decoupled from your TX or RX antenna.

Before you give up on this, try removing the duplexer T & feed the TX & RX 
legs of the duplexer straight to your 2 antennas.  Separating them 
vertically as much as possible just might solve the problem.

>I don't have a circulator in line.

Would be a good idea to have, but I don't think it would help in this case 
- no other in-band signals to isolate.

Bob NO6B

[Repeater-Builder] Zetron 38A and Max Manuals

[Eric Lemmon]

Thanks to the generous contributions of George, N3GH, and Jack, K6YC, I have
collected and resized the needed schematics and merged them into complete
manuals- one for the Zetron 38A and one for the Zetron 38Max.

I have already uploaded both manuals in full-page PDF to the Zetron folder
in the Files section of the Repeater-Builder Group.  The same manuals will
soon be available in the Zetron section of the RBTIP.  The schematics are in
their correct locations within each manual, so you don't have to download
them separately.

73, Eric Lemmon WB6FLY

Re: [Repeater-Builder] Re: Feedback Problem

[Mike Morris WA6ILQ]

At 07:06 PM 07/31/08, you wrote:
>...Or two FM stations 1.6 mc. apart.  We've had this problem on 2m
>with two stations 600 kc. apart.
>
>With FM stations the intermod product is far wider than the IF
>bandwidth of your receiver, so it isn't much of a problem until 
>stations are silent, such as between words/sentences.  It can make for
>a tough-to-find source.  A spectrum analyzer and beam can be useful to
>*see* the intermod product to help find the source of mixing.
>
>Laryn K8TVZ

When the 220MHz repeater band was first getting started in Los
Angeles there was a local gentleman that was importing Midland
13-509s - Bill DuHaime, WA6NTW.  I suspect that 90% of the
'509s in southern California went through his garage at one point.

He used to sell them with 223.5 simplex, 223.0 simplex, 223.94
(his box), and he sold crystals for 223.98 (the ARES box),
224.94 (the Mount Wilson box) and a few more.

He had built up the 223.94 repeater from a high band RCA
500 receiver, a 13-509 transmitter backed off to 5 watts and a
homebrew 60 watt tube PA deck.
People were amazed that a 509 mobile could live with a duty
cycle that approached continuous keydown from 4pm to 8pm
every day.

Anyway Bil invited me to a coordination meeting, and it
turned out to be the first 220MHZ coordination council
meeting after 220 split off from one of the other councils.

One comment made at that meeting, by a very well known
broadcast engineer, was that 1.6 was absolutely the worst
choice for 220 repeaters.   He commented that 1.6 was the
most common co-tower spacing for FM stations across the
country.  He said that 1.4, 1.5, 1.7, 1.8 anything would have
been better than 1.6.

I have no idea if that was or is true but if so, then it is an
interesting bit of trivia...

Mike WA6ILQ

Re: [Repeater-Builder] GLB (was Re: MSR2000 narrow banding)

[Mike Morris WA6ILQ]

The manual including schematics is on repeater-builder.

At 02:05 PM 07/31/08, you wrote:
>Somewhere in a junk box, I think I still have a set of
>bare PC boards for one  schematic & parts list are
>long gone, thought.  (high parts count, too...)
>
>73,
>
>George, KA3HSW / WQGJ413
>
>--- MCH <[EMAIL PROTECTED]> wrote:
>
> > GLB made them and called them a "channelizer".
> >
> > Joe M.
> >
> > Wayne wrote:
> > >   There were some frequency synthesizers made for
> > the GE Prog lines, and a
> > > few others, back in the 70's to 80's, though I
> > think they were mainly for
> > > ham radio use.
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>

[Repeater-Builder] Re: Feedback Problem

[Laryn Lohman]

...Or two FM stations 1.6 mc. apart.  We've had this problem on 2m
with two stations 600 kc. apart.  

With FM stations the intermod product is far wider than the IF
bandwidth of your receiver, so it isn't much of a problem until 
stations are silent, such as between words/sentences.  It can make for
a tough-to-find source.  A spectrum analyzer and beam can be useful to
*see* the intermod product to help find the source of mixing.

