The PINs are Microsemi/Unitrode UM4001s; they're not rare and I have a few.
A variety of MSC/UTR PINs will work. DigiKey used to stock them, maybe not
now. I would not use Richardson. 😊
-----Original Message-----
From: Amps <amps-bounces@contesting.com> On Behalf Of gudguyham--- via Amps
Sent: Saturday, January 13, 2024 1:55 PM
To: Ed Swiderski, KU4BP <ku4bp@triad.rr.com>; Amps@contesting.com
Subject: Re: [Amps] QSK5-PC in a AL1200
FWIW….I’ve removed more of those boards in Ameritron amps than I installed.
It’s not if, but when you have trouble with it. The diodes are no longer
available and they are so expensive!!
Sent from the all new AOL app for iOS
On Saturday, January 13, 2024, 1:04 PM, Ed Swiderski, KU4BP
<ku4bp@triad.rr.com> wrote:
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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