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
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
If we think amateurs are ignorant about propagation now, wait until digital
takes over completely, and an entire generation of hams and commercial techs
has never heard what fading or multipath actually sounds like over an analog
circuit.
You may not realize how much you learn about
Interesting topic.
I'm alarmed at how quickly digital mobile phones have dumbed down consumer
expectations for telephone audio quality. I figured Vonage would have tough
going, but people were so used to crummy cellphone audio by then that they
didn't even flinch. Now, Vonage is often better
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
The cable I used was armored with a spiral copper
shield over 5 twisted pair lines. I did try grounding
the shield at one end, and at both ends with no
results. Putting caps across the twisted pair and to
ground also did not eliminate the problem, but did
reduce it. I used 600:600 isolation
On Mon, 19 Nov 2007, Paul Plack wrote:
But if I hear one more salesman call 3 kHz / 8-bit digital sampling
CD quality, I think I'll scream!
I wasn't aware there were that many salesmen that were hard of hearing
or perhaps completely suckered in by whoever sold them thier stereo...
--
Kris
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
Duplexers are Telwave BpBr 4 cavity. added 2 more BpBr cavities
at 104.9. To my surprise I was getting -8 dbm
You can try a stub to NOTCH 104.9, but I would suggest using 1-2 BANDPASS
cavities tuned to your receive frequency.
BPBR cans are pretty wide open once you get past the operating
Hello Ron,
My 53.41Mhz repeater here in Connecticut has been on the air for years
using a MASTRII conversion. I have had very few problems over the years
with this equipment. The Hamtronics that I have belongs to a club and I
was trying to help them get it up and operational. I think I will
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:
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
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]
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
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
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
At 11:22 PM 11/21/2007, you wrote:
Here it is mostly the opposite. People will use a club owned,
linked, high level, wide coverage system before using a low level
machine. Of the 2m low level machines, only one or two see limited
use. There are many UHF machines in the area, but they see
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:
Well, yeah our mountains sure can't compete with yours.
Richard
http://www.n7tgb.net/ www.n7tgb.net
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Nate Duehr
Sent: Wednesday, November 21, 2007 9:45 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re:
Up until some recent interference problems up there, our UHF up
there
has been known to hear mobiles traveling Interstate 80 through
Wyoming... but unless they're going north through Denver and we
ask
them to stay with us to see how far they go, they'd never think
to
look up our
Joe,
Would you be willing to send me the exciter for experimental modification?
Kevin Custer
I think I am coming to the realization that this transmitter strip might
end up on the shelf too. I've been trying to fix this for a local club
and I think I have finally given
The 900 MHz Maxtrac receiver's IF is 45.1 MHz I believe. Have you
looked around there for any possible signals?
And are there any studio transmitter links around 947-950 MHz?
--- In Repeater-Builder@yahoogroups.com, David Epley [EMAIL PROTECTED]
wrote:
I have a repeater receiver overload
Curious if anyone has built one for 2/440 version. Even better...a
2/220/440 :-) Would be interested in using 1/2 hardline as well. I
know there are tons of single band ones around. I wonder how well
these would duplex on a repeater as well.
73 and Happy Thanksgiving,
Robert
KD4YDC
Yes I have looked + and - the IF for a signal
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Steve
Sent: Thursday, November 22, 2007 11:10 AM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Re: Receiver overload
The 900 MHz Maxtrac
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
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
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
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
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,
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
I have come across a Wacom 641 retired from commercial
use. It was factory tuned to 153.905 / 158.805 MHz. Will it
tune down to 146.34/94?
Were the notch stubs all the same, or are were there different
lengths of the brass tube, center rod, or the plastic insert for
differerent
If you want to try constructing a stub filter to notch out the FM carrier,
look here:
www.repeater-builder.com/ge/datafile-bulletin/df-10002-01.pdf
73, Eric Lemmon WB6FLY
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of David Epley
Sent:
Although the outside dimensions were the same between Wacom WP-641 cavities
for commercial frequencies and those for 2m frequencies, the harness and
stub lengths were customized for the specific operating frequencies. My
recommendation is to ship the duplexer to Telewave for conversion and tuning
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
It is more than possible you have a crystal cut on the wrong
mode. It's not hard to order replacement crystals although you
run into the min order or higher costs depending on where the
new rocks are ordered.
