Topics

KPA1500 Output Power

Jeff Clarke
 

My friend K4BAI bought a KPA1500 around August of last year. It's been humming along and working great for him until last week. He was able to get full legal limit driving it with 30 watts from his Kenwood TS590SG. All of a sudden he's only getting only about 700 watts out with the same drive power. The most power he is able to get out is 1100 watts with about 60 watts of drive. Above that drive power the overdrive light will come on. He contacted Elecraft support and they want him to send the configuration file to them. I went over his house the other night and we were going to check it out. We couldn't find the cable to connect the computer to the amp. It turns out he left it in the box and his wife accidentally threw the boxes away. So he's going to have to order the cable so we can download the configuration file to send to Elecraft.

One concern I have is that for 160 meters he shorts the coax for his 80 meter antenna thru an antenna tuner to use it on that band. My guess is there has to be lots of RF floating around his shack with the feed point of that antenna being inside his shack.  We did install a decent ground last year when he bought the amp. Maybe that RF has damaged some electronic circuitry in his amp? I own a KPA500 and I was having some issues with my 80 meter zepp dipole making the amp act funny. When I moved the tuner and feed line far away from the amp it appeared to resolve the issue.

I was wondering if anyone else has ever had this problem? Also, will just reloading the configuration file maybe fix this? 

Thanks, Jeff  KU8E

Ed Muns, W0YK
 

The PC to KPA1500 cable is a standard USB A-B cable readily available.   You and John most likely each have them in your home somewhere.  If not, they're widely available, even in grocery and convenience stores.

73,
Ed W0YK


-------- Original message --------
From: Jeff Clarke <ku8e@...>
Date: 2/29/20 09:17 (GMT-08:00)
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] KPA1500 Output Power

My friend K4BAI bought a KPA1500 around August of last year. It's been humming along and working great for him until last week. He was able to get full legal limit driving it with 30 watts from his Kenwood TS590SG. All of a sudden he's only getting only about 700 watts out with the same drive power. The most power he is able to get out is 1100 watts with about 60 watts of drive. Above that drive power the overdrive light will come on. He contacted Elecraft support and they want him to send the configuration file to them. I went over his house the other night and we were going to check it out. We couldn't find the cable to connect the computer to the amp. It turns out he left it in the box and his wife accidentally threw the boxes away. So he's going to have to order the cable so we can download the configuration file to send to Elecraft.

One concern I have is that for 160 meters he shorts the coax for his 80 meter antenna thru an antenna tuner to use it on that band. My guess is there has to be lots of RF floating around his shack with the feed point of that antenna being inside his shack.  We did install a decent ground last year when he bought the amp. Maybe that RF has damaged some electronic circuitry in his amp? I own a KPA500 and I was having some issues with my 80 meter zepp dipole making the amp act funny. When I moved the tuner and feed line far away from the amp it appeared to resolve the issue.

I was wondering if anyone else has ever had this problem? Also, will just reloading the configuration file maybe fix this? 

Thanks, Jeff  KU8E

Everett N4CY
 

The cable is know as a USB printer cable. 

Everett N4CY

On Feb 29, 2020, at 11:35 AM, Ed Muns, W0YK <ed@...> wrote:


The PC to KPA1500 cable is a standard USB A-B cable readily available.   You and John most likely each have them in your home somewhere.  If not, they're widely available, even in grocery and convenience stores.

73,
Ed W0YK


-------- Original message --------
From: Jeff Clarke <ku8e@...>
Date: 2/29/20 09:17 (GMT-08:00)
To: Elecraft-K3@groups.io
Subject: [Elecraft-K3] KPA1500 Output Power

My friend K4BAI bought a KPA1500 around August of last year. It's been humming along and working great for him until last week. He was able to get full legal limit driving it with 30 watts from his Kenwood TS590SG. All of a sudden he's only getting only about 700 watts out with the same drive power. The most power he is able to get out is 1100 watts with about 60 watts of drive. Above that drive power the overdrive light will come on. He contacted Elecraft support and they want him to send the configuration file to them. I went over his house the other night and we were going to check it out. We couldn't find the cable to connect the computer to the amp. It turns out he left it in the box and his wife accidentally threw the boxes away. So he's going to have to order the cable so we can download the configuration file to send to Elecraft.

