Hi AMSAT friends,
I'm having a technical problem and was wondering if anyone had any suggestions. I've been experimenting with using an FT-991A transmitter and SDR receiver to run full-duplex on the satellites. My problem is as soon as I key the FT-991A transmitter, my SDR receiver waterfall goes completely white and I don't hear anything but static. Classic overload symptoms.
I've tried several things: - Upgrading my receiver from an RTL-SDR to an SDRplay RSP1A: no improvement. - Adding a duplexer as a band pass filter: no improvement. - Transmitting with a vertical antenna about 40' away from my yagis: YES it did solve the problem but is not a suitable solution.
I'm using the same yagi antenna setup that I've used successfully for years with an FT-847, and have also had the same problem with a handheld Arrow.
At last I tried transmitting with a different radio, and the problem disappears. I figured the problem was in my FT-991A so I sent it for warranty repair, but just got the call that they can't find anything wrong with it. It has no measurable spurious or out of band emissions. I'm at a loss here... I know people are using the same equipment (FT-991 + SDRplay) successfully; Simon Brown comes to mind.
Here is a video I created demonstrating the problem with the FT-991 and showing that it doesn't appear with an Icom ID-880H. https://youtu.be/gXOIK5gLjgs
I still think the problem must be in the radio, but if they can't find anything to fix then I'm out of luck. I'd love to hear any suggestions or feedback.
Thanks, Alex VA3ASE
Did you try a duplexer on both the input and output side?
73.
Paul, N8HM
On Thu, Aug 2, 2018 at 2:35 PM, VA3ASE va3ase@gmail.com wrote:
Hi AMSAT friends,
I'm having a technical problem and was wondering if anyone had any suggestions. I've been experimenting with using an FT-991A transmitter and SDR receiver to run full-duplex on the satellites. My problem is as soon as I key the FT-991A transmitter, my SDR receiver waterfall goes completely white and I don't hear anything but static. Classic overload symptoms.
I've tried several things:
- Upgrading my receiver from an RTL-SDR to an SDRplay RSP1A: no improvement.
- Adding a duplexer as a band pass filter: no improvement.
- Transmitting with a vertical antenna about 40' away from my yagis: YES it
did solve the problem but is not a suitable solution.
I'm using the same yagi antenna setup that I've used successfully for years with an FT-847, and have also had the same problem with a handheld Arrow.
At last I tried transmitting with a different radio, and the problem disappears. I figured the problem was in my FT-991A so I sent it for warranty repair, but just got the call that they can't find anything wrong with it. It has no measurable spurious or out of band emissions. I'm at a loss here... I know people are using the same equipment (FT-991 + SDRplay) successfully; Simon Brown comes to mind.
Here is a video I created demonstrating the problem with the FT-991 and showing that it doesn't appear with an Icom ID-880H. https://youtu.be/gXOIK5gLjgs
I still think the problem must be in the radio, but if they can't find anything to fix then I'm out of luck. I'd love to hear any suggestions or feedback.
Thanks, Alex VA3ASE _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
On 8/2/18 1:35 PM, VA3ASE wrote:
I'm having a technical problem and was wondering if anyone had any suggestions. I've been experimenting with using an FT-991A transmitter and SDR receiver to run full-duplex on the satellites. My problem is as soon as I key the FT-991A transmitter, my SDR receiver waterfall goes completely white and I don't hear anything but static. Classic overload symptoms.
Hello Alex,
Plastic case of the RSP1A == no shielding. The front-end filters can't stop that which goes right around them.
If you put the RSP1A into a metal box and install a USB EMI filter, I'd wager the problem will go away.
--- Zach N0ZGO
Hello. I have two 991A radios, and both do the same thing. I am unable to use them for transmit on two meters without killing the 70 CM RX. I use a Kenwood TS 2000 for transmit and 991A for receive. Not the way I want to do it, but I am for now, this allows the spectrum and waterfall for checking out the entire transponder. Hope someone finds a solution. 73,N4IQV, Terry
----- Original Message ----- From: "VA3ASE" va3ase@gmail.com To: amsat-bb@amsat.org Sent: Thursday, August 2, 2018 2:35:54 PM Subject: [amsat-bb] FT-991A Transmit Interference
Hi AMSAT friends,
I'm having a technical problem and was wondering if anyone had any suggestions. I've been experimenting with using an FT-991A transmitter and SDR receiver to run full-duplex on the satellites. My problem is as soon as I key the FT-991A transmitter, my SDR receiver waterfall goes completely white and I don't hear anything but static. Classic overload symptoms.
