Re: 145 MHz signal blocking 435 MHz downlink
Greg, I had a problem with 70cm jamming 2401 down link many years ago. The problem turned out to be corrosion between the coax connector shell and the aluminum antenna element. Cleaning up the connection solved the problem. The corrosion acts like a diode and will make enough 3 order products to trash any receiver. Use liquid electrical tape or non-corrosive (doesn't smell like vinegar) silicon seal to keep these connections dry and clean. Art, KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of g0mrf@aol.com Sent: Monday, January 20, 2014 1:23 AM To: ko6th.greg@gmail.com; kq6ea@verizon.net; w4tas@gte.net; amsat-bb@amsat.org Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
Hi Greg.
Most decent VHF transmitters will already have a pretty good LPF on the output to reduce the harmonics.
However, receivers these days tend to be DC-Daylight, so frequently need a filter to prevent 'blocking' by unwanted high level signals. In that case preventing the VHF coming into the UHF receiver can be important
Thanks
David
-----Original Message----- From: Greg D ko6th.greg@gmail.com To: Jim Jerzycke kq6ea@verizon.net; w4tas w4tas@gte.net; 'AMSAT Mailing List' amsat-bb@amsat.org Sent: Mon, 20 Jan 2014 3:47 Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
I know this has been answered before, but I forget. Given one Diplexer, is it better to put it on the Tx side to limit the 3rd harmionic going out, or better on the Rx side to limit the VHF fundamental coming in? Tony's diagram shows the later; I would have thought the former would be more effective (hitting the problem at its source).
Greg KO6TH
Jim Jerzycke wrote:
Yep, been using one of those for years!
I have a Sinclair Labs unit that provides 100dB rejection outside of the 2 Meter band.
Jim KQ6EA
On 01/19/2014 07:32 PM, w4tas wrote:
I would also suggest a low pass filter on the two meter transmitter. A diplexer will work well for this also. This will reduce the third harmonic which is causing your problem.
Good luck,
-----Original Message----- From: Jim Jerzycke Sent: Sunday, January 19, 2014 2:09 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
Buy a diplexer, and connect it as shown in the linked article:
http://www.amsat.org/amsat-new/articles/Mode-J/
I also tilt both of my Yagis so they're 45* to the boom, which makes them 90* to each other.
Yes, I lose some signal on terrestrial use, but ti helped cut the coupling, and desense, down quite a bit.
73, Jim KQ6EA
On 01/19/2014 06:56 PM, Gabriel - EA6VQ wrote:
Hi all,
I have a coupling problem in my station when trying to work FO-29. My 2m signal is completely blocking the 435 MHz downlink, and so I can't hear my signal off the satellite. I guess it must be something related to the distance between the two yagis. (I use the terrestrial horizontal yagis you can see at http://www.dxmaps.com/jm19hn.html ). With mode-B satellites there is no problem. I have tried it with two different 435 receivers, and it's exactly the same.
Anyone has had this problem o have an idea of the possible reason? And what is more important, of some way to solve it?
Thanks for any possible help.
- Gabriel - EA6VQ
Web-Site: HTTP://www.dxmaps.com VQLog 3.1 (build 78): HTTP://www.vqlog.com _________________________________________________________
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hi Art,
Yep, corrosion is a great source for harmonics. I had a similar problem with AO-40, only mine turned out to be the relay contacts on the 70cm antenna's RHCP / LHCP relay. Cycle them a few times and things quieted down. But I only heard the problem when I was aimed at the big oak tree behind our house, which was odd because the 70cm transmit antenna was literally a few inches away from the edge of the 2.4 ghz receive dish. Never heard of a tree acting as a diode before. Maybe the squirrels were up to something...
Greg KO6TH
kc6uqh@cox.net wrote:
Greg, I had a problem with 70cm jamming 2401 down link many years ago. The problem turned out to be corrosion between the coax connector shell and the aluminum antenna element. Cleaning up the connection solved the problem. The corrosion acts like a diode and will make enough 3 order products to trash any receiver. Use liquid electrical tape or non-corrosive (doesn't smell like vinegar) silicon seal to keep these connections dry and clean. Art, KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of g0mrf@aol.com Sent: Monday, January 20, 2014 1:23 AM To: ko6th.greg@gmail.com; kq6ea@verizon.net; w4tas@gte.net; amsat-bb@amsat.org Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
Hi Greg.
Most decent VHF transmitters will already have a pretty good LPF on the output to reduce the harmonics.
However, receivers these days tend to be DC-Daylight, so frequently need a filter to prevent 'blocking' by unwanted high level signals. In that case preventing the VHF coming into the UHF receiver can be important
Thanks
David
-----Original Message----- From: Greg D ko6th.greg@gmail.com To: Jim Jerzycke kq6ea@verizon.net; w4tas w4tas@gte.net; 'AMSAT Mailing List' amsat-bb@amsat.org Sent: Mon, 20 Jan 2014 3:47 Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
I know this has been answered before, but I forget. Given one Diplexer, is it better to put it on the Tx side to limit the 3rd harmionic going out, or better on the Rx side to limit the VHF fundamental coming in? Tony's diagram shows the later; I would have thought the former would be more effective (hitting the problem at its source).
Greg KO6TH
Jim Jerzycke wrote:
Yep, been using one of those for years!
I have a Sinclair Labs unit that provides 100dB rejection outside of the 2 Meter band.
Jim KQ6EA
On 01/19/2014 07:32 PM, w4tas wrote:
I would also suggest a low pass filter on the two meter transmitter. A diplexer will work well for this also. This will reduce the third harmonic which is causing your problem.
