Re: [Elecraft] K3 - Erratic receive

[Mark Musick]

Hi Pete,
The gold pins did not appear as part of production until somewhere around 
serial #4100.
I had K3 Serial #3505 and had to have the front panel pins upgraded to the gold 
standard.

73,
Mark, WB9CIF

-Original Message-
From: elecraft-boun...@mailman.qth.net  On 
Behalf Of Pete Smith N4ZR
Sent: Wednesday, November 29, 2023 20:35
To: Elecraft List 
Subject: Re: [Elecraft] K3 - Erratic receive

Hi Bill - I'm pretty sure my radio is late enough so that it has the upgraded 
pins that were introduced to deal with that problem, but thanks for responding.

73, Pete N4ZR

On 11/29/2023 3:28 PM, Bill Johnson wrote:
> Pete,  have  the front panel pins corroded?  There is an upgrade
> available.
>
> Bill
> K9YEQ
> --
> --
> *From:* elecraft-boun...@mailman.qth.net
>  on behalf of Pete Smith N4ZR
> 
> *Sent:* Wednesday, November 29, 2023 1:11:14 PM
> *To:* Elecraft List 
> *Subject:* [Elecraft] K3 - Erratic receive My 2400-serial number K3
> has begun to have a sporadic receive problem, which has gotten much
> worse recently.  It's really weird.
>
> What happens is this - the receiver sporadically loses most of its
> audio output level, until I move the AF pot a couple of degrees either
> way, at which point it immediately restores the audio.  Often, but not
> always, this occurs right after a transmission (on CW), so I was
> initially suspecting a failing relay, but the way it responds to a
> minute change in the AF level setting makes me think something subtler. Any 
> ideas?
>
> --
> 73, Pete N4ZR
> __
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Re: [Elecraft] K3 - Erratic receive

[Michael Carter via Elecraft]

+1 for what Brian, K0DTJ suggested!

The front panel buttons use a similar
voltage divider with a multiplexed
A/D converter to determine which button
has been depressed.

73,
Mike, K8CN
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Re: [Elecraft] K3 - Erratic receive

[Brian Hunt]

According to the schematics, those two double pots on the front panel are 
merely voltage dividers. They provide 0 to 5v signals to the front panel MCU 
which controls the function, eg: AF_GAIN. It’s possible the pot has developed a 
dropout right at the point where you usually set the AF level. Maybe turning 
the pot stop to stop a half dozen times will improve it??  Worth a try. 

73,
Brian, K0DTJ

> On Nov 29, 2023, at 12:12, Pete Smith N4ZR  wrote:
> 
> My 2400-serial number K3 has begun to have a sporadic receive problem, which 
> has gotten much worse recently.  It's really weird.
> 
> What happens is this - the receiver sporadically loses most of its audio 
> output level, until I move the AF pot a couple of degrees either way, at 
> which point it immediately restores the audio.  Often, but not always, this 
> occurs right after a transmission (on CW), so I was initially suspecting a 
> failing relay, but the way it responds to a minute change in the AF level 
> setting makes me think something subtler.  Any ideas?
> 
> --
> 73, Pete N4ZR
> __
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Re: [Elecraft] K3 - Erratic receive

[Bill Johnson]

You're most welcome!

Bill
K9YEQ

From: elecraft-boun...@mailman.qth.net  on 
behalf of Pete Smith N4ZR 
Sent: Wednesday, November 29, 2023 1:34:40 PM
To: Elecraft List 
Subject: Re: [Elecraft] K3 - Erratic receive

Hi Bill - I'm pretty sure my radio is late enough so that it has the
upgraded pins that were introduced to deal with that problem, but thanks
for responding.

73, Pete N4ZR

On 11/29/2023 3:28 PM, Bill Johnson wrote:
> Pete,  have  the front panel pins corroded?  There is an upgrade
> available.
>
> Bill
> K9YEQ
> 
> *From:* elecraft-boun...@mailman.qth.net
>  on behalf of Pete Smith N4ZR
> 
> *Sent:* Wednesday, November 29, 2023 1:11:14 PM
> *To:* Elecraft List 
> *Subject:* [Elecraft] K3 - Erratic receive
> My 2400-serial number K3 has begun to have a sporadic receive problem,
> which has gotten much worse recently.  It's really weird.
>
> What happens is this - the receiver sporadically loses most of its audio
> output level, until I move the AF pot a couple of degrees either way, at
> which point it immediately restores the audio.  Often, but not always,
> this occurs right after a transmission (on CW), so I was initially
> suspecting a failing relay, but the way it responds to a minute change
> in the AF level setting makes me think something subtler. Any ideas?
>
> --
> 73, Pete N4ZR
> __
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to k9...@live.com
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Re: [Elecraft] K3 - Erratic receive

[Pete Smith N4ZR]

Hi Bill - I'm pretty sure my radio is late enough so that it has the 
upgraded pins that were introduced to deal with that problem, but thanks 
for responding.