I've tried several things: - Upgrading my receiver from an RTL-SDR to an SDRplay RSP1A: no improvement. - Adding a duplexer as a band pass filter: no improvement. - Transmitting with a vertical antenna about 40' away from my yagis: YES it did solve the problem but is not a suitable solution.
I'm using the same yagi antenna setup that I've used successfully for years with an FT-847, and have also had the same problem with a handheld Arrow.
At last I tried transmitting with a different radio, and the problem disappears. I figured the problem was in my FT-991A so I sent it for warranty repair, but just got the call that they can't find anything wrong with it. It has no measurable spurious or out of band emissions. I'm at a loss here... I know people are using the same equipment (FT-991 + SDRplay) successfully; Simon Brown comes to mind.
Here is a video I created demonstrating the problem with the FT-991 and showing that it doesn't appear with an Icom ID-880H. https://youtu.be/gXOIK5gLjgs
I still think the problem must be in the radio, but if they can't find anything to fix then I'm out of luck. I'd love to hear any suggestions or feedback.
Thanks, Alex VA3ASE _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
It sounds like the FT-991A’s harmonic suppression isn’t quite up to par.
73,
Paul, N8HM
On Thu, Aug 2, 2018 at 19:51 TERRY SURFACE terrysurface1@centurylink.net wrote:
Hello. I have two 991A radios, and both do the same thing. I am unable to use them for transmit on two meters without killing the 70 CM RX. I use a Kenwood TS 2000 for transmit and 991A for receive. Not the way I want to do it, but I am for now, this allows the spectrum and waterfall for checking out the entire transponder. Hope someone finds a solution. 73,N4IQV, Terry
----- Original Message ----- From: "VA3ASE" va3ase@gmail.com To: amsat-bb@amsat.org Sent: Thursday, August 2, 2018 2:35:54 PM Subject: [amsat-bb] FT-991A Transmit Interference
Hi AMSAT friends,
I'm having a technical problem and was wondering if anyone had any suggestions. I've been experimenting with using an FT-991A transmitter and SDR receiver to run full-duplex on the satellites. My problem is as soon as I key the FT-991A transmitter, my SDR receiver waterfall goes completely white and I don't hear anything but static. Classic overload symptoms.
I've tried several things:
- Upgrading my receiver from an RTL-SDR to an SDRplay RSP1A: no
improvement.
- Adding a duplexer as a band pass filter: no improvement.
- Transmitting with a vertical antenna about 40' away from my yagis: YES it
did solve the problem but is not a suitable solution.
I'm using the same yagi antenna setup that I've used successfully for years with an FT-847, and have also had the same problem with a handheld Arrow.
At last I tried transmitting with a different radio, and the problem disappears. I figured the problem was in my FT-991A so I sent it for warranty repair, but just got the call that they can't find anything wrong with it. It has no measurable spurious or out of band emissions. I'm at a loss here... I know people are using the same equipment (FT-991 + SDRplay) successfully; Simon Brown comes to mind.
Here is a video I created demonstrating the problem with the FT-991 and showing that it doesn't appear with an Icom ID-880H. https://youtu.be/gXOIK5gLjgs
I still think the problem must be in the radio, but if they can't find anything to fix then I'm out of luck. I'd love to hear any suggestions or feedback.
Thanks, Alex VA3ASE _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
If you have access to the ARRL QST test archives, their review of the FT-991A is worth reading. While meeting all FCC requirements, neither TX or RX signals are as clean as some other rigs. That _might_ be enough to account for the differences.
