flexradio 1500 switch tx rx noise

ik5sre

Hello,
i'm novice with flex radio 1500,i  buy it on ebay used. I have a problem when switch tx / rx a noise  on my display. This is the video  where you can see the problem
https://youtu.be/2YY13m7Bf0c
Sorry for my bad english. My flex 1500 n. si 1312-2266
I had already reset to default factory the flex 1500,use another pc with windows 7 and XP,use a different usb cable,but i have always the problem. Perhaps this is a hardware problem? rele'?
Thank you
73 de Ik5sre Francesco

Bill -VA3WTB

Try this again with nothing connected to radio other than antenna, it may be feed back from something. No mic nothing connected..

Bill -VA3WTB

Also I see you have the AGC-T set at 73, try bringing it down to around 50 to 45, the radio will be easy on the ears and you can still hear signals. And you can turn on AVG to slow the signals down on the panadaptor, better for your eyes. Then go into setup and adjust the rate speed for that as you like it. Just a few operating hints.

Dudley-WA5QPZ

Francesco,

Looking at your video,   you do have the receiver at 5 kHz wide,  the tone is part of transition from TX to RX,  but the tone is at the DC crossing or IF of the radio.   Either you can narrow your receive passband or you can move that crossing..   The setting is the IF in the DDS window of PowerSDR setup -> General -> Hardware Config  ..  Move 3800 to 5100 to take it out of your passband..    Unfortunately this also will move the centerline of the radio in the Panadapter ,  as you will notice that the centerline when zoomed in all the way will move slightly to the right..   Kind of a cause and effect with the 1500 and USB. 

ik5sre

thank you,i already try it but i have  again the noise.

John

try another mode ? Does this happen in all modes ?

ik5sre

i have the same problem also when i move to another band (10,15,20 m...) this happen when the rele' switch

John

what happens when you use ssb mode and you click ptt and speak ?

ik5sre

the same thing,when i turn by tx to rx i have this noise,this happen with the mic,with cw key and also when i move by a band to another,.When the internal rele' switch.

Bill -VA3WTB

You may have to have it fixed, nothing seems to help.

John

It looks like you are zoomed in on the waterfall display. Click on the 0.5x button below the waterfall display and can you make another video when you key the microphone on ssb and cw ? Also, what version software are you using ? please show us the whole screen if you can

Tim - W4TME

Everybody needs to pause for a moment.  This is NOT A PROBLEM.  This is normal for the FLEX-1500.  This is the DC "noise (0 Hz IF) being nulled by the wide band image rejection (WBIR).  The default DDS offset for the FLEX-1500 is 3850 Hz below the carrier (LSB).    Please take note of the comments by Dudley as his description on how to move the DDS offset to a greater value so that it is outside of the RX passband filter.

ik5sre

ok thank you for information, i'm happy if this is not a problem,i'm novice with flexradio.

John

Just wondering why the 1500 would have this problem unless the previous user fiddled with it Tim ?

Tim - W4TME

No problem, Francesco

Tim - W4TME

This isn't a problem ;-) 

The issue is only an issue on LSB or AM where the RX filter is wider than the maximum TX filter for a 1500 (3800 Hz).  Since the 1500 can only show 38 kHz of spectrum, we moved the DDS offset on the 1500 so that the receiver carrier line was more centered in the panadapter, rather than being shifted down by 9 kHz as it is with the 3000 and 5000.  By moving it 3850 Hz, it is outside of the maximum TX bandwidth of 3800 Hz

Based on the video, the DDS offset is exactly where I would expect it to be with the default setting at ~ 4 kHz

John

I see it on mine. Its 9Khz down on lsb

Villas - PY5VB

In Setup Menu, Hardware Config, click in Expert DDS frame, and in IF(Hz) change Flex IF frequencie, probably yours config is 0Hz and SR button is selected. Change to maximum value. In Flex5000 defaul is 9000Hz anda maximum is 20000. In my Flex5000 if I put 0 hertz in this box and press SR button, when I release PTT have same behavior your Flex1500 no mater BW TX is.

ik5sre

thank you to all comunity for the help.

Bill -VA3WTB

Is it ok now?