Topics

Maximum Aux Cable Length?


K9MA
 

I'm thinking of someday putting the KPA1500 in another room to isolate the fan noise, but I'd like to retain the tight integration with the K3. Is there a maximum length spec for the AUX cable? (In my case, 20-30 feet is enough.)

Note that this is a different issue from the usual remote operation.

73,

Scott K9MA

-- 
Scott  K9MA

k9ma@...


Ken K6MR
 

I’ve never seen a spec, but mine is about 20 feet long.  No problems.  There is nothing speedy on the AuxBus.  1K one direction, 2K going the other way. 

 

Ken K6MR

 

From: K9MA
Sent: Saturday, February 13, 2021 18:46
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] Maximum Aux Cable Length?

 

I'm thinking of someday putting the KPA1500 in another room to isolate the fan noise, but I'd like to retain the tight integration with the K3. Is there a maximum length spec for the AUX cable? (In my case, 20-30 feet is enough.)

Note that this is a different issue from the usual remote operation.

73,

Scott K9MA

-- 
Scott  K9MA
 
k9ma@...

 


Clay Autery
 

Correct Answer:  It depends.

Depends on the hardware used in the communication.
Depends on the communication protocol.
Depends A LOT on the quality and construction of the cable.

FYI, back in the days of flat parallel conductor IDE/EIDE cables, the "spec" was no longer than 18" for IDE and no longer than 24 inches for EIDE.
With a proper design, using CAT-5e cables where every signal line was paired with a twisted pair ground, and the terminations were perfect, etc, etc, et al., I created IDE/EIDE cables well over 50 feet that functioned as well or better than "in spec" cables from the best manufacturers.  Using a much larger wire gauge with pigtails to fit the IDC connectors on each end, and some other design specs to address capacitance issues, et al. We made one that was almost 100 feet that also functioned properly.

Later, I created one of the first successful rounded, shielded HDD cables.... which were immediately ripped off by the Chinese and not too long down the road replaced when IDE/EIDE, et al. went to the technology bone yard.  <smile>

So yes, it IS possible.  Assuming you can find all the parts, use the right design, cable stock, and superior construction skills.
Of course, it may be possible without crazy engineering lengths....  I am not privy to the specs of the AUX circuitry, ICs, et al.
MAIN thing in my book is to make sure whatever creation you wind up with does not become either a receiving or transmitting antenna.

73,

______________________
Clay Autery, KY5G
(318) 518-1389
On 02/13/21 20:46, K9MA wrote:

I'm thinking of someday putting the KPA1500 in another room to isolate the fan noise, but I'd like to retain the tight integration with the K3. Is there a maximum length spec for the AUX cable? (In my case, 20-30 feet is enough.)

Note that this is a different issue from the usual remote operation.

73,

Scott K9MA

-- 
Scott  K9MA

k9ma@...


Keith KV5J
 

Kind of a shameless post but, if your are going to move your KPA1500 away from your operating position.  You might find one of these useful.

https://kv5j.com/store/product/digital-display-unit-for-elecrafts-kpa1500-amplifier-1

Keith


K9MA
 

Thanks, Ken.

73,
Scott K9MA

On 2/13/2021 9:24 PM, Ken K6MR wrote:

I’ve never seen a spec, but mine is about 20 feet long.  No problems.  There is nothing speedy on the AuxBus.  1K one direction, 2K going the other way. 

 

Ken K6MR

 

From: K9MA
Sent: Saturday, February 13, 2021 18:46
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] Maximum Aux Cable Length?

 

I'm thinking of someday putting the KPA1500 in another room to isolate the fan noise, but I'd like to retain the tight integration with the K3. Is there a maximum length spec for the AUX cable? (In my case, 20-30 feet is enough.)

Note that this is a different issue from the usual remote operation.

73,

Scott K9MA

-- 
Scott  K9MA
 
k9ma@...

 


-- 
Scott  K9MA

k9ma@...