One concern I have is that for 160 meters he shorts the coax for his 80 meter antenna thru an antenna tuner to use it on that band. My guess is there has to be lots of RF floating around his shack with the feed point of that antenna being inside his shack.  We did install a decent ground last year when he bought the amp. Maybe that RF has damaged some electronic circuitry in his amp? I own a KPA500 and I was having some issues with my 80 meter zepp dipole making the amp act funny. When I moved the tuner and feed line far away from the amp it appeared to resolve the issue.

I was wondering if anyone else has ever had this problem? Also, will just reloading the configuration file maybe fix this? 

Thanks, Jeff  KU8E

Ray Maxfield
 

Try a Goodwill Store !     ray

 

From: Ed Muns, W0YK
Sent: Saturday, February 29, 2020 9:35 AM
To: Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA1500 Output Power

 

The PC to KPA1500 cable is a standard USB A-B cable readily available.   You and John most likely each have them in your home somewhere.  If not, they're widely available, even in grocery and convenience stores.

 

73,

Ed W0YK

 

 

-------- Original message --------

From: Jeff Clarke <ku8e@...>

Date: 2/29/20 09:17 (GMT-08:00)

To: Elecraft-K3@groups.io

Subject: [Elecraft-K3] KPA1500 Output Power

 

My friend K4BAI bought a KPA1500 around August of last year. It's been humming along and working great for him until last week. He was able to get full legal limit driving it with 30 watts from his Kenwood TS590SG. All of a sudden he's only getting only about 700 watts out with the same drive power. The most power he is able to get out is 1100 watts with about 60 watts of drive. Above that drive power the overdrive light will come on. He contacted Elecraft support and they want him to send the configuration file to them. I went over his house the other night and we were going to check it out. We couldn't find the cable to connect the computer to the amp. It turns out he left it in the box and his wife accidentally threw the boxes away. So he's going to have to order the cable so we can download the configuration file to send to Elecraft.

One concern I have is that for 160 meters he shorts the coax for his 80 meter antenna thru an antenna tuner to use it on that band. My guess is there has to be lots of RF floating around his shack with the feed point of that antenna being inside his shack.  We did install a decent ground last year when he bought the amp. Maybe that RF has damaged some electronic circuitry in his amp? I own a KPA500 and I was having some issues with my 80 meter zepp dipole making the amp act funny. When I moved the tuner and feed line far away from the amp it appeared to resolve the issue.

I was wondering if anyone else has ever had this problem? Also, will just reloading the configuration file maybe fix this? 

Thanks, Jeff  KU8E

 

Paul Baldock
 

Sounds like one of the two output devices has died, hence half power out. Not unusual. Good job its still in warranty.

- Paul


At 09:17 AM 2/29/2020, Jeff Clarke wrote:
My friend K4BAI bought a KPA1500 around August of last year. It's been humming along and working great for him until last week. He was able to get full legal limit driving it with 30 watts from his Kenwood TS590SG. All of a sudden he's only getting only about 700 watts out with the same drive power. The most power he is able to get out is 1100 watts with about 60 watts of drive. Above that drive power the overdrive light will come on. He contacted Elecraft support and they want him to send the configuration file to them. I went over his house the other night and we were going to check it out. We couldn't find the cable to connect the computer to the amp. It turns out he left it in the box and his wife accidentally threw the boxes away. So he's going to have to order the cable so we can download the configuration file to send to Elecraft.

One concern I have is that for 160 meters he shorts the coax for his 80 meter antenna thru an antenna tuner to use it on that band. My guess is there has to be lots of RF floating around his shack with the feed point of that antenna being inside his shack.  We did install a decent ground last year when he bought the amp. Maybe that RF has damaged some electronic circuitry in his amp? I own a KPA500 and I was having some issues with my 80 meter zepp dipole making the amp act funny. When I moved the tuner and feed line far away from the amp it appeared to resolve the issue.

