KX3 keyline questions

[Steve Zabarnick]

I'm exploring using my KX3 with the QRP-Labs 50W Amplifier. In measuring
the keyline output, I get zero volts to ground when in receive and about
0.5 volts in transmit. When measuring resistance across the keyline I get
about 70 ohms in receive and 5K ohms in transmit.

Isn't the keyline supposed to be open in receive and grounded in transmit?

Steve N9SZ
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[wayne burdick]

Steve,

Are you sure you're looking at the ACC2 ring contact? Ring is KEY OUT; tip is GPIO, a logic signal configurable in the ACC2 IO Menu entry.

Wayne
N6KR

> On Nov 21, 2020, at 1:12 PM, Steve Zabarnick <[hidden email]> wrote:
>
> I'm exploring using my KX3 with the QRP-Labs 50W Amplifier. In measuring
> the keyline output, I get zero volts to ground when in receive and about
> 0.5 volts in transmit. When measuring resistance across the keyline I get
> about 70 ohms in receive and 5K ohms in transmit.
>
> Isn't the keyline supposed to be open in receive and grounded in transmit?
>
> Steve N9SZ

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[Don Wilhelm]

Steve,

Are you measuring with the amplifier connected?  That could be a reason.
Put in a plug with nothing connected and remeasure.  Be careful with
autoranging meters, they can fool you.  Make certain you know what your
meter displays for infinite resistance - it should be the same as shown
with the probes apart and connected to nothing.
Make certain you are measuring between the ring and shell of the plug.
The tip is GPIO and its behavior is controlled in the KX3 menu.

You should read an infinite resistance in receive and near zero ohms in
transmit.  Voltage measurements of an open drain FET do not have much
meaning.  Make certain your test plug is fully seated in the jack.

73,
Don W3FPR

On 11/21/2020 4:12 PM, Steve Zabarnick wrote:
> I'm exploring using my KX3 with the QRP-Labs 50W Amplifier. In measuring
> the keyline output, I get zero volts to ground when in receive and about
> 0.5 volts in transmit. When measuring resistance across the keyline I get
> about 70 ohms in receive and 5K ohms in transmit.
>
> Isn't the keyline supposed to be open in receive and grounded in transmit?
>
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[Steve Zabarnick]

I'm pretty sure that I am measuring the ring to ground for ACC2. The amp is
not connected. Is there a menu setting I could have wrong? If not is the
keyline output transistor bad? How do I diagnose the problem in the KX3?

Steve N9SZ

Steve,

Are you sure you're looking at the ACC2 ring contact? Ring is KEY OUT;
tip is GPIO, a \
logic signal configurable in the ACC2 IO Menu entry.

Wayne
N6KR


On Sat, Nov 21, 2020 at 4:12 PM Steve Zabarnick <[hidden email]> wrote:

> I'm exploring using my KX3 with the QRP-Labs 50W Amplifier. In measuring
> the keyline output, I get zero volts to ground when in receive and about
> 0.5 volts in transmit. When measuring resistance across the keyline I get
> about 70 ohms in receive and 5K ohms in transmit.
>
> Isn't the keyline supposed to be open in receive and grounded in transmit?
>
> Steve N9SZ
>
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[Steve Zabarnick]

I ended up replacing Q5, the keyline output transistor on the KX3 RF board.
It had a hole in it and apparently the magic smoke had come out. Keyline is
now working. This KX3 was purchased used and I had never used an amp or the
keyline.

Steve N9SZ

On Sat, Nov 21, 2020 at 8:13 PM Steve Zabarnick <[hidden email]> wrote:

> I'm pretty sure that I am measuring the ring to ground for ACC2. The amp
> is not connected. Is there a menu setting I could have wrong? If not is the
> keyline output transistor bad? How do I diagnose the problem in the KX3?
>
> Steve N9SZ
>
> Steve,
>
> Are you sure you're looking at the ACC2 ring contact? Ring is KEY OUT; tip is GPIO, a \
> logic signal configurable in the ACC2 IO Menu entry.
>
> Wayne
> N6KR
>
>
> On Sat, Nov 21, 2020 at 4:12 PM Steve Zabarnick <[hidden email]>
> wrote:
>
>> I'm exploring using my KX3 with the QRP-Labs 50W Amplifier. In measuring
>> the keyline output, I get zero volts to ground when in receive and about
>> 0.5 volts in transmit. When measuring resistance across the keyline I get
>> about 70 ohms in receive and 5K ohms in transmit.
>>
>> Isn't the keyline supposed to be open in receive and grounded in transmit?
>>
>> Steve N9SZ
>>
>

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