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K2 - Problem With KAT2 Installation

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Peter Barville

K2 - Problem With KAT2 Installation

Hello Don

Firstly, my apologies as I am currently experiencing a few mail
problems, and this note won't 'flow' as part of the original message thread.

I am very grateful to you Don for your reply. Over the years I can't
imagine just how many you have patiently helped.

I obviously didn't explain the problem very clearly, but will try and
clarify things.

J8 is oriented correctly, with the green wire towards the top. I have
checked the other end of the cable and confirmed there are no shorts, or
open circuits.

As you suggest, P4 pin 4 has been removed as part of the KPA100
installation, but I'm not sure what you mean by "Since you have already
removed P4 pin 4 for the KPA100 you will have U8 also keyed."

No doubt I'm being a little slow, but perhaps you would put me straight?

To clarify the symptoms (I hope):

With KAT2 *not* connected, the rig will power up and perform normally.

With KAT2 *connected*, when I power-up the rig, the S meter goes full
deflection, and there is no audio output. However, the rig does allow me
to navigate to, and through, the KAT2 options.

Since my first post, I have removed KAT2 and re-seated U1 in case the
passing years had resulted in a poor connection between chip and socket.
As part of that work, the pin mating between the L-C board and control
board has, by default, been re-seated. No improvement resulted.

73 Peter G3XJS (In hope!)

Don Wilhelm wrote:

>Peter,

>Is the green wire in J8 positioned toward the top? If not, things will
>not work well.
>If U8 is oriented correctly, check the other end of the cable for broken
>wires and shorts.

>Even so, I am a bit confused, you say you cannot power up the K2
>correctly, but you can access the ATU menu. Please elaborate, because
>on the surface, those two statements seem contradictory, the ATU menu
>will only display -- if the KAT2 is not connected.

>You could avoid plugging U8 incorrectly by using the same technique as
>the KPA100 ribbon cable - just stuff something in U8 at the pin 4
>location (toothpick, wire, anything that works, you might even glue it
>in). Since you have already removed P4 pin 4 for the KPA100 you will
>have U8 also keyed.

>73,
>Don W3FPR

>Peter Barville wrote:
> Folks
>
> I'm hoping somebody might be able to point me in the right direction, so
> thank you in advance for reading this.
>
> My K2 is serial number 573, so you can see that that I built it many
> years ago. Similarly, I built and incorporated the KAT2 Antenna Tuner
> almost as many years ago. However, the KAT2 has not been used for a long
> time, as I later moved on to installing the 100W PA lid.
>
> Although the KAT 2 was working fine when I last had it in the K2 (must
> be a good few year ago), when I came to replace the 100W lid with the
> KAT2 (and battery) lid yesterday I discovered there is now a problem
> with the KAT2.
>
> With J8 securely and correctly mated with P4 on the K2 Control Board,
> the rig will not power up properly. After an extremely brief burst of
> (probably normal) sound from the speaker, the S Meter goes to full
> deflection, and the rig goes silent. It is as if the rig is in Tx mode,
> although there is no RF output.
>
> I can access the KAT2 related items in the menu but, unless KAT2's J8
> is disconnected from P4, the rig will not power up correctly.
>
> I am not aware of any mishap having occurred to KAT2 whilst it resided
> mounted in its lid, but stored away in a box, but wonder whether anybody
> has any suggestions as to where first to look?
>
> Many thanks.
>
> 73 Peter G3XJS
>

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Don Wilhelm-4

Re: K2 - Problem With KAT2 Installation

Peter,

While I should say "That can't happen", it obviously is happening.
There is no signal on the P4/J8 connector that should cause those symptoms.
It sounds like, when the KAT2 is connected, there is some signal being
injected at the antenna which is causing the AGC to fully activate and
that reduces the audio significantly. I cannot conceive how the KAT2
could create an oscillation, it is only an L network with parallel C and
series L elements.

The other possibility is that somehow connecting the KAT2 is causing
your K2 to go into transmit - that will create no audio and a deflection
of the S-meter - However, if that were true, you could not navigate the
menu during transmit, so I don't think that is what is happening.

Try connecting the cable to CB P4 but do not connect the KAT2 RF input
(coax cable) to RF Board P6 - is the problem still present? If not,
then the KAT2 is picking up some strong local signal and injecting it
into the receiver.

What I meant for the keying of J8 was to stick something in the pin 4
position on the connector and it will be impossible to plug J8 into P4
the wrong way. Pin 4 has already been removed from P4 during the
installation of the KPA100. Use the same technique to key J8.