I was wondering if anyone else has ever had this problem? Also, will just reloading the configuration file maybe fix this?

Thanks, Jeff  KU8E

N6RV
 

The idle current for the KPA 1500 is 2 amps. If a device failed then the idle current would drop to 1 amp. Key the amp with no drive and not the quiescent current. One device failed two weeks after I received the amp. The current was 1 amp. They replaced both transistors. If you do not have the latest firmware there is a danger of a device failure. Also, they suggest putting Zener diodes on the gates. That is something you should request they do if you are sending it back

 

Bill N6RV

 

From: Elecraft-K3@groups.io <Elecraft-K3@groups.io> On Behalf Of Paul Baldock
Sent: Saturday, February 29, 2020 9:58 PM
To: Elecraft-K3@groups.io; Elecraft-K3@groups.io
Subject: Re: [Elecraft-K3] KPA1500 Output Power

 

Sounds like one of the two output devices has died, hence half power out. Not unusual. Good job its still in warranty.

- Paul

At 09:17 AM 2/29/2020, Jeff Clarke wrote:

My friend K4BAI bought a KPA1500 around August of last year. It's been humming along and working great for him until last week. He was able to get full legal limit driving it with 30 watts from his Kenwood TS590SG. All of a sudden he's only getting only about 700 watts out with the same drive power. The most power he is able to get out is 1100 watts with about 60 watts of drive. Above that drive power the overdrive light will come on. He contacted Elecraft support and they want him to send the configuration file to them. I went over his house the other night and we were going to check it out. We couldn't find the cable to connect the computer to the amp. It turns out he left it in the box and his wife accidentally threw the boxes away. So he's going to have to order the cable so we can download the configuration file to send to Elecraft.

One concern I have is that for 160 meters he shorts the coax for his 80 meter antenna thru an antenna tuner to use it on that band. My guess is there has to be lots of RF floating around his shack with the feed point of that antenna being inside his shack.  We did install a decent ground last year when he bought the amp. Maybe that RF has damaged some electronic circuitry in his amp? I own a KPA500 and I was having some issues with my 80 meter zepp dipole making the amp act funny. When I moved the tuner and feed line far away from the amp it appeared to resolve the issue.

I was wondering if anyone else has ever had this problem? Also, will just reloading the configuration file maybe fix this?

Thanks, Jeff  KU8E

N6RV
 

One device in my KPA-1500 failed. Make sure that your firmware is current. If you have a device that failed you will see it in the idle current. If the amplifier is keyed with no power applied, the current should be 2 amps. In my case, when the device failed, it was 1 amp. I sent it in under warranty and they replaced both devices. Also, if you send it in make sure they put the Zener diodes across the gate of each device. This prevents input over voltage which damages the gate.

Jeff Clarke
 

Thanks all for your help. We found a cable and were able to download the configuration file to email to Elecraft. I also sent them the fault log where you can see the date when the output started to go down. We also loaded the latest firmware but that didn't fix anything.It's beginning to sound like one of the transistors might have blown and John is going to have to send it back to Elecraft for a repair.

Jeff KU8E

Jim Denneny
 

Hi Jeff.  Long time no see from OH days.  I am retired near Seattle.  No problem here getting full legal power from KPA1500 on 160 with 25 watts drive.

73, Jim K7EG

Paul Baldock
 

That's 17.8 dB gain. Max allowed by FCC is 15dB. Check your power meters.

From my experience and others I think the amps require around 45W, but it varies from band to band and SWR to the finals.

- Paul KW7Y.


At 08:46 AM 3/1/2020, Jim Denneny wrote:
Hi Jeff.  Long time no see from OH days.  I am retired near Seattle.  No problem here getting full legal power from KPA1500 on 160 with 25 watts drive.

73, Jim K7EG