I've had luck finding these kinds of problems by bringing a spectrum
analyzer to the site and connecting it to an antenna. I look at
10-20Mhz sections of the spectrum and try to find a spike that comes up
at the same time as the interference. It is time consuming and
dependent upon the
That's how I found 157.74. We're going back up on Tuesday to look some more.
--
Tim
:wq
On Aug 21, 2010, at 4:52 AM, Joe wrote:
I've had luck finding these kinds of problems by bringing a spectrum
analyzer to the site and connecting it to an antenna. I look at
10-20Mhz sections of the
I have paging intermod from 157.740 Mhz. My receiver is on 144.540 Mhz. I'm
100% sure there is another transmitter involved in the mix because sometimes
the pager is transmitting and I have no interference.
I have an intermod calculator program but it wants all the known transmitters
and the
...@yahoogroups.com] On Behalf Of Tim Sawyer
Sent: Friday, August 20, 2010 6:36 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Intermod Calculation
I have paging intermod from 157.740 Mhz. My receiver is on
144.540 Mhz. I'm 100% sure there is another transmitter
Most likely suspects would be 151.140 and 170.940 MHz.
Joe M.
Tim Sawyer wrote:
I have paging intermod from 157.740 Mhz. My receiver is on 144.540 Mhz. I'm
100% sure there is another transmitter involved in the mix because sometimes
the pager is transmitting and I have no interference.
I'll watch those. How did you calculate them?
--
Tim
:wq
On Aug 20, 2010, at 5:38 PM, MCH wrote:
Most likely suspects would be 151.140 and 170.940 MHz.
Joe M.
Tim Sawyer wrote:
I have paging intermod from 157.740 Mhz. My receiver is on 144.540 Mhz. I'm
100% sure there is another
2A-B solving for once for A and once for B.
Or, to make it more clear (maybe), the sum of your receiver and half the
difference between the two (IOW, the frequency directly half way between
two two others), and the sum of the full difference plus the paging
transmitter frequency.
Putting it
Does anyone know who would do an Intermod study for a site that has
900MHZ spread spectrum on it? I have done some very basic intermod
runs, but don't quite know how to handle spread spectrum nor who to
refer to for this service.
Any ideas?
Thanks, Joe, K1ike
...@yahoogroups.com] On Behalf Of n3dab
Sent: Tuesday, March 17, 2009 7:59 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Intermod. question
A recent post concerning intermod created by rusty bolts, washers, etc.
caught my attention the other day. Someone suggested using Lithium Grease
, March 18, 2009 11:51 AM
Subject: RE: [Repeater-Builder] Intermod. question
Doug,
I use Penetrox AR (made by Burndy Electrical) to assemble antennas and
such. It's available from ham sources (AES, HRO, etc) or commercial
vendors
(Tessco, Hutton, etc).
I'm not sure of the conductivity
Thanks to Chuck, Mark,and Greg for the suggestions on different lubricants to
use. This will give me something to research and check-out. Thanks again.
Doug /n3dab
A recent post concerning intermod created by rusty bolts, washers, etc. caught
my attention the other day. Someone suggested using Lithium Grease on and
between the components when assembling them. I understand the logic behind the
suggestion, but I'm wondering if there is any other grease
Every IM calculator I've seen only deals with those freqs entered
into a list. All well and good when you're analyzing known factors
but what if you're trying to nail down a mix/IM that is caused by an
unknown third party (offsite) source?
Anyone know of such a program that will allow you to
this in the
past. Very tedious approach. Time to start coding - in my *free* time!
Stu
W3STU
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Ken Arck
Sent: Saturday, February 02, 2008 13:05
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder
At 10:37 AM 2/2/2008, you wrote:
I suppose that could be done for a single unknown but more than one
unknown candidate frequency would result in unlimited combinations.
I would find useful a program that could handle broadband candidate
signal sources. I've used multiple narrowband sources
Find software called RFS.exe, it is an older DOS program but it does have an
intermod calculator.
On 2/2/08, Ken Arck [EMAIL PROTECTED] wrote:
At 10:37 AM 2/2/2008, you wrote:
I suppose that could be done for a single unknown but more than one
unknown candidate frequency would result in
At 12:59 PM 2/2/2008, you wrote:
Find software called RFS.exe, it is an older DOS program but it does
have an intermod calculator.
---Does RFS allow for 3rd party variables?
(I already have IM software - that's not the issue)
Ken
I just used RFS.EXE the other day to calculate passive intermodulation.
It's my favorite program for years, but can only calculate hits on
specific frequencies. What the original question asked was how to
calculate a frequency that will cause a known intermod. I don't know of
any software
I would strongly suspect that new preamp to be the culprit.
73
Gary K4FMX
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Nate Duehr
Sent: Saturday, February 03, 2007 2:35 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder
I have come to the same conclusion.