73,
Don W3FPR

Peter Barville wrote:

> Hello Don
>
> Firstly, my apologies as I am currently experiencing a few mail
> problems, and this note won't 'flow' as part of the original message thread.
>
> I am very grateful to you Don for your reply. Over the years I can't
> imagine just how many you have patiently helped.
>
> I obviously didn't explain the problem very clearly, but will try and
> clarify things.
>
> J8 is oriented correctly, with the green wire towards the top. I have
> checked the other end of the cable and confirmed there are no shorts, or
> open circuits.
>
> As you suggest, P4 pin 4 has been removed as part of the KPA100
> installation, but I'm not sure what you mean by "Since you have already
> removed P4 pin 4 for the KPA100 you will have U8 also keyed."
>
> No doubt I'm being a little slow, but perhaps you would put me straight?
>
> To clarify the symptoms (I hope):
>
> With KAT2 *not* connected, the rig will power up and perform normally.
>
> With KAT2 *connected*, when I power-up the rig, the S meter goes full
> deflection, and there is no audio output. However, the rig does allow me
> to navigate to, and through, the KAT2 options.
>
>

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Peter Barville

Re: K2 - Problem With KAT2 Installation

In reply to this post by Peter Barville

Many thanks once again Don.

I agree with your thoughts, but KAT2 is currently a 'stand alone unit'
with the RF connectors not connected. I'm only connecting J8.

So, like you, I am at a loss to understand what is happening.

Even with a very strong (and loud) signal at the Rx input, no audio is
present when J8 is mated with P4. Just a full scale reading on the S meter.

Understood re "keying J8".

73 Peter G3XJS

Don Wilhelm wrote:

>
> Peter,
>
> While I should say "That can't happen", it obviously is happening.
> There is no signal on the P4/J8 connector that should cause those symptoms.
> It sounds like, when the KAT2 is connected, there is some signal being
> injected at the antenna which is causing the AGC to fully activate and
> that reduces the audio significantly. I cannot conceive how the KAT2
> could create an oscillation, it is only an L network with parallel C and
> series L elements.
>
> The other possibility is that somehow connecting the KAT2 is causing
> your K2 to go into transmit - that will create no audio and a deflection
> of the S-meter - However, if that were true, you could not navigate the
> menu during transmit, so I don't think that is what is happening.
>
> Try connecting the cable to CB P4 but do not connect the KAT2 RF input
> (coax cable) to RF Board P6 - is the problem still present? If not,
> then the KAT2 is picking up some strong local signal and injecting it
> into the receiver.
>
> What I meant for the keying of J8 was to stick something in the pin 4
> position on the connector and it will be impossible to plug J8 into P4
> the wrong way. Pin 4 has already been removed from P4 during the
> installation of the KPA100. Use the same technique to key J8.
>
> 73,
> Don W3FPR
>
> Peter Barville wrote:
>> Hello Don
>>
>> Firstly, my apologies as I am currently experiencing a few mail
>> problems, and this note won't 'flow' as part of the original message
>> thread.
>>
>> I am very grateful to you Don for your reply. Over the years I can't
>> imagine just how many you have patiently helped.
>>
>> I obviously didn't explain the problem very clearly, but will try and
>> clarify things.
>>
>> J8 is oriented correctly, with the green wire towards the top. I have
>> checked the other end of the cable and confirmed there are no shorts,
>> or open circuits.
>>
>> As you suggest, P4 pin 4 has been removed as part of the KPA100
>> installation, but I'm not sure what you mean by "Since you have
>> already removed P4 pin 4 for the KPA100 you will have U8 also keyed."
>>
>> No doubt I'm being a little slow, but perhaps you would put me straight?
>>
>> To clarify the symptoms (I hope):
>>
>> With KAT2 *not* connected, the rig will power up and perform normally.
>>
>> With KAT2 *connected*, when I power-up the rig, the S meter goes full
>> deflection, and there is no audio output. However, the rig does allow
>> me to navigate to, and through, the KAT2 options.
>>
>>
>
>
>

Don Wilhelm-4

Re: K2 - Problem With KAT2 Installation

Peter,

In that case, I would suggest looking at the control board to see is
there is something awry there causing a path to the AGC circuits below
P4. Also you might check the VRFDET signal line on the KAT2 - hint,
removing R6 should disconnect the VRFDET signal line but leave the cable
connection present.
Check the cable for internal shorts between the conductors with an
ohmmeter - that might happen in storage if the cable was sharply bent
and insulation creep occurred.

73,
Don W3FPR

Peter Barville wrote:

> Many thanks once again Don.
>
> I agree with your thoughts, but KAT2 is currently a 'stand alone unit'
> with the RF connectors not connected. I'm only connecting J8.
>
> So, like you, I am at a loss to understand what is happening.
>
> Even with a very strong (and loud) signal at the Rx input, no audio is
> present when J8 is mated with P4. Just a full scale reading on the S meter.
>
>

Peter Barville

Re: K2 - Problem With KAT2 Installation

In reply to this post by Peter Barville

Hi Don

Don't want to take up your time, but thanks again.