You might order and try both the oven and non-oven operation.
I run a TA51 6 Meter
If you're sure the just rf at the front end of receiver is
the entire problem..?
Install a High-Q Notch cavity (with a probe dc ground return) on
the receiver and try a 3dB pad (on the receiver) to start things
out.
I sourced a similar problem with a Yaesu/Vertex repeater...
their receivers
In this case... I would expect the band-pass cavity option
to be a popcorn fart. See my post about the High-Q notch
cavity (with the dc return probe) and the attenuator, which
should help if the problem is source to the RF coming in
the coax port is the sole source.
s.
David Epley [EMAIL
I think your title says it, overload.
Parelectronics makes a little 3 pole filter, is that the one you
tried? You can tweak all 3 poles to 104.9 for about 50 db attnuation.
http://www.parelectronics.com/vhf-fm.htm
A shorted stub would be easy to try too, there are several designs.
Since the FM
There's also an aspect to this which is analogous to the reason some people
like little neighborhood bars over big discos.
I personally buy into the idea that some of these repeater systems reach
tech overkill. I've grown weary of intrusive courtesy tones and overused
voice ID. I think some
David,
An open 1/4-wave stub will also be broadly resonant at the ninth harmonic,
or 944.1...a little close to your operating frequencies.
A better option in your situation might be a shorted 1/2-wave stub at your
receive frequency. Using good coax, fed on a tee connector, it should be
nearly
The Devil is in the details...
I glazed over the original post and just noticed.
David Epley [EMAIL PROTECTED] wrote:
My transmitter is a Motorola Purc 5000 running 75 watts the
receiver is a converted maxtrac 800mhz radio.
Using the converted Maxtrac Mobile might just be the fly in
your
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
Well...
The crystal could easily be the problem. Group member Sal
sent me a Uniden ARU-251 Repeater to re-crystal and align.
The crystal was cut on the wrong mode and a real
cluster $#* to the problem sort out.
The transmitter would partially align but not remain stable.
The sanity check
I have a handful of different size attenuators and will try in the morning.
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of skipp025
Sent: Thursday, November 22, 2007 2:03 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Re: Receiver
Along a theme you might have a look at the instructions
for the 8920a, 8920b Service Monitors.
And of course Agilent has a web page for manuals and information:
http://www.home.agilent.com/agilent/facet.jspx?to=80029.k.0c=79712.f.1cc=USlc=eng
cheers,
skipp
Kruser [EMAIL PROTECTED]
I am looking for a cavity now
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of skipp025
Sent: Thursday, November 22, 2007 2:07 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Re: Receiver overload
In this case... I would expect
As a generic rule of thumb... the larger the cavity
diameter the higher the internal Q. If nothing else
don't forget you can use low band cavities in the 3/4
wave mode. Trying to find an min 8 to 15 inch diameter
notch cavity on 104 MHz might be a bit of fun for the
average Joe.
As an
At 07:50 PM 11/21/07, you wrote:
Hi,
Does anyone have any information on interfacing to the old xx10 series
of Icom repeaters? ACC used to have an application note for the
1.2ghz version. Thanks!
There are MSF5000 and Mastr II articles in the 850 section of the
ACC page at
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
Trying to get a notch cavity for 104 MHz that will pass 900 MHz might be a
problem.
Also using coax as a notch one has to make sure it does not do same at 900 MHz.
A 1/4 wave at 104 MHz has lots of notches at the high frequencies, but I would
give it a try.
A bandpass at 900 would probably
Paul,
Where you been. Don't you know a controller that talks a lot makes the
receiver work better and gives better coverage.
I think some repeaters transmit more controller audio than user audio, hi.
73, ron, n9ee/r
From: Paul Plack [EMAIL PROTECTED]
Date: 2007/11/22 Thu PM 01:31:23 CST
I've seen typical BpBr duplexers in mid 150 tune at 146.
One problem is for optimum performance the cabling would need to be changed,
but still should work for most repeater applications.
73, ron, n9ee/r
From: Chappy [EMAIL PROTECTED]
Date: 2007/11/22 Thu AM 11:11:22 CST
To:
I've got the chip pulled, and a socket installed, but I'd prefer to wait on
sending a chip out until my replacement programmer gets here and I can
validate the chip myself.. if I'm lucky it will be here tomorrow.
