Winlink Wednesday #6

[Chris Sullivan]

Good morning. WW #6 has been changed for this round, and is mostly based on the format WW #10. This is because exercises 6-9 would be better served if my station was active, and I've been doing some renovations on it and I need more time to get it ready.

This exercise asks you to make an inventory of your connectivity to Winlink RMS stations by radio. It is an opportunity to experiment, but it will also allow us to figure out our combined communications options in case of emergency.

As I've done previously, this is a PDF file to make it easy to include screen shots and for you to print if desired.

73,

Chris

[Matthew VE3XYU]

Is there a way to determine if a VARA HF RMS station is "open for business"? And also, where exactly I should be aiming for? (Skip zones and NVIS and all that). With so many links in the chain, between the programs on my computer and my antenna, it's hard to know if anything is getting out at all. My hardware setup is probably working otherwise because I have seen myself show up on PSK reporter using FT8, JS8, and VarAC, though I have not yet had any successful contacts.

I've got about 8 watts into a 20m inverted-V hanging in the roof of my garage. It reads well on the NanoVNA and doesn't need much tuning. The peak is a little less than a quarter wavelength off the ground (~4.5m) so I imagine this is NVIS territory.

I tuned my radio using CHU 14.67 and audibly compared the pitch to a youtube video of a 1000Hz tone.

Does anyone have any thoughts? Should I look into WSPR or a similar tool to figure out some of this?

I'm very new to HF.

Thanks, and 73.

Matthew VE3XYU

P.S. I'd be on the WinLink video call tonight but my wife decided to have a birthday today 🤷

[Chris Sullivan]

NVIS on 20 is going to be difficult. It might be possible in the middle of the day, but the antennas on the other end aren't likely to be NVIS too, so that will be a disadvantage. Even an NVIS antenna will have some low-angle radiation, so you might be able to work some stations 1 hop away. You might try sending out a few CQs on FT-8 and checking PSKreporter for locations where you are heard with a strong SNR (say, -5 or better),  and then finding RMS stations at similar distance and bearing to try with VARA..VARA needs a better SNR than FT8.

You could also look up VOACAP online or similar for propagation predictions. 

Regarding CHU. If you are in AM mode, the pitch should be exact. In SSB mode, the difference will be the tuning error in your receiver, assuming you are listening to the CHU audio and not the AM carrier frequency. It is easy to tell the difference. The audio will be modulated with beeps and speech, while the carrier is just a steady tone. You will not be able to hear the carrier in a correctly tuned radio in SSB mode because it will be 0 Hz. As you approach the correct frequency you will hear the pitch of the carrier go down until it become inaudible at 200-300 Hz. In CW mode, the tuning will be offset so the carrier will be heard at the CW sidetone frequency (which is usually selectable on the radio) when the radio is correctly tuned. To calibrate my radio, I have the radio output the sidetone frequency and tune it to WWV carrier and match the pitch. When it is very close, you can hear the beating between the two tones. If the beats are more than a second apart, you're within 1 Hz.

Some receivers, especially modern ones, have a frequency calibration adjustments. If you are within 100 Hz or so, you shouldn't have a problem with VARA, but if you are more than that, you should calibrate or make manual adjustments to the frequency.

Make sure when connecting you let it go through all its retries. Some stations are monitoring multiple frequencies and can't listen to them all at the same time, so it may take more than 10 transmissions before your connection transmission is acknowledged. 

73

[Matthew VE3XYU]

Thank you, Chris.

I hadn't considered that the RMS would also need to be NVIS, but yes, that makes sense. 

My radio is a (tr)usdx; it's a kit radio which requires manual calibration. Regarding CHU, I was listening to the rhythmic beeping on USB to determine the correct pitch. I adjusted the radio's reference frequency until it sounded correct. I've just listened to it again on AM and I hear, as you say, that the pitch doesn't change.

So if the pitch sounds correct on USB while tuned to 14.670, is that properly calibrated?

I will try your suggestion about FT8 and look into VOACAP.

This little radio can only do five bands, 80-60-40-30-20. Is there another band that might work better given my antenna height (15')?

When time (and weather) permits I will try to set up an end-fed outside temporarily, which I believe may allow for more flexibility in band choice, but I have more reading to do about this.

I appreciate your response.

73,

Matthew VE3XYU

[Chris Sullivan]

Yes. Correct pitch on 14.670 is properly calibrated. You would also get the same pitch in LSB. CHU, being an AM station, transmits on both sidebands. If the radio's frequency is lower than indicated, you will hear the lower sideband audio at a lower pitch than the upper sideband, and vice-versa. This is because a lower actual suppressed carrier frequency is closer to the lower sideband than the upper sideband, and you are hearing the difference between them. 

The higher HF frequencies are less useful because their performance varies so much with the ionosphere conditions, although 15' antenna height on the 10m band is almost a 1/2 wave, so it favours lower angles. The bands your radio supports are probably the best. Note that VARA-HF wide mode is illegal on 30m, as it is limited to 1 kHz bandwidth.

73

[Matthew VE3XYU]

Thanks again, Chris.

73