Good luck,
-----Original Message----- From: Jim Jerzycke Sent: Sunday, January 19, 2014 2:09 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
Buy a diplexer, and connect it as shown in the linked article:
http://www.amsat.org/amsat-new/articles/Mode-J/
I also tilt both of my Yagis so they're 45* to the boom, which makes them 90* to each other.
Yes, I lose some signal on terrestrial use, but ti helped cut the coupling, and desense, down quite a bit.
73, Jim KQ6EA
On 01/19/2014 06:56 PM, Gabriel - EA6VQ wrote:
Hi all,
I have a coupling problem in my station when trying to work FO-29. My 2m signal is completely blocking the 435 MHz downlink, and so I can't hear my signal off the satellite. I guess it must be something related to the distance between the two yagis. (I use the terrestrial horizontal yagis you can see at http://www.dxmaps.com/jm19hn.html ). With mode-B satellites there is no problem. I have tried it with two different 435 receivers, and it's exactly the same.
Anyone has had this problem o have an idea of the possible reason? And what is more important, of some way to solve it?
Thanks for any possible help.
- Gabriel - EA6VQ
Web-Site: HTTP://www.dxmaps.com VQLog 3.1 (build 78): HTTP://www.vqlog.com _________________________________________________________
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
I have experienced some desense on the past two passes of FO-29, so after this pass, I checked all the connectors in my system.
Turns out one of the elements of my Elk antenna was very slightly loose. Tightened it up and I don't hear any hash at all on my 435 MHz receive.
It doesn't take much to throw everything out of whack!
73,
Paul, N8HM
On Mon, Jan 20, 2014 at 9:02 PM, Greg D ko6th.greg@gmail.com wrote:
Hi Art,
Yep, corrosion is a great source for harmonics. I had a similar problem with AO-40, only mine turned out to be the relay contacts on the 70cm antenna's RHCP / LHCP relay. Cycle them a few times and things quieted down. But I only heard the problem when I was aimed at the big oak tree behind our house, which was odd because the 70cm transmit antenna was literally a few inches away from the edge of the 2.4 ghz receive dish. Never heard of a tree acting as a diode before. Maybe the squirrels were up to something...
Greg KO6TH
kc6uqh@cox.net wrote:
Greg, I had a problem with 70cm jamming 2401 down link many years ago. The problem turned out to be corrosion between the coax connector shell and the aluminum antenna element. Cleaning up the connection solved the problem. The corrosion acts like a diode and will make enough 3 order products to trash any receiver. Use liquid electrical tape or non-corrosive (doesn't smell like vinegar) silicon seal to keep these connections dry and clean. Art, KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of g0mrf@aol.com Sent: Monday, January 20, 2014 1:23 AM To: ko6th.greg@gmail.com; kq6ea@verizon.net; w4tas@gte.net; amsat-bb@amsat.org Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
Hi Greg.
Most decent VHF transmitters will already have a pretty good LPF on the output to reduce the harmonics. However, receivers these days tend to be DC-Daylight, so frequently need a filter to prevent 'blocking' by unwanted high level signals. In that case preventing the VHF coming into the UHF receiver can be important
Thanks
David
-----Original Message----- From: Greg D ko6th.greg@gmail.com To: Jim Jerzycke kq6ea@verizon.net; w4tas w4tas@gte.net; 'AMSAT Mailing List' amsat-bb@amsat.org Sent: Mon, 20 Jan 2014 3:47 Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
I know this has been answered before, but I forget. Given one Diplexer, is it better to put it on the Tx side to limit the 3rd harmionic going out, or better on the Rx side to limit the VHF fundamental coming in? Tony's diagram shows the later; I would have thought the former would be more effective (hitting the problem at its source).
Greg KO6TH
Jim Jerzycke wrote:
Yep, been using one of those for years!
I have a Sinclair Labs unit that provides 100dB rejection outside of the 2 Meter band.
Jim KQ6EA
On 01/19/2014 07:32 PM, w4tas wrote:
I would also suggest a low pass filter on the two meter transmitter. A diplexer will work well for this also. This will reduce the third harmonic which is causing your problem.
Good luck,
-----Original Message----- From: Jim Jerzycke Sent: Sunday, January 19, 2014 2:09 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: 145 MHz signal blocking 435 MHz downlink
Buy a diplexer, and connect it as shown in the linked article:
http://www.amsat.org/amsat-new/articles/Mode-J/
I also tilt both of my Yagis so they're 45* to the boom, which makes them 90* to each other.
Yes, I lose some signal on terrestrial use, but ti helped cut the coupling, and desense, down quite a bit.
73, Jim KQ6EA
On 01/19/2014 06:56 PM, Gabriel - EA6VQ wrote:
Hi all,
I have a coupling problem in my station when trying to work FO-29. My 2m signal is completely blocking the 435 MHz downlink, and so I can't hear my signal off the satellite. I guess it must be something related to the distance between the two yagis. (I use the terrestrial horizontal yagis you can see at http://www.dxmaps.com/jm19hn.html ). With mode-B satellites there is no problem. I have tried it with two different 435 receivers, and it's exactly the same.
Anyone has had this problem o have an idea of the possible reason? And what is more important, of some way to solve it?
Thanks for any possible help.
- Gabriel - EA6VQ
Web-Site: HTTP://www.dxmaps.com VQLog 3.1 (build 78): HTTP://www.vqlog.com _________________________________________________________
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (3)
-
Greg D -
kc6uqh＠cox.net -
Paul Stoetzer