Lou Laderman W0FK
 

On Sat, Feb 13, 2021 at 08:46 PM, K9MA wrote:
Is there a maximum length spec for the AUX cable? (In my case, 20-30 feet is enough.)
You shouldn’t have an issue with the AUX cable length Scott. Your bigger issues the DC cable length and gauge. That line carries a lot of current. I used 6 gauge wire to extend my line 8 feet, with 12” 8 gauge ends soldered on so that 75 amp power pole connectors would fit. I don’t know what size you’ll need for an additional 20-30 feet, but I anticipate it will be sizable. The RF deck is very sensitive to low voltages and will go into a default mode if the DC current drops very much.

lou, W0FK 


K9MA
 

Hi Lou,

I would locate the power supply near the RF deck, so DC power cables won't be an issue. It would indeed take a lot of copper to make a 20 foot DC cable!

73,
Scott K9MA

On 2/14/2021 9:22 AM, Lou Laderman W0FK wrote:
On Sat, Feb 13, 2021 at 08:46 PM, K9MA wrote:
Is there a maximum length spec for the AUX cable? (In my case, 20-30 feet is enough.)
You shouldn’t have an issue with the AUX cable length Scott. Your bigger issues the DC cable length and gauge. That line carries a lot of current. I used 6 gauge wire to extend my line 8 feet, with 12” 8 gauge ends soldered on so that 75 amp power pole connectors would fit. I don’t know what size you’ll need for an additional 20-30 feet, but I anticipate it will be sizable. The RF deck is very sensitive to low voltages and will go into a default mode if the DC current drops very much.

lou, W0FK 


-- 
Scott  K9MA

k9ma@...


Tom Schaefer NY4I
 

Wouldn’t it make sense to put the power supply with the KPA1500? I must be missing something.

Tom NY4I

Principal Solutions Architect
Better Software Solutions, Inc.
727-437-2771


Ed Muns, W0YK
 

Yes, but the AUX bus cable goes back the radio.

73,
Ed W0YK


-------- Original message --------
From: Tom Schaefer NY4I <thomasmschaefer@...>
Date: 2/14/21 11:13 (GMT-08:00)
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Maximum Aux Cable Length?

Wouldn’t it make sense to put the power supply with the KPA1500? I must be missing something.

Tom NY4I

Principal Solutions Architect
Better Software Solutions, Inc.
727-437-2771





Tom Schaefer NY4I
 

Indeed. The poster was cautioning about voltage drop from the power supply which I couldn’t imagine why one would separate them. 

You might need to build a 30 foot cable HDE-15 to RJ45 and Ethernet patch cord maybe. It might be hard to find a 30 foot straight through HDE cable. Simple enough to test on the desk. 

Tom NY4I 

Principal Solutions Architect
Better Software Solutions, Inc. 
727-437-2771

On Feb 14, 2021, at 2:16 PM, Ed Muns, W0YK <ed@...> wrote:


Yes, but the AUX bus cable goes back the radio.

73,
Ed W0YK


-------- Original message --------
From: Tom Schaefer NY4I <thomasmschaefer@...>
Date: 2/14/21 11:13 (GMT-08:00)
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] Maximum Aux Cable Length?

Wouldn’t it make sense to put the power supply with the KPA1500? I must be missing something.

Tom NY4I

Principal Solutions Architect
Better Software Solutions, Inc.
727-437-2771





K9MA
 

Of course, the power supply goes by the amp.

The ACC cable has the DB15HD connectors, with all 15 pins connected. The longest ready-made cable I can find that I would trust is 10 feet from Winford. Another vendor has longer ones, with all pins connected, but with a combination of coax and twisted pairs, and apparently no overall shield. In any case, it's not a big deal to make a cable. However, the Winford cables are cheap enough to string 2 or 3 together.

Even 20 feet is too far for a USB cable, so amp control would have to be via Ethernet.  I think that's just a matter of installing the software and setting up IP addresses, etc.

73,
Scott K9MA



On 2/14/2021 1:19 PM, Tom Schaefer NY4I wrote:
Indeed. The poster was cautioning about voltage drop from the power supply which I couldn’t imagine why one would separate them. 

