Expert AMP interface cable Hardware

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  • Updated 9 months ago
I'm hearing tell of hooking the amp via the RS 232 portion of the DB 15 connectors provided
by SPE, then to a USB to serial adapter that plugs into the USB port of the Flex. This appears to suggest a breakout connector for adding connections to the RS232 part of the connection? No one is talking about the hardware needed to do this or suggestions in that regard.. Who has done this. A diagram would be great.. please...Thanks

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Barry Isseks

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Posted 9 months ago

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Lawrence Kellar KB5ZZB

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KC5PCB makes these cables. Look him up. He might even tell you his “secrets”
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Barry Isseks

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Thanks, yes indeed, ... but I need to understand the method of this madness rather then just buying a solution...
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Mark - WS7M

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It is just a straight USB-RS232 adapter and cable to the SPE.  No magic.  You plug it in.  Set SPE to be 9600 baud, Flex Radio.  Set Flex Radio to have USB cable follow TX slice, 9600 baud and it just works.  There are however here in this forum some recommended known to work USB-Serial adapters.

Your amp will follow your radio frequency wise.  It will also when online limit your drive as fer the PC settings in the SPE amp.  Read up in the amp on PC where is where you can set the percent of drive to use on each band.

What does not work and there is no provision for is using SSDR to take amp online and offline.  You need to do that either using the SPE software or a solution like I have created with a custom software that can control the amp.
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Mike Presnell

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Mark,   how did you determine what PC settings?  I just didn't understand, after reading through the Expert manual.    Also,  did you put in a TX delay in your Flex?
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KY6LA - Howard, Elmer

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I have been using DDUTIL for years to control my SPE 2k_FA  - Following the SPE Cable Interface Instructions from SPE.. they work

Correct Cable

DB- 9 F   <-------------------------------->   DB-15M

Pin 2   RX232 <--------------------------  Pin 9 TX 232

Pin 3   TX 232  -------------------------> Pin 1 RX232

Pin 5   GND  <---------------------------> Pin 4  GND

The real advantage of DDUTIL over the totally inadequate Flex Solution is that you can

1.  Turn your Amp On

2.   Turn your Amp Off

3.   Go from Standby to Operate and vice versa

4.  Control Power, Antenna, etc

See the screen shot

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Mike Presnell

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Howard ,  have you been manually controlling the power out of your Expert amp, by manually adjusting your power out of the Flex? I am just really slow to understand the Low-Mid-High preset business with this Expert per their manual.   I had been using an Alpha 9500, and just simply used the power slider of my Flex to determine my amplified power level.
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Rick - N4RZ

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Dan's cable and the SPE Term_2k_232 program can give you complete control over the amp without using DDUTIL. 

From the Term_2k_232 program or from the front of the amp you can set the drive power on the Flex when the amp is in operate mode. You can set the radio drive power for each of the amps three power output levels (Low/Mid/Max) on each band you use.  Note: the maximum power your radio will transmit should be set in excess of the largest drive power you require for the amp.  I have mine set to 50 watts.  When the amp is in standby, the power output from the radio will revert to this value.

Dan's cable also provides amp relay keying and turns the amp on/off when the radio powers on/off using the Flex accessory connector.   With the 2K-FA, the amp needs to be on even if you are not using it unless all of your antennas are connected to the amp's Ant  1 port since the amp's antenna defaults to this port when it is turned off.

While I was lazy and bought a ready-made cable you can build your own using the manuals for the radio and the amp as other's have already indicated above.    
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GOOGLE is your friend.
Took me 5 seconds to find this Manual just for the asking on google. 

You can buy a USB to Serial RS-232 cable or a USB to BIT cable for BCD control.
The only cables that will work are the REAL FTDI chip set cables and NOT the clone when connected to the signature 6xxx series Radio's USB ports.

Hope your info is in it this manual and good luck.


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NC4AB - Andy

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Ria (N2RJ) had an excellent step by step explanation of how to hook the SPE Expert to the Flex 6500 using the USB off the Flex and the DB-15 connector on the Expert but the link that I had book marked is now dead.  Maybe someone else has the info that she had posted.  All that is required is a USB to RS 232 converter cable and wiring it to the DB 15 plug.

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Barry Isseks

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Hi again... comments like “it’s just a straight usb to serial.. plug it in to the Expert” is not helpful. The usb to serial is a 9 pin connector.. the Expert CAT port is db15.... A bit more hardware granularity is requested in this post gentlemen. I know you can do it...Ria’s Site might have held the answers.. alas.
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Mark Erbaugh

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Howard's pinout is all you need to go from the SPE DB15 to a 9 pin serial port. To connect that DB9 pin serial port to the Flex USB port, you need a FTDI based USB to serial port adapter. That's all there is to have the Flex control the SPE amp. You will also have to connect a phono plug cable from one of the TX# connectors on the Flex to the Relay connector on the amp to control TX/RX and of course the RF.

I use that setup with my Flex 6700 and SPE 2K-FA. I use the SPE Term program on my PC which is connected via a USB cable to control the front panel settings on the amp.
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Rick Hadley - W0FG

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Or you can use FRStacks to control the front panel of the SPE and dispense with SPE Term.