73,
Alan WA4SCA
<-----Original Message----- <From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Paul <Stoetzer <Sent: Thursday, August 02, 2018 18:53 PM <To: TERRY SURFACE terrysurface1@centurylink.net <Cc: VA3ASE va3ase@gmail.com; amsat-bb@amsat.org <Subject: Re: [amsat-bb] FT-991A Transmit Interference < <It sounds like the FT-991A’s harmonic suppression isn’t quite up to par. < <73, < <Paul, N8HM < <On Thu, Aug 2, 2018 at 19:51 TERRY SURFACE terrysurface1@centurylink.net <wrote: < <> Hello. I have two 991A radios, and both do the same thing. I am unable to <> use them for transmit on two meters without killing the 70 CM RX. I use a <> Kenwood TS 2000 for transmit and 991A for receive. Not the way I want to <do <> it, but I am for now, this allows the spectrum and waterfall for checking <> out the entire transponder. Hope someone finds a solution. <> 73,N4IQV, Terry <> <> ----- Original Message ----- <> From: "VA3ASE" va3ase@gmail.com <> To: amsat-bb@amsat.org <> Sent: Thursday, August 2, 2018 2:35:54 PM <> Subject: [amsat-bb] FT-991A Transmit Interference <> <> Hi AMSAT friends, <> <> I'm having a technical problem and was wondering if anyone had any <> suggestions. I've been experimenting with using an FT-991A transmitter and <> SDR receiver to run full-duplex on the satellites. My problem is as soon as <> I key the FT-991A transmitter, my SDR receiver waterfall goes completely <> white and I don't hear anything but static. Classic overload symptoms. <> <> I've tried several things: <> - Upgrading my receiver from an RTL-SDR to an SDRplay RSP1A: no <> improvement. <> - Adding a duplexer as a band pass filter: no improvement. <> - Transmitting with a vertical antenna about 40' away from my yagis: YES it <> did solve the problem but is not a suitable solution. <> <> I'm using the same yagi antenna setup that I've used successfully for years <> with an FT-847, and have also had the same problem with a handheld Arrow. <> <> At last I tried transmitting with a different radio, and the problem <> disappears. I figured the problem was in my FT-991A so I sent it for <> warranty repair, but just got the call that they can't find anything wrong <> with it. It has no measurable spurious or out of band emissions. I'm at a <> loss here... I know people are using the same equipment (FT-991 + SDRplay) <> successfully; Simon Brown comes to mind. <> <> Here is a video I created demonstrating the problem with the FT-991 and <> showing that it doesn't appear with an Icom ID-880H. <> https://youtu.be/gXOIK5gLjgs <> <> I still think the problem must be in the radio, but if they can't find <> anything to fix then I'm out of luck. I'd love to hear any suggestions or <> feedback. <> <> Thanks, <> Alex VA3ASE <> _______________________________________________ <> Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum <available <> to all interested persons worldwide without requiring membership. <Opinions <> expressed <> are solely those of the author, and do not reflect the official views of <> AMSAT-NA. <> Not an AMSAT-NA member? Join now to support the amateur satellite <program! <> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb <> _______________________________________________ <> Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum <available <> to all interested persons worldwide without requiring membership. <Opinions <> expressed <> are solely those of the author, and do not reflect the official views of <> AMSAT-NA. <> Not an AMSAT-NA member? Join now to support the amateur satellite <program! <> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb <> <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions <expressed <are solely those of the author, and do not reflect the official views of AMSAT- <NA. <Not an AMSAT-NA member? Join now to support the amateur satellite <program! <Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
The wideband noise generated by the FT-991 has been noted in all the reviews I've seen e.g. Peter Hart's Radcom review said "The wideband transmitter noise output is rather poor, particularly on VHF". Have you tried using a bandpass filter on the FT-991A ? 73 Trevor M5AKA
On Friday, 3 August 2018, 02:55:36 GMT+1, Alan wa4sca@gmail.com wrote:
If you have access to the ARRL QST test archives, their review of the FT-991A is worth reading. While meeting all FCC requirements, neither TX or RX signals are as clean as some other rigs. That _might_ be enough to account for the differences.