Fred N4GER
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Gary Schafer
Sent: Saturday, February 03, 2007 2:05 PM
To: Repeater-Builder@yahoogroups.com
Subject: [SPAM] RE: [Repeater-Builder
] On Behalf Of Gary Schafer
Sent: Saturday, February 03, 2007 5:02 PM
To: Repeater-Builder@yahoogroups.com
Subject: [SPAM] RE: [Repeater-Builder] Intermod
The 165 repeater needs an additional notch in its transmitter.
73
Gary K4FMX
_
From: Repeater-Builder@yahoogroups.com
: [Repeater-Builder] Intermod
The 165 repeater needs an additional notch in its transmitter.
73
Gary K4FMX
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Fred Flowers
Sent: Saturday, February 03, 2007 5:04 PM
To: Repeater-Builder@yahoogroups.com
I knew what you meant, thanks.
Fred N4GER
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Gary Schafer
Sent: Monday, February 05, 2007 11:43 AM
To: Repeater-Builder@yahoogroups.com
Subject: [SPAM] RE: [Repeater-Builder] Intermod
Does anyone have a source for an intermod calculation program?
Fred N4GER
Check the repeater-builder web site.
Bob M.
==
--- Fred Flowers [EMAIL PROTECTED] wrote:
Does anyone have a source for an intermod
calculation program?
Fred N4GER
We won't tell. Get more
Fred Flowers wrote:
Does anyone have a source for an intermod calculation program?
http://www.repeater-builder.com/antenna/ant-sys-index.html
Click on the Calculators shortcut.
Kevin
I configured my Yahoo mailbox so it put spam into the
BULK folder rather than immediately deleting it.
I found this message between 1200 and 1226 EST.
So nice of Yahoo to consider this SPAM ! I would
surmise that this is why I'm not seeing any of Kevin's
messages.
Bob M.
==
--- Kevin Custer
03, 2007 11:17 AM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Intermod
Fred Flowers wrote:
Does anyone have a source for an intermod calculation program?
http://www.repeater-builder.com/antenna/ant-sys-index.html
Click on the Calculators shortcut.
Kevin
Kevin,
Please allow me to pick your brain.
I was just informed of an intermod problem with 2 two meter repeaters. They
are on towers about 2 miles apart. The frequencies are 147.33+ tone 107.2
147.165+ no tone. Two weeks ago I replaced the 147.33 equipment with a
Mastr II station repeater
Shouldn't the 147.765 subscriber station be counted in the mix? While the
distance and field strength may vary, the user sending to the 147.165 does
make a contribution to the mix. sb
On 2/3/07, Fred Flowers [EMAIL PROTECTED] wrote:
Kevin,
Please allow me to pick your brain.
I was just
@yahoogroups.com
Subject: Re: [Repeater-Builder] Intermod
Shouldn't the 147.765 subscriber station be counted in the
mix? While the distance and field strength may vary, the
user sending to the 147.165 does make a contribution to the mix. sb
On 2/3/07, Fred Flowers [EMAIL PROTECTED
On 2/3/07, Jeff DePolo [EMAIL PROTECTED] wrote:
I think I see how Steve's logic is leaning, and I agree - I don't see any
logical mix here until you include a user's transmission on one of the
repeater's inputs. Fred - do you hear ALL 147.33 transmitter activity
coming in on the 147.765
, 2007 1:35 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Intermod
On 2/3/07, Jeff DePolo [EMAIL PROTECTED] wrote:
I think I see how Steve's logic is leaning, and I agree - I don't see any
logical mix here until you include a user's transmission on one of the
repeater's
Thanks
-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Paul Finch
Sent: Saturday, February 03, 2007 5:14 PM
To: Repeater-Builder@yahoogroups.com
Subject: [SPAM] RE: [Repeater-Builder] Intermod
Google Commshop.
_
From
Some one heard the owner of 165 talk about having to keep the
power down
because of desense.
A perfect example of bandaidsmanship.
What about a band pass on 147.765?
Nah, it would only buy you a couple of dB of attenuation at 147.93.
It may take a crystal
filter or just
padding the
Every once in a while we get FM broadcast interference on our DCR
442.425 uhf repeater here in Dallas Texas. It apparently bothers other
440 ham repeaters in the area as well. Seeing how the broadcast FM is
250mhz+ away from our input, and a DCI bandpass filter is inline with
our rx, could
Actually that is 442.075
dallasreact112 wrote:
Every once in a while we get FM broadcast interference on our DCR
442.425 uhf repeater here in Dallas Texas. It apparently bothers other
440 ham repeaters in the area as well. Seeing how the broadcast FM is
250mhz+ away from our input, and a
Help us to help you. The more information you can provide the faster a
solution will reveal its self.
What channel is the FM station on that is interfering with you, how
much power is it running, and how close is it? Is the audio coming
through it distorted or understandable? What repeater are
Apparently you can nail down which station is the troublemaker...