73, Pete N4ZR

On 11/29/2023 3:28 PM, Bill Johnson wrote:
Pete,  have  the front panel pins corroded?  There is an upgrade 
available.


Bill
K9YEQ

*From:* elecraft-boun...@mailman.qth.net 
 on behalf of Pete Smith N4ZR 


*Sent:* Wednesday, November 29, 2023 1:11:14 PM
*To:* Elecraft List 
*Subject:* [Elecraft] K3 - Erratic receive
My 2400-serial number K3 has begun to have a sporadic receive problem,
which has gotten much worse recently.  It's really weird.

What happens is this - the receiver sporadically loses most of its audio
output level, until I move the AF pot a couple of degrees either way, at
which point it immediately restores the audio.  Often, but not always,
this occurs right after a transmission (on CW), so I was initially
suspecting a failing relay, but the way it responds to a minute change
in the AF level setting makes me think something subtler. Any ideas?

--
73, Pete N4ZR
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Re: [Elecraft] K3 - Erratic receive

[Bill Johnson]

Pete,  have  the front panel pins corroded?  There is an upgrade available.

Bill
K9YEQ

From: elecraft-boun...@mailman.qth.net  on 
behalf of Pete Smith N4ZR 
Sent: Wednesday, November 29, 2023 1:11:14 PM
To: Elecraft List 
Subject: [Elecraft] K3 - Erratic receive

My 2400-serial number K3 has begun to have a sporadic receive problem,
which has gotten much worse recently.  It's really weird.

What happens is this - the receiver sporadically loses most of its audio
output level, until I move the AF pot a couple of degrees either way, at
which point it immediately restores the audio.  Often, but not always,
this occurs right after a transmission (on CW), so I was initially
suspecting a failing relay, but the way it responds to a minute change
in the AF level setting makes me think something subtler.  Any ideas?

--
73, Pete N4ZR
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[Elecraft] K3 - Erratic receive

[Pete Smith N4ZR]

My 2400-serial number K3 has begun to have a sporadic receive problem, 
which has gotten much worse recently.  It's really weird.


What happens is this - the receiver sporadically loses most of its audio 
output level, until I move the AF pot a couple of degrees either way, at 
which point it immediately restores the audio.  Often, but not always, 
this occurs right after a transmission (on CW), so I was initially 
suspecting a failing relay, but the way it responds to a minute change 
in the AF level setting makes me think something subtler.  Any ideas?


--
73, Pete N4ZR
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Re: [Elecraft] USB/3.5mm Extension?

[Jim Brown]

On 11/29/2023 7:47 AM, Andy Durbin wrote:

The MAX3232 terminates the input with 5k which is almost identical to the 
KAT500 transmitter source impedance.


The impedance that must be matched to preserve waveshape is that of the 
transmission line. The RS232 protocol does not do that. Most other 
protocols do. Zo of practical cables is in the range of 50-100 ohms.


73, Jim K9YC


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Re: [Elecraft] USB/3.5mm Extension?

[Andy Durbin]

"Scope traces for a typical KAT500 serial data interface can be found here -

https://www.dropbox.com/scl/fi/ypk0ks16rl03d55ugm4t9/KAT500-signal-levels.pdf?rlkey=7iahis4xp0jnua3c8s577cxjq&dl=0";


The depicted voltage levels for KAT500 driving the KXUSB were not typical.  In 
my station the KAT500 serial port transmitter connects to both the KXUSB 
receiver and a MAX3232.  The MAX3232 terminates the input with 5k which is 
almost identical to the KAT500 transmitter source impedance.  The observed 
voltage is higher when this 5k load is not present.

Thanks to Jack, W6FB, for spotting this error.

73,
Andy, k3wyc

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