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KPA500 strange behavior

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Jerry

KPA500 strange behavior

Good morning,

I have an interesting problem in which I hope the group here has an easy
solution.

My KPA 500 is hooked to a TS-2000 outputting 20 watts to the KPA500 and
displays the following abnormalities :

1. At frequencies between 4581 kc to 4601.6 (we are working on MARS
frequencies) using USB and a waveform of M110A, the following
characteristics are observed.
2. The amplifier stops transmitting briefly (less than a blink of an eye)
and then resumes during a M110A transmission at multiple random times.
3. Does not appear to happen when using voice, although some stations on the
MARS net have mentioned that my transmissions sometimes do drop to very low
levels.
4. This drop out does not occur:
a. On frequencies outside the range as listed in item #1.
b. If the emission is any other type other than USB/LSB.
c. When I turn off the amplifier and only transmitting using the
TS2000 at 100watts.
5. Occasionally, but not every time when this event occurs I hear a relay
inside the KPA500 click
6. I did the following tests in an attempt to located the problem.
a. The conditions occurs whether I am attached to any one of the
antennas I have here.
b. It also occurs when a dummy load is attached.
c. It still occurs when I switch out KAT500 antenna tuners (I have
two of them).

Initially, my thoughts were that the frequency range seems to lie some where
in the boundary between 3.5 and 5.0 band

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Bob McGraw - K4TAX

Re: KPA500 strange behavior

How are you handling the PTT?   Direct from the KPA-500 to the TS-2000
via the PA Key on the amp or by the KPA-500 Aux connector pin #10.
Check cables as one of those commands is being dropped.

Add a ferrite choke on the PTT line if using the PA Key command
method.    Or, reduce drive power to 5 to 10 watts and see if it
occurred. If it doesn't occur at 5 to 10 watts of drive, you can bet it
is and RFI issue and the ferrite choke may correct it.

73

Bob, K4TAX

On 7/20/2018 8:58 AM, W1IE wrote:

> Good morning,
>
> I have an interesting problem in which I hope the group here has an easy
> solution.
>
> My KPA 500 is hooked to a TS-2000 outputting 20 watts to the KPA500 and
> displays the following abnormalities :
>
> 1. At frequencies between 4581 kc to 4601.6 (we are working on MARS
> frequencies) using USB and a waveform of M110A, the following
> characteristics are observed.
> 2. The amplifier stops transmitting briefly (less than a blink of an eye)
> and then resumes during a M110A transmission at multiple random times.
> 3. Does not appear to happen when using voice, although some stations on the
> MARS net have mentioned that my transmissions sometimes do drop to very low
> levels.
> 4. This drop out does not occur:
> a. On frequencies outside the range as listed in item #1.
> b. If the emission is any other type other than USB/LSB.
> c. When I turn off the amplifier and only transmitting using the
> TS2000 at 100watts.
> 5. Occasionally, but not every time when this event occurs I hear a relay
> inside the KPA500 click
> 6. I did the following tests in an attempt to located the problem.
> a. The conditions occurs whether I am attached to any one of the
> antennas I have here.
> b. It also occurs when a dummy load is attached.
> c. It still occurs when I switch out KAT500 antenna tuners (I have
> two of them).
>
>
>
>
> Initially, my thoughts were that the frequency range seems to lie some where
> in the boundary between 3.5 and 5.0 band
>
> ______________________________________________________________
> 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]
>

______________________________________________________________
Elecraft mailing list
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Elecraft mailing list

Re: KPA500 strange behavior

In reply to this post by Jerry

4600 KHz is the threshold for 80/60 meters. Below is 80, above 60. Your KPA is trying to decide which band it needs to be on and is switching back and forth with the modulation as it causes the frequency to change.
The delay is simply the band change. It would require firmware changes to fix this one.

73,
Jack, W6FB

> On Jul 20, 2018, at 6:58 AM, W1IE <[hidden email]> wrote:
>
> Good morning,
>
> I have an interesting problem in which I hope the group here has an easy
> solution.
>
> My KPA 500 is hooked to a TS-2000 outputting 20 watts to the KPA500 and
> displays the following abnormalities :
>
> 1. At frequencies between 4581 kc to 4601.6 (we are working on MARS
> frequencies) using USB and a waveform of M110A, the following
> characteristics are observed.
> 2. The amplifier stops transmitting briefly (less than a blink of an eye)
> and then resumes during a M110A transmission at multiple random times.
> 3. Does not appear to happen when using voice, although some stations on the
> MARS net have mentioned that my transmissions sometimes do drop to very low
> levels.
> 4. This drop out does not occur:
> a. On frequencies outside the range as listed in item #1.
> b. If the emission is any other type other than USB/LSB.
> c. When I turn off the amplifier and only transmitting using the
> TS2000 at 100watts.
> 5. Occasionally, but not every time when this event occurs I hear a relay
> inside the KPA500 click
> 6. I did the following tests in an attempt to located the problem.
> a. The conditions occurs whether I am attached to any one of the
> antennas I have here.
> b. It also occurs when a dummy load is attached.
> c. It still occurs when I switch out KAT500 antenna tuners (I have
> two of them).
>
>
>
>
> Initially, my thoughts were that the frequency range seems to lie some where
> in the boundary between 3.5 and 5.0 band
>
> ______________________________________________________________
> 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]