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K3 receiver gain problem

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Ron W3ZV

K3 receiver gain problem

I am playing in the contest today. I have had two instances where my
receiver gain has gone down dramatically. It sounds like I have switched
to the second antenna with nothing attached. Engaging PTT brings it
back. I installed the second receiver and DVR a week ago. Has been
working fine until today. The problem is not reproducible. Happens on
its own schedule.

K3/100 #1248
FW 3.79
No modifications

Any magic out there, or do I wait for Elecraft to wake up Monday?

Ron W3ZV

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Vic K2VCO

Re: K3 receiver gain problem

On 3/27/2010 9:02 AM, Ron W3ZV wrote:
> I am playing in the contest today. I have had two instances where my
> receiver gain has gone down dramatically. It sounds like I have switched
> to the second antenna with nothing attached. Engaging PTT brings it
> back. I installed the second receiver and DVR a week ago. Has been
> working fine until today. The problem is not reproducible. Happens on
> its own schedule.

Often this kind of problem is caused by an intermittent poor connection somewhere in the
antenna system, a dirty relay contact if you have any relays in the path, etc. As soon as
you hit it with a bit of RF, it cleans up and works for a while. But in receive, the
voltage is so low that it stays in high-resistance mode.

Check the coax connectors, relays if any, etc.

I had the exact symptom about a year ago when I had a balun with a corroded solder connection.
--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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Joe Planisky

Re: K3 receiver gain problem

Hoo boy! I know about this one. I actually sent my rig back to
Elecraft for repair when it was happening to me. Imagine my chagrin
when my backup rig started behaving the same way.

73
--
Joe KB8AP

On Mar 27, 2010, at 10:44 AM, Vic K2VCO wrote:

> On 3/27/2010 9:02 AM, Ron W3ZV wrote:
>> I am playing in the contest today. I have had two instances where my
>> receiver gain has gone down dramatically. ... Engaging PTT brings it
>> back.
> Often this kind of problem is caused by an intermittent poor
> connection somewhere in the
> antenna system, ... As soon as you hit it with a bit of RF, it
> cleans up and works for a while. But in receive, the voltage is so
> low that it stays in high-resistance mode.
> ...
> Vic, K2VCO

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Dick Dievendorff

Re: K3 receiver gain problem

In reply to this post by Vic K2VCO

I had these symptoms (with another radio) and eventually tracked it
down to a corroded junction where a saddle clamp joined parts of the
linear loading wire on my short 40m beam.

Dick, K6KR

Sent from my iPhone

On Mar 27, 2010, at 10:44 AM, Vic K2VCO <[hidden email]> wrote:

> On 3/27/2010 9:02 AM, Ron W3ZV wrote:
>> I am playing in the contest today. I have had two instances where my
>> receiver gain has gone down dramatically. It sounds like I have
>> switched
>> to the second antenna with nothing attached. Engaging PTT brings it
>> back. I installed the second receiver and DVR a week ago. Has been
>> working fine until today. The problem is not reproducible. Happens on
>> its own schedule.
>
> Often this kind of problem is caused by an intermittent poor
> connection somewhere in the
> antenna system, a dirty relay contact if you have any relays in the
> path, etc. As soon as
> you hit it with a bit of RF, it cleans up and works for a while. But
> in receive, the
> voltage is so low that it stays in high-resistance mode.
>
> Check the coax connectors, relays if any, etc.
>
> I had the exact symptom about a year ago when I had a balun with a
> corroded solder connection.
> --
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
> ______________________________________________________________
> 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

Guy, K2AV

Re: K3 receiver gain problem

In reply to this post by Ron W3ZV

Besides the K3 there is a long list of other possibles, but since you
WERE into the cables inside the K3, if all those mini-coax connectors
did not get seated correctly...I found that a little tricky and there
is a certain feel to it when they go in right and seat solid. That an
unrelated intermittent could occur the same weekend as a K3 upgrade is
likely due to passing through a nexus of murphyite entropy, our your
neighbor casting spells.

Mostly it sounds like this kind of stuff that has happened to me
personally over time. I'm sure the list is really much longer if we
add in everyone's experience.

* Connection of coax shield to dipole half was parted but still
touching when it was convenient.
* Connection of yagi matching device to driven element corroded and loose.
* Water in barrel connector splice in feedline, getting green.
* Center connection in hardline connector soldered too far down on
hardline center conductor (didn't use the little spacer to do it
because I couldn't find it) and cold wx would separate it at night. In
the morning when sun hit it would close up.
* PL259 on back of rig cross-threaded and making poor contact.
* PL259 on back of rig not tightened at all.
* Amp relay contacts burned by running at contest station with no
delay set up for transceiver-amp keying sequence, causing hot
switching.
* Amp relay contacts worn out from years of QSK.
* Unsoldered connection in commercial balun.
* Unsoldered connection in homemade balun. (Apparently a communicable disease.)
* Balun hit by lightning, odd thing that it had periods of apparently
working OK. It was full of loose pieces inside.
* Heathkit SB series setup. RCA plugs wore out and got loose.
* Worn out T/R relays of many kinds.
* Conductor in 450 window line parted inside the polyethylene due to
wind flexing.
* Center conductor in RG8 pulled apart due to stretching under weight
of ice, would only part in coldest weather.
* Incomplete crimp on BNC center conductor.
* Going way back to novice days when I could barely tell difference
between coax and rope, unsoldered shield and center conductors in
PL259 conveniently fogotten and still in service.

In most of the above, hitting the key and putting the connection under
power would close the gap temporarily, for a second, an hour, a
month.... Couple others, for fairness:

* Incomplete solder joint in transceiver SMD board. Was making
connection as glued, but would sometimes not make contact. Hitting
transmit did nothing. Only found it with freeze spray and what
amounted to a low grade microscope. It ran AOK for a long time before
the trouble surfaced.

* Burned transformer in TRX input due to inband power (100w+?) on the
line back to the TRX in RX state. It worked part of the time.

Longer I think about it the longer the upper list gets.

73 and good luck. Guy.

On Sat, Mar 27, 2010 at 12:02 PM, Ron W3ZV <[hidden email]> wrote:

> I am playing in the contest today. I have had two instances where my
> receiver gain has gone down dramatically. It sounds like I have switched
> to the second antenna with nothing attached. Engaging PTT brings it
> back. I installed the second receiver and DVR a week ago. Has been
> working fine until today. The problem is not reproducible. Happens on
> its own schedule.
>
> K3/100 #1248
> FW 3.79
> No modifications
>
> Any magic out there, or do I wait for Elecraft to wake up Monday?
>
> Ron W3ZV
>
> ______________________________________________________________
> 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
>