[Elecraft] K3S "HI-RFI" warning a bit too sensitive?

Chris L forzaferrari at gmail.com
Fri Jun 17 07:30:53 EDT 2016


I believe the manual states that it takes a watt or two of power at the
antenna connector to set off the HI-RFI warning. Imagine my surprise when I
began seeing the warning on my brand new K3S just days after I'd assembled
it. Almost everyone else who has seen this error has been using a K3 in a
contest environment with multiple transmitters, so I was particularly
stumped as there are no other transmitters in my shack (everything is
boxed) and no active hams in my neighborhood. I did some testing and traced
it to a signal coming in on my 6 meter antenna, which when I disconnected
it caused the HI-RFI warning to go away. Using a VHF capable SDR in
wideband mode, I found a strong FM signal on 49.850 and traced it to...

A baby monitor. Yep, not one block from my house lives a couple with a
cheap 49MHz baby monitor blasting away on 49.850MHz all hours of the day
and night. A short "fox hunt" with a service monitor confirmed this. There
is 100KHz worth of splatter coming from this thing and my old Icom 706
shows it as S9 with the attenuator on (and S9 +60 without). I spoke with
someone at the house and confirmed that this was the problem by shutting
down the device for an hour. Unfortunately, the couple's mother-in-law
lives with them and insists on using the baby monitor all day and night.

I will continue to press for a diplomatic solution (possibly offering to
buy them a newer 800/900MHz unit), but should I fail at that, is this
something I should worry about as far as damaging my K3S? I find it hard to
believe that a baby monitor is pumping out more than 1 watt, so I'm
inclined to believe that the K3S is being a bit overprotective. This plus
the fact that my 6 meter antenna is a PAR Omniangle which is
omnidirectional and according to PAR has no appreciable gain. I'm tempted
to program the K3S to ignore the HI-RFI warning for the time being.
Thoughts?

Chris
KB9SDX


More information about the Elecraft mailing list