You might need to build a 30 foot cable HDE-15 to RJ45 and Ethernet patch cord maybe. It might be hard to find a 30 foot straight through HDE cable. Simple enough to test on the desk. 

Tom NY4I 

Principal Solutions Architect
Better Software Solutions, Inc. 
727-437-2771

On Feb 14, 2021, at 2:16 PM, Ed Muns, W0YK <ed@...> wrote:


Yes, but the AUX bus cable goes back the radio.

73,
Ed W0YK


-------- Original message --------
From: Tom Schaefer NY4I <thomasmschaefer@...>
Date: 2/14/21 11:13 (GMT-08:00)
Subject: Re: [Elecraft-K3] Maximum Aux Cable Length?

Wouldn’t it make sense to put the power supply with the KPA1500? I must be missing something.

Tom NY4I

Principal Solutions Architect
Better Software Solutions, Inc.
727-437-2771





-- 
Scott  K9MA

k9ma@...


N2TK, Tony
 

Hi Scott,

I have both the KPA-500 and KPA-1500 mounted on a shelf in the basement. They are literary beneath my feet when operating.

The AUX cable is about 15’ long. I use a N6TV interface box. I can’t remember where I bought the cable that works between the amp and Y-Box. But for sure it is not a VGA monitor cable.

I use the “KPA1500 Remote by Elecraft” program to operate the amp. All works very well.

GL

N2TK, Tony

 

From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of K9MA
Sent: Saturday, February 13, 2021 9:47 PM
To: elecraft-K3@groups.io
Subject: [Elecraft-K3] Maximum Aux Cable Length?

 

I'm thinking of someday putting the KPA1500 in another room to isolate the fan noise, but I'd like to retain the tight integration with the K3. Is there a maximum length spec for the AUX cable? (In my case, 20-30 feet is enough.)

Note that this is a different issue from the usual remote operation.

73,

Scott K9MA

-- 
Scott  K9MA
 
k9ma@...


K9MA
 

Hi Tony,

Well, that's one way to cut down on the fan noise! Unfortunately, my shack is already in the basement, and I don't think putting the amplifier above my head in the dining room would be popular with my YL. Out by the water heater would be OK, though, as long as I can find another place for all the stuff on the shelf.

73,
Scott K9MA

On 2/14/2021 5:36 PM, N2TK, Tony via groups.io wrote:

Hi Scott,

I have both the KPA-500 and KPA-1500 mounted on a shelf in the basement. They are literary beneath my feet when operating.

The AUX cable is about 15’ long. I use a N6TV interface box. I can’t remember where I bought the cable that works between the amp and Y-Box. But for sure it is not a VGA monitor cable.

I use the “KPA1500 Remote by Elecraft” program to operate the amp. All works very well.

GL

N2TK, Tony

 

From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of K9MA
Sent: Saturday, February 13, 2021 9:47 PM
To: elecraft-K3@groups.io
Subject: [Elecraft-K3] Maximum Aux Cable Length?

 

I'm thinking of someday putting the KPA1500 in another room to isolate the fan noise, but I'd like to retain the tight integration with the K3. Is there a maximum length spec for the AUX cable? (In my case, 20-30 feet is enough.)

Note that this is a different issue from the usual remote operation.

73,

Scott K9MA

-- 
Scott  K9MA
 
k9ma@...


-- 
Scott  K9MA

k9ma@...


Bob Wilson, N6TV
 

On Sun, Feb 14, 2021 at 12:44 PM K9MA <K9ma@...> wrote:
The ACC cable has the DB15HD connectors, with all 15 pins connected.

Careful!  Never connect a cable with all 15 pins wired between a K3, K3S, or K4 to a KPA500 or KPA1500, unless that cable is used as a M/F series extension to lengthen an existing Elecraft KPAK3AUX cable, or instead, connected directly to a Y-BOX AMP AUX port.  The AUX cable must have no electrical connection between K3 ACC and KPA1500 AUX on Pins 1, 4, 6, 7, and 8, which is how the Elecraft KPAK3AUX cable (P/N E850463) is wired.

