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,

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.

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

On Wed, Sep 12, 2018 at 08:41 PM, AA7US wrote:

I wound up having the potentiometer set to about 80% (just a rough guess) which results about 100 mW's of continuos heater current. ?Maximum startup current is about 225 mW. ?I can live with that.

Correction: That’s 100 mA and 225 mA (not mW).

John
AA7US

From an early thread....
Regarding the?clockand the checksum validation. I have not done aClockfirmware release since the checksum validation release on the U3S. Nextclockfirmware release, I will include the checksum validation flag. 73 Hans G0UPL

Maybe there is a clue here??


Ken G4APB

Andy,

I finished building and testing my OCXO today...

I started out trying a 15K resistor for R5 but found it limited the BS170 MOSFET's gate voltage too much. ?I could only get about 2.95 volts maximum on the gate with the temp adjustment potentiometer fully open. ?The MOSFET's took a long time to heat up like that. ?Next I tried a 27K resistor for R5 and found it to be just about perfect. ?Now the maximum gate voltage reaches about 3.35 with the potentiometer fully open.

I wound up having the potentiometer set to about 80% (just a rough guess) which results about 100 mW's of continuos heater current. ?Maximum startup current is about 225 mW. ?I can live with that.

73,

John
AA7US

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

M0RON for the win!
I tweaked my ref osc up by 1khz. Now the spotters I see have my freq spot on or w/in 100hz at numerous frequencies. Lacking anything better, I may be able to live with that.
Thanks for the good info, Alan and M0!

Tony N0BPA

Hi Ken,
I checked Clock Kit page on web and there is no info about any improvement in C1.01a - only a compilation method change :-(
(see screenshot)

In FILE section here on groups.io there is only c1.01 fro download (oram ?I missed something?)

We will see.
thanks
L. -dst-

Surely 27mhz is almost 4x 7mhz, 5x 7mhz would be 35mhz, so should the change be 1khz?

Andy,

I did say "I hope I got that right..."
I did not:-) Maths was never my best subject.

73 Alan G4ZFQ

How much? 27MHz is approximately 5x 7MHz so raise the number by around 1250Hz.

Surely 27mhz is almost 4x 7mhz, 5x 7mhz would be 35mhz, so should the change be 1khz?
Andy

I tried it and found 3 spots on my 1^st xmission; showed me +200hz or +300hz @7053, depending on the listening station report.? Not sure what I can do about it…

Tony,

Apply reasoning. Mine is that menu 8.5 is the frequency at which the controller "thinks" the reference crystal is working.
Your very approximate check shows you are roughly 250Hz high at 7MHz.
Therefore the controller is being told your reference is lower than it actually is.
So you have to tell the controller that, raise the number in 8.5.
How much? 27MHz is approximately 5x 7MHz so raise the number by around 1250Hz.
With an accurate reference you could calculate more precisely.
I hope I got that right...

But you will not get it accurate until you find an accurate receiver or reference.
As mentioned before WSPR station K9AN is one who should be very accurate. Or see it you can find CHU or WWV.

73 Alan G4ZFQ

What about a CQ Call on the reverse beacon net. They indicate your frequency.

Hi Ken and Steve,

- Hans is aware of it, he is back but overloaded by agenda now ;-) - it is not so critical but good to know and solve if possible
- there is c1.01 firmware (no "a" suffix)

73
-dst-

Hi Lexa,
I could not tell from this thread but are you using the latest version c1.01a firmware? I had a similar problem with the original code (JO01cl area) but it is ok now.

73 Ken G4APB

Hi John,?
I popped a 33k in to experiment with. I had worked out the resistor value equivalent but I went higher to measure current draw at 33k and how long it takes to heat up and stabilise and then drop to a lower resistor and repeat the experiment.?
I have two OCXO's to set up but on different u3s's so I might drop one down to a lower value and run them side by side. Halving the time to complete the task.
It was simply because I was interested in seeing what difference it makes.
Andy

开云体育

Thanks, Paul, I think that is going to work. ? I looked on Mouser, and did not find this one, so many thanks!

73
--
Harv
K2PI
Warrenton, VA