Laryn K8TVZ

Re: [Repeater-Builder] Re: Feedback Problem

[Jim Brown]

You might be surprised as to how far away a station can be that causes 
problems.  Back in the '70s I had a station on 600 kHz 80 miles away that 
modulated our repeater as soon as it was keyed.  We verified the station 
programming with a BC Band receiver tuned to 600 kHz to be the same audio mixed 
with our repeater output.  In our case, the guy wires to the tower were not 
insulated, and the tower was rusty.  Perfect oxide rectifier and antenna for 
the BC station.  A heavy fog made it much worse, but that only happened a few 
days a year, so we just ignored it.

73 - Jim  W5ZIT

--- On Thu, 7/31/08, Jeff Lehmann <[EMAIL PROTECTED]> wrote:
From: Jeff Lehmann <[EMAIL PROTECTED]>
Subject: [Repeater-Builder] Re: Feedback Problem
To: Repeater-Builder@yahoogroups.com
Date: Thursday, July 31, 2008, 1:52 PM











> I don't think they are your problem, at 15 miles and with this

pattern (scroll down on page)

> 

>

http://www.fccinfo. com/CMDProEngine .php?sCurrentSer vice=AM&tabSearc 
hType=Appl& sAppIDNumber= 594312&sHours= D



They may not yet be operating with that power level and/or pattern yet

though. Right now, 1330 WRCA and 1600 WUNR are operating from that

site, and nobody seems to know for sure what configuration they're in,

other than it's not the final one. Eventually 1200 WKOX will be there

as well.



73

Jeff  N1ZZN




  




 

















  

Re: [Repeater-Builder] Re: MSR2000 narrow banding

[George Henry]

Somewhere in a junk box, I think I still have a set of
bare PC boards for one  schematic & parts list are
long gone, thought.  (high parts count, too...)

73,

George, KA3HSW / WQGJ413

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

> GLB made them and called them a "channelizer".
> 
> Joe M.
> 
> Wayne wrote:
> >   There were some frequency synthesizers made for
> the GE Prog lines, and a  
> > few others, back in the 70's to 80's, though I
> think they were mainly for  
> > ham radio use.

[Repeater-Builder] Re: Feedback Problem

[Jeff Lehmann]

> I don't think they are your problem, at 15 miles and with this
pattern (scroll down on page)
> 
>
http://www.fccinfo.com/CMDProEngine.php?sCurrentService=AM&tabSearchType=Appl&sAppIDNumber=594312&sHours=D

They may not yet be operating with that power level and/or pattern yet
though. Right now, 1330 WRCA and 1600 WUNR are operating from that
site, and nobody seems to know for sure what configuration they're in,
other than it's not the final one. Eventually 1200 WKOX will be there
as well.

73
Jeff  N1ZZN

Re: [Repeater-Builder] Re: Feedback Problem

[Gary Glaenzer]

I don't think they are your problem, at 15 miles and with this pattern (scroll 
down on page)

http://www.fccinfo.com/CMDProEngine.php?sCurrentService=AM&tabSearchType=Appl&sAppIDNumber=594312&sHours=D


  - Original Message - 
  From: Jeff Lehmann 
  To: Repeater-Builder@yahoogroups.com 
  Sent: Thursday, July 31, 2008 1:23 PM
  Subject: [Repeater-Builder] Re: Feedback Problem


  > what direction from you to their site ?

  Northwest: http://tinyurl.com/62k5dc

  73
  Jeff N1ZZN



   
No virus found in this incoming message.
Checked by AVG - http://www.avg.com 
Version: 8.0.138 / Virus Database: 270.5.10/1584 - Release Date: 7/31/2008 
12:00 PM

[Repeater-Builder] Re: Feedback Problem

[Jeff Lehmann]

> what direction from you to their site ?

Northwest: http://tinyurl.com/62k5dc

73
Jeff  N1ZZN

Re: [Repeater-Builder] Re: Feedback Problem

[Gary Glaenzer]

what direction from you to their site ?


