Just to follow up on this for anyone who might be searching the
archives, the problem was traced to the power supply. It was undersized
and wasn't what everyone remembered it as being, and after being pulled
out from under the desk it turned out to be an Astron 20, rather than an
Astron 35.
On
I'm glad that switching to a bigger Astron supply solved your problem. I
would
note, however, that I've been running my KPA100 with an Astron 20 at the 100
watt level for the past year with no problems.
Best regards -
Bruce K1FFX
-
Bruce Rosen
K1FFX
K2/100 6982
--
View this message in
Ditto here with my K3/100, except that the Astron 20 recently developed a
bad habit of crowbar'ing when I get on 20 meters with the KPA500. Slams off
IMMEDIATELY on transmit with the amp. I guess it doesn't like 500+ watts @
20' (my vertical). Waiting for the KAT500, which will resolve that
OK, it's S/N 4355 with all the latest mods and it used to just reset
when I got on 15M phone. Now it's resetting on 30M CW while I'm trying
to work DX so it's bugging me. :)
Besides the standard checking for 10-year-old cold solder joints, is
there anything else to check right away?
--
Hisashi
Hi Hisashi,
Could it be your power supply? It could either be hitting a max current limit,
or getting RF back into the supply. The latter is common with some supplies.
One other area to look at is the 12V power cord and fuse holders. If the cord
is too small, or the fuse holders are not making
I think I see HiRefl even though at lower power I saw lower than 2:1
SWR. I do have an SWR meter external to the K2. I'll look to see what it
tells me.
Thanks!
On Mon, 2 Apr 2012, Don Wilhelm wrote:
Hisashi,
If by reset you mean the power turns off, you are most likely seeing the
internal
Hisashi,
If by reset you mean the power turns off, you are most likely seeing
the internal resettable fuse trip.
Normally you would see a HiCur message too.
Usual causes for that behavior are either that the KPA100 wattmeter
diodes have been damaged or you have a damaged PA transistor in the
After getting the suggestions from Eric and you, I looked at the
metering I have already.
I don't think it's the SWR bridge because the power reading matches the
wattmeter on my MFJ-1788. It steadily increases and looks about the same
as what the K2 shows.
However, the voltage/current meter I
Hisashi,
OK, so that sounds like the KPA100 may be oscillating. First things to
check are the diodes in the T/R switch, the high voltage bias supply
(check during transmit too) and the operation of Q6 and Q7.
Is this the newer KPA100 design with blue toroid cores at L16 and RFC1?
If not,
I just installed the KPA100UPKT about a month ago.
Just to be clear, as I turn up the power, the internal metering shows
1.5A while the external metering shows the current increasing as the
power increases.
I'll check the voltages around the diodes and the HV bias supply to
begin with. Thanks
Hisashi,
The current indicated by tapping the DISPLAY button is the current drawn
by the base K2, and not the current into the KPA100. Your 2.5 amp
current at 10 watts is normal, as is the drop in current as you go into
the KPA100 is on stage because at low KPA100 power levels, the base K2
11 matches
Mail list logo