73,
Alan WA4SCA
<-----Original Message----- <From: AMSAT-BB [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Paul <Stoetzer <Sent: Thursday, August 02, 2018 18:53 PM <To: TERRY SURFACE terrysurface1@centurylink.net <Cc: VA3ASE va3ase@gmail.com; amsat-bb@amsat.org <Subject: Re: [amsat-bb] FT-991A Transmit Interference < <It sounds like the FT-991A’s harmonic suppression isn’t quite up to par. < <73, < <Paul, N8HM < <On Thu, Aug 2, 2018 at 19:51 TERRY SURFACE terrysurface1@centurylink.net <wrote: < <> Hello. I have two 991A radios, and both do the same thing. I am unable to <> use them for transmit on two meters without killing the 70 CM RX. I use a <> Kenwood TS 2000 for transmit and 991A for receive. Not the way I want to <do <> it, but I am for now, this allows the spectrum and waterfall for checking <> out the entire transponder. Hope someone finds a solution. <> 73,N4IQV, Terry <> <> ----- Original Message ----- <> From: "VA3ASE" va3ase@gmail.com <> To: amsat-bb@amsat.org <> Sent: Thursday, August 2, 2018 2:35:54 PM <> Subject: [amsat-bb] FT-991A Transmit Interference <> <> Hi AMSAT friends, <> <> I'm having a technical problem and was wondering if anyone had any <> suggestions. I've been experimenting with using an FT-991A transmitter and <> SDR receiver to run full-duplex on the satellites. My problem is as soon as <> I key the FT-991A transmitter, my SDR receiver waterfall goes completely <> white and I don't hear anything but static. Classic overload symptoms. <> <> I've tried several things: <> - Upgrading my receiver from an RTL-SDR to an SDRplay RSP1A: no <> improvement. <> - Adding a duplexer as a band pass filter: no improvement. <> - Transmitting with a vertical antenna about 40' away from my yagis: YES it <> did solve the problem but is not a suitable solution. <> <> I'm using the same yagi antenna setup that I've used successfully for years <> with an FT-847, and have also had the same problem with a handheld Arrow. <> <> At last I tried transmitting with a different radio, and the problem <> disappears. I figured the problem was in my FT-991A so I sent it for <> warranty repair, but just got the call that they can't find anything wrong <> with it. It has no measurable spurious or out of band emissions. I'm at a <> loss here... I know people are using the same equipment (FT-991 + SDRplay) <> successfully; Simon Brown comes to mind. <> <> Here is a video I created demonstrating the problem with the FT-991 and <> showing that it doesn't appear with an Icom ID-880H. <> https://youtu.be/gXOIK5gLjgs <> <> I still think the problem must be in the radio, but if they can't find <> anything to fix then I'm out of luck. I'd love to hear any suggestions or <> feedback. <> <> Thanks, <> Alex VA3ASE <> _______________________________________________ <> Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum <available <> to all interested persons worldwide without requiring membership. <Opinions <> expressed <> are solely those of the author, and do not reflect the official views of <> AMSAT-NA. <> Not an AMSAT-NA member? Join now to support the amateur satellite <program! <> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb <> _______________________________________________ <> Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum <available <> to all interested persons worldwide without requiring membership. <Opinions <> expressed <> are solely those of the author, and do not reflect the official views of <> AMSAT-NA. <> Not an AMSAT-NA member? Join now to support the amateur satellite <program! <> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb <> <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions <expressed <are solely those of the author, and do not reflect the official views of AMSAT- <NA. <Not an AMSAT-NA member? Join now to support the amateur satellite <program! <Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Hi Alex,
Think of ways to identify the RF path from the Yaesu to the SDR thats overloading and obfuscating what you want to see on the SDR receiver. Is it radiated or conducted in your cabling.
Have you isolated your power supplies between the SDR and the Yaesu ?
Perhaps RF is riding the DC cable. (So run the SDR and the Yaesu on completely separate supplies, i.e. run the Yaesu on a sufficient battery)
Also, if you transmit with the Yaesu into a dummy load directly attached, is there RF overloading the SDR ? (This may verify the effectiveness of the shielding of the transmitter) Do the same with the ID880 to know if your dummy load is radiating, which is a good control test case.