I open these pins inside the Y-BOX, so that any straight 15-pin cable works the same as an AUX cable.  A VGA monitor cable will never work and must never be used because they usually have pins shorted together to a common ground, or Pin 9 is missing.

I supplied a 25' Amphenol® 15-pin cable to WD6DBM with his Y-BOX, but I don't know if he ever had a chance to test it with his KPA1500 AUX port.  I believe this length will work fine using that high quality shielded cable.  

One advantage of using the Y-BOX + 15-pin cable vs. the Elecraft KPAK3AUX cable is that there's a shunt jumper inside the Y-BOX (v2 and later) that can connect K3 ACC Pin 11 (DIGOUT1) to AMP AUX Pin 8 (KPA500 or KPA1500 PWR ON).  Then you can remotely power the a KPA500 or KPA1500 ON or OFF with a K3 macro button, and no KPA1500 control software is required (see here for the details).  Of course, you may also need a long Ethernet, USB or Serial cable if you want to display the KPA1500 power meters on a PC in the shack and run the software.  Another option is to locate an old laptop near the RF Deck to provide metering, then use KPA1500 Remote Software to view the meters in your shack, using your home LAN or WiFi connections.
  
The longest ready-made cable I can find that I would trust is 10 feet from Winford. Another vendor has longer ones, with all pins connected, but with a combination of coax and twisted pairs, and apparently no overall shield. In any case, it's not a big deal to make a cable. However, the Winford cables are cheap enough to string 2 or 3 together.

It is a big deal to make a reliable 15-pin cable with 10 or 11 pins wired.  It's very easy to make a mistake soldering those high-density, 3-row D-SUB connectors.  How much time do you want to spend doing that?

I'd recommend using a commercial molded cable with thumbscrews and full shielding, especially for a 25-ft run, unless minimum cost is more important than time spent, including time spent adding ferrites or debugging crossed wires or shorted connections.

Even 20 feet is too far for a USB cable, so amp control would have to be via Ethernet.  I think that's just a matter of installing the software and setting up IP addresses, etc.

Yes, but I strongly recommend using a shielded twisted pair (STP) Ethernet cable, or a long serial cable.  The KPA1500's Ethernet connector operates at 100 Mbps max, a speed that generates loud carriers around 14.030 MHz, especially when using unshielded twisted pair (UTP) Ethernet cables, the most common type.  Shielded Ethernet cables have metal on three sides of both RJ-45 connectors.  No metal = no shielding, and 14.030 MHz RFI is almost guaranteed on any 100 Mbps connection if you use such cables.  The K4 provides a 1 Gbps Ethernet connector, which generates far less RFI, but the K4 will have the same Ethernet RFI problem if you connect it to a 100 Mbps switch or to a 100 Mbps Router port with an unshielded Ethernet cable.

Another fix for unshielded cables at 100 Mbps is the DX Engineering ISO-PLUS Ethernet EMI Filters.  These work much better than unshielded Ethernet cable wrapped around Mix 31 ferrite cores, in my experience.

73,
Bob, N6TV


Jim Brown
 

On 2/14/2021 12:44 PM, K9MA wrote:
The longest ready-made cable I can find that I would trust is 10 feet from Winford. Another vendor has longer ones, with all pins connected, but with a combination of coax and twisted pairs, and apparently no overall shield. In any case, it's not a big deal to make a cable. However, the Winford cables are cheap enough to string 2 or 3 together.
Quality DB15 connectors are available, soldering a 15-conductor cable to them is not all that difficult. It does require something on the bench to hold the connector while soldering to it and a decent iron.

It IS, however, important to buy quality connector inserts (the housings with the contacts you solder to and the part of the connector that plugs into the one mounted on the equipment. The connector housings are not all that critical, except that a good strain relief is important.