  - Original Message - 
  From: Jeff Lehmann 
  To: Repeater-Builder@yahoogroups.com 
  Sent: Thursday, July 31, 2008 12:28 PM
  Subject: [Repeater-Builder] Re: Feedback Problem


  > >I've been pulling my hair out trying to figure out a problem with my
  > >224.060 repeater in Norwell, MA. Somehow the transmitter is feeding
  > >back into the receiver. This all started happening back during the
  > 
  > Got a 1600 AM station nearby?

  Yes, 1600 WUNR is probably about 15 miles away, and they've been in
  the middle of a complete rebuild of their transmitter plant. They're
  in the process of upgrading to 20kW with a new pattern, with shorter
  towers, and the addition of 2 more stations at the same site.

  73
  Jeff N1ZZN



   
No virus found in this incoming message.
Checked by AVG - http://www.avg.com 
Version: 8.0.138 / Virus Database: 270.5.10/1584 - Release Date: 7/31/2008 
12:00 PM

Re: [Repeater-Builder] Re: MSR2000 narrow banding

[MCH]

GLB made them and called them a "channelizer".

Joe M.

Wayne wrote:
>   There were some frequency synthesizers made for the GE Prog lines, and a  
> few others, back in the 70's to 80's, though I think they were mainly for  
> ham radio use.
>   I had, for a while, a prog line base on 2 meters with a synthesizer. easy  
> dial up of frequency desired. This was back in the 80's mind you.
>   I don't recall the make now, but I think it was made somewhere in NY  
> state.
>   And unknown if it was legal for commercial use. By that time, most progs  
> had been removed from commercial service...
> 
>   So, such things do exist...
> 
>   Wayne WA2YNE
> 
> On Wed, 16 Jul 2008 18:48:08 -0500, Ron Wright <[EMAIL PROTECTED]> wrote:
> 
>> Mike,
>>
>> I did wonder about the "special RSS" comment, no license aggreement and  
>> calling ICM.   I thought well maybe it was something someone came up  
>> with on their own, but ICM was out of place for even that.  But wanted  
>> to make sure.
>>
>> Actually I was thinking maybe someone came up with a synth to replace  
>> the MSR2000 ch ele.  I had thought of this while back for some of the  
>> older GEs and Mot rigs.  I bet one could manuf for the price of a  
>> crystals especially when a complete synth HT goes for $100-140.  Synths  
>> are all over the place.
>>
>> 73, ron, n9ee/r
>>
>>
> 





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:
mailto:[EMAIL PROTECTED] 
mailto:[EMAIL PROTECTED]

<*> 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: Re: [Repeater-Builder] Re: MSR2000 narrow banding

[Wayne]

  There were some frequency synthesizers made for the GE Prog lines, and a  
few others, back in the 70's to 80's, though I think they were mainly for  
ham radio use.
  I had, for a while, a prog line base on 2 meters with a synthesizer. easy  
dial up of frequency desired. This was back in the 80's mind you.
  I don't recall the make now, but I think it was made somewhere in NY  
state.
  And unknown if it was legal for commercial use. By that time, most progs  
had been removed from commercial service...

  So, such things do exist...

  Wayne WA2YNE

On Wed, 16 Jul 2008 18:48:08 -0500, Ron Wright <[EMAIL PROTECTED]> wrote:

> Mike,
>
> I did wonder about the "special RSS" comment, no license aggreement and  
> calling ICM.   I thought well maybe it was something someone came up  
> with on their own, but ICM was out of place for even that.  But wanted  
> to make sure.
>
> Actually I was thinking maybe someone came up with a synth to replace  
> the MSR2000 ch ele.  I had thought of this while back for some of the  
> older GEs and Mot rigs.  I bet one could manuf for the price of a  
> crystals especially when a complete synth HT goes for $100-140.  Synths  
> are all over the place.
>
> 73, ron, n9ee/r
>
>

-- 
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/





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:
mailto:[EMAIL PROTECTED] 
mailto:[EMAIL PROTECTED]

<*> 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/

[Repeater-Builder] Re: Feedback Problem

[Jeff Lehmann]

> If you've got the patience... drop the transmitter down to 
> the exciter only power and see if you can reproduce the 
> problem at any time. 
> 
> Do you have a circulator on the power amplifier's output? 

