K3 loss of rx signal

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K3 loss of rx signal

LA7NO
Hello group,

I have several times experienced that the K3 receiver goes 100% dead. Same as if no antenna was connected.
A smart bump on the K3 brings it back to normal.

I suspect a relay. The question is which one?
Suggestion anyone?

73,

Per-Tore / LA7NO
73,

Per-Tore / LA7NO
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Re: K3 loss of rx signal

Guy Olinger K2AV
Could be a relay, however....

The most common source of intermittents is cords and connectors that are
either only partially connected or have had wires stressed past breaking
but held together intermittently by insulation, or were never soldered, or
were poorly crimped in manufacture.

Banging on the K3 jiggles all the connections on the back of the K3.

Then there's RCA connectors not pushed in all the way or with too-short
pins for the socket and BNC connectors not twisted home.

RULE OUT the connections before tearing apart your K3.

Then inside there are the TMP mini coax connectors inside the K3 not seated
properly. Then pin connections to reseat several times. All these before
relays.

Relays will usually close again by repeatedly going TX RX TX RX TX RX....

Don't ask me how much I tore apart before I figured it out or how close I
came to putting the K3 in the shipping box......

73, Guy K2AV

On Mon, Apr 3, 2017 at 4:43 AM LA7NO <[hidden email]> wrote:

> Hello group,
>
> I have several times experienced that the K3 receiver goes 100% dead. Same
> as if no antenna was connected.
> A smart bump on the K3 brings it back to normal.
>
> I suspect a relay. The question is which one?
> Suggestion anyone?
>
> 73,
>
> Per-Tore / LA7NO
>
>
>
>
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/K3-loss-of-rx-signal-tp7628912.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Message delivered to [hidden email]
>
--
Sent via Gmail Mobile on my iPhone
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Re: K3 loss of rx signal

Nr4c
In reply to this post by LA7NO
Don't overlook the obvious.  Check to make sure the connectors are all very tight. "Hand snug" is not good enough!

Sent from my iPad
...bc nr4c

> On Apr 3, 2017, at 4:41 AM, LA7NO <[hidden email]> wrote:
>
> Hello group,
>
> I have several times experienced that the K3 receiver goes 100% dead. Same
> as if no antenna was connected.
> A smart bump on the K3 brings it back to normal.
>
> I suspect a relay. The question is which one?
> Suggestion anyone?
>
> 73,
>
> Per-Tore / LA7NO
>
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3-loss-of-rx-signal-tp7628912.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> 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]

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Re: K3 loss of rx signal

G3XVR
In reply to this post by Guy Olinger K2AV
I had a similar frustrating problem with a BNC patch lead. I bought some cheap leads at a rally and I didn’t notice that the plugs were 75 Ohms. The leads worked OK, but the centre pin was thicker than the 50 Ohm version and it splayed out the centre connector of the socket, so when I plugged a 50 Ohm patch cable back in, the centre pin did not make contact any more. It took me a long time to find the cause, and now all the 75 Ohm leads are in the bin.

73,

Danny, G3XVR

From: Guy Olinger K2AV
Sent: 03 April 2017 11:56
To: LA7NO; [hidden email]
Subject: Re: [Elecraft] K3 loss of rx signal

Could be a relay, however....

The most common source of intermittents is cords and connectors that are
either only partially connected or have had wires stressed past breaking
but held together intermittently by insulation, or were never soldered, or
were poorly crimped in manufacture.

Banging on the K3 jiggles all the connections on the back of the K3.

Then there's RCA connectors not pushed in all the way or with too-short
pins for the socket and BNC connectors not twisted home.

RULE OUT the connections before tearing apart your K3.

Then inside there are the TMP mini coax connectors inside the K3 not seated
properly. Then pin connections to reseat several times. All these before
relays.

Relays will usually close again by repeatedly going TX RX TX RX TX RX....

Don't ask me how much I tore apart before I figured it out or how close I
came to putting the K3 in the shipping box......

73, Guy K2AV


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: K3 loss of rx signal

Paul Antos
In reply to this post by LA7NO
Had same problem … retightened mounting hardware on synthesizer board.