73, Jim K9YC


K9MA
 

I did not know about the unconnected pins. Though I can see why, based on the K3 schematic, I don't know why they weren't just left open at the KPA500/1500 end. RFI perhaps? Or maybe, with a long cable, capacitive loading on those lines might cause problems.

The shielded Amphenol cable is available from DigiKey up to 25 feet. A bit cheaper from Amazon, but I wonder of those are counterfeit copies.

73,
Scott K9MA


On 2/14/2021 6:33 PM, Bob Wilson, N6TV wrote:
On Sun, Feb 14, 2021 at 12:44 PM K9MA <K9ma@...> wrote:
The ACC cable has the DB15HD connectors, with all 15 pins connected.

Careful!  Never connect a cable with all 15 pins wired between a K3, K3S, or K4 to a KPA500 or KPA1500, unless that cable is used as a M/F series extension to lengthen an existing Elecraft KPAK3AUX cable, or instead, connected directly to a Y-BOX AMP AUX port.  The AUX cable must have no electrical connection between K3 ACC and KPA1500 AUX on Pins 1, 4, 6, 7, and 8, which is how the Elecraft KPAK3AUX cable (P/N E850463) is wired.

I open these pins inside the Y-BOX, so that any straight 15-pin cable works the same as an AUX cable.  A VGA monitor cable will never work and must never be used because they usually have pins shorted together to a common ground, or Pin 9 is missing.

I supplied a 25' Amphenol® 15-pin cable to WD6DBM with his Y-BOX, but I don't know if he ever had a chance to test it with his KPA1500 AUX port.  I believe this length will work fine using that high quality shielded cable.  

One advantage of using the Y-BOX + 15-pin cable vs. the Elecraft KPAK3AUX cable is that there's a shunt jumper inside the Y-BOX (v2 and later) that can connect K3 ACC Pin 11 (DIGOUT1) to AMP AUX Pin 8 (KPA500 or KPA1500 PWR ON).  Then you can remotely power the a KPA500 or KPA1500 ON or OFF with a K3 macro button, and no KPA1500 control software is required (see here for the details).  Of course, you may also need a long Ethernet, USB or Serial cable if you want to display the KPA1500 power meters on a PC in the shack and run the software.  Another option is to locate an old laptop near the RF Deck to provide metering, then use KPA1500 Remote Software to view the meters in your shack, using your home LAN or WiFi connections.
  
The longest ready-made cable I can find that I would trust is 10 feet from Winford. Another vendor has longer ones, with all pins connected, but with a combination of coax and twisted pairs, and apparently no overall shield. In any case, it's not a big deal to make a cable. However, the Winford cables are cheap enough to string 2 or 3 together.

It is a big deal to make a reliable 15-pin cable with 10 or 11 pins wired.  It's very easy to make a mistake soldering those high-density, 3-row D-SUB connectors.  How much time do you want to spend doing that?

I'd recommend using a commercial molded cable with thumbscrews and full shielding, especially for a 25-ft run, unless minimum cost is more important than time spent, including time spent adding ferrites or debugging crossed wires or shorted connections.

Even 20 feet is too far for a USB cable, so amp control would have to be via Ethernet.  I think that's just a matter of installing the software and setting up IP addresses, etc.

Yes, but I strongly recommend using a shielded twisted pair (STP) Ethernet cable, or a long serial cable.  The KPA1500's Ethernet connector operates at 100 Mbps max, a speed that generates loud carriers around 14.030 MHz, especially when using unshielded twisted pair (UTP) Ethernet cables, the most common type.  Shielded Ethernet cables have metal on three sides of both RJ-45 connectors.  No metal = no shielding, and 14.030 MHz RFI is almost guaranteed on any 100 Mbps connection if you use such cables.  The K4 provides a 1 Gbps Ethernet connector, which generates far less RFI, but the K4 will have the same Ethernet RFI problem if you connect it to a 100 Mbps switch or to a 100 Mbps Router port with an unshielded Ethernet cable.

Another fix for unshielded cables at 100 Mbps is the DX Engineering ISO-PLUS Ethernet EMI Filters.  These work much better than unshielded Ethernet cable wrapped around Mix 31 ferrite cores, in my experience.