I have taken the amplifier out of line and had the same results. I've
also taken the duplexer out completely, and run the RX on the top
antenna, and TX on the bottom. I thought for a while that this solved
the problem, but it ended coming back eventually. There was quite a
bit of desense in this configuration obviously, so the feedback
probably just wasn't strong enough to overcome it, for a while.

I don't have a circulator in line.

73
Jeff  N1ZZN

[Repeater-Builder] Re: Feedback Problem

[Jeff Lehmann]

> >I've been pulling my hair out trying to figure out a problem with my
> >224.060 repeater in Norwell, MA. Somehow the transmitter is feeding
> >back into the receiver. This all started happening back during the
> 
> Got a 1600 AM station nearby?

Yes, 1600 WUNR is probably about 15 miles away, and they've been in
the middle of a complete rebuild of their transmitter plant. They're
in the process of upgrading to 20kW with a new pattern, with shorter
towers, and the addition of 2 more stations at the same site.

73
Jeff  N1ZZN

[Repeater-Builder] Re: Zetron 38A Manual

[n3gh_1]

Eric,

Take a look under files, directory Zetron, on this site.
I have copied from my manual the schematics you describe.
Let me know if you find anything missing from them.

73,
N3GH
George
--- In Repeater-Builder@yahoogroups.com, "Eric Lemmon" <[EMAIL PROTECTED]> 
wrote:
>
> We're still not home yet- the copies of the schematics on the link shown
> below do not overlap, so there is a data gap at that point.  Please, if
> someone has the original paper copies of the schematics, take them to a
> Kinko's or a commercial graphics shop and have them scanned as 11 by 17
> sheets directly into PDF.  If that is too much trouble, please
contact me
> directly at mycall at verizon dot net.
> 
> 73, Eric Lemmon WB6FLY
>  
> 
> -Original Message-
> From: Repeater-Builder@yahoogroups.com
> [mailto:[EMAIL PROTECTED] On Behalf Of Mike Morris
WA6ILQ
> Sent: Tuesday, July 29, 2008 9:57 PM
> To: Repeater-Builder@yahoogroups.com
> Subject: Re: [Repeater-Builder] Re: Zetron 38A Manual
> 
> Look on   >
> 
> The Zetron 38a manual and schematics are there.
> 
> Mike WA6ILQ
> 
> At 05:36 PM 07/29/08, you wrote:
> >Tim,
> >
> >Did you ever get the schematics for the Zetron 38a?
> >I have them in PDF files and can email them to you.
> >Let me know.
> >
> >N3GH
> >George
> >
> >
> >--- In Repeater-Builder@yahoogroups.com
>  , "m0hlm"  wrote:
> > >
> > > Hi I got the Manual incl. scematic, diagram, for diffrent Zetron
> > > Logics .send me an email >M0HLM@<
> > >
> > >
> > >
> > > --- In Repeater-Builder@yahoogroups.com
>  , "Scott Zimmerman"
> > >  wrote:
> > > >
> > > > I apologize. I didn't realize that the PDF had blank pages.
> > > >
> > > > Scott
> > > >
> > > > Scott Zimmerman
> > > > Amateur Radio Call N3XCC
> > > > 474 Barnett Road
> > > > Boswell, PA 15531
> > > > - Original Message -
> > > > From: Mike Morris WA6ILQ
> > > > To: Repeater-Builder@yahoogroups.com
>  
> > > > Sent: Friday, April 25, 2008 1:52 AM
> > > > Subject: Re: [Repeater-Builder] Zetron 38A Manual
> > > >
> > > >
> > > > Yep, he did.
> > > >
> > > > The schematics pages in that PDF file are blank (unfortunately
> > > it's all we have).
> > > > A good example of Zetron customer service at its best.
> > > >
> > > > I've heard it from several people - they buy Zetron, they shelve
> > > the manual. Several
> > > > years later the unit needs repair - maybe they zap a COR input,
> > > or something.
> > > > They pull the manual off the shelf, and the schematics are
> > > blank. Unhappy
> > > > customers tend to make later purchases elsewhere.
> > > >
> > > > Mike
> > > >
> > > > At 12:06 PM 04/24/08, you wrote:
> > > >
> > > > Doesn't anyone check the website or do a google search
> > > anymore??
> > > >
> > > > http://www.repeater-builder.com/zetron/zetron-model-38a-inst%
>  
> > > 20manual-025-9043y.pdf
> > > >
> > > > Scott
> > > >
> > > > Scott Zimmerman
> > > > Amateur Radio Call N3XCC
> > > > 474 Barnett Rd
> > > > Boswell, PA 15531
> > > >
> > > > - Original Message -
> > > >
> > > > From: Jack Davis
> > > >
> > > > To: Repeater-Builder@yahoogroups.com
>  
> > > >
> > > > Sent: Wednesday, April 23, 2008 11:24 PM
> > > >
> > > > Subject: [Repeater-Builder] Zetron 38A Manual
> > > >
> > > >
> > > > Does anyone have the schematics for a Zetron Model 38A
> > > repeater controller? The pages are blank in my manual and I need to
> > > fix it.
> > > >
> > > >
> > > >
> > > > Thanks,
> > > >
> > > > Jack
> > > >
> > > > K6YC
> > > >
> > > >
> > > > --
> > > ---
> > > >
> > > > No virus found in this incoming message.
> > > >
> > > > Checked by AVG.
> > > >
> > > > Version: 7.5.524 / Virus Database: 269.23.2/1389 - Release
> > > Date: 4/21/2008 8:34 AM
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > --
> > > ---
> > > >
> > > >
> > > > No virus found in this incoming message.
> > > > Checked by AVG.
> > > > Version: 7.5.524 / Virus Database: 269.23.5/1399 - Release Date:
> > > 4/26/2008 2:17 PM
> > > >
> > >
> >
> >
> >
> >
> >
> >
> >
> >Yahoo! Groups Links
> >
> >
> >
>

