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Elecraft KPA 1500 thoughts

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Randy (Art)

Elecraft KPA 1500 thoughts

I recently got the KPA 1500 amp and guess I have some observations an
possible upgrades that maybe considered.
1. I use my K3 and amp on all bands 160 thru 6 and have the internal 2
meter xfter using with a HB PQL LDMOS amp I built. It uses RCA phone for
its PTT and the KPA 1500 is using the enhanced cable. When I go from 6 to 2
meters the amp clicks and the freq indicates 5 MHz in the display. If the
amp was in oper mode on 6 it then keys on when I tx on 2 meters. Seems to
me it should recognize that it is on 2 and best case boot itself into
neutral.
2. I also would think a 1/2 speed of speed 1 would be a nicer starting
point. I can handle 1 & 2 speeds but not totally used to it as the last amp
was quieter than this one.
3. On ssb and had TX Test mode selected so as not to TX. When I hit
the paddle the amp goes TX mode and actually put out a little RF on the
LP100 meter. Should not key amp in my thinking.

Hopefully I have entered this all correctly and am not booted off. Thanks
for any answers and thoughts.

Randy WB8ART

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N4ZR

Re: Elecraft KPA 1500 thoughts

TX Test mode? On the K3 or the KPA-1500?

73, Pete N4ZR
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On 8/25/2019 3:58 PM, Randy (Art) wrote:

>
> I recently got the KPA 1500 amp and guess I have some observations an
> possible upgrades that maybe considered.
> 1. I use my K3 and amp on all bands 160 thru 6 and have the internal 2
> meter xfter using with a HB PQL LDMOS amp I built. It uses RCA phone for
> its PTT and the KPA 1500 is using the enhanced cable. When I go from 6 to 2
> meters the amp clicks and the freq indicates 5 MHz in the display. If the
> amp was in oper mode on 6 it then keys on when I tx on 2 meters. Seems to
> me it should recognize that it is on 2 and best case boot itself into
> neutral.
> 2. I also would think a 1/2 speed of speed 1 would be a nicer starting
> point. I can handle 1 & 2 speeds but not totally used to it as the last amp
> was quieter than this one.
> 3. On ssb and had TX Test mode selected so as not to TX. When I hit
> the paddle the amp goes TX mode and actually put out a little RF on the
> LP100 meter. Should not key amp in my thinking.
>
> Hopefully I have entered this all correctly and am not booted off. Thanks
> for any answers and thoughts.
>
> Randy WB8ART
>
>
>
>
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> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Bob Wilson, N6TV

Re: Elecraft KPA 1500 thoughts

In reply to this post by Randy (Art)

On Sun, Aug 25, 2019 at 12:59 PM Randy (Art) <[hidden email]> wrote:

> 1. I use my K3 and amp on all bands 160 thru 6 and have the internal 2
> meter xfter using with a HB PQL LDMOS amp I built. It uses RCA phone for
> its PTT and the KPA 1500 is using the enhanced cable. When I go from 6 to
> 2
> meters the amp clicks and the freq indicates 5 MHz in the display. If the
> amp was in oper mode on 6 it then keys on when I tx on 2 meters. Seems to
> me it should recognize that it is on 2 and best case boot itself into
> neutral.
>

This feature is already built in to the K3 / KPA500 or KPA1500 combo, but
not well known.

1. While on 2m, go to the CONFIG:DIGOUT1 menu of the K3, set set DIGOUT1
ON. This drives ACC Pin 11 low when you are on 2m.
2. This setting is per band and per antenna, so make sure DIGOUT1 is set
to OFF on all other bands / antennas.
3. Go to the KPA1500 menu TECH MODE and make it ENBALED
4. Go to the KPA1500 menu TX INHIBIT and set it to ENABLED. Pin 11 on
the amplifier end is the Inhibit pin.

Per the KPA1500 manual, "When enabled and the INHIBIT line is pulled down,
the PA stage is bypassed. The MODE LED will remain in OPER.".

I just tested this an it works perfectly. If DIGOUT1 is ON, and TX INHIBIT
ENABLED in the amp., the amp. does not KEY even though it remains in OPER
mode. As soon as you set DIGOUT1 OFF (which will happen automatically on
other a bands), the amp. is keyed normally. Please try this.

3. On ssb and had TX Test mode selected so as not to TX. When I hit
> the paddle the amp goes TX mode and actually put out a little RF on the
> LP100 meter. Should not key amp in my thinking.
>

TX TEST mode has always closed the relay and keying lines even though the
rig is putting out no RF. This is a safe way to test your keying relay
connections and amp. keying light, and perhaps it also protects the
receiver from getting a bunch of internal noise from inside the radio, so
that is working as designed. Any RF you see could be caused by some static
when the amp relay is keyed, nothing more. The K3 puts out no power when
in TX TEST mode, even if you have CW in SSB enabled and tap the key (which
you probably did at some point by going to CONFIG: CW WGHT and tapping [1]
to enabled it, which is useful in VHF bands it seems. You can disable the
feature if you don't want RF to come out or don't want the relay to close
while you're in SSB mode and accidentally tap the paddle.