Paul WB2ABD

Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

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Re: K3 loss of rx signal

Phil Hystad-3
In reply to this post by Nr4c

> On Apr 3, 2017, at 5:25 AM, Nr4c <[hidden email]> wrote:
>
> Don't overlook the obvious.  Check to make sure the connectors are all very tight. "Hand snug" is not good enough!
>
> Sent from my iPad
> ...bc nr4c

What do you mean “Hand Snug” is not good enough?  I don’t remember any connectors in the K3 that required a wrench to tighten nor do I ever use any wrenches or even screwdrivers on any of the connectors outside the box (Coax, RS232 serial, etc.).

Curious in Rainy Kirkland (nr Seattle)…

73, phil, K7PEH

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Re: K3 loss of rx signal

LA7NO
In reply to this post by Guy Olinger K2AV
Thanks for the suggestions. You are of course right.

The antenna connector is good, so I'll have to open up the K3 and check around here and there.
It is quite 'full' with 2nd rx, PA and tuner, so some dismantling could be required to check most connections.

73,

Per-Tore / LA7NO
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Re: K3 loss of rx signal

kg9hfrank@gmail.com
You may want to tap individual connectors carefully so “just one gets tapped”.
Frank KG9H

> On Apr 3, 2017, at 9:26 AM, LA7NO <[hidden email]> wrote:
>
> Thanks for the suggestions. You are of course right.
>
> The antenna connector is good, so I'll have to open up the K3 and check
> around here and there.
> It is quite 'full' with 2nd rx, PA and tuner, so some dismantling could be
> required to check most connections.
>
>
>
>
>
> -----
> 73,
>
> Per-Tore / LA7NO
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/K3-loss-of-rx-signal-tp7628912p7628922.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> 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
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Re: K3 loss of rx signal

Don Wilhelm
In reply to this post by Phil Hystad-3
Phil,

PL-259s depend on tightness to make a good connection to the shield.
This is an often overlooked cause of problems.
After hand tightening, snug them up just a bit more with pliers if you
want them to be reliable.

73,
Don W3FPR

On 4/3/2017 10:19 AM, Phil Hystad wrote:
>
>> On Apr 3, 2017, at 5:25 AM, Nr4c <[hidden email]> wrote:
>>
>> Don't overlook the obvious.  Check to make sure the connectors are all very tight. "Hand snug" is not good enough!
>>
>> Sent from my iPad
>> ...bc nr4c
>
> What do you mean “Hand Snug” is not good enough?
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Re: K3 loss of rx signal

Phil Hystad-3
Don,

In my experience, PL-259s do not get tightened properly when the little teeth on the end do not engage properly.  So, when I tighten PL-259s, I make sure that the teeth fit in together properly and this always gives a snug fit.  Note: I am not sure if these are called teeth or not.

In almost 60 years of dealing with PL-259s the only time I needed pliers was to undo the PL-259 connector that I had on my truck that had sealant on it (it was very much in the weather) and stuck besides.

Then again, I don’t ever remember having any loose connection problems with PL-259s either.  

73, phil, K7PEH


> On Apr 3, 2017, at 7:42 AM, Don Wilhelm <[hidden email]> wrote:
>
> Phil,
>
> PL-259s depend on tightness to make a good connection to the shield.
> This is an often overlooked cause of problems.
> After hand tightening, snug them up just a bit more with pliers if you want them to be reliable.
>
> 73,
> Don W3FPR
>
> On 4/3/2017 10:19 AM, Phil Hystad wrote:
>>
>>> On Apr 3, 2017, at 5:25 AM, Nr4c <[hidden email]> wrote:
>>>
>>> Don't overlook the obvious.  Check to make sure the connectors are all very tight. "Hand snug" is not good enough!
>>>
>>> Sent from my iPad
>>> ...bc nr4c
>>
>> What do you mean “Hand Snug” is not good enough?

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Re: K3 loss of rx signal

Guy Olinger K2AV
In reply to this post by Phil Hystad-3
On Mon, Apr 3, 2017 at 10:19 AM, Phil Hystad <[hidden email]> wrote:
> What do you mean “Hand Snug” is not good enough?

Lordee, I've seen, done, and heard of these things so many times...

