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

[Joe Subich, W4TV]

> Using a VHF capable SDR in wideband mode, I found a strong FM signal
> on 49.850 and traced it to...

The SDR should be capable of providing a calibrated (dBm) signal
strength.  With that information and the distance from the target
it should be relatively simple to calculate the ERP of the baby
monitor.

Given that you report the "HI-RFI" indicator is being activated on the
K3S, I would suspect the baby monitor is producing an illegal ERP -
whether it is out of spec accidentally (manufacturing) or has been
tampered with by the owner is not an issue.  I would generate a letter
of complaint to the FCC (with calculated ERP data) indicating that you
believe the baby monitor is not in compliance with regulations and must
cease.  Send a copy to the owners of the baby monitor a week before
mailing the complaint to the Commission.

73,

   ... Joe, W4TV



> 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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html