RE: [Repeater-Builder] Curious Situation

[Michael Ryan]

Doug, Thank you ( and all the others who have commented ). The responses are
what I had hoped for when joining the reflector, a great resource.  I will
go over the connections and cables as suggested and re-run some tests
tonight. - Mike

 

From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Doug Bade
Sent: Thursday, July 31, 2008 9:32 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Curious Situation

 

Just re-reading your post I thought I would add the following thoughts.

If 25 watts from a particular antenna is 
full quieting and 15 watts from the same antenna 
sequentially measured...is noop... this is not a 
duplexer problem... those 2 numbers are less than 
2 db apart you should not be able to see or 
hear a difference at the full quieting zone of a 
receiver ( this would imply greater than 12db 
sinad SNR for the full quieted signal...) ... let 
alone drop out entirely...that is not 
possible you are overlooking something.. like 
the 15w radio is on simplex a 6-10db drop you 
might hear at a full quieted signal... but not 2 
db... going from 25 watts to 5 for instance is a 
little better than 6db drop... 25 to 2.5 would be 
a 10db dropbut if it is a full quieting 
signal it still would need to drop 10+ db to be a 
significant drop and close to maybe 15-20db to 
drop out entirelyI would re-run the test and 
check connections and gear carefully... as the numbers do not seem to add
up...

