Elecraft

K3: SSB Audio Stops-Quits-Kaput on 160

Classic

List

Threaded

2 messages Options

k0wa@swbell.net

K3: SSB Audio Stops-Quits-Kaput on 160

Here is the scenario....

NAQP Contest - SSB
100 watts
Heil Headset with HC-4
Using VOX
Connected to the front (not the back)
Only 160 meters
Antenna - Inverted-L with feed point less than 10 feet from the K3
Radials - 20 random length radials in the yard. City lot
Tuned using a Palstar AT2K
SWR - none (I am tuned)
Station Ground: 8 foot ground rod right below the desk tied to single point

Narrative: I am calling CQ (of course you do this many times during the course of the contest) and the audio on the K3 stops - quits - nil. I can shout in the mike, but nada. K3 is in Xmit mode...using VOX. No audio output can he heard in the Monitor (headphones) and not meter movement or output occurs. Stop speaking...VOX drops. Call CQ again, does not happen this time, but three times later....audio stops on xmit. Place a choke bead on the Heil Mic adapter, does not help, still quits. Reduce power to 90 watts. Still does it. 160 meters is the only band this occurs. Did not happen on CW during NAQP CW.

RF induced? This is the only thing I can come up with. Anyone else seen this or has an idea to fix it - except ideas should not included quit contesting, stay off 160 meters, sell the rig, etc. etc. etc. :>)

Lee - K0Wa

In our day and age it seems that Common Sense is in short supply. If you don't have any Common Sense - get some Common Sense and use it. If you can't find any Common Sense, ask for help from somebody who has some Common Sense. Is Common Sense divine?

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

Don Wilhelm-4

Re: K3: SSB Audio Stops-Quits-Kaput on 160

Lee,

Have you installed the Front Panel Microphone Circuit Modification in
your K3?
http://www.elecraft.com/K3/mods/K3_Application_Note_Front_Panel_Microphone_Grounding.pdf
I would do that as a first step.

If that does not cure your problem, then I would suggest work with the
antenna system to get rid of the 160 meter 'RF in the shack' - perhaps
in your situation, some sort of artificial ground may be necessary. One
thing for certain, that ground rod will not act as an adequate RF ground
(ground rods seldom do).

Since you suspect RF feedback problems, I would make a quick check by
operating into a dummy load - if you still have a problem, it is not RF
induced, and you can call it a real K3 problem.

73,
Don W3FPR

Lee Buller wrote:

>
> Here is the scenario....
>
> NAQP Contest - SSB
> 100 watts
> Heil Headset with HC-4
> Using VOX
> Connected to the front (not the back)
> Only 160 meters
> Antenna - Inverted-L with feed point less than 10 feet from the K3
> Radials - 20 random length radials in the yard. City lot
> Tuned using a Palstar AT2K
> SWR - none (I am tuned)
> Station Ground: 8 foot ground rod right below the desk tied to single
> point
>
> Narrative: I am calling CQ (of course you do this many times during
> the course of the contest) and the audio on the K3 stops - quits -
> nil. I can shout in the mike, but nada. K3 is in Xmit mode...using
> VOX. No audio output can he heard in the Monitor (headphones) and not
> meter movement or output occurs. Stop speaking...VOX drops. Call CQ
> again, does not happen this time, but three times later....audio stops
> on xmit. Place a choke bead on the Heil Mic adapter, does not help,
> still quits. Reduce power to 90 watts. Still does it. 160 meters is
> the only band this occurs. Did not happen on CW during NAQP CW.
>
> RF induced? This is the only thing I can come up with. Anyone else
> seen this or has an idea to fix it - except ideas should not included
> quit contesting, stay off 160 meters, sell the rig, etc. etc. etc. :>)
>
> Lee - K0Wa
>
>