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