Do not trust PL-259 connectors installed only "finger tight". Today many
of those PL-259 connectors "look good" but are really poor quality
connectors. ALWAYS snug the PL-259's with a pair of 4" channel lock
pliers. You'd be amazed how many strange issues will go away.
Not saying this is or was the cause of failure, but I've seen it and
experienced it too many times.
Also, for other reasons, I run the ALC from my KPA500 to my K3S.
Again, another issue of concern resolved.
73
Bob, K4TAX
On 2/16/2019 10:13 AM, Dave wrote:
His radio blew one final while driving the KPA1500 in the fall.
Now his amp blew one LDMOS.
I’ve been to Peter’s house and used a TDR to check all of his antennas,
cabling, and switching. Cable connectors replaced last year.
I agree it is good idea to check everything again. Looking at the amp fault log
today did not show signs of anything arcing
Dave wo2x
Sent from my waxed string and tin cans.
On Feb 16, 2019, at 11:01 AM, Mark Goldberg <marklgoldb...@gmail.com> wrote:
It's been said there are no coincidences. Have you checked your coaxes /
connectors? I agree that protection built in should not allow radios to blow
finals, but this sounds like too much of a coincidence with two different
radios blowing to not be an external intermittent connection. Try wiggling all
the cables with low power. Unfortunately, sometimes a problem will only show up
as arcing at high power. Is there another HAM near you with a powerful amp and
antenna close to yours?
Best of luck,
Mark
W7MLG
On Sat, Feb 16, 2019 at 8:50 AM <li...@w2irt.net> wrote:
Exact same thing happened to my K3s in October, now my KPA-1500. Yeah, So
done here. Once repaired and confirmed working it will be up for sale. Going
back to a tube amp after this.
- pjd
-----Original Message-----
From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On
Behalf Of Paul Baldock
Sent: Saturday, February 16, 2019 10:28 AM
To: rocke...@gmail.com; elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA-1500 failed!
It sounds like one of the output devices have failed. Half power out is
usually the indicator. A number here have reported this happening.
It would be nice to know why this problem is occurring and if Elecraft are
working on a fix.
- Paul
At 07:10 AM 2/16/2019, rocke...@gmail.com wrote:
I talked to Peter on the phone. He has no bias current when amp is
transmitting with no power applied (key on SSB without talking. He is
reading 54 volts and has tried power cycling amp from power supply
switch and reseated all cables. Definitely BAD distortion on SSB (we
are close enough to hear each other). Looks like one RF device let
loose and it is dragging down the bias voltage. That is my guess.
Dave wo2x
-----Original Message-----
From: elecraft-boun...@mailman.qth.net
<elecraft-boun...@mailman.qth.net> On Behalf Of Wes
Sent: Saturday, February 16, 2019 9:49 AM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KPA-1500 failed!
I think a two-tone test is the best evaluation tool.. The generator is
built into the K3 if you have another receiver that you can use to
listen to the amp output. I use an SDR-IQ which is a very nice tool
for this but any other SDR would do.
Sorry for your pain.
Wes N7WS
On 2/16/2019 7:28 AM, li...@w2irt.net wrote:
I was operating in the ARRL-CW contest this morning and on 20m, with
a
1.2:1 SWR on the Yagi, all of a sudden I saw my power drop to about
450-500W with about 40W in. Worked a few stations but not as easily
as when I turned everything on this morning. Switched over to phone
and made a few contacts.
Audio is fine barefoot with 100W out of the K3s-which suffered blown
finals itself during CQWW SSB last fall, but with the amp in I got
reports that my audio was badly distorted.
Before I send it in, is there anything I should look at or any
diagnostics I can easily perform? For the cost of this, I'd have
thought protection would have kicked in to prevent anything untoward
from happening. I'm in complete disbelief, to be honest.
---------------------------------------------
73 and Good DX
Peter, W2IRT
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