KPA1500 connections to Flex 6500?

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  • Updated 3 months ago
What is the best way to connect he KPA1500 to the Flex6500. Would like the Flex to control the amp as much as possible. And what can be controled.
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Bill -VA3WTB

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Posted 5 months ago

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Craig - KØCF

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You need this cable:
  Item       : KAT500 USB Serial Cable
  SKU        : KXUSBa
  Item Price : $32.95
From Elecraft. This plugs into one of the USB connectors on the back of the Flex and goes to the "XCVR Serial" connector on the back of the KPA1500.You will then have to go into the menu on the KPA1500 and select Radio Type as "Serial" and set up baud rates, etc. on both the KPA1500 and the Flex USB port menus.The KPA1500 will then follow the radio, even setting the tuner for whatever band segment you are on, for instantaneous band switching and transmit with no waiting for re-tuning. It is truly like having a 1500-watt transceiver!You may also wish to set up transmit profiles, setting the power output on each band for proper drive to the amp. I have both low- and high-power profiles for 1500-watt and 700-watt output power. You could also do a "barefoot" transmit profile that would disable TX1 and set full power on the Flex.This is a great combo!73,
Craig, KØCF
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Craig - KØCF

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I should  have also mentioned that you need an RCA-RCA cable to connect from TX1 on the Flex to the "Key In" connector on the KPA1500. Don't use ALC!
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Roger J. Buffington

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Why no ALC, out of idle curiosity?
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Craig - KØCF

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ALC should be considered a safety feature only. Using ALC to control your amp's output will result in wide signals. Flex has always recommended NOT using it, as does Elecraft. You should set your transceiver output power to produce the correct power output from the amplifier. This requires a different power setting for each band because most amps do not have flat gain across a wide frequency range. I dare say most of the broad signals that you can see so easily with a Flex-6000 receiver are due to using ALC to control the amp output.
73,
Craig, KØCF
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KENT HUFFORD

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Have a KPA1500 coming next week for my FLEX6600. Currently the FLEX6600 is connected via Ddutil to a KPA500.

I have one USB port on a DV3000 stick, and the other USB port on a cable to my STEPIR control box. 

Will the FLEX work with a USB hub, and more than two USB ports? 

DDUTIL currently does not have a menu option for KPA1500

Thanks,
KEnt
KQ4KK
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Craig - KØCF

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Yes, a USB hub will work -- Flex even recommends using one!The direct CAT connection from the 6500 to the KPA1500 is the way to go. Use the
Elecraft cable mentioned in my reply above. Using profiles to set the 6500 power level by band completely eliminates the need for DDUtil.
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Rich - N5ZC

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Ditto what Craig, K0CF, says.  Works for me.  The KPA-1500 follows right along with the 6600.  No need for external software for control.

Don't forget to set up a profile after you have set all the power levels in the 6600.  I have several profiles.  For example I have the following:
Amp on - which remembers all of the power settings to drive the amp to 1500 watts, Amp off - I have the power level on each band set to 80 watts out, QRP - I have the power level set to 5 watts for each band.  And several others depending what I'm doing with rig at the time.
Rich - N5ZC
(Edited)
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KENT HUFFORD

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Once I got it pugged into the A/C. (AC power cable much shorter than the one on my PW1) it took me 5 min. to get the KPA1500 to track the 6600. Plugged in the KXUSB cable to a small USB hub. Also on the hub is a cable to my STEPir. Plugged in the key line, and the rf. Changed the KPA1500 to SERIAL. Set the 6600 usb port to 38,400 AND clicked on AUTO REPORT, everything tracked. 

On 20m, 1500 watts out with 30 watts DSTAR. Works just like my great 2 year old KPA500/KTA500, but at 1500 watts.  thanks to all.
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Charles - K5UA

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I don't see an "XCVR Serial Port on the back of the KPA-1500.  In addition, the optional "KXUSB Serial Cable for KX2 or KX3"  is specified by Elecraft for Enhanced control of the KPA-1500 when used with a KX2 or KX3.  The KPA-1500 ships with a USB A-B cable for BASIC operation with the Flex transceivers.  Is this included USB A-B cable the one that is being used from the Flex USB-A port to the KPA-1500 USB-B port?
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Craig - KØCF

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In early prototypes, the "XCVR Serial" port was labeled "PC Data". The KXUSB cable is the correct one to connect the Flex to the KPA1500 for complete control of band switching and tuner. I have and am using the KPA1500 (serial # 99) with the Flex 6500, and this setup is what works.

Before I got the KPA1500, I talked to Elecraft support and the KXUSB cable is exactly what they recommend for control from the Flex. It is an FTDI USB to serial cable with a 3.5mm plug on the amplifier end.
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Craig - KØCF

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The USB A-B cable can be used to connect the KPA1500 to your PC for use with the KPA1500 Utility program, and for updating the firmware. Both cables can be connected to the amplifier at once.
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Charles - K5UA

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Ah ha!  What a difference an updated manual can make.  I guess I was using the old manual.  The new manual revision B clearly shows the optional Flex cable.  As SNL's Rosanne-Rosanna Dannah would say......"Never mind".