Look at all of your cables and question "could that be the RF path to the RX ?" RF will ride a shield or a DC cable if permitted.
Interesting problem to solve.
73 Mike W4UOO
On Thu, Aug 2, 2018 at 7:53 PM, Paul Stoetzer n8hm@arrl.net wrote:
It sounds like the FT-991A’s harmonic suppression isn’t quite up to par.
73,
Paul, N8HM
On Thu, Aug 2, 2018 at 19:51 TERRY SURFACE terrysurface1@centurylink.net wrote:
Hello. I have two 991A radios, and both do the same thing. I am unable to use them for transmit on two meters without killing the 70 CM RX. I use a Kenwood TS 2000 for transmit and 991A for receive. Not the way I want to
do
it, but I am for now, this allows the spectrum and waterfall for checking out the entire transponder. Hope someone finds a solution. 73,N4IQV, Terry
----- Original Message ----- From: "VA3ASE" va3ase@gmail.com To: amsat-bb@amsat.org Sent: Thursday, August 2, 2018 2:35:54 PM Subject: [amsat-bb] FT-991A Transmit Interference
Hi AMSAT friends,
I'm having a technical problem and was wondering if anyone had any suggestions. I've been experimenting with using an FT-991A transmitter
and
SDR receiver to run full-duplex on the satellites. My problem is as soon
as
I key the FT-991A transmitter, my SDR receiver waterfall goes completely white and I don't hear anything but static. Classic overload symptoms.
I've tried several things:
- Upgrading my receiver from an RTL-SDR to an SDRplay RSP1A: no
improvement.
- Adding a duplexer as a band pass filter: no improvement.
- Transmitting with a vertical antenna about 40' away from my yagis: YES
it
did solve the problem but is not a suitable solution.
I'm using the same yagi antenna setup that I've used successfully for
years
with an FT-847, and have also had the same problem with a handheld Arrow.
At last I tried transmitting with a different radio, and the problem disappears. I figured the problem was in my FT-991A so I sent it for warranty repair, but just got the call that they can't find anything
wrong
with it. It has no measurable spurious or out of band emissions. I'm at a loss here... I know people are using the same equipment (FT-991 +
SDRplay)
successfully; Simon Brown comes to mind.
Here is a video I created demonstrating the problem with the FT-991 and showing that it doesn't appear with an Icom ID-880H. https://youtu.be/gXOIK5gLjgs
I still think the problem must be in the radio, but if they can't find anything to fix then I'm out of luck. I'd love to hear any suggestions or feedback.
Thanks, Alex VA3ASE _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions
expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions
expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Thank you to everyone who has replied, I appreciate it. I'll try to address everything in one reply.
Paul, Alan and Trevor, I borrowed a duplexer rated for 40dB isolation. I tried installing it on both the transmit side and on the receive side in various configurations. I think that counts as a band pass filter. It made no noticeable changes. I did read the QST report on the FT-991A mentioning the output, but my impression was that it wasn't a huge deal. I would be surprised if that was bad enough to cause this.
Zach my understanding is that the RSP1A is still shielded despite the plastic box, but I actually have access to an RSP2pro in a metal case that I can try out as well. I've never heard of a USB EMI filter before, I'll look into that. I'm using a quality TrippLite USB cable with molded chokes at each end.
Mike, I've tried both a linear power supply and a newer switching supply to power the 991 with no change. In the video I was using the same supply on both rigs. The SDR is powered through my laptop's USB port. I might have already tried transmitting into a dummy load but I'll try it again. I do know that switching the transmit antenna from my yagi to a rooftop vertical eliminates the problem, which suggests to me that the interference is not coming from inside the shack but from the transmit antenna's near field. I made the switch at an outdoor patch panel, so nothing inside changed.
Terry, this is the first time I've heard of any other 991 owners with the same problem. While it isn't what I want to hear, at least it might not just be me.
