FT8, now have birdies on Xmit

Posts: 21
Joined: Thu Oct 31, 2019 10:54 am

FT8, now have birdies on Xmit

Postby Dave30019 » Sat Dec 05, 2020 1:32 pm

I powered off the SDR 2 weeks ago and I used my IC7300 for a couple of weeks. I powered the 7K DLE MKII back on and started up FT8. I immediately noticed the birdies (marked in RED) on my signal. The Green dot is my normal looking signal. I have never had these before on FT8 using PowerSDR, Thetis any version, before. I am using 64 bit 2.8.11 and have had no issues before.
I checked all settings, reset the Database, imported different one's from about month or two ago. Still have what I call birdies, marked in RED.
I've made several FT8 contacts and the station I worked said my signal looked good no issues they could see. I've tried several bands, different antennas and a dumy load, still there.
I have changed nothing at all, hardware or software. The IC7300 is on a separate computer.

Any ideas?

Screenshot 2020-12-05 080634.png
Screenshot 2020-12-05 080634.png (120.71 KiB) Viewed 266 times
Posts: 188
Joined: Sun Apr 09, 2017 5:53 pm

Re: FT8, now have birdies on Xmit

Postby w9mdb » Sat Dec 05, 2020 1:56 pm

Those birdies are 55B or more below your signal....to be expected and actually very good rejection.
RIght in line with the specifications of the rig and you can get better with PureSignal.

IMD3 typically -68dB below PEP @ 100W output on 20M (with PureSignal)

Use of LDMOS drivers and an optimized final Amplifier stage with adaptive Predistortion Algorithm (PureSignal) yields transmit IMD of -68db @ 100W PEP, this is at least 20dB better than any Class A transmitter and over 30dB better than the competition.

https://en.wikipedia.org/wiki/Intermodu ... tion_order

Mike W9MDB

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