[CQ-Contest] Elecraft KPA 1500

[K9MA]

My experience agrees with Dave’s. The early ATU firmware didn’t always get a good match, but it’s much better now. 

Some report, however, running full power into 3:1. I don’t understand that, unless they mean 3:1 at the ATU output, and something close to 1:1 at the PA output. 

73,
Scott K9MA 

----------

Scott Ellington. K9MA

 --- via iPhone

> On Mar 5, 2020, at 7:57 PM, Dave Hachadorian <k6ll.dave at gmail.com> wrote:
> 
> I had access to a KPA1500 for one day during ARRL DX CW 2018.  I found that 1500 watts into 1.5 SWR always produced a hard fault.  SWR had to be 1.4 or less on every tuner segment.  The tuner had to be carefully trained in the middle of each 20 KHz segment, that is: 010, 030, 050...right up to the upper band edge.  For some segments, I had to use the double-tap method to get SWR low enough.  In that method you tap ATU TUNE a second time, within three seconds after tuning is completed, then it tries to find a better match.  Maybe things have gotten better in the last two years.
> 
> 
> Dave Hachadorian, K6LL
> Yuma, AZ
> 
> -----Original Message----- From: K9MA
> Sent: Thursday, March 5, 2020 10:22 AM
> To: Dan
> Cc: k9yc at arrl.net ; Alan M. Eshleman ; cq-contest
> Subject: Re: [CQ-Contest] Elecraft KPA 1500 vs.OM 2000A
> 
> Perhaps there’s something wrong with my KPA1500. (Yes, I did RTFM.) At any SWR above 1.5:1, according to the meter on the amp, it will usually fault due to either high current or excessive drive power (saturation).  The “trained” ATU doesn’t always keep the SWR low enough, despite antennas which are quite flat. I haven’t tried it, but I’m sure it would never approach 1500 W into a 3:1 SWR.
> 
> There’s nothing wrong with the supply voltage.
> 
> I’d like to know why my experience differs from others’.  I’m away from home now, but I’ll further investigate when I get back.
> 
> 73,
> Scott K9MA
> 
> ----------
> 
> Scott Ellington
> 
> --- via iPad
> 
>> On Mar 5, 2020, at 10:54 AM, Dan <w8car at buckeye-express.com> wrote:
>> 
>> I agree with Jim's comment. My KPA 1500 does not fold back until I reach close to 3 to 1. I rarely use the tuner and my CC 2L 40 will cover the whole band without using a tuner. I would imagine that certain combinations of impedance and reactance might have an effect on the fold back. The other elephant in the room is SWR being read on meters is not always what it seems. My Daiwa, KPA 1500 and K3 (running bare foot so not into amp input) can all have different SWR readings on the same frequency.
>> 
>> Dan W8CAR
>> 
>> 
>> -----Original Message----- From: Alan M. Eshleman
>> Sent: Wednesday, March 4, 2020 12:48 PM
>> To: k9yc at arrl.net
>> Cc: cq-contest
>> Subject: Re: [CQ-Contest] Elecraft KPA 1500 vs.OM 2000A
>> 
>> that's been my experience with my KPA1500...
>> ----- Original Message -----
>> From: Jim Brown <k9yc at audiosystemsgroup.com>
>> To: cq-contest <cq-contest at contesting.com>
>> Sent: Tue, 03 Mar 2020 17:57:05 -0800 (PST)
>> Subject: Re: [CQ-Contest] Elecraft KPA 1500 vs.OM 2000A
>> 
>>>> On 3/3/2020 10:13 AM, Edward Sawyer wrote:
>>> super SWR sensitive doesn’t sound like good characteristics for an amp.
>> 
>> I have NOT experienced SWR sensitivity with reasonable antennas that the
>> KPA1500's built-in tuner can't handle. I suspect someone having this
>> problem has not RTFM, which describes how to train the tuner for each
>> antenna for each band, or has not taken the time to do it.
>> 
>> The KPA1500 can memorize settings for three different antennas for each
>> band for each of the two antenna ports.
>> 
>> And I DO get pretty close to 1.5kW on 6M.
>> 
>> 73, Jim K9YC
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