Posts by PA3FYM

Yes, like Achim said , that delivers the most spectral pure impact. With these multi carrier signals it's not anymore 'adjust bias for max output' (like with single carriers in the old days ; -)

No, these modifications were already there before QO-100, especially for 10 GHz (10.368 MHz) usage as alternative for the famous DB6NT transverters.

B.t.w. Thomas, when will we hear you on the satellite?

Quote from SV1BDS

I have to work now on clearing the output signal from harmonics etc. The OCXO alone is clean but when others units powered is become dirty.

Yep, known issue ; -) That's why I always emphasize denoising power supplies when using this kind of applications (accuracy & stability), but apparently you have to experience it to place my comments into perspective ; -)

In the end noise (reduction) influences the time constant (TC). I regularly see a TC > 500, so that must be possible for you too.

Some other tips/hints I did:
I placed a temp sensor (LM35) on (I think ADC2). When you don't use temp compensation, ground that ADC pin , otherwise it is left open and produces noise.

It is not by coincidence that open ADC inputs are used to produce cryptographic keys ; -) Same accounts for the other T-sense ADC pin.

I placed a 100 uF cap between Vref and GND on the Nano board (on the board is 100n, but I increased that ; -)

Thanks for this comprehensive experiment Armin : -)

Sorry to read that one LNB was sacrified. May it RIP for the good cause ; -)

SV1BDS Promising video ! : -)

It is now interesting to which your TC converges. I placed a 10 uF cap between the RESET-pin and GND to prevent rebooting the Nano when connecting a RS-232 terminal (e.g. Putty) (cap has to be removed when reprogramming the Nano)

Here the TC 'wobbles' a little due to the statistics I apply on diff_ns as an attempt to 'restrain' the contraption, so that it can't drift away, read: prevent loosing lock

DB2OS Thanks for the posting/link. From the information I (me, myself and I) have the Dutch administration (so the 'boss' of the German BNetzA) doesn't oppose to the French proposal .... Unfortunately the only person with in depth technical knowledge of radio (frequencies) at the policy department (Ministry, The Hague <-- they decide, not our BNetzA) passed away recently , so our lobby was/is unfortunately 'de facto' unsuccessful . . .

The question remains if the amateur service (not having a formal vote in the ITU/WRC in the end ... ) is able to convince others / administrations to 'reconsider this proposal'.

DD4YR It has all to do with linearity, so that 'in channel intermodulation' (free translation from Dutch) doesn't smear out (to other channels).

Just like the old analogue CATV systems, which used e.g. BFW16's or other 'power' transistors in their distribution amplifiers. In my (illegal) FM transmitters at that time (80's) these BFW16's were able to produce almost 1 Watt, but for linear purposes there needs to be an OPBO (Output Power BackOff) of ... say .. 10 dB (or more depending on the application).

SV1BDS did you (already) try my sketch?

To clarify, this thread is not intended to 'poke' but merely to document the development of new phrases/sentences which seem to develop as a kind of 'QO-100 language'.

G8UGD In most cases the sentence concerning SDR Console is followed by "locked on the PSK-beacon" ; -)

Quote (just heard): "This is [censored] calling for CQ for any station"

: -)

yes, therefore you need the TC optimising algorithm , change adc parameter at the beginning of the source and run my sketch

Quote (just heard): "I use a single dish with a dualband feed in the same dish."

See my sketch. My intention is to let the contraption converge to its optimal TC-value.

Yes, the cheaper the GPS module, the better it works ;; -)

With the normal software, when you have a long TC initially , then it takes ages for a lock.

What I do is the following:

1 warm up time = 10s (i.e. short)

2 initially TC = 16 and wait for lock (usually few minutes)

3 if lock, check every TC if there is a lock

4 if lock and DEMA of nanoseconds is below certain value, increase TC with TC>>4 and goto 3

5 if DEMA is above certain value, decrease TC with TC>>4 and goto 3

6 if system once locked but lost lock (for whatever reason) halve current TC and go to 3

DEMA = Double Exponential Moving Average (of the nanoseconds variable, i.e. differnece of the system vs GPS PPS

George, I filled in your contact form on your website, i.e. check your mail ; -)

What gain factor did you determine with your OCXO?

Edit: Made a screenshot of my contraption a while ago, see below. Note the large TC (941 s), an indicator that the stability is good, which is confirmed by a non varying DAC value (in my case the DAC apparently converged to 24029).

DL1GNM I use the NB-beacons for comparison measurements (fiddling with LNB's, lenses etc) too and learned to live with +/- 1 dB accuracy due to all kinds of fluctuations in the radio path ('QSB') , but that's good enough for me.

Being active on QO100 since day one (Feb 12th) -with a deviant setup- I managed to work 70 DXCC and (almost) 290 grid squares I reckon I know 'what I'm talking about'. Listening to various QSO's certain patterns appear (to me).

So it may be an idea to publish some 'QO-100-talk':

1. "I have a SG-labs transverter with a modified (Octagon) LNB
2. "I use a single dish with a dual band patch feed"
3. "CQ QO100, CQ satellite, this is X0ABC calling QO100"

4. . . . anyone else . . . ? (fill in below ; -)

I remember almost being banned from Earth here using this approach.

In fact the first NB hardware posting here was 'transceive' (or simplex), look here (and read the reactions (in another thread).

(that posting was the incentive to add the rule "Full-Duplex operation is mandatory (you must be able to monitor your own downlink while transmitting!)"

It's always the same: people who scream the hardest .. you don't hear them ...

SV1BDS My implementation of the Lars GPSDO is fed with 220V.

A small 10V transformer -rectified, blah blah- goes into a 7808 (decoupled etc).

The Arduino is connected to that 8V point, as well as the Ublox Neo 7M fed from 8V with a capacitance multiplier (with resistor divider in the base). The OCXO has a separate capacitance multiplier (with resistor divider in the base and the cap is 1000 μF, so the effect of the cap will be 100000 - 200000 μF or so). With a capacitance multiplier the capacitance of the elco is multiplied by the Hfe (or β) of the transistor and therefore denoising the power supply, which improves stability and/or phase noise.

That are a lot of screws! My experiment screws the amp above with (if that amp delivers really 30W) by +10 dB.

You have 30W out with 29 screws, that is 1W/screw.

I have 20W out with 2 screws, that is 10W/screw.

So my 'screw factor' = 10log (10/1) = +10 dB and/or
my screw factor = 10log(1/10) = -10 dB.

Screw factor ≠ 'screw factor' (note the quotes)

;; -)