PL259 the worst offender, with BNC close second. Mini-coax TMP in a
class by itself.

On the PL259, if the teeth around the edge of the mating shell aren't
aligned to move down into the teeth of the SO239, you can "tighten"
the PL259 to what seems tight, but a temperature change or a jiggle
will let the teeth align. The connector is now loose.  A variety of
"false snugs" can occur with PL259, barrel, SO239 that have been
outdoors and gotten stuff in threads.

BNC's, if not inserted straight on, can seem snug, but not go down all
the way. Then the twist shell can go a distance and won't seem to want
to go any farther. It's very easy to not have enough finger strength
to twist the shell enough to go all the way down.

Mini-coax TMP connectors are bad because if the center pin does not
match inside the socket it won't go down and cause an infamous
intermittent that many have experienced. The flares on the male TMP
have to go down until they are prevented from further insertion by the
socket.

73, Guy K2AV
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Re: K3 loss of rx signal

Guy Olinger K2AV
In reply to this post by Phil Hystad-3
Outdoors, PL259 tightened by hand in cool/cold weather will come loose
in warm weather. This is particularly vexing when the connection is up
on a tower out on a boom to a balun on the driven element.

Pliers plus maxi-sealing against the weather is the rule for these.

The teeth can be misaligned with stiff coax where you have to twist
the coax a bit to get the teeth.

Then there are the female UHF connections where there are only FOUR
notches on the female connection for the two teeth on the male
connector. That's very easy to get wrong.

73, Guy K2AV

On Mon, Apr 3, 2017 at 10:58 AM, Phil Hystad <[hidden email]> wrote:

> Don,
>
> In my experience, PL-259s do not get tightened properly when the little teeth on the end do not engage properly.  So, when I tighten PL-259s, I make sure that the teeth fit in together properly and this always gives a snug fit.  Note: I am not sure if these are called teeth or not.
>
> In almost 60 years of dealing with PL-259s the only time I needed pliers was to undo the PL-259 connector that I had on my truck that had sealant on it (it was very much in the weather) and stuck besides.
>
> Then again, I don’t ever remember having any loose connection problems with PL-259s either.
>
> 73, phil, K7PEH
>
>
>> On Apr 3, 2017, at 7:42 AM, Don Wilhelm <[hidden email]> wrote:
>>
>> Phil,
>>
>> PL-259s depend on tightness to make a good connection to the shield.
>> This is an often overlooked cause of problems.
>> After hand tightening, snug them up just a bit more with pliers if you want them to be reliable.
>>
>> 73,
>> Don W3FPR
>>
>> On 4/3/2017 10:19 AM, Phil Hystad wrote:
>>>
>>>> On Apr 3, 2017, at 5:25 AM, Nr4c <[hidden email]> wrote:
>>>>
>>>> Don't overlook the obvious.  Check to make sure the connectors are all very tight. "Hand snug" is not good enough!
>>>>
>>>> Sent from my iPad
>>>> ...bc nr4c
>>>
>>> What do you mean “Hand Snug” is not good enough?
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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> Please help support this email list: http://www.qsl.net/donate.html
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Re: K3 loss of rx signal

George Thornton
In reply to this post by Guy Olinger K2AV
Exerting too much force with PL259’s can put stress on the radio SO 239 connectors, I have had some of the internal mounts work loose over time.

Top quality Amphenol connectors are more precisely machined, fit better and are much easier to work with.  I don’t get failures with these and hand tightening seems to be sufficient in most situations.

From: Elecraft [mailto:[hidden email]] On Behalf Of Guy Olinger K2AV
Sent: Monday, April 3, 2017 8:04 AM
To: Phil Hystad <[hidden email]>
Cc: Elecraft Reflector <[hidden email]>
Subject: Re: [Elecraft] K3 loss of rx signal

On Mon, Apr 3, 2017 at 10:19 AM, Phil Hystad <[hidden email]><mailto:[hidden email]%3e> wrote:
> What do you mean “Hand Snug” is not good enough?

Lordee, I've seen, done, and heard of these things so many times...

PL259 the worst offender, with BNC close second. Mini-coax TMP in a
class by itself.