73,
Bob, N6TV
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Randy (Art)

Re: Elecraft KPA 1500 thoughts

Thanks Bob and yes that worked.

Randy WB8ART

From: Bob Wilson, N6TV [mailto:[hidden email]]
Sent: Monday, August 26, 2019 7:45 PM
To: Randy (Art)
Cc: Elecraft Reflector
Subject: Re: [Elecraft] Elecraft KPA 1500 thoughts

On Sun, Aug 25, 2019 at 12:59 PM Randy (Art) <[hidden email]> wrote:

1. I use my K3 and amp on all bands 160 thru 6 and have the internal 2
meter xfter using with a HB PQL LDMOS amp I built. It uses RCA phone for
its PTT and the KPA 1500 is using the enhanced cable. When I go from 6 to 2
meters the amp clicks and the freq indicates 5 MHz in the display. If the
amp was in oper mode on 6 it then keys on when I tx on 2 meters. Seems to
me it should recognize that it is on 2 and best case boot itself into
neutral.

This feature is already built in to the K3 / KPA500 or KPA1500 combo, but not well known.

1. While on 2m, go to the CONFIG:DIGOUT1 menu of the K3, set set DIGOUT1 ON. This drives ACC Pin 11 low when you are on 2m.
2. This setting is per band and per antenna, so make sure DIGOUT1 is set to OFF on all other bands / antennas.
3. Go to the KPA1500 menu TECH MODE and make it ENBALED
4. Go to the KPA1500 menu TX INHIBIT and set it to ENABLED. Pin 11 on the amplifier end is the Inhibit pin.

Per the KPA1500 manual, "When enabled and the INHIBIT line is pulled down, the PA stage is bypassed. The MODE LED will remain in OPER.".

I just tested this an it works perfectly. If DIGOUT1 is ON, and TX INHIBIT ENABLED in the amp., the amp. does not KEY even though it remains in OPER mode. As soon as you set DIGOUT1 OFF (which will happen automatically on other a bands), the amp. is keyed normally. Please try this.

3. On ssb and had TX Test mode selected so as not to TX. When I hit
the paddle the amp goes TX mode and actually put out a little RF on the
LP100 meter. Should not key amp in my thinking.

TX TEST mode has always closed the relay and keying lines even though the rig is putting out no RF. This is a safe way to test your keying relay connections and amp. keying light, and perhaps it also protects the receiver from getting a bunch of internal noise from inside the radio, so that is working as designed. Any RF you see could be caused by some static when the amp relay is keyed, nothing more. The K3 puts out no power when in TX TEST mode, even if you have CW in SSB enabled and tap the key (which you probably did at some point by going to CONFIG: CW WGHT and tapping [1] to enabled it, which is useful in VHF bands it seems. You can disable the feature if you don't want RF to come out or don't want the relay to close while you're in SSB mode and accidentally tap the paddle.

73,

Bob, N6TV

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Wes Stewart-2

Re: Elecraft KPA 1500 thoughts

In reply to this post by Bob Wilson, N6TV

Actually, it does. I reported on this in a message to the reflector titled "TX
Test Mode Garbage" dated 7-25-2017

As a follow up Wayne wrote:

Hi Wes,

TX TEST mode activates the entire TX strip because it turns on PTT to test the keying of downstream devices. This was requested by our original field testers. The only thing that isn’t turned on is the carrier. It could be that in SSB modes there’s noise in the voice passband, producing the result you observed.

I can clarify this in an errata item for the owner’s manual.

It may also be possible for me to disable the TX AF path via a DSP command, and I’ve added that to the firmware task list.

Thanks for the input--

Wayne"

Unfortunately, as I responded, I first observed it in CW mode, and I had at the
time, confirmation from three other guys who observed a similar situation.

Wes N7WS

On 8/26/2019 4:44 PM, Bob Wilson, N6TV wrote:

>
> The K3 puts out no power when
> in TX TEST mode, even if you have CW in SSB enabled and tap the key (which
> you probably did at some point by going to CONFIG: CW WGHT and tapping [1]
> to enabled it, which is useful in VHF bands it seems. You can disable the
> feature if you don't want RF to come out or don't want the relay to close
> while you're in SSB mode and accidentally tap the paddle.
>
> 73,
> Bob, N6TV