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.
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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