Broken relay in KAT2

[Charles Greene]

Hi,

One of the relays in my KAT2 is stuck or a relay contact is shorted. When
you select antenna 1 it is ok. When you select antenna 2 both antennas are
selected (bad), and the indicator stays on Ant1. I guess replacing the
relay is necessary. I don't know why it stuck. I first noticed it this
morning while running the 5 watt beacon on 14102 KHz testing my EH antenna
against my Hustler 6BTV vertical. Both external SWR meters read and the
antenna was detuned. The beacon software is not supposed to hot switch, and
the SWR on both antennas is less than 1.8:1. I have been running the beacon
for over a month, and it switches antennas from 1 to 2 and back to 1 every
5 minutes. We have had only one lightning storm since the summer, and that
was about a month ago. My K2 is S/N 462, but it has not seen hard or
frequent use. Seems the relays should be good for more cycles than that.

  Any suggestions which relay is malfunctioning or why?

73,  Chas,  W1CG

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[Don Wilhelm-3]

Chas,

Look for a short between either pins 2 and 3 or pins 8 and 9 of KAT2 K18.
As you have concluded, a short batween those points or a faulty relay is the
only thing that could allow output on ANT 1 when ANT2 is selected.

But OTOH, if the indicator says ANT 1 in all cases, that indicates a problem
with the controls somewhere - double check that the indicator really always
stays at ANT 1 - the combination of the two situations just doesn't make
sense to me right now (the indication comes from the control software while
the RF path comes from the relay points, and I can't see that they are
related under fault conditions.

73,
Don W3FPR

> -----Original Message-----
>
> One of the relays in my KAT2 is stuck or a relay contact is shorted. When
> you select antenna 1 it is ok. When you select antenna 2 both
> antennas are
> selected (bad), and the indicator stays on Ant1. I guess replacing the
> relay is necessary. I don't know why it stuck. I first noticed it this
> morning while running the 5 watt beacon on 14102 KHz testing my
> EH antenna
> against my Hustler 6BTV vertical. Both external SWR meters read and the
> antenna was detuned. The beacon software is not supposed to hot
> switch, and
> the SWR on both antennas is less than 1.8:1. I have been running
> the beacon
> for over a month, and it switches antennas from 1 to 2 and back
> to 1 every
> 5 minutes. We have had only one lightning storm since the summer,
> and that
> was about a month ago. My K2 is S/N 462, but it has not seen hard or
> frequent use. Seems the relays should be good for more cycles than that.
>
>   Any suggestions which relay is malfunctioning or why?
>
> 73,  Chas,  W1CG
>

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[Charles Greene]

Tom and Don,

I think the problem has cured itself.  Now only the ant1 external meter
reads power when ant1 is selected.  Before both ant1 and ant2 were reading
power when ant1 was selected.  There's no indicator on ant1, just on
ant2.  I was mistaken about that.  Tnx for the response.

At 07:54 AM 4/1/2005, Tom Hammond wrote:

>Charles:
>
>I'm not aware of ANY 'signaling' in the KAT2 which 'senses' relay
>position. As a result, even though the relay might be stuck, there's NO
>REASON I can think of that the indicator would remain on ANT1 unless the
>logic is not telling the relay to switch... e.g. the logic should still
>think ANT2 has been selected and it should still illuminate the ANT2 LED
>regardless of whether the relay switched or not!
>
>73,
>
>Tom   N0SS
>
>At 08:40 PM 3/31/05, you wrote:
>>Hi,
>>
>>One of the relays in my KAT2 is stuck or a relay contact is shorted. When
>>you select antenna 1 it is ok. When you select antenna 2 both antennas
>>are selected (bad), and the indicator stays on Ant1. I guess replacing
>>the relay is necessary. I don't know why it stuck. I first noticed it
>>this morning while running the 5 watt beacon on 14102 KHz testing my EH
>>antenna against my Hustler 6BTV vertical. Both external SWR meters read
>>and the antenna was detuned. The beacon software is not supposed to hot
>>switch, and the SWR on both antennas is less than 1.8:1. I have been
>>running the beacon for over a month, and it switches antennas from 1 to 2
>>and back to 1 every 5 minutes. We have had only one lightning storm since
>>the summer, and that was about a month ago. My K2 is S/N 462, but it has
>>not seen hard or frequent use. Seems the relays should be good for more
>>cycles than that.
>>
>>  Any suggestions which relay is malfunctioning or why?
>>
>>73,  Chas,  W1CG
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>>Elecraft mailing list
>>Post to: [hidden email]
>>You must be a subscriber to post to the list.
>>Subscriber Info (Addr. Change, sub, unsub etc.):
>>http://mailman.qth.net/mailman/listinfo/elecraft
>>
>>Help: http://mailman.qth.net/subscribers.htm
>>Elecraft web page: http://www.elecraft.com

73,  Chas,  W1CG

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[Andrew Moore-4]

I don't have an exte

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[Andrew Moore-4]

I just finished building the KAT2 internal auto antenna tuner for my K2.
I don't yet have access to an external wattmeter, or RF probe, so I'm
wondering: are the last couple alignment / calibration steps necessary
for operation of the KAT2, or will the KAT2 still reach a proper match
even if SWR and power "calibration" has not been performed per the last
bit of the manual?  May I use the KAT2 for now and simply ignore the
possibly erroneous readings, or does the KAT2 actually rely on them for
finding a match?

Thanks,
--Andrew, NV1B


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[Don Wilhelm-3]

Andrew,

The KAT2 does use the SWR readings for determining the best match, and it
uses the power calibration to determine the power output. So, yes it should
be calibrated.  The K2 will function, but the power output may be very
incorrect and the antenna match obtained will not be correct.

You can build an RF Probe easily from a diode (preferably germanium - like a
1N34A), a capacitor and a resistor.  If you keep the frequency to 40 meters
and below (which is perfectly adequate for the purpose), it will be
sufficiently accurate by just connecting your DMM probe to the resistor end
and ground - no need for the RG174 coax leads.  There is a schematic in the
back of the K2 manual that will tell you how to connect the 3 parts.  Use a
short ground and connect it directly across your 50 ohm dummy load.

You WILL have to have a good 50 ohm dummy load to do this accurately, but
the dummy load can be easily checked with an antenna analyzer, or even a
simple 50 ohm SWR meter.

73,
Don W3FPR

> -----Original Message-----
>
>
> I just finished building the KAT2 internal auto antenna tuner for my K2.
> I don't yet have access to an external wattmeter, or RF probe, so I'm
> wondering: are the last couple alignment / calibration steps necessary
> for operation of the KAT2, or will the KAT2 still reach a proper match
> even if SWR and power "calibration" has not been performed per the last
> bit of the manual?  May I use the KAT2 for now and simply ignore the
> possibly erroneous readings, or does the KAT2 actually rely on them for
> finding a match?
>
> Thanks,
> --Andrew, NV1B
>
>

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