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K3 intermittent receive issue

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Chris Rolinson G7DDN

K3 intermittent receive issue

Hi friends

I seem to have some issues with my K3 on receive.

It presents as a seemingly complete loss of either RF or IF gain - The S meter goes dead and there are no signals audible or visible on the S meter.

After a few seconds usually, everything comes back. Turning the radio off and on again nearly always cures it.

Happens on all HF bands - doesn't seem related to relays - seems to respond well to the standard "gentle tap on the top panel" (on the RH side as you look at the front panel)

It doesn't seem to be related to anything I am doing as I operate.

Any thoughts?

Regards

Chris G7DDN
Sent from my iPad Air
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Phil Wheeler-2

Re: K3 intermittent receive issue

I'd suspect a loose cable/connector -- or a bad
one -- inside the rig. You should open it up and
take a look.

73, Phil w7ox

On 4/21/14, 8:52 AM, Chris G7DDN wrote:

> Hi friends
>
> I seem to have some issues with my K3 on receive.
>
> It presents as a seemingly complete loss of either RF or IF gain - The S meter goes dead and there are no signals audible or visible on the S meter.
>
> After a few seconds usually, everything comes back. Turning the radio off and on again nearly always cures it.
>
> Happens on all HF bands - doesn't seem related to relays - seems to respond well to the standard "gentle tap on the top panel" (on the RH side as you look at the front panel)
>
> It doesn't seem to be related to anything I am doing as I operate.
>
> Any thoughts?
>
> Regards
>
>
>
>
> Chris G7DDN
> Sent from my iPad Air

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Bill-3

Re: K3 intermittent receive issue

In reply to this post by Chris Rolinson G7DDN

Sounds like a mechanical issue to me. That would mean a loose connector,
loose wire inside of a connector, or a cold solder joint.

To start trouble shooting, you will need:

1. A small non-conductive probe - part of an old pen case will do well
as will a plastic cable tie. Lightly tap each connector with the probe
and lightly pull/push on the wires going to the connectors.

2. A can of "Freeze" to selectively spray soldered connections. Fast
cooling will often cause a failure if said connection is faulty.

Both of the above tests will cause the problem to appear and/or correct.
Gently is the operative word of the day.

In most instances, these methods will find the offending part(s). Again,
DO NOT use force when pulling/pushing connectors or wires. What you have
is slight - else tapping the case would have no effect.

Bill K-Line

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Don Wilhelm-4

Re: K3 intermittent receive issue

One easy thing that can be done quickly - give each of the TMP
connectors a slight turn - use long nose pliers (fingers are not small
enough in crowded areas).

If it fixes the problem, great. Otherwise, continue with the other
troubleshooting steps indicated by others.

73,
Don W3FPR

On 4/21/2014 1:11 PM, Bill W2BLC wrote:

> Sounds like a mechanical issue to me. That would mean a loose
> connector, loose wire inside of a connector, or a cold solder joint.
>
> To start trouble shooting, you will need:
>
> 1. A small non-conductive probe - part of an old pen case will do well
> as will a plastic cable tie. Lightly tap each connector with the probe
> and lightly pull/push on the wires going to the connectors.
>
> 2. A can of "Freeze" to selectively spray soldered connections. Fast
> cooling will often cause a failure if said connection is faulty.
>
> Both of the above tests will cause the problem to appear and/or
> correct. Gently is the operative word of the day.
>
> In most instances, these methods will find the offending part(s).
> Again, DO NOT use force when pulling/pushing connectors or wires. What
> you have is slight - else tapping the case would have no effect.
>

Re: K3 intermittent receive issue

In reply to this post by Chris Rolinson G7DDN

Chris -

The power on -off cycle "cure" does not tally with the below but its worth a
try .

Having just put a KAT3 in my K3 this weekend to replace the KANT3 - from
what you describe - take the top cover off - and if you have the KAT3
tuner - check the two pigtails from the SO239's to the board - make sure
both are plugged in , or not broken at the connector . If its a no tuner
KANT3 - there is just one pigtail. If those are Ok , In either case gently
wiggle the board a bit and see if the sigs re-appear like they do with
tapping the top.(You may have to loosen the standoff at the upper rear side
of the board.) Look carefully at the connector between the board and the
main RF board at the bottom front of the board. Make sure all pins made it
into the socket.

Guess it might also be worthwhile to follow the manual instructions
for"enable" of the KAT3 in the Config menu ( be sure to turn off the K3 for
5 - 10 seconds after the reset and let it re-find /test the device. Maybe
just try that first . (page 47 of my mid 2013 manual )

Good l.uck.

73 Hank K7HP

----- Original Message -----
From: "Chris G7DDN" <[hidden email]>
To: <[hidden email]>
Sent: Monday, April 21, 2014 8:52 AM
Subject: [Elecraft] K3 intermittent receive issue

> Hi friends
>
> I seem to have some issues with my K3 on receive.
>
> It presents as a seemingly complete loss of either RF or IF gain - The S
> meter goes dead and there are no signals audible or visible on the S
> meter.
>
> After a few seconds usually, everything comes back. Turning the radio off
> and on again nearly always cures it.
>
> Happens on all HF bands - doesn't seem related to relays - seems to
> respond well to the standard "gentle tap on the top panel" (on the RH side
> as you look at the front panel)
>
> It doesn't seem to be related to anything I am doing as I operate.
>
> Any thoughts?
>
> Regards
>
>
>
>
> Chris G7DDN
> Sent from my iPad Air
> ______________________________________________________________
> 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]