73,
Bob, N6TV


-- 
Scott  K9MA

k9ma@...


Bob Wilson, N6TV
 

In the KPA500 & KPA1500 AUX connectors (well documented in the amplifier manuals), Pins 1 and 6 are used for Icom Band Data via legacy Icom Band Voltage, Pin 7 is "ALARM OUT  - Must NOT be connected to K3s/K3", and only Pin 4 is unused.  Pin 11 can be used as an amplifier Inhibit line when enabled in the amplifier menu, but that's DIGOUT1 in the K3 ACC so it would need software coordination to be used for that.

73,
Bob, N6TV


On Mon, Feb 15, 2021 at 10:06 AM K9MA <k9ma@...> wrote:
I did not know about the unconnected pins. Though I can see why, based on the K3 schematic, I don't know why they weren't just left open at the KPA500/1500 end. RFI perhaps? Or maybe, with a long cable, capacitive loading on those lines might cause problems.

The shielded Amphenol cable is available from DigiKey up to 25 feet. A bit cheaper from Amazon, but I wonder of those are counterfeit copies.

73,
Scott K9MA


On 2/14/2021 6:33 PM, Bob Wilson, N6TV wrote:
On Sun, Feb 14, 2021 at 12:44 PM K9MA <K9ma@...> wrote:
The ACC cable has the DB15HD connectors, with all 15 pins connected.

Careful!  Never connect a cable with all 15 pins wired between a K3, K3S, or K4 to a KPA500 or KPA1500, unless that cable is used as a M/F series extension to lengthen an existing Elecraft KPAK3AUX cable, or instead, connected directly to a Y-BOX AMP AUX port.  The AUX cable must have no electrical connection between K3 ACC and KPA1500 AUX on Pins 1, 4, 6, 7, and 8, which is how the Elecraft KPAK3AUX cable (P/N E850463) is wired.

I open these pins inside the Y-BOX, so that any straight 15-pin cable works the same as an AUX cable.  A VGA monitor cable will never work and must never be used because they usually have pins shorted together to a common ground, or Pin 9 is missing.

I supplied a 25' Amphenol® 15-pin cable to WD6DBM with his Y-BOX, but I don't know if he ever had a chance to test it with his KPA1500 AUX port.  I believe this length will work fine using that high quality shielded cable.  

One advantage of using the Y-BOX + 15-pin cable vs. the Elecraft KPAK3AUX cable is that there's a shunt jumper inside the Y-BOX (v2 and later) that can connect K3 ACC Pin 11 (DIGOUT1) to AMP AUX Pin 8 (KPA500 or KPA1500 PWR ON).  Then you can remotely power the a KPA500 or KPA1500 ON or OFF with a K3 macro button, and no KPA1500 control software is required (see here for the details).  Of course, you may also need a long Ethernet, USB or Serial cable if you want to display the KPA1500 power meters on a PC in the shack and run the software.  Another option is to locate an old laptop near the RF Deck to provide metering, then use KPA1500 Remote Software to view the meters in your shack, using your home LAN or WiFi connections.
  
The longest ready-made cable I can find that I would trust is 10 feet from Winford. Another vendor has longer ones, with all pins connected, but with a combination of coax and twisted pairs, and apparently no overall shield. In any case, it's not a big deal to make a cable. However, the Winford cables are cheap enough to string 2 or 3 together.

It is a big deal to make a reliable 15-pin cable with 10 or 11 pins wired.  It's very easy to make a mistake soldering those high-density, 3-row D-SUB connectors.  How much time do you want to spend doing that?

I'd recommend using a commercial molded cable with thumbscrews and full shielding, especially for a 25-ft run, unless minimum cost is more important than time spent, including time spent adding ferrites or debugging crossed wires or shorted connections.

Even 20 feet is too far for a USB cable, so amp control would have to be via Ethernet.  I think that's just a matter of installing the software and setting up IP addresses, etc.

