Posts by pe1hzg

While making adjustments to my station I must admit being guilty to triggering LEILA (I'm sorry, guys!).

But, I found that I didn't hear LEILA, I only saw LEILA on monitoring. So I investigated closer.

When sending a carrier, my radio sends a carrier on "carrier frequency" of the USB signal. Using USB means that the modulation will be above the carrier frequency.

When LEILA triggered, I found it sends a carrier on the frequency it "discovered" and a lower frequency. That means the LEILA signal will be outside my filter, which explains why I didn't hear it.

My question: why does LEILA use the "discover frequency" and a lower frequency for signalling instead of using a higher frequency so it would be in the passband of my receiver?

Hi,

I recently purchased https://www.ebay.com/itm/332389156868

This is an OCXO, so it is with an oven. It takes 90 seconds to stabilize (and the casing gets warm as the oven heats up).

I got these as frequency reference for by QO100 setup if GPS isn't available or if I want to test something quick - GPSDO takes more time to synchonize.

Mind you, this thing does 10 MHz, not 40. But if stability is an issue - give it a spin!

73,

Geert Jan PE1HZG

For those wondering, the goonhilly crew is having bad luck and is now reporting issues with the GPS antenna. The GPSDO is still stable but a few kHz off. Maintaining some repeater sites myself, I feel for the crew because Corona generally makes access to these sites very complicated if not impossible. The webSDR is still very usable but keep in mind it is a few kHz off.

Status info is given on the info on top of the page (yup, the info I skipped too)

This actually gives an interesting side effect. When looking at the upper beacon, I always heard an extra carrier (have the same problem in my setup). This is probably related to the reference frequency sent to the LNB. Because the reference is now slightly off, the reference harmonic and the beacon signal are now on different frequencies. You may want to study the upper beacon while this situation persists.

Quote from DL1GNM

I'm using CH3+8 (2.4GHz) and 5GHz as well. My Antenna is 10m away from my house. No problems so far using the NB transponder (2W+POTY+1.2m offset dish).

WB and more power could be different...

Keep in mind that with the higher wifi speeds, the channels are wider and hence channels overlap. If you are using channel1 then channel 2,3 are unusable. Industry practice therefore is to (only) use channel 1, 6, and 11. WIth QO100 activity that leaves channel 6 and 11. Use of channel 3 and 8 is like transmitting on 145.505: you block 145.500 and 145.5125.

I realize that signals are local but I still remember when I was the only one with wifi - these days I see 30-40 SSID's easily and unfortunately not all of them use this scheme. wifi on 13cm in city areas is a zoo.

I realize this is out of scope for this forum but if people tinker with these settings they might as well know.

Not intending to kick up a lot of dust, I am asking:

In some local QSO's there has been, for a number of days, a discussion on QO100 frequency accuracy.

On my own station, i find that I typically need to tune 70-100 Hz down to be on frequency. I blamed that on my own equipment (even if every single component is GPS-locked), though I wasn't sure where it would come from.

All that, until I heard in the discussion that others are reporting same.

People using the beacons for reference are OK and don't report anything.

We know that the LO in QO100 is spot-on (see the NDA discussion elsewhere).

Without wanting to blame others: can anyone confirm the correctness of the frequencies of the beacons?

I know there have been issues in the past and realize that maintenance in Corona days is a challenge, but a brief "yup, we know" helps me to stop searching my own kit.

There also have been discussions on a small offset in BG7TBL references, but that offset is constant and for this issue, the numbers don't add up, so I don't think it is that.

Clue appreciated,

Geert Jan

Sorry for playing my own harp but as to frequency stabilisation, have a look at this discussion on the forum: 432/28 MHz transverter from transverters-store.com

As to the Anglian converters, they are good but parts may be an issue.

Keep in mind that for QO100 the dynamic range is limited. On WebSDR, the beacons are less than 20dB above the noise floor and stronger signals than that yield QSL's from LEILA. My suggestion is to focus on reciprocal mixing given the relatively high noise floor. In my experiments, I find that receivers that are quoted to have good LO's give me better signals.

Hi,

I'm using the Goonhilly WebSDR to monitor my transmissions. Unfortunately, something has changed:

It used to be that if you put your mouse pointer inside the frequency bar, you can use the scroll wheel of the mouse to change frequency.

This was cool, because I had re-programmed one of those "USB volume knobs" to generate generate mouse-wheel events. This means I could use the knob to tune the frequency I was tuning to.

But something has changed. Putting the mouse pointer inside the frequency bar and clicking no longer lets the wheel to be used as frequency adjust; instead, the web page scrolls. That makes the knob useless.

Has anybody found a way to make the mouse-wheel work again for frequency adjustments?

When I built mine, I found that standard M4 nuts had exact the right 3.0mm thickness.

Update: because of the current Corona-situation in the Netherlands, the Dutch government has come with new struct rules under which doing JOTA is not feasible for us. We will therefore not be active with JOTA on QO100 this year.

Hopefully next year QO100 will still have TWT's and we will be able to create some activity then. So it goes!

Hello,

Last year we used QO100 during Jamboree On The Air (JOTA). We made only a few QSO's but the scouts enjoyed them.

This year JOTA will be 16-18 october and I am considering setting up the QO100 station again.

This year, we have Corona restrictions and there will be fewer stations. Additionally, stations doing JOTA may decide not to set up their QO100 station because of lack of space in the scouting hut (distance rules) or less hamradio operators to operate the equipment.

Still, I am considering setting up the station.