The unit was previously programmed for 451.125/456.125.. I'm moving it down
10mhz
skipp025 wrote:
Well...
The crystal could easily be the problem.
How?
I don't think he was having any trouble tuning it up, getting expected
power output, or having stability issues; he is only complaining about
proper modulation capability.
Kevin
Seller claimed the repeater was removed from operation, and it was labeled
451/456 - so it should be the right one to tune down
The 1st 4 bytes are CC 84 3C 83 if you can compare that to the data your
programmer would write.. The target frequencies are 441.350 TX and 456.350
RX
I've
David,
I suspect that the issue is 104.9 mhz energy coming down the outside of
the feedline and into your receiver. As others have mentioned the maxtrac
has a lot of plastic. A shielded box with no unbypassed wires going in and
out may help. Ferrites on the feedline or a coil in the
Sorry, no. A shorted 1/2 wave stub at your frequency connected to a tee
would be a dead short at your frequency. A 1/4 wave shorted stub at your
frequency may work very well.
Al,
K9SI
A better option in your situation might be a shorted 1/2-wave stub at your
receive frequency. Using good
What is your opinion on a ¼ wave open stub installed in the receiver side
cut for 104.9?
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Al Wolfe
Sent: Thursday, November 22, 2007 5:50 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder]
Hi Joe,
TA51 transmitter. Here is the real problem. I can only get 2.5Khz
deviation of clean 1000Hz audio out of the transmitter. I can push it
to 3Khz, but it gets distorted.
That transmitter uses an RC phase modulator instead of an LC phase
modulator, which means the maximum phase
Looking to trade a EF Johnson 7164 VHF 99 Channel Mobile with Hand
Mic , And Mounting Hardware , For a Radio Shack PRO-2067 Scanner .
I can Program the EF Johnson 7164 Rig For you if Needed . Please
Contact me if you Have any Questions . Thank you . 73
Steve efj44
Chescopa Yahoo group Owner .
Sorry, but it does not belong to me or I would. This belongs to the
local club that I am helping out.
73, Joe, K1ike
Kevin Custer wrote:
Joe,
Would you be willing to send me the exciter for experimental modification?
.
An open qtr wave at 104.5 will notch out 104.5, but make sure it is not off
muliple qtr wave at your 925/905 freq or it could notch it out also. Just have
to do the calculation.
Qtr wave with .66 velocity factor cable at 104.5 MHz is about 1.55 ft. I
believe this is 9 qtr wavelengths at
I think you may be on the right track with a ¼ wave open stub
between the duplexer and the receiver. try and use a good low loss
piece of coax for the stub...like ¼ or half inch superflex the lower
loss the higher Q the notch will be. start a bit long and shorten it
a bit at a time to tune.
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
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
--- In Repeater-Builder@yahoogroups.com, David Epley [EMAIL PROTECTED]
wrote:
What is your opinion on a ¼ wave open stub installed in the receiver
side
cut for 104.9?
David,
This is the first thing I'd try. I have much success using stubs
to eliminate problems such as yours. However, it
Joe wrote:
Sorry, but it does not belong to me or I would. This belongs to the
local club that I am helping out.
When you talk to them Joe, see if they would be willing to send the
exciter to me. I'd be willing to do some experimenting on it to see if
it could be FM'd satisfactorily.
I
70s Rock
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of skipp025
Sent: Thursday, November 22, 2007 10:11 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Re: Receiver overload
Anyone bother to ask what format is playing on the
Hi All,
I am looking for a simple circuit that I could use to connect either 2x RX's or
2x TX's onto 1 port of my controller.
Reason, I am dealing with a split site repeater. So I don't want to waste a
port for half a system, that I could use for another use.
I was then thinking about using the
Anyone bother to ask what format is playing on the broadcast
station? You could have some hip-hop or thug music playing
and that could be a potential problem?
:-)
s.
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
In NZ we used to have VHF repeater services on 101-108 MHz (AM) and there were
quite a number of surplus cavity filters floating around from the old TX
combiners and RX multicouplers. If you are in need of something email me off
list.
Cheers
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