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After building the 20m QCX I checked voltages and at that time I was reading ~1.70 on both CLK0 & CLK1.? Last night, I was troubleshooting another problem and decided to re-check the voltages and noticed CLK0 was ~1.70 BUT CLK1 was 0!? I haven't yet hooked up my scope but I am assuming something is holding down CLK1 or I have a failed IC.? I notice on the schematics (Rev 1.10) that CLK1 is produced by IC1 p9 (SI5351A_MSOP) and CLK1 is shared with IC4 p2.? My worst-case scenario is a faulty IC1and/or IC4.? If IC1 requires replacement, is this a programed IC?? If so, where do I order one from?? Any luck getting the IC4 (FST3253)?? Hopefully after I pull out the scope I'll have a better idea of what's going on.? If anyone has answers I would certainly appreciate a reply.

73 John KF6QPC

BUT CLK1 was 0!? I haven't yet hooked up my scope but I am assuming something is holding down CLK1 or I have a failed IC.? I notice on the schematics (Rev 1.10) that CLK1 is produced by IC1 p9 (SI5351A_MSOP) and CLK1 is shared with IC4 p2.? My worst-case scenario is a faulty IC1and/or IC4.? If IC1 requires replacement, is this a programed IC?

John,

A few faulty components have been reported but faulty new components are rare.
More often faulty components are due to a constructor's mistake.
Most faults found are due to bad solder joints or solder bridges.
Bad soldering on the Si5351 has been reported a few times. A very careful look at all joints with magnification is essential.

The components are available, yes, if you decide you need something make sure it is the correct type.

73 Alan G4ZFQ

Hello Alan,

Thank you for your reply.? As mentioned previously, after building the QCX, the voltages of both clocks WERE the same and for some reason CLK1 is now 0v.? As for the SI5351A_MSOP, it is my understanding that this IC may be a pre-programmed component.? I need to know if QCX's IC1 is pre-programmed or not.? IF programmed, how do I go about getting one?? Otherwise, I can order a non-programmed one from Digi-Key.? The IC4 appears to come in a couple shapes/sizes.? I don't think I can order the correct one (rectangular) within the States.? I know Digi-Key only offers the "square" one.

BTW, I did reset IC2 but that did not improve this situation.

As mentioned previously, after building the QCX, the voltages of both clocks WERE the same

John,

Yes, but bad joints/bridges can show afterwards. Have you checked for grounding or with the scope yet?

and for some reason CLK1 is now 0v.? As for the SI5351A_MSOP, it is my understanding that this IC may be a pre-programmed component.

The one used is not pre-programmed, if you look back in the posts (search) the exact replacement has been quoted in the past. Maybe someone will know and save you the trouble.

73 Alan G4ZFQ

Hello Alan,

I think this is the info he needs from a quick search of my folder:

"This has come around before, but here's a reminder.

The part you want is the Si5351A-B. It comes in a 10-MSOP package. You
can buy it either on a cut tape (-GTR) or bulk from a tube (-GT)
according to taste; same chip either way. You want to avoid the
variants that have a modified I2C address such as the Si5351A-B04486;
the QCX firmware expects the chip to use the standard I2C address,
0x60. You also want to avoid the Si5351B-B or Si5351C-B, which come in
larger square packages.

Digikey sells them for 92 cents in quantity one. They're a bit more
expensive at Mouser: $1.15. (But it might be worth paying the higher
price to Mouser if you're already ordering from them for other
reasons.) Non-US distributors also sell them. "

Thursday, September 13, 2018

--
Best regards, Chris Wilson (2E0ILY)

Hello Chris and Alan, after hooking up my oscilloscope, I noticed both CLK0 and CLK1 are active.? The only? time CLK1 would be 0 is after placing the QCX in menu 9 Test Equipment | 9.2 RF Power and depress the key.? If I move up the menu back to 9 Test Equipment, CLK1 is active once again.? I suppose because CLK1 is missing only during test 9.2 plus key depression, this observation now becomes a mute point.

I want to thank you both for taking the time responding to my question/concern.

73 John KF6QPC?

Hans, thank you very much for the explanation of CLK1 not enabled when receiver is muted.? This transceiver kit has certainly been an excellent learning experience!

73 John KF6QPC