My 991 is still in the shop (Radioworld) but I can try to pick it up this weekend and keep experimenting. My original plan was to buy this FT-991A and SDRplay to run a satellite base station, but I recently inherited an FT-847 from a close friend, Brad VE3HII (SK). That opens a lot of (probably superior) options for my station but I'd still really like to see the FT-991A working as originally planned, and as it should. My friend's satellite antennas are still on his tower so I may also try to take my 991 there and repeat my tests.
73, Alex VA3ASE
On Fri, Aug 3, 2018 at 9:19 AM, Mike Sprenger mikesprenger@gmail.com wrote:
Hi Alex,
Think of ways to identify the RF path from the Yaesu to the SDR thats overloading and obfuscating what you want to see on the SDR receiver. Is it radiated or conducted in your cabling.
Have you isolated your power supplies between the SDR and the Yaesu ?
Perhaps RF is riding the DC cable. (So run the SDR and the Yaesu on completely separate supplies, i.e. run the Yaesu on a sufficient battery)
Also, if you transmit with the Yaesu into a dummy load directly attached, is there RF overloading the SDR ? (This may verify the effectiveness of the shielding of the transmitter) Do the same with the ID880 to know if your dummy load is radiating, which is a good control test case.
Look at all of your cables and question "could that be the RF path to the RX ?" RF will ride a shield or a DC cable if permitted.
Interesting problem to solve.
73 Mike W4UOO
On Thu, Aug 2, 2018 at 7:53 PM, Paul Stoetzer n8hm@arrl.net wrote:
It sounds like the FT-991A’s harmonic suppression isn’t quite up to par.
73,
Paul, N8HM
On Thu, Aug 2, 2018 at 19:51 TERRY SURFACE <terrysurface1@centurylink.net
wrote:
Hello. I have two 991A radios, and both do the same thing. I am unable
to
use them for transmit on two meters without killing the 70 CM RX. I use
a
Kenwood TS 2000 for transmit and 991A for receive. Not the way I want
to do
it, but I am for now, this allows the spectrum and waterfall for
checking
out the entire transponder. Hope someone finds a solution. 73,N4IQV, Terry
----- Original Message ----- From: "VA3ASE" va3ase@gmail.com To: amsat-bb@amsat.org Sent: Thursday, August 2, 2018 2:35:54 PM Subject: [amsat-bb] FT-991A Transmit Interference
Hi AMSAT friends,
I'm having a technical problem and was wondering if anyone had any suggestions. I've been experimenting with using an FT-991A transmitter
and
SDR receiver to run full-duplex on the satellites. My problem is as
soon as
I key the FT-991A transmitter, my SDR receiver waterfall goes completely white and I don't hear anything but static. Classic overload symptoms.
I've tried several things:
- Upgrading my receiver from an RTL-SDR to an SDRplay RSP1A: no
improvement.
- Adding a duplexer as a band pass filter: no improvement.
- Transmitting with a vertical antenna about 40' away from my yagis:
YES it
did solve the problem but is not a suitable solution.
I'm using the same yagi antenna setup that I've used successfully for
years
with an FT-847, and have also had the same problem with a handheld
Arrow.
At last I tried transmitting with a different radio, and the problem disappears. I figured the problem was in my FT-991A so I sent it for warranty repair, but just got the call that they can't find anything
wrong
with it. It has no measurable spurious or out of band emissions. I'm at
a
loss here... I know people are using the same equipment (FT-991 +
SDRplay)
successfully; Simon Brown comes to mind.
Here is a video I created demonstrating the problem with the FT-991 and showing that it doesn't appear with an Icom ID-880H. https://youtu.be/gXOIK5gLjgs
I still think the problem must be in the radio, but if they can't find anything to fix then I'm out of luck. I'd love to hear any suggestions
or
feedback.
Thanks, Alex VA3ASE _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions
expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions
expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
-- Thanks, Mike Sprenger (37.9167N 81.1244W is the Summit)
On 8/3/18 10:07 AM, VA3ASE wrote:
Zach my understanding is that the RSP1A is still shielded despite the plastic box, but I actually have access to an RSP2pro in a metal case that I can try out as well. I've never heard of a USB EMI filter before, I'll look into that. I'm using a quality TrippLite USB cable with molded chokes at each end.
Hello Alex,
Based on the pictures shown in the review located at the following URL, there does not appear to be any shielding over any RF component.
https://www.rtl-sdr.com/a-review-of-the-sdrplay-rsp1a/
--- Zach N0ZGO
Zach,
The RF shielding isn't over components on the circuit board. The inside of the RSP1A's plastic case has metallic paint which serves as the shielding. From the same review you cited at:
https://www.rtl-sdr.com/a-review-of-the-sdrplay-rsp1a/
"Like the RSP2 the plastic case is now spray painted with metallic paint on the inside. This works almost as well as a full metal case to shield from unwanted signals entering directly through the PCB, instead of through the antenna. We do still notice some leakage making its way in through the coax shield, but it is relatively minor with the shielding."
I have used my RSP1A to receive satellite downlinks, and have not experienced issues as VA3ASE mentioned. I'm not using an FT-991 or FT-991A, but use a variety of other radios (HTs, IC-2730A, FT-817, TM-D710G) for the uplink side of my station with the RSP1A and a tablet with HDSDR for the downlink.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK or http://twitter.com/WD9EWK
On Fri, Aug 3, 2018 at 3:50 PM, Zach Metzinger zmetzing@pobox.com wrote:
On 8/3/18 10:07 AM, VA3ASE wrote:
Zach my understanding is that the RSP1A is still shielded despite the
plastic box, but I actually have access to an RSP2pro in a metal case that I can try out as well. I've never heard of a USB EMI filter before, I'll look into that. I'm using a quality TrippLite USB cable with molded chokes at each end.
Hello Alex,
Based on the pictures shown in the review located at the following URL, there does not appear to be any shielding over any RF component.
https://www.rtl-sdr.com/a-review-of-the-sdrplay-rsp1a/
--- Zach N0ZGO
This is very likely a IM3 issue. Shielding won't help. You need to surpress the IM3 on the 2M output.
I have a torpedo sized cavity filter that knocks down the IM3 by 40 dB and I see no desense.
GL - 73 - Paul - W2HRO
On Fri, Aug 3, 2018, 12:11 Patrick STODDARD (WD9EWK/VA7EWK) < amsat-bb@wd9ewk.net> wrote:
Zach,
The RF shielding isn't over components on the circuit board. The inside of the RSP1A's plastic case has metallic paint which serves as the shielding. From the same review you cited at:
https://www.rtl-sdr.com/a-review-of-the-sdrplay-rsp1a/
"Like the RSP2 the plastic case is now spray painted with metallic paint on the inside. This works almost as well as a full metal case to shield from unwanted signals entering directly through the PCB, instead of through the antenna. We do still notice some leakage making its way in through the coax shield, but it is relatively minor with the shielding."
I have used my RSP1A to receive satellite downlinks, and have not experienced issues as VA3ASE mentioned. I'm not using an FT-991 or FT-991A, but use a variety of other radios (HTs, IC-2730A, FT-817, TM-D710G) for the uplink side of my station with the RSP1A and a tablet with HDSDR for the downlink.
73!
Patrick WD9EWK/VA7EWK http://www.wd9ewk.net/ Twitter: @WD9EWK or http://twitter.com/WD9EWK
On Fri, Aug 3, 2018 at 3:50 PM, Zach Metzinger zmetzing@pobox.com wrote:
On 8/3/18 10:07 AM, VA3ASE wrote:
Zach my understanding is that the RSP1A is still shielded despite the
plastic box, but I actually have access to an RSP2pro in a metal case
that
I can try out as well. I've never heard of a USB EMI filter before, I'll look into that. I'm using a quality TrippLite USB cable with molded
chokes
at each end.
Hello Alex,
Based on the pictures shown in the review located at the following URL, there does not appear to be any shielding over any RF component.
https://www.rtl-sdr.com/a-review-of-the-sdrplay-rsp1a/
--- Zach N0ZGO
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
participants (9)
-
Alan -
M5AKA -
Mike Sprenger -
Patrick STODDARD (WD9EWK/VA7EWK) -
Paul Andrews -
Paul Stoetzer -
TERRY SURFACE -
VA3ASE -
Zach Metzinger