2db rf power decrease is audible in the bottom 
3db of the rx... but not at 20db quieting area

Doug
KD8B

>At 11:37 PM 7/29/2008, you wrote:
>
> >Rber's, I posted a note very early this week
> >about my looking for a someplace to get a 220
> >duplexer tuned in the TAMPA area. Having not
> >much luck I contacted a local MOTOROLA shop and
> >paid $95 for the service. The receipt returned
> >with the cans indicates that the specifications
> >published by WACOM are very close. Having tuned
> >these merely to incoming signals before, peaking
> >them while the repeater is still in a testing
> >mode, seemed to return decent results but the
> >tune-up was thought to be a better idea. Not
> >so.. Today's tune-up hardly was worth the wait
> >or the price based on the results. While a 5
> >watt HT 10 miles away could work the repeater,
> >now 25 watts from a roof top antenna is now just
> >about full quieting. Fifteen watts does not
> >make the repeater through the same roof top
> >ground plane. Does logic dictate that we go
> >back to seat of the pants tuning and cast fate to the wind? - Mike
> >
>
>

 

__ NOD32 3301 (20080727) Information __

This message was checked by NOD32 antivirus system.
http://www.eset.com

RE: [Repeater-Builder] Feedback Problem

[no6b]

At 7/31/2008 04:59, you wrote:

>Not sure about the band plan on 220 but is it possibla thet someone put up 
>a repeater with a reverse split.  What about turning off the tx pl and 
>turning on the rx pl.

While theoretically possible, highly unlikely.  AFAIK no 220 bandplan in 
use in the U.S. has repeater pairs with a positive RX offset, & 220 isn't 
exactly a "full" band in most places so little reason for someone to run an 
uncoordinated repeater.

My guess is a mix with a 1600 AM station.  BTDT.  The fix is to remove all 
nonlinearities at the site.  Some RDFing of the mix signal using a portable 
RF-proofed RX may help identify specific sources.

Bob NO6B

Re: [Repeater-Builder] Feedback Problem

[no6b]

At 7/30/2008 17:52, you wrote:

>I've been pulling my hair out trying to figure out a problem with my
>224.060 repeater in Norwell, MA. Somehow the transmitter is feeding
>back into the receiver. This all started happening back during the

Got a 1600 AM station nearby?

Bob NO6B

Re: [Repeater-Builder] Curious Situation

[Doug Bade]

Just re-reading your post I thought I would add the following thoughts.

 If 25 watts from a particular antenna is 
full quieting and 15 watts from the same antenna 
sequentially measured...is noop... this is not a 
duplexer problem... those 2 numbers are less than 
2 db apart you should not be able to see or 
hear a difference at the full quieting zone of a 
receiver ( this would imply greater than 12db 
sinad SNR for the full quieted signal...) ... let 
alone drop out entirely...that is not 
possible you are overlooking something.. like 
the 15w radio is on simplex a 6-10db drop you 
might hear at a full quieted signal... but not 2 
db... going from 25 watts to 5 for instance is a 
little better than 6db drop... 25 to 2.5 would be 
a 10db dropbut if it is a full quieting 
signal it still would need to drop 10+ db to be a 
significant drop and close to maybe 15-20db to 
drop out entirelyI would re-run the test and 
check connections and gear carefully... as the numbers do not seem to add up...

2db rf power decrease is audible in the bottom 
3db of the rx... but not at 20db quieting area

Doug
KD8B


>At 11:37 PM 7/29/2008, you wrote:
>
> >Rber’s, I posted a note very early this week
> >about my looking for a someplace to get a 220
> >duplexer tuned in the TAMPA area. Having not
> >much luck I contacted a local MOTOROLA shop and
> >paid $95 for the service. The receipt returned
> >with the cans indicates that the specifications
> >published by WACOM are very close. Having tuned
> >these merely to incoming signals before, peaking
> >them while the repeater is still in a testing
> >mode, seemed to return decent results but the
> >tune-up was thought to be a better idea. Not
> >so…. Today’s tune-up hardly was worth the wait
> >or the price based on the results. While a 5
> >watt HT 10 miles away could work the repeater,
> >now 25 watts from a roof top antenna is now just
> >about full quieting. Fifteen watts does not
> >make the repeater through the same roof top
> >ground plane. Does logic dictate that we go
> >back to seat of the pants tuning and cast fate to the wind? - Mike
> >
>
>

RE: [Repeater-Builder] Feedback Problem

[Robert Pease]

Not sure about the band plan on 220 but is it possibla thet someone put up a 
repeater with a reverse split.  What about turning off the tx pl and turning on 
the rx pl.

