Topband: Any Linrad selective limiter noise blanker experts here?

Tim Shoppa tshoppa at gmail.com
Mon Jan 20 10:43:33 EST 2020


My horrible utility line noise (which afflicted me in ARRL 160) continues
and I'm looking to operate in the CQ 160 test this weekend and not be an
alligator. I've located the offending pole but lack any way of getting it
fixed on such short notice.

In a quiet non-contest topband session, my rig's noise blanker does a very
decent job eliminating the 120Hz impulses. I have to operate many kc away
from any loud locals but it's effective. In a low-power contest like NAQP
SSB the rigs noise blanker is still useful although not a cure-all.

But in a 160 contest with a huge density of loud local signals, the rigs
noise blanker's action just mixes all the super-loud dense signals together
and isn't really effective anymore.

I read in N2NC's NCJ article, about the powerful technique of using a SDR
with Linrad configured to not apply the noise blanker to the loud signals.
He goes on to say "The Linrad noise blanker, combined with the 768kHz
bandwidth of the Airspy HF+, has been a big plus when the noise pops up. It
makes the noise a non-issue, and I notice no distortion, even on a band
packed with strong signals". N2NC's article here:
https://ncjweb.com/bonus-content/N2NC-Linrad/N2NC-Linrad-Main.pdf

Can any topbanders familiar with Linrad, please give me some hints on this
configuration? Either on this list or by E-mail to me.

Tim N3QE tshoppa at gmail.com


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