[Elecraft] K2 PLL reference oscillator test failure
Ken Wagner
[email protected]
Wed May 28 20:05:01 2003
Hi Harlan:
I'm certainly no expert on this, but I would go back and check everything
around the PLL Reference Oscillator(everything in the upper left hand corner
of sheet 1/4 of the RF board schematic) and the 12 bit DAC(U5) including RP2
and RP3. I don't know what the history has been of U4 but I would be
surprised if it has failed. If there is nothing obvious and you don't get a
better response from someone else, then pop off an email to Gary ...
[email protected]. I'd be willing to bet that he has encountered this
before.
GL & 73,
Ken K3IU
K2 920 & 3442
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
----- Original Message -----
From: "Harlan Braude" <[email protected]>
To: "Elecraft Mailinglist" <[email protected]>
Sent: Wednesday, May 28, 2003 19:27
Subject: [Elecraft] K2 PLL reference oscillator test failure
| I sent this before the Memorial Day weekend, but haven't seen a response,
so
| I'm sending it again in case it was missed...
|
| ====
| Hi gang!
|
| With serial #3398, I'm getting the "changing rapidly" syndrome
| when I perform the "4 MHz Oscillator Calibration" step on pg 57
| of the K2 manual (Rev E, 02/16/03).
|
| I confirmed that the frequency counter probe itself is working by
| repeating the test from page 45 (the F.Counter showed ~3999.)
|
| I also confirmed that I have the correct IC in U4 and the solder
| connections look fine under magnification.
|
| I did apply the change described in the "K2 Manual Errata" (Rev
| E-2, 03/12/03), which involves soldering C91 and RFC15 on the
| bottom of the RF board between pin 16 of U4 and the pad that pin
| 16 had been connected to in earlier versions of the RF board.
|
| I've gone over that modification, too, and it seems fine to me.
|
| Is replacing U4 the next step or are there other possibilities I should
look
| into first?
|
| Suggestions would be appreciated.
|
| Thank you.
|
| Regards,
| Harlan
| KC2KUK
|
|
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