Does is happen when someone is talking on it or just during no rx.

Maybe you could record it to an mp3 and post it, sometimes it is easier to 
identify if we can hear it.

Rob KS4EC

Sent by Good Messaging (www.good.com)


 -Original Message-
From:   Jeff Lehmann [mailto:[EMAIL PROTECTED]
Sent:   Thursday, July 31, 2008 02:22 AM Eastern Standard Time
To: Repeater-Builder@yahoogroups.com
Subject:[Repeater-Builder] Feedback Problem

I've been pulling my hair out trying to figure out a problem with my
224.060 repeater in Norwell, MA. Somehow the transmitter is feeding
back into the receiver. This all started happening back during the
winter when a tower crew started working on the tower. Whether that is
a coincidence or not, I have no idea. 

My original antenna was at 120 feet (Hustler G7-220). After the tower
work was complete, I was able to get a Comet CA-Super22 installed at
the top of the tower (180 feet). Sometime during all of this work, the
feedback began to happen, while I was still transmitting and receiving
on the original antenna. The duplexer is a Wacom 6 cavity, transmitter
is a Hi Pro, and receiver is a Hamtronics. I also have a Kendecom 75
watt amplifier, and the noise has been present with and without that
in line.

Without the repeater transmitting, everything is fine, the receiver
has no noise at all, which I can listen to via the 6 meter repeater
that is on the same RC-210 controller. My latest theory was that it
happens more when there is slight tropo enhancement on the band,
usually in the evenings or early mornings, but I haven't proven this
yet. The duplexer has been tuned probably 3 or 4 times at this point,
by about as many different people, and it looks fine. I'd have no
problem buying a new duplexer if I could find that somehow, it was the
problem, even though it looks fine on test equipment.

The latest things I tried was a DCI filter, which had the repeater
working great for about 10 minutes, then the noise came roaring back
in again. I don't know what else to try at this point. One idea that I
have is to try someone else's complete repeater system up there for a
couple days, so it doesn't involve tuning anyone else's duplexer. If
that repeater, on a different frequency still had a problem, then I
would know that it was something with the site/antenna system. If it
worked fine, I'd then know that it's something either wrong with my
transmitter/receiver or duplexer.

I've tried different combinations of the 2 antennas, receiving on one,
TXing on the other, with some success at times, but the noise always
comes back eventually. If anyone has any suggestions, it would be
greatly appreciated. I just want to solve this once and for all. I've
got a great site, and want to use it to it's full potential.

73
Jeff Lehmann - N1ZZN
Hanson, MA


Since 1974, the award-winning Alpert JFCS has helped families of all faiths 
throughout most of Palm Beach County, FL, via counseling, seniors services, 
residences for the disabled, mentoring children, support groups and a lot more.

SOLUTIONS FOR LIVING 
www.JFCSonline.com 

Please take note of our new website and E-Mail Addresses. Please update your 
contacts ASAP.
 
 
 
 

 
 
NOTICE:
 
This e-mail message and all attachments transmitted with it are intended solely 
for the use of the addressee and may contain legally privileged and 
confidential information. If the reader of this message is not the intended 
recipient, or an employee or agent responsible for delivering this message to 
the intended recipient, you are hereby notified that any dissemination, 
distribution, copying, or other use of this message or its attachments is 
strictly prohibited. If you have received this message in error, please notify 
the sender immediately by replying to this message and please delete it from 
your computer.

[Repeater-Builder] Re: FS: Celwave 6 Cavity UHF Repeater-Base Station Duplexer

[sgreact47]

Jerry,

Please take the time to measure the cable lengths so they can be
posted here on R_B.

