HI RFI Message - what to do?

If you have been reading the reflector for the past couple of days, the K3 we were using got a HI RFI message on the screen.  Yes, the books says that someone is feeding the K3 more RF than it needs in the antenna terminals.  The books states 1 or 2 watts is all that it will take.

Yes, this is exactly what happened.  The K3 was on 7040 and the Orion was on 3520.  Each were on a horizontal antenna and we were no where near 1000 feet apart.  The 2nd harmonic got the K3.  Many people emailed me and said D25 is blown and it is an easy fix.  That is OK...things like this will happen.  (It was not my K3, but....)

What do you do if you get the message>  Turn off the rig immediately?  Or, is it to late by the time you get the message?  What is the parameter that the CPU is looking at when you get the message and how much time is there to do something?  Or, should be keep some pin switching diodes in the shack from quick repair?

The book is very unclear as to what all this means.  What to do.  Or any more information that what I've already stated.  I wonder if this could be clarified a little by Wayne or Eric concerning front end issues in a FD type setting.  I know the Multi-Multi guys figure this out, but heck FD is just about a free for all.  

Lee Buller
PS:  The k3 did kick A......

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[Bill W4ZV]

Lee Buller wrote

The K3 was on 7040 and the Orion was on 3520.

A shorted 1/4 wl stub (~46' of Vf 0.66 coax) on the Orion 80m output would have given ~30 dB of attenuation on 40m.  For best results stubs should be tuned to exact resonance using an analyzer (most tell you how to do this).  Plan ahead for next year!

http://www.k1ttt.net/technote/k2trstub.html

73,  Bill

[Mel]

I like Bill's answer for a fixed multi-station setup.  Not good enough for a roughly controlled enviornment of FD. Or when a friend drives up to your house running a KW mobile.

I think the bottom line is what the receiver front end was designed to "handle" and how much head room there is from that point to HI RFI message TO the point of failure of the front end device.  It would be nice to know these numbers.   But Alass, we are confronted with the age old saying, " when in doubt, protect thy self with back to back Hot carrier diodes on the receiver."  This doesn't mean this solution won't have possible intermod problems in fringe high RF enviornments of FD, but you won't lose a front end.  FWTW.

Mel K6KBE




--- On Mon, 6/29/09, Bill W4ZV <[hidden email]> wrote:

From: Bill W4ZV <[hidden email]>
Subject: Re: [Elecraft] HI RFI Message - what to do?
To: [hidden email]
Date: Monday, June 29, 2009, 1:28 PM



Lee Buller wrote:
>
> The K3 was on 7040 and the Orion was on 3520.
>

A shorted 1/4 wl stub (~46' of Vf 0.66 coax) on the Orion 80m output would
have given ~30 dB of attenuation on 40m.  For best results stubs should be
tuned to exact resonance using an analyzer (most tell you how to do this).
Plan ahead for next year!

http://www.k1ttt.net/technote/k2trstub.html

73,  Bill




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Mel Farrer wrote....

I think the bottom line is what the receiver front end was designed to "handle" and how much head room there is from that point to HI RFI message TO the point of failure of the front end device.  It would be nice to know these numbers.  

Mel K6KBE

This is the question I have.  What are the parameters.  And what do you do when you get HI RFI.  Should there be something in the manual that states:

"When your K3 shows a HI RFI error it is to late to save it.  Turn off your radio and contact K3 Support for the appropriate replacement parts. and instructions."

Something more than what the manual says would be appreciated.

Lee - K0WA
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[KK7P]

Hello Lee!

The HI RFI message is informing you that there is a problem in the
station which is resulting in potentially damaging levels of RF being
applied to the K3 receiver.

This could be due to another transmitting radio's antenna(s) being too
close, someone accidentally connecting their transmitter to the K3's
feedline and keying that transmitter, or any number of other possibilities.

It does not necessarily mean "The K3 front end is damaged and needs to
be repaired."  It only means it was subjected to dangerous levels of RF.
It may or may not have sustained damage.

What does need to be done, and done immediately, is to ensure that the
problem causing the excessive RF be remedied.  Step one is probably to
disconnect the feedline from the K3.  The reason for the excessive RF
needs to be identified and appropriate remedial action(s) taken.  Then,
the radio needs to be evaluated to see if it has been damaged.

Often, the cause for this symptom comes down to station engineering.
Sometimes, it is the result of a failure of a system component, or
incorrect operation of the station.

Some Field Day sites are complex, with multiple transmitters and
antennas operating on various bands simultaneously.  The more complex
the station, the more important it becomes that careful system
engineering be performed.

We'll review the manual to see if we can improve the description of the
error message so the person seeing it and referring to the manual can
better understand what it means.

73,

Lyle KK7P

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[Joe Planisky]

Hi Lyle,

Having the HI RFI detection and warning message is great.  If I ever  
saw it, my first reaction would be to turn the K3 off.  Does turning  
the rig off provide any more protection from the high RF levels than  
what the built-in protection circuits do when operating?

The next thing I would do is look in the manual index for "HI RFI".  
In rev D2 of the manual, there's no index entry for that.  (There is  
an entry for "RFI detection", but not for "HI RFI").  Given that  
immediate action should be taken to prevent damage to the rig, it  
might be good to have an index entry for the message for quick access.

73
--
Joe KB8AP


On Jun 30, 2009, at 8:26 AM, Lyle Johnson wrote:

> Hello Lee!
>
> The HI RFI message is informing you that there is a problem in the
> station which is resulting in potentially damaging levels of RF being
> applied to the K3 receiver.
>
> This could be due to another transmitting radio's antenna(s) being too
> close, someone accidentally connecting their transmitter to the K3's
> feedline and keying that transmitter, or any number of other  
> possibilities.
>
> It does not necessarily mean "The K3 front end is damaged and needs to
> be repaired."  It only means it was subjected to dangerous levels of  
> RF.
> It may or may not have sustained damage.
>
> What does need to be done, and done immediately, is to ensure that the
> problem causing the excessive RF be remedied.  Step one is probably to
> disconnect the feedline from the K3.  The reason for the excessive RF
> needs to be identified and appropriate remedial action(s) taken.  
> Then,
> the radio needs to be evaluated to see if it has been damaged.
>
> Often, the cause for this symptom comes down to station engineering.
> Sometimes, it is the result of a failure of a system component, or
> incorrect operation of the station.
>
> Some Field Day sites are complex, with multiple transmitters and
> antennas operating on various bands simultaneously.  The more complex
> the station, the more important it becomes that careful system
> engineering be performed.
>
> We'll review the manual to see if we can improve the description of  
> the
> error message so the person seeing it and referring to the manual can
> better understand what it means.
>
> 73,
>
> Lyle KK7P
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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[KK7P]

> Having the HI RFI detection and warning message is great.  If I ever saw
> it, my first reaction would be to turn the K3 off.  Does turning the rig
> off provide any more protection from the high RF levels than what the
> built-in protection circuits do when operating?

Turning the K3 off is not a bad idea, but that may not protect it from
energy coming down the feedline.

> The next thing I would do is look in the manual index for "HI RFI".  In
> rev D2 of the manual, there's no index entry for that.  (There is an
> entry for "RFI detection", but not for "HI RFI").  Given that immediate
> action should be taken to prevent damage to the rig, it might be good to
> have an index entry for the message for quick access.

We'll be looking at improving the message lookup in the manual.

73,

Lyle KK7P

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