My question on the forum: will there be other JOTA stations in 2020? Doing the effort makes no sense if there are no other stations to make QSO with.

Plans can change if Corona restrictions change obviously, and rule changes in PA0 are, eumm, erratic.

But I only want to do the effort of setup if if there are other JOTA stations planning to become active.

I suspect the noisyness and instability of the DRO would not help your efforts as I'd expect the signals to be "smeared out". I'd suggest to get a PLL LNB still. If you webshop, order two or three, so you can have an "accident" with one should you decide to GPS-lock your LNB in the future.

Hi,

The lower beacon (10489.500) beacon is FSK (much appreciated!) but the top beacon, at least on the Goonhilly SDR, has an additional carrier. Is this intended? Why?

Since we're now using the skirts of the transponder filter, sensitivity varies and with that the operational instructions on uplink power become more confusing.

I'm using the Goonhilly WebSDR, assuming that it's calibration has been looked at.

In the old days, there already was a difference between the PSK beacon (-69 dB) and the CW beacon (-72 dB)

In the new situation, the PSK beacon is still -69dB, but the lower CW beacon is now at -76 dB, the upper CW beacon has a similar level (but I'm not sure, since the space carrier doesn't seem to switch off)

In any case, this now gives 7dB of ambiguity as to the max uplink level ("not stronger than the beacon"). Comments?

One thing to consider is that by adding a reference frequency input via the coax, we make the voltage of the coax available via a series resonant circuit. So, any alien voltage (think ESD voltage) now finds it's way to the sensitive ports of the oscillator of the LNB chip.

The standard F connector connects inner pin first before ground connection is made. This is like the audio tulip plug; the hum of connecting an audio source to an amplifier via tulip has blown many speakers.
With the F connector, the inner pin can launch ESD voltage to the inner oscillator before ground is made.

In my LNB's, I have modifications to make them run on low-noise 5V (for the PE1CMO kit) and to avoid connecting 13/18V to the 5V input I permanently added an F->BNC converter, tied ans secured through heat schrink tube. This has the advantage that on connect, the connection is made to ground first, so I don't have the ESD issue.

Perhaps something to ponder,

Geert Jan

A question: asked before but unanswered: why do satellites like this use LO's with this accuracy?

Is there a technical reason for this?

Related.. I wonder why the transponders in these sats (not ours, the regular transponders) need to have such a high stability?

After all, regular TV transponders are 8MHz "bent pipe" frequency translators.

For analog CATV on modern, I know that all the carriers of all the analog TV signals were phase-locked, the reason being that the intermodulation product of the carriers of these AM signals would then be a DC signal, and hence not visible, so CATV operators were able to push more channels on the bandwidth.

I'm not sure the same argument applies for sat-TV: on CATV, the signals all have the same strength and there is quite some amplification / processing in the network. On sat-TV, signals are spread by direction and polarization so I'd expect intermodulation to be less of an issue.

Yet, sat operators use these ultra-stable frequency references. What am I missing?

Quote from DK2ZF

But this tower not exclusively for QO-100, I suppose.

For QO-100 just a small tripod with 60cm dish would be sufficient.

The tower pictures are from previous year. But I agree, I won't use the tower for QO100 use.
For one, because a tower like this is always moving a bit because of wind and temperature changes, which will play havoc with the small opening angle of the dish (new PA3FYM QO100 term: "tower QSB").
Secondly, because adding a large dish at height will seriously add to the wind load of the mast, which will be substantial because the dish will need to peek over the row of trees

Thirdly, because adjusting the dish at height is awkward and frankly I rather let the builders deal with the climbing procedure (*not* trivial - everybody has double security!)

The tower will sport HF dipoles and quad antennas, 2m (beam and vertical), 70cm, 23cm, and ATV on 23 and 13 cm.

I think we'll be around .740 as a frequency suggested earlier by Remco. Note that it is likely you will find another operator: there are several licensed scouts in our group and as none of them have used QO100, I'd like to given them the opportunity to experience the bird.

Thanks for the detailed explanation.

You subtract the transmitter instability from the receiver instability. I agree that would be true if I were to listen to my own signals. But, if I were to listen to your signal, would the total drift not be the addition of the drift of your transmission equipment added to the drift of my receiver equipment? .

Quote from PA3FYM

pe1hzg How high is the tower?

In final configuration, 44m, measured by the remaining length of the coax cable on the ground. At the time the picture was taken, the middle tower was still being constructed. Once constructed, the centre pole gets the antennas and rotor installed, then hoisted up, so the final config is higher than shown in the picture.

Construction starts tonight, will complete on Friday morning, dismantling starts Sunday afternoon and tower is completely dismantled Sunday night; we are in the city and need to consider vandalism so we cannot leave stuff "out".

I feel privileged to be able to support this group. Call us via PA1PTP/J!

Quote from ik4hps

sbout jota in the coming days what frequency should you use QO-100?

Is there a list of Jota stations operating on qo-100 ??

Please see this link for a discussion on the Dutch hamradio forum:

http://zendamateur.com/viewtopic.php?f=21&t=21287

From the thread I see PA6PSG/J, PA1PTP/J, PE2AAB/J, PE6SBW/J, PA3RVG/J, PE1NIL/J, PA4AGO/J, PI4ADH/J, PA6SHB/J (tree issues), so that's 9 stations already (that's 5% of the JOTA stations registered for the event in the Netherlands).

Unless the forum thinks otherwise, I was planning just to call CQ jamboree and see who answers. Note that we are also interested in non-JOTA stations, especially in foreign locations.