Mike has one that is missing a couple of cables.  Thank you

 
>   -- Original message -- 
>   From: "Jerry Dubzak" <[EMAIL PROTECTED]> 

>   For Sale:
>   
>   Celwave 6 Cavity UHF (435 to 470 MHz.) Repeater-Base Station
> Duplexer! 
>   This unit is in excellent condition, and is currently tuned for: 
>   TX=444.0625 MHz. & RX: 449.0625 MHz. with 0.9 dB insertion loss. The
> 
>   unit was originally pulled from a Motorola Quantar repeater system 
>   and retuned for use in my D-Star repeater system which I have 
>   recently sold.
>   
>   The duplexer's specifications are as follows:
>   
>   Frequency Coverage = 435 to 470 MHz.
>   Frequency Spacing, MHz. = 3
>   TX to RX Isolation, dB = 100
>   Max Insertion Loss, dB = 1.0
>   TX Bandwidth, MHz. = 0.025
>   RX Bandwidth, MHz. = 0.025
>   Maximum Power Input = 250 watts
>   Connectors = N-Female
>   VSWR, Max. (50 ohms) = 1.3:1
>   Standard 19" Rack Mount Design
>   
>   Photos:
>   
>   http://i305.photobucket.com/albums/nn216/gldubzakjr/Duplexer0.jpg
>  
>   http://i305.photobucket.com/albums/nn216/gldubzakjr/Duplexer1.jpg
>  
>   http://i305.photobucket.com/albums/nn216/gldubzakjr/Duplexer2.jpg
>  
>   
>   I am asking $800, o.b.o. plus $30 shipping (PayPal +3%)
>   
>   Interested parties, please e-mail me directly at: [EMAIL PROTECTED]
>   with 
>   any questions.
>   
>   Thanks,
>   
>   Jerry - K8GLD
>

[Repeater-Builder] Re: Feedback Problem

[skipp025]

Hi Jeff, 

If you've got the patience... drop the transmitter down to 
the exciter only power and see if you can reproduce the 
problem at any time. 

Do you have a circulator on the power amplifier's output? 

your turn 
 
cheers,
skipp 


> "Jeff Lehmann" <[EMAIL PROTECTED]> wrote:
>
> I've been pulling my hair out trying to figure out a problem with my
> 224.060 repeater in Norwell, MA. Somehow the transmitter is feeding
> back into the receiver. This all started happening back during the
> winter when a tower crew started working on the tower. Whether that is
> a coincidence or not, I have no idea. 
> 
> My original antenna was at 120 feet (Hustler G7-220). After the tower
> work was complete, I was able to get a Comet CA-Super22 installed at
> the top of the tower (180 feet). Sometime during all of this work, the
> feedback began to happen, while I was still transmitting and receiving
> on the original antenna. The duplexer is a Wacom 6 cavity, transmitter
> is a Hi Pro, and receiver is a Hamtronics. I also have a Kendecom 75
> watt amplifier, and the noise has been present with and without that
> in line.
> 
> Without the repeater transmitting, everything is fine, the receiver
> has no noise at all, which I can listen to via the 6 meter repeater
> that is on the same RC-210 controller. My latest theory was that it
> happens more when there is slight tropo enhancement on the band,
> usually in the evenings or early mornings, but I haven't proven this
> yet. The duplexer has been tuned probably 3 or 4 times at this point,
> by about as many different people, and it looks fine. I'd have no
> problem buying a new duplexer if I could find that somehow, it was the
> problem, even though it looks fine on test equipment.
> 
> The latest things I tried was a DCI filter, which had the repeater
> working great for about 10 minutes, then the noise came roaring back
> in again. I don't know what else to try at this point. One idea that I
> have is to try someone else's complete repeater system up there for a
> couple days, so it doesn't involve tuning anyone else's duplexer. If
> that repeater, on a different frequency still had a problem, then I
> would know that it was something with the site/antenna system. If it
> worked fine, I'd then know that it's something either wrong with my
> transmitter/receiver or duplexer.
> 
> I've tried different combinations of the 2 antennas, receiving on one,
> TXing on the other, with some success at times, but the noise always
> comes back eventually. If anyone has any suggestions, it would be
> greatly appreciated. I just want to solve this once and for all. I've
> got a great site, and want to use it to it's full potential.
> 
> 73
> Jeff Lehmann - N1ZZN
> Hanson, MA
>