Yes, but I strongly recommend using a shielded twisted pair (STP) Ethernet cable, or a long serial cable.  The KPA1500's Ethernet connector operates at 100 Mbps max, a speed that generates loud carriers around 14.030 MHz, especially when using unshielded twisted pair (UTP) Ethernet cables, the most common type.  Shielded Ethernet cables have metal on three sides of both RJ-45 connectors.  No metal = no shielding, and 14.030 MHz RFI is almost guaranteed on any 100 Mbps connection if you use such cables.  The K4 provides a 1 Gbps Ethernet connector, which generates far less RFI, but the K4 will have the same Ethernet RFI problem if you connect it to a 100 Mbps switch or to a 100 Mbps Router port with an unshielded Ethernet cable.

Another fix for unshielded cables at 100 Mbps is the DX Engineering ISO-PLUS Ethernet EMI Filters.  These work much better than unshielded Ethernet cable wrapped around Mix 31 ferrite cores, in my experience.

73,
Bob, N6TV


-- 
Scott  K9MA

k9ma@...


K9MA
 

Thanks, Bob. I didn't think to look at the amplifier manuals. That all makes perfect sense, as the K3 uses those pins for other functions, and connecting them to the amplifier would make a mess of things.

73,
Scott K9MA


On 2/15/2021 12:17 PM, Bob Wilson, N6TV wrote:
In the KPA500 & KPA1500 AUX connectors (well documented in the amplifier manuals), Pins 1 and 6 are used for Icom Band Data via legacy Icom Band Voltage, Pin 7 is "ALARM OUT  - Must NOT be connected to K3s/K3", and only Pin 4 is unused.  Pin 11 can be used as an amplifier Inhibit line when enabled in the amplifier menu, but that's DIGOUT1 in the K3 ACC so it would need software coordination to be used for that.

73,
Bob, N6TV


On Mon, Feb 15, 2021 at 10:06 AM K9MA <k9ma@...> wrote:
I did not know about the unconnected pins. Though I can see why, based on the K3 schematic, I don't know why they weren't just left open at the KPA500/1500 end. RFI perhaps? Or maybe, with a long cable, capacitive loading on those lines might cause problems.

The shielded Amphenol cable is available from DigiKey up to 25 feet. A bit cheaper from Amazon, but I wonder of those are counterfeit copies.

73,
Scott K9MA


On 2/14/2021 6:33 PM, Bob Wilson, N6TV wrote:
On Sun, Feb 14, 2021 at 12:44 PM K9MA <K9ma@...> wrote:
The ACC cable has the DB15HD connectors, with all 15 pins connected.

Careful!  Never connect a cable with all 15 pins wired between a K3, K3S, or K4 to a KPA500 or KPA1500, unless that cable is used as a M/F series extension to lengthen an existing Elecraft KPAK3AUX cable, or instead, connected directly to a Y-BOX AMP AUX port.  The AUX cable must have no electrical connection between K3 ACC and KPA1500 AUX on Pins 1, 4, 6, 7, and 8, which is how the Elecraft KPAK3AUX cable (P/N E850463) is wired.

I open these pins inside the Y-BOX, so that any straight 15-pin cable works the same as an AUX cable.  A VGA monitor cable will never work and must never be used because they usually have pins shorted together to a common ground, or Pin 9 is missing.

I supplied a 25' Amphenol® 15-pin cable to WD6DBM with his Y-BOX, but I don't know if he ever had a chance to test it with his KPA1500 AUX port.  I believe this length will work fine using that high quality shielded cable.  

One advantage of using the Y-BOX + 15-pin cable vs. the Elecraft KPAK3AUX cable is that there's a shunt jumper inside the Y-BOX (v2 and later) that can connect K3 ACC Pin 11 (DIGOUT1) to AMP AUX Pin 8 (KPA500 or KPA1500 PWR ON).  Then you can remotely power the a KPA500 or KPA1500 ON or OFF with a K3 macro button, and no KPA1500 control software is required (see here for the details).  Of course, you may also need a long Ethernet, USB or Serial cable if you want to display the KPA1500 power meters on a PC in the shack and run the software.  Another option is to locate an old laptop near the RF Deck to provide metering, then use KPA1500 Remote Software to view the meters in your shack, using your home LAN or WiFi connections.
  
