Elecraft

K3S oscillation issue

Classic

List

Threaded

3 messages Options

Elecraft mailing list

K3S oscillation issue

My recent model K3S feeds a SteppIR 3-element beam with the 30/40 meter trombone-shaped driven element on a (short) 40-foot tower. Thanks to the SteppIR's tuneability, the SWR is always at or close to 1:1. I operate primarily CW, primarily using the internal keyer.

I have noticed that on 20 meters, primarily, but not only, when I am sending a contest-type message from the K3S's internal memories, the rig occasionally seems to go into some kind of self-oscillation loop. Because it seems to happen more often when my beam is pointed in particular directions, I think it's most likely an as-yet unsolved RFI/insufficient or improper grounding problem in my shack.

But I would appreciate hearing whether you have experienced, and hopefully solved, similar problems with the K3 or K3S?

Please let me know, and thanks!

Rich, K1DJ
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Guy Olinger K2AV

Re: K3S oscillation issue

Talking to the masses as well as the original poster.

Many of us, this writer included, have experienced RFI, and it almost
never involves something wrong with the K3, or any transceiver, for
that matter. It was lack of bonding and/or grounding, loose leads,
plugs only halfway in, PL259's or BNC's not fastened down all the way,
broken or unsoldered or untightened shield connections, some
unfortunate wide-open physical path into the shack, an RF open barn
door, and more, a long list, sometimes humorous, but all physical,
physical, physical.

Sometimes double digit volts RF wandering around on station conductors.

Need RF blocking? Read K9YC's web page until you understand it, do the
work, don't cheat, don't cheep, don't use junk toroids you can't
positively identify, follow the formula. Do it everywhere, all the
way, by the book.

Many people simply cannot provide sufficient linear separation and the
station is unavoidably in the near field of one antenna or another.
Then the station wiring, RF wise, needs to get clean and tight, just
because the RF is so unavoidably high. Your club buddy can get away
with some stuff, but you can't.

Everyone I personally know that went after RFI studiously and
seriously, also solved it. And it was never fixed by modifying the
transceiver, and I'm talking about multiple brands and models.

If you get RFI now and then, and if you get in contests, be firmly
assured that Murphy knows it, and he will strike in the middle of the
best run you ever had. :>)

Do the work.

73 and good luck,
Guy K2AV

On Wed, May 31, 2017 at 5:49 AM, Richard Hoffman, K1DJ via Elecraft
<[hidden email]> wrote:

> My recent model K3S feeds a SteppIR 3-element beam with the 30/40 meter trombone-shaped driven element on a (short) 40-foot tower. Thanks to the SteppIR's tuneability, the SWR is always at or close to 1:1. I operate primarily CW, primarily using the internal keyer.
>
> I have noticed that on 20 meters, primarily, but not only, when I am sending a contest-type message from the K3S's internal memories, the rig occasionally seems to go into some kind of self-oscillation loop. Because it seems to happen more often when my beam is pointed in particular directions, I think it's most likely an as-yet unsolved RFI/insufficient or improper grounding problem in my shack.
>
> But I would appreciate hearing whether you have experienced, and hopefully solved, similar problems with the K3 or K3S?
>
> Please let me know, and thanks!
>
> Rich, K1DJ
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

k6dgw

Re: K3S oscillation issue

As Guy says, "... it almost never involves something wrong with any
transceiver." At former QTH, my 70' tower/tribander was out back on 5
acres, about 200 ft from the shack. I was running RTTY then with my
K2/100, and to aid in cooling, I mounted a computer muffin fan on top of
the heat sink. It made a huge difference. On 15, only, with the beam
pointed over the shack, every time the TX came on the fan stopped. The
suspended coax from the tower to the shack was along that same azimuth,
the antenna wascreating common mode currentswhen pointed in that
directionand for some reason, the brushless fan motor was sensitive. A
common mode choke at the shack entrance fixed the problem.

73,

Fred ("Skip") K6DGW
Sparks NV USA
Washoe County DM09dn

On 5/31/2017 10:05 AM, Guy Olinger K2AV wrote:

> Talking to the masses as well as the original poster.
>
> Many of us, this writer included, have experienced RFI, and it almost
> never involves something wrong with the K3, or any transceiver, for
> that matter. It was lack of bonding and/or grounding, loose leads,
> plugs only halfway in, PL259's or BNC's not fastened down all the way,
> broken or unsoldered or untightened shield connections, some
> unfortunate wide-open physical path into the shack, an RF open barn
> door, and more, a long list, sometimes humorous, but all physical,
> physical, physical.
>