Jim

Re: K3 intermittent receive issue

In reply to this post by Chris Rolinson G7DDN

I recently corrected a similar problem on the K3 I put together. Same symptoms, and I found when moving the coaxial cable on the main antenna on the outside of the radio, I could duplicate the problem. I replaced my exterior rg-58 cable/connector three times without relief, then found that the SO-259 on the radio was the problem as it makes its shield connection by mechanical contact with the case. Cleaned all, tightened, all works good now. I think someone had posted that they made a redundant jumper to tie the connector to the antenna shield by way of one of the connector nuts to prevent this problem. Good luck. Jim WN8A
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Andy Wood

Re: K3 intermittent receive issue

In reply to this post by Chris Rolinson G7DDN

Hi Chris,

I have had a few weird intermittent problems over the years, including something similar to your description. After a few false starts, I eventually separated the front panel from the main pcb and gave the connectors some treatment with Deoxit. Since then, none of the previous gremlins have returned.

Andy VK4KY

Elecraft mailing list

Re: K3 intermittent receive issue

In reply to this post by Chris Rolinson G7DDN

I had something similar a month ago. When I would touch a switch or front mic plug, the receive would come back.
I'm not sure it would completely disappear but definitely attenuated.

Turned out to be a PL-259 that was snug but apparently not tight enough.

73
Mike R

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gm3sek

Re: K3 intermittent receive issue

In reply to this post by Jim

"Any or all of the above" - several people have suggested good ideas.
The strongest possibilities are a loose TMP connector or a multi-way
connector that needs re-seating. Since the faulty connection is "right
on the edge" between working and not working, even a very gentle tug on
a TMP connector or a gentle jiggle of a board should reveal the problem.

The best tool that I have found for inserting, checking and removing the
TMP connectors is a pair of artery forceps. The finger loops and the
click lock give far better control than long-nosed pliers (smart people,
those surgeons!). Forceps are available in several different sizes and
shapes, and probably the best choice for working inside the K3 is the
straight 6-7in pattern. They are cheap and easy to find on eBay, and
well worth trying.

Since Chris is in the UK, a good alternative to Deoxit for treatment of
connector pins is Contralube 770 which is available from Maplin.

Regarding the rear-panel SO239, I was the person who suggested making a
direct ground return between the connector flange and the KANT3 or KAT3
board. OK, so "it works already" and "7999 other K3s can't be wrong"...
but it still isn't good practice to make a single-wire link to the
center pin while leaving the equal and opposite return current to find
its own way back to the board through a single-point connection between
the rear panel followed by a long, thin support pillar. The new
connection is made by attaching a solder tag under the 4-40 screw (as
seen in the Assembly Manual, Figure 29) and another tag to the nearest
point on the flange of the SO239. No wire is needed; the two tags are
simply bent until they overlap, and then soldered to make a shortest
possible return connection. Ohm's law dictates that this will now be the
preferred return path, so the poorer path through the metalwork is the
one that becomes redundant.

73 from Ian GM3SEK

>-----Original Message-----
>From: Elecraft [mailto:[hidden email]] On Behalf Of
>Jim LeFevre
>Sent: 21 April 2014 21:03
>To: [hidden email]
>Subject: Re: [Elecraft] K3 intermittent receive issue
>
>I recently corrected a similar problem on the K3 I put together. Same
>symptoms, and I found when moving the coaxial cable on the main antenna
>on the outside of the radio, I could duplicate the problem. I replaced

my
>exterior rg-58 cable/connector three times without relief, then found
that
>the SO-259 on the radio was the problem as it makes its shield
connection
>by mechanical contact with the case. Cleaned all, tightened, all works
good
>now. I think someone had posted that they made a redundant jumper to
tie
>the connector to the antenna shield by way of one of the connector nuts
to

>prevent this problem. Good luck. Jim WN8A
>______________________________________________________________
>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]

Phil Wheeler-2

Re: K3 intermittent receive issue

Ah yes, the good old hemostat -- one of my most
used building tools, Ian :-)

Phil w7ox

On 4/22/14, 1:20 AM, Ian White wrote:

> The best tool that I have found for inserting, checking and removing the
> TMP connectors is a pair of artery forceps. The finger loops and the
> click lock give far better control than long-nosed pliers (smart people,
> those surgeons!). Forceps are available in several different sizes and
> shapes, and probably the best choice for working inside the K3 is the
> straight 6-7in pattern. They are cheap and easy to find on eBay, and
> well worth trying.
>
>
> 73 from Ian GM3SEK
>
>> -----Original Message-----
>> From: Elecraft [mailto:[hidden email]] On Behalf Of
>> Jim LeFevre
>> Sent: 21 April 2014 21:03
>> To: [hidden email]
>> Subject: Re: [Elecraft] K3 intermittent receive issue
>>
>> I recently corrected a similar problem on the K3 I put together. Same
>> symptoms, and I found when moving the coaxial cable on the main antenna
>> on the outside of the radio, I could duplicate the problem. I replaced
> my
>> exterior rg-58 cable/connector three times without relief, then found
> that
>> the SO-259 on the radio was the problem as it makes its shield
> connection
>> by mechanical contact with the case. Cleaned all, tightened, all works
> good
>> now. I think someone had posted that they made a redundant jumper to
> tie
>> the connector to the antenna shield by way of one of the connector nuts
> to
>> prevent this problem. Good luck. Jim WN8A
>> ______________________________________________________________
>> 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
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> 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]
>