Thanks Bill. I'll check that out.
On 1/13/2024 5:43 PM, hzp_electronics@juno.com wrote:
Hi Ed,
I don't know if this will help. I repaired an external QSK-5 for a SK's widow.
I think it uses the same PCB as the internal unit. The problem was that Q4
2N6740 was shorted to ground. The device Collector-to-Emitter is rated for 400
volts. However, the voltage on its collector can exceed 400 volts at times. I
installed a 800 volt device (2SC3460) which solved the problem for that unit.
The point is that your PIN diodes might be OK. It is worth a check. Getting
PIN replacements is very difficult.
73
.... Bill K3HZP
---------- Original Message ----------
From: "Ed Swiderski, KU4BP"<ku4bp@triad.rr.com>
To:Amps@contesting.com
Subject: [Amps] QSK5-PC in a AL1200
Date: Sat, 13 Jan 2024 13:01:51 -0500
Hello all,
As the subject line says, I have an issue with the QSK5-PC board in my
AL1200. The QSK5 board has been blowing it's fuse lamps. I think I've
replaced them 3 times in the past 12 months.
I haven't been doing anything abnormal with the board in the years I've
had the amp. It was already installed when I purchased it in 2009. Never
had any issues with it and I have only used it with SSB. The only time I
use CW with it has been to tune it up in a dummy load with a straight
key. A couple times during normal use in SSB, the fuse lamps on the
board would blow. The latest use had the lamps blow while tweaking my
settings on the amp.
I contacted Ameritron for advice. They told me to "try operating in semi
break mode and increase the delay speed and see if that clears it up". I
did that but since I'm not operating CW in the first place, it didn't
help. Ameritron also said the board may have a bad PIN diode. I haven't
removed any of them to check. I think it's possible because the board
was installed in 1994(30 years).
So, I'm asking first if anyone has had a similar issue that can give any
advice. Second, I'm toying with either getting a new board or, just
undoing the modification altogether. Doing either is not a problem. I
would like to keep the mod in place though which is why I'm indecisive
right now. Hope to get the amp back in use by the end of this year for
when 3Y0/B is planned to come on.
I hope I have given enough information. When I first had this problem
last year, I didn't provide enough information and I think I upset a
couple people by not doing so and I apologize for that.
Will try to respond to replies promptly.
Thank you,
Ed KU4BP
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