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@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@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@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@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@audiosystemsgroup.com>
>> To: cq-contest <cq-contest@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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