On the PL259, if the teeth around the edge of the mating shell aren't
aligned to move down into the teeth of the SO239, you can "tighten"
the PL259 to what seems tight, but a temperature change or a jiggle
will let the teeth align. The connector is now loose. A variety of
"false snugs" can occur with PL259, barrel, SO239 that have been
outdoors and gotten stuff in threads.

BNC's, if not inserted straight on, can seem snug, but not go down all
the way. Then the twist shell can go a distance and won't seem to want
to go any farther. It's very easy to not have enough finger strength
to twist the shell enough to go all the way down.

Mini-coax TMP connectors are bad because if the center pin does not
match inside the socket it won't go down and cause an infamous
intermittent that many have experienced. The flares on the male TMP
have to go down until they are prevented from further insertion by the
socket.

73, Guy K2AV
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Re: K3 loss of rx signal

Charlie T, K3ICH
In reply to this post by G3XVR
I would have thought the center pin would be smaller for higher Z connections (???).

Look at the size of the center conductor in a piece of RG-59/U.

Although, as usual I may have that completely wrong.

73, Charlie k3ICH





-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of [hidden email]
Sent: Monday, April 03, 2017 8:43 AM
To: Guy Olinger K2AV <[hidden email]>; LA7NO <[hidden email]>; [hidden email]
Subject: Re: [Elecraft] K3 loss of rx signal

I had a similar frustrating problem with a BNC patch lead. I bought some cheap leads at a rally and I didn’t notice that the plugs were 75 Ohms. The leads worked OK, but the centre pin was thicker than the 50 Ohm version and it splayed out the centre connector of the socket, so when I plugged a 50 Ohm patch cable back in, the centre pin did not make contact any more. It took me a long time to find the cause, and now all the 75 Ohm leads are in the bin.

73,

Danny, G3XVR



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Re: K3 loss of rx signal

Nr4c
In reply to this post by Phil Hystad-3
There's a difference in snug and tight.

Sent from my iPhone
...nr4c. bill


> On Apr 3, 2017, at 10:19 AM, Phil Hystad <[hidden email]> wrote:
>
>
>> On Apr 3, 2017, at 5:25 AM, Nr4c <[hidden email]> wrote:
>>
>> Don't overlook the obvious.  Check to make sure the connectors are all very tight. "Hand snug" is not good enough!
>>
>> Sent from my iPad
>> ...bc nr4c
>
> What do you mean “Hand Snug” is not good enough?  I don’t remember any connectors in the K3 that required a wrench to tighten nor do I ever use any wrenches or even screwdrivers on any of the connectors outside the box (Coax, RS232 serial, etc.).
>
> Curious in Rainy Kirkland (nr Seattle)…
>
> 73, phil, K7PEH
>

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Re: K3 loss of rx signal

Jim Brown-10
In reply to this post by George Thornton
When that happens, the connector inside the radio is either of inferior
quality or the installation method is wrong. A PROPER chassis-mount
female UHF connector either has four mounting screws to prevent it from
rotating . While there are also connectors without those mounting screws
with a square side to their circular body, they must be mounted on a
chassis with a hole of the same shape, and the chassis must be "hard"
enough that the connector cannot rotate. Any connector that rotates when
pliers are used to tighten or remove a mating connector is WRONG!

73, Jim K9YC

On Mon,4/3/2017 8:50 AM, George Thornton wrote:
> Exerting too much force with PL259’s can put stress on the radio SO 239 connectors, I have had some of the internal mounts work loose over time.


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Re: K3 loss of rx signal

Edward R Cole
In reply to this post by LA7NO
Simple - use something better than PL-259's:

I mainly use N connectors for low loss/high power and BNC for low
power inside the shack connections.  I also have TNC and sma connectors.

Most connectors need a 1/4 turn beyond finger tight for reliable
connections.  Sure cure for loose connectors is heat shrink over
them.  Not only seals from wx but also loosening due to vibration.

Want to see what vibration does?  Install a radio in a D8 cat without
some kind of vibration damping.  I did long ago, and the Motorola
100w VHF radio was a cabinet full of loose parts after 8-hours
running of the cat.  Wonder why military radios are full of glyptol,
or completely potted in plastic?

