[Elecraft] Sudden KpA1500 power reduction

[Ken K6MR]

It wouldn’t be above your skill level if they would release the schematics.  Solid state amps are not any more complicated than tube amps, and I think easier (and safer!) than tubes.  My early KPA1500 (#76) has been great, but not having the schematics really bugs me.  I know everyone at Space Galactic Headquarters is busy with the K4 but posting the KPA1500 schematics would not take more than a few minutes.  And my amp is way out of warranty so they aren’t risking anything.  Internally it looks like a pretty generic design.  I’ve reverse engineered the power supply unit but the RF deck is going to take some time.  I’d rather not if I don’t have to.

Ken K6MR

From: Dana Roode K6NR<mailto:dana.roode at gmail.com>
Sent: Sunday, February 21, 2021 11:03
To: Frank Scolaro<mailto:fscolaro at mindspring.com>
Cc: Elecraft Reflector<mailto:Elecraft at mailman.qth.net>
Subject: Re: [Elecraft] Sudden KpA1500 power reduction

Ok thanks everyone, I will lug the amp back home and contact Elecraft.  Ive
had it for about 2 years, everything breaks now and again.  I've got my
AL1200 here, I could use it at least when I'm here locally.  I can't count
how many times I repaired that amp.  But the KPA is above my skill level.

  Dana


On Sun, Feb 21, 2021 at 9:32 AM Frank Scolaro <fscolaro at mindspring.com>
wrote:

>
> Happened to me several months ago...  one LDMOS out! same symptoms.  You
> need the power with such great band conditions...
>
> GL
> Frank, W2YK
>
>
>
>
> -----Original Message-----
> >From: rocketnj at gmail.com
> >Sent: Feb 21, 2021 12:23 PM
> >To: 'Dana Roode K6NR' <dana.roode at gmail.com>, 'Elecraft Reflector' <
> Elecraft at mailman.qth.net>
> >Subject: Re: [Elecraft] Sudden KpA1500 power reduction
> >
> >Just my guess is one of the LDMOS devices let out the magic smoke?
> >Just a thought...
> >
> >Dave wo2x
> >
> >
> >-----Original Message-----
> >From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net>
> On
> >Behalf Of Dana Roode K6NR
> >Sent: Saturday, February 20, 2021 9:16 PM
> >To: Elecraft Reflector <Elecraft at mailman.qth.net>
> >Subject: [Elecraft] Sudden KpA1500 power reduction
> >
> >I'm in the ARRL CW contest this weekend and the KPA1500 has been working
> >fine.  However, a few minutes ago I noticed I was getting about half the
> >output power on 20 meters that I typically get with around 30 watts drive
> >(about 600w vs 1200w).  PA current is less than normal, around 30a.
> >Similar problem on the higher bands, I can no longer get 1000w.  On 40m I
> >can, but it requires more drive.
> >
> >Seems like something died in the amp; I'm not familiar with the design,
> but
> >perhaps an output module.  No errors or ill behavior from the amp other
> than
> >the loss of power.
> >
> >I will contact Elecraft support unless there is something I'm missing
> here.
> >I just looked in the archive and see that this has happened to
> others....  I
> >use the amp remotely so I guess I'll have to take it home with me.
> >
> >  Dana
> >______________________________________________________________
> >Elecraft mailing list
> >Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >Help: http://mailman.qth.net/mmfaq.htm
> >Post: mailto:Elecraft at mailman.qth.net
> >
> >This list hosted by: http://www.qsl.net
> >Please help support this email list: http://www.qsl.net/donate.html
> Message
> >delivered to rocketnj at gmail.com
> >
> >______________________________________________________________
> >Elecraft mailing list
> >Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >Help: http://mailman.qth.net/mmfaq.htm
> >Post: mailto:Elecraft at mailman.qth.net
> >
> >This list hosted by: http://www.qsl.net
> >Please help support this email list: http://www.qsl.net/donate.html
> >Message delivered to fscolaro at mindspring.com
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to k6mr at outlook.com