Thinking about possible unusual suspects ...
IIRC, there's an allocation for BC Remote Pickup in the 450-451 range ..
which wouldn't necessarily be continous.. and if they're using that as a
'talk-back' or cueing channel, it may
I'm looking for a decent intermod program. I'm aware of the one from EMR called IMCALC, but don't particularly care for it. Anything else out there? I poked around with Google, but didn't have much luck.ChuckWB2EDV
YAHOO! GROUPS LINKS
Visit your group
with the
software. Here's the Web site:
http://www.dcico.com/dcilmr.htm
73, Eric Lemmon WB6FLY
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of
[EMAIL PROTECTED]Sent: Thursday, December 29, 2005 6:09
AMTo: Repeater-Builder@yahoogroups.comSubject:
[Repeater-Builder] Intermod
I disagree, because he says it happens only when things are linked.
I would think it has something to do with the link transmitter
intermoding the repeater receiver, or the repeater transmitter
intermoding the link receiver. He doesn't elaborate enough on when it
happens, like after the
Hey Guys;
Why does my 146.970/Rptr when linked to a 147.240/Rptr get interference
from a 146.700/Rptr. The 146.700/R is about 5-7 miles from my
146.970/R. When the link is up and someone uses the 146.700/R it
creates terrible interference and you can actually understand what is
being said on
Dennis,
You have classic third-order intermodulation interference. 146.970 times 2
= 293.940 MHz. Subtract the 146.700 signal and you have 293.940 - 146.700
= 147.240 MHz, the output of your linked repeater. Other mixing products
are possible. I suspect that neither the 146.970 repeater nor
kc4ih [EMAIL PROTECTED] wrote:
After much head scratching I believe that the
difference in frequency of the pager transmitter
of 600 khz is the problem
Head scratching doesn't provide real answers. Are
the paging transmitters running circulators? Are
they licensed for the rated power
and see if it helps any.
- Original Message -
From: mch [EMAIL PROTECTED]
To: Repeater-Builder@yahoogroups.com
Sent: Sunday, October 03, 2004 7:11 PM
Subject: Re: [Repeater-Builder] Intermod problem? Yes!
By that statement, you are saying that the 146.670 repeater is
coordinated
Q,
I had a IM problem several years ago with our 146.940
repeater. The repeater was a GE MastrII station with a
dual isolator on the transmitter and a bandpass
bandreject duplexer. The antenna was a Sinclair SRL229
mounted to a 40 Ft wood pole. The other transmitters
found in the IM mix were AM
if it helps any.
- Original Message -
From: mch [EMAIL PROTECTED]
To: Repeater-Builder@yahoogroups.com
Sent: Sunday, October 03, 2004 7:11 PM
Subject: Re: [Repeater-Builder] Intermod problem? Yes!
By that statement, you are saying that the 146.670 repeater is
coordinated? If so, what
Trying to troubleshoot an intermod??? problem between two repeaters. The
146.10/.70 repeater's receiver gets blasted by the 147.90/.30 transmitter
but only when they are both transmitting. Yes,the transit freqs are 600khz
apart and they are only 5 miles apart. Would a circulator help this
I would try one or two bandpass cavities between the duplexer and the
receiver of the victim repeater. The symptom you describe is that of
poor selectivity and possibly receiver IM. A ferrite isolator on either
transmitter won't have much effect on signals that mix in the receiver
front end.
The isolator might fix the problem. The second
harmonic of the 146.7 is 293.4. If you subtract 147.3,
it comes up right on your input, 146.1.(Classic 2A-B
intermod) Same thing is going on with the other freqs.
Could also be mixing in your RX, or about any other
non-linear spot between the two
They are all GE MastrII base stations so I dont think its a receiver
problem...
- Original Message -
From: Eric Lemmon [EMAIL PROTECTED]
To: Repeater-Builder@yahoogroups.com
Sent: Sunday, October 03, 2004 2:07 AM
Subject: Re: [Repeater-Builder] Intermod problem?
I would try one or two
I agree. We have had similar problems with 146.745 and 147.345,
146.67, and 147.27, 146.625, and 147.225 here locally. All of these
were traced to mixing in the PA stage of the repeaters. In some
instances, isolators were needed on both repeaters to eliminate the
problem totally.
Kevin
Maybe not the answer you want to hear, but have the uncoordinated
repeater (147.300 or 146.670) solve the problem. If that means moving
location farther away, so be it. ;-
As for the technical side, it may help, but it all depends on where the
mixing is happening.
Joe M.
Q wrote:
Trying to
By that statement, you are saying that the 146.670 repeater is
coordinated? If so, what is the callsign and location? eMail me
privately if you wish.
Joe M.
Q wrote:
Unfortunately,only the 147.30 is un-coordinated. Now for the
politics of the hobby...
- Original Message -
From:
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