I doubt there will be a problem on the K2 control board, as it runs
happily without KAT2 and/or with KPA100 installed.

I did check the J8 cable carefully right at the outset, but can find no
sign of shorts or open circuits.

I've not looked at removing R6 yet, but will do when I have a chance.

I really am puzzled by this - not to say frustrated!

73 Peter G3XJS

Don Wilhelm wrote:

>
> Peter,
>
> In that case, I would suggest looking at the control board to see is
> there is something awry there causing a path to the AGC circuits below
> P4. Also you might check the VRFDET signal line on the KAT2 - hint,
> removing R6 should disconnect the VRFDET signal line but leave the cable
> connection present.
> Check the cable for internal shorts between the conductors with an
> ohmmeter - that might happen in storage if the cable was sharply bent
> and insulation creep occurred.
>
> 73,
> Don W3FPR
>
> Peter Barville wrote:
>> Many thanks once again Don.
>>
>> I agree with your thoughts, but KAT2 is currently a 'stand alone unit'
>> with the RF connectors not connected. I'm only connecting J8.
>>
>> So, like you, I am at a loss to understand what is happening.
>>
>> Even with a very strong (and loud) signal at the Rx input, no audio is
>> present when J8 is mated with P4. Just a full scale reading on the S
>> meter.
>>
>
>
>

Eugene Balinski

K2/100 RF Power Output Control (SSB)

All,

Still new to the K2/100 (6k serial number). I have a
question about the power output control in SSB mode. I
was hoping to be able to vary the RF output from QRP all
the way to the 100W level, however when I advance the RF
Power knob past the 12W indicated on the display, I hear a
relay click and the radio goes to the 100W+ output level.
This causes the power supply (RS-20) to actually go out
of regulation (more than 22A) on voice peaks.

Is there an issue with the PO control, or does it
behave differently with the 100W amp ?

73 and thanks in advance,

Gene K1NR

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Don Wilhelm-4

Re: K2/100 RF Power Output Control (SSB)

Gene,

You may have a simple problem - diodes D16 and D17 in the KPA100
wattmeter may be damaged.
When that happens, the K2 microprocessor thinks there is no power being
developed and increases the drive to the maximum.
To test for that condition, set the power control to 4 or 5 watts and
measure the actual power output. If it is 14 or 15 watts (maximum power
from the base K2) then it is a sure bet that there is something wrong
with the wattmeter in the KPA100, and the diodes are the most probable
source.

If you have proper power control up to 12 watts, then several other
problems might be present. If that is the case ask again and we can
advise you where to check next - but do the diode checks first. You can
check them like any diode with an ohmmeter.

If the diodes are bad, you will have to remove the KPA100 and take off
its shield plate. There is a chance that you can replace the diodes
(they are near the SO239 jack) from the top of the board, leaving short
leads above the board to solder the new diodes - worst case, you will
have to remove the board from the heat sink and unsolder the diodes from
the bottom.

You may have heard advice to disconnect the K2 from the antenna when not
in use, and you should heed that advice. Those diodes can be damaged by
static discharges coming in on the feedline. Static can be caused by
wind, rain, snow, lightning, etc. Plus, for your personal safety and the
safety of those in your household, disconnecting the antennas is good
insurance against fire or lightning induced shocks during a lightning storm.

73,
Don W3FPR

Eugene Balinski wrote:

> All,
>
> Still new to the K2/100 (6k serial number). I have a
> question about the power output control in SSB mode. I
> was hoping to be able to vary the RF output from QRP all
> the way to the 100W level, however when I advance the RF
> Power knob past the 12W indicated on the display, I hear a
> relay click and the radio goes to the 100W+ output level.
> This causes the power supply (RS-20) to actually go out
> of regulation (more than 22A) on voice peaks.
>
> Is there an issue with the PO control, or does it
> behave differently with the 100W amp ?
>
> 73 and thanks in advance,
>
>

Peter Barville

Re: K2 - Problem With KAT2 Installation - SOLVED!

In reply to this post by Peter Barville

Hi Don

Simple logic on your part, and careful inspection and application of a
DVM on my part has revealed the cause of the problem.

R6 was mounted on the back of the KAT2 control board, with slightly
longer than necessary leads, and at some stage the lead closest to the
edge of the board had been pushed such that it was shorting with the pad
of U1 pin 1, thereby putting +5v onto the VRFDET line.

Needless to say, I have now re-mounted R6 well away from adjoining pads.

KAT2 is currently still a 'stand alone unit', but rig + KAT2 now powers
up normally, without full scale S meter deflection. No doubt all will
continue to be fully functional when KAT2 is mounted back in the lid and
operational.

Once again, very many thanks for your patience and help.

73 Peter G3XJS (Much relieved)

Don Wilhelm wrote:
> Also you might check the VRFDET signal line on the KAT2 - hint,
> removing R6 should disconnect the VRFDET signal line

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