The longest ready-made cable I can find that I would trust is 10 feet from Winford. Another vendor has longer ones, with all pins connected, but with a combination of coax and twisted pairs, and apparently no overall shield. In any case, it's not a big deal to make a cable. However, the Winford cables are cheap enough to string 2 or 3 together.

It is a big deal to make a reliable 15-pin cable with 10 or 11 pins wired.  It's very easy to make a mistake soldering those high-density, 3-row D-SUB connectors.  How much time do you want to spend doing that?

I'd recommend using a commercial molded cable with thumbscrews and full shielding, especially for a 25-ft run, unless minimum cost is more important than time spent, including time spent adding ferrites or debugging crossed wires or shorted connections.

Even 20 feet is too far for a USB cable, so amp control would have to be via Ethernet.  I think that's just a matter of installing the software and setting up IP addresses, etc.

Yes, but I strongly recommend using a shielded twisted pair (STP) Ethernet cable, or a long serial cable.  The KPA1500's Ethernet connector operates at 100 Mbps max, a speed that generates loud carriers around 14.030 MHz, especially when using unshielded twisted pair (UTP) Ethernet cables, the most common type.  Shielded Ethernet cables have metal on three sides of both RJ-45 connectors.  No metal = no shielding, and 14.030 MHz RFI is almost guaranteed on any 100 Mbps connection if you use such cables.  The K4 provides a 1 Gbps Ethernet connector, which generates far less RFI, but the K4 will have the same Ethernet RFI problem if you connect it to a 100 Mbps switch or to a 100 Mbps Router port with an unshielded Ethernet cable.

Another fix for unshielded cables at 100 Mbps is the DX Engineering ISO-PLUS Ethernet EMI Filters.  These work much better than unshielded Ethernet cable wrapped around Mix 31 ferrite cores, in my experience.

73,
Bob, N6TV


-- 
Scott  K9MA

k9ma@...


-- 
Scott  K9MA

k9ma@...


wb6bee
 

I moved my KPA 1500 into a tall crawl space under my shack.   It is dry and cool.    The fan noise becomes a non-existent problem.     I got a 15 pin extension cable off Amazon for the K3s control.    Combined length of the original Elecraft cable and the extension is about 20 feet.    I ran a 25 ft USB cable down for control from the Computer.    I also ran an ethernet cable to the Wifi Router that is also located in the crawl space.   My RBN skimmer hardware is down there.

I have utilized several programs for control of the amp.   You can use the Utility through the ethernet or the USB.    Elecraft also has a slick remote control program that can be used.   Win4K3 has a very nice set up for monitoring and managing the KPA 1500 in a remote location.  He recently added fan control and monitoring so you can monitor what the fans are doing.   .    Recently, I have been using Fanticipator  for control.   That program has some fan control functions built it.

A big issue with a remote location is knowing when the amp is on or off.    The default antenna connector is Ant 1.   When the amp is off, Ant 1 feeds through.   I connected my Dummy Load to Ant 1.   I connected my antenna lead to Antenna 2.   The result is when the amp is on, you will hear noise in the receiver.  When the amp is off, you won't hear anything.   The amp remembers to use Ant 2 when on.  You can manually switch to Ant 1 for the dummy load for a test if you desire.  This configuration provides an "audible" double check on the amp being off.    Both the Elecraft control programs and Win4k3 have an On/Off switch.   Fanticipator is ethernet only and has a wake on LAN and off when closing Fanticipator.   Win4k3 will automatically shut off the amp when you close the Win4k3 program.    Regardless of all these mechanisms, the Ant1/ Ant 2 configuration has proved invaluable to confirm the amp is actually off.   

You won't regret moving the amp to an isolated location.  Best thing I ever did.

Don
WB6BEE