73, Ed - KL7UW
   http://www.kl7uw.com
Dubus-NA Business mail:
   [hidden email]

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Re: K3 loss of rx signal

Matthew Cook
In reply to this post by LA7NO
Ok.. My K3 has done something similar recently.

When you suspect that the RX has gone dead, try holding the Tune button and
force the radio to transmit a CW carrier.  I suspect you'll find that you
will get no output power aswell...  In this case the problem is with the
local oscillator and you won't see any error codes on the display either.

In my case I'd run into trouble with low out of from the KREF3 reference
oscillator which was fixed with a resistor change as per these instructions
(
http://www.elecraft.com/manual/E740278%20KREF3%20Output%20Level%20Modification.pdf).
  From memory the green LED on the top of the KSYN3A I'd installed would
not light when it decided it didn't like the look of the reference
oscillator, hence no LO would be generated and the symptoms were similar to
the ones you described.

It was intermittent and could be solved by power cycling the radio a few
times, I could have sworn the odd "calibrated bump" would restore operation
as well  but I'm not so sure.

Otherwise I'd be cleaning all of the TMP connectors with something like
deoxit and making sure all of the LO and Reference oscillator connections
are right.

I certainly hope that you find the gremlin in your radio.

73

Matthew
VK5ZM

On 3 April 2017 at 18:11, LA7NO <[hidden email]> wrote:

> Hello group,
>
> I have several times experienced that the K3 receiver goes 100% dead. Same
> as if no antenna was connected.
> A smart bump on the K3 brings it back to normal.
>
> I suspect a relay. The question is which one?
> Suggestion anyone?
>
> 73,
>
> Per-Tore / LA7NO
>
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.
> nabble.com/K3-loss-of-rx-signal-tp7628912.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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Re: K3 loss of rx signal

Bill Frantz
In reply to this post by LA7NO
When I was plugging and unplugging stubs and traps chasing the
broadcast interference problem and testing mitigations, it got a
lot easier when I add a bunch of adapters to make the process
attaching a BNC instead of a UHF. UHF connectors seem easier to
fit onto 1/2 inch coax though.

73 Bill AE6JV

On 4/3/17 at 7:18 PM, [hidden email] (Walter Underwood) wrote:

>According to Amphenol, UHF connectors have the same rating as
>BNC, 500V. Type N connectors can handle 1500V.
>
>I use BNC and N connectors wherever possible.

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Re: K3 loss of rx signal

donovanf
In reply to this post by LA7NO
BNC connectors rate high for convenience and low for performance,
especially leakage performance.


BNC connector leakage typicallymeasures in the range from -25 to
-50 dB vs -60 to -90 dB for N connectors. Any BNC connector
that does not fit snugly should replaced and discarded


73
Frank
W3LPL




----- Original Message -----

From: "Ron D'Eau Claire" <[hidden email]>
To: "Edward R Cole" <[hidden email]>, "Elecraft Reflector" <[hidden email]>
Sent: Tuesday, April 4, 2017 2:12:03 AM
Subject: Re: [Elecraft] K3 loss of rx signal

Note that BNC connectors can easily handle a kW of RF power unless there is
a high SWR on the line. They are rated for 500V.

73 Ron AC7AC

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Edward
R Cole
Sent: Monday, April 3, 2017 6:24 PM
To: Elecraft Reflector
Subject: Re: [Elecraft] K3 loss of rx signal

Simple - use something better than PL-259's:

I mainly use N connectors for low loss/high power and BNC for low power
inside the shack connections. I also have TNC and sma connectors.

Most connectors need a 1/4 turn beyond finger tight for reliable
connections. Sure cure for loose connectors is heat shrink over them. Not
only seals from wx but also loosening due to vibration.

Want to see what vibration does? Install a radio in a D8 cat without some
kind of vibration damping. I did long ago, and the Motorola 100w VHF radio
was a cabinet full of loose parts after 8-hours running of the cat. Wonder
why military radios are full of glyptol, or completely potted in plastic?

73, Ed - KL7UW
http://www.kl7uw.com 
Dubus-NA Business mail:
[hidden email]

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