Birdies at 820 kHz BCAM

Mark K1LSB

I posted this in the wrong forum, so I'm re-posting here.

I'm getting several irregularly spaced birdies in the 820 kHz area of the broadcast AM band on my Flex 6300, which do not appear when I'm using my SDRPlay RSP2.

https://drive.google.com/file/d/1X0yjP0ySOF51DLetmoJK7UfX5rV83vwT/view?usp=sharing

https://drive.google.com/file/d/1qp6WV_nGyKDQY9KyKPwh3UNYQOXTfacc/view?usp=sharing

Please see the attached pics.  As you can see, the birdies in SSDR aren't dead-steady (as a carrier would be) but rather wander very slightly.  The first pic was taken from inside SSDR with no antenna connected - in fact, the only cables connected to the 6300 are the power cord (heavily choked with a thoroughly wrapped FT240-31 toroid) and the CAT5e cable between the computer and 6300.  The second pic was taken from inside SDR-Console using an RSP2 tuned to the same band segment, also with no antenna connected. NOTE: There is a strong local broadcast AM station at 820 kHz that is picked up very faintly by both radios even with no antennae connected, so disregard that signal in both pics.

Here's a pic with the antenna connected.  The birdies are still there, in the same strength as when no antenna was connected.

https://drive.google.com/file/d/1vtnZqJXqXuZ-GQQzs3jLLQiMfUCyHqXh/view?usp=sharing

Some notes:

1)  The power supply is an Astron RS-35M linear (non-switching) supply.  The 6300 is the only thing connected to the Astron.  As noted earlier, the power cord to the 6300 is heavily wrapped through a large FT240-31 toroid.

2)  At the low power levels used by the Flex during receive mode, I'd expect the Astron's line-out to be exceedingly clean, certainly free from any birdies such as seen in the pics.

3)  The SDRPlay is USB-powered.  If anything, I would expect the SDRPlay to be displaying the rippled birdies, not the Flex.


Is anyone else seeing anything like this on your Flex in the broadcast AM band segment (or anywhere else, for that matter) when no antenna is connected?

Thanks in advance,

Mark  K1LSB

Dudley WA5QPZ

Mark, You should place a Help Desk ticket with Flex Support. You may have an ESD diode that is giving you trouble. Dudley WA5QPZ

WK2Y

ESD diode?

Bob
WK2Y

VK7WH Winston

As I understand it, the ESD diode is a protective device on the input to the FPGA

WK2Y

Thanks. That's a really specific diagnosis.

Dudley WA5QPZ

Seen it before. ESD is just ahead of SCU. Dudley WA5QPZ