Re: ProgRock not working #progrock
Alan de G1FXB
Hi Robin,toggle quoted messageShow quoted text
"? It is far more stable & accurate without GPS discipline; I have the standard issue crystal, the die cast aluminum housing (Bud 234) for the project & a 5 volt TO-220 regulator thermally bonded together in close proximity. The indoor room temperature is stable within 5?F. When operated in this mode (no GPS discipline), I find the ProgRock to run within 5-10 Hz. of desired frequency. Like your set up, my power supplies are clean. "
the sweet spot for stable operation of cheap xtals tends to be around 45 DegC but needs to be found for each individual xtal by experimentation,
heating the xtal to some arbitrary level above ambient using the 5V regulator perhaps yields minimal improvements especially as the xtal and improvised heater combo would also be losing heat to the thermally bonded diecast enclosure described??
It very likely could be improved by use of the dedicated OCXO type module (if for no other reason than the Discrete Colpitts Osc, Buffer stage so negating loading changes from within the Si5351
and adj temperature controlled oven.)
Please report back when you have characterised the results once your OCXO & QLG1 arrive.
(Remember you may need to revisit the PSU circuit of the progrock with the OCXO option, depending how you have the power feeds to the synth / 3.3v regulator & noise filter currently configured.)
"? Clearly, some of these boards aren't quite ripe for use under GPS discipline. "
(There are no particularly frequency conscious components actually on the progrock PCB?
The ATtiny84 AVR uses a RC Oscilator to clock it's program cycles. with no particular requirement for it's Osc frequency accuracy.
If the progrock programs the CLK0-1 outputs correctly on yor build it is perhaps a confidence "pass" to it's functionality.
Beyond the firmware settings, (Like Sid, note that the default settings allow a measure of drift before applying correction) building your second progrock kit is unlikely to provide a cure,
As you already have it to hand and it's socketed, substitute the AVR IC and see if anything changes.)
Hans never seemingly uses any special GPS Types. Timing optimised, or other for his testing.
Just what ever the current QRP-Labs offered at that time, a double check of your results with the Trimble against the QLG1 is good check to a known GPS RX.
(although you really shouldn't have to if you have tried it both alone and with a pulse stretcher.....
In the past it sold the VK16 GPS module using the then "new kid on the block" SiRF III chipset, and perhaps one that with hindsight gained a reputation for it's rather indifferent PPS signal.
But still performed adequately with some choice firmware settings.....
Just because GPS discipline is an option, do you need to use it? perhaps that's worth a further trial.
Others have proven a free running OCXO Kit can produce 0.5Hz accuracy over many hours.
I believe the discipline operation and arithmetic accuracy are handled differently in the Progrock to that of the U3S / VFO kits. (other than the obvious different processors...
Only Hans will know the In / out's of that and which has the greatest "on paper" resolution and under what conditions )
Other builders took the commercial SMD style TCXO route seeking accurate HF QRSS or VHF WSPR operation with their U3S,
only to re-discover after a couple of different threads that a correctly set up OCXO was perhaps the best choice,
" I have recently relocate the mept into the summer house (AKA a shed) since that I have noticed a lot more thermal drift over a 24hr period, at night when its cold it drift up in freq and on a hot day it drifts down (about 25hz max over the swing so about +/-? 15 hz or so) "
" I was getting about 15 hz drift over night when the ?summer house? (shed really)? got cool over night, it was also drifting the other way when its hot (high freq drift when cold, low freq drift when hot ) well I recalibrated the OCXO and did find it was past the flat part of the curve and the current was rather high, I reset it and found a lower current setting (about 150mA give or take a bit) which seemed to be on the flat part of the curve. Its been running in the shed since about 4pm yesterday and I have been monitoring it with Argo set to 30 sec dots slow (0.1Hz steps at that speed) .
I am pleased with its performance the worst drift was about 0.5Hz over that time and now back to the point it started "
another free running OCXO build
" On an overnight run, with typical California indoor temperature changes, I occasionally saw beat frequencies ranging from 0.014 to 0.067 Hz, which yields a peak relative drift of about 5 ppb (= 0.005 ppm). That's amazing! "
" My desire for this oscillator is a base for a set of propagation beacons, so frequency accuracy & stability are of high interest & desire. "
+/- half a hertz at say 10MHz you will be in good company,
If you are looking for your own "local" signal source with accuracy to traceable to NIST, it may require more than a progrock, even if driven with the best PPS signal.
?You may need need to visit the time nuts forum where a lucky few discuss home labs, and their primary standards and others just make do..... ? :-[
On 12/07/2019 14:45, Robin Midgett wrote: