Reception of HZH Navtex from Jeddah

 Earlier this moring, I found a new entry in the log of YAND:

HZH received on 518 kHz at 1:20 UTC January the 2nd 2025.

RX: ATS 25 Amp

Antenna: miniwhip PA0RDT

HanRongDa HRD C-919 (Raddy RF919)

I've been following on youtube the reviews of this radio, released by various reviewers and users, starting from spring 24.

And I finally decided to buy one from Aliexpress where I paid 190 Euros + 11 euros for import duties.

The devices is full of features out of which the most interesting to me are:

- the coverage up to 999 MHz starting from 153 kHz.,

- two LNA,

- an antenna tuner, 

- low pass and high pass band filters, 

- 3 possible external antennas: 1 for VHF/UHF (with a SMA connector), 1 tunable loop for LW, MW and SW with a 3.5mm jack on the top panel and 1 external antenna with a 3.5mm Jack input on the back panel, this is conected to a further pass band tuner with 3 positions (MW, lower SW, upper SW), these are alternative to an internal ferrite rod for LW and MW and an quite long telescopic whip mounted on the top panel of the radio.

 

Reception mode : AM WFM NFM USB LSB, but not everywhere, SSB reception is available only between 2.3 and 30 MHz. VHF/UHF only in NFN, FM in WFM, LW/MW only in AM, SW in AM/USB/LSB.

On top of these a large number of gadgets: scan function, 1600 memories, sound equalizer, selectable bandwidth, different colours for the main screen, a second smaller screen with VU-meter and signal strength detection (RSSI and SNR), sleep function, timer, alarm, squelch, sub bands, recording function on microSD, bluetooth, an android/iPhone app to controll the radio from remote, update of the firmware through PC connection....a million stuff. I would recommend to watch on youtube for a detailed description.

But how it works???

Not so bad, it has quite good sensitivity and not desperately noisy when the Low Passband filter is selected for the SW reception. Air band: good, WB: who knows? there's no WB in Europe. UHF I could not tune anything, but I don't know what to tune where. VHF on the 2 m band I could recognize the IQ2MI CW beacon but in NFM because SSB reception is not available in VHF. MW not bad too with its own ferrite rod. LW: uhm....so and so.

During the afternoon and early evening I could reach rank 2 in DSC reception on 16804.5 kHz.

Lowlight: it mutes while tuning, it mutes a lot!

The antenna selection and tuner section

I always recommend to read carefully the instructions booklet provided with the radios. But at the same time is exactly what I never do. I read the quick start guide when available and I give a diagonal read to the remaining pages. With the HRD C-919 understanding how the antenna settings work is quite complicated, there's a schematic which one gets with the radio, mine one is in Chinese and even looking at the block diagram the understanding takes some time.

As of today, my understanding is the following:

the rear antenna socket surely works for MW and SW, the switch control (MW-SW1-SW2) on the back of the radio allows to pre-select the band on which the antenna is receiving. Now, selecting from the antenna select button on the front panel under the main screen:

 the loop

with "Internal"

and "manual tuning"

is possible to use the antenna tuning knob on the right panel for the received band, selected with the rear switch. I have to admit that it is quite effective

Apparently (to my understanding) using the 3.5mm socket on the top panel and swithcing on the breaker to activate it, the signal is not routing anyore through any of the LNA installed and signals are much lower. Honestly speaking I do not see any advantage in SW using the 3.5mm socket on the upper panel, unless a strong signal is injected.

All settings related to the manual RF channel selection in the center of the picture above, are available for operating the radio while using an antenna connected to the 3.5 mm socket in the back panel. All those selections can be activated with the settings button in the front panel above-right the tuning knobs while the screen shows:

both in local or DX position. Having this icon activated also turn all the system in Automatic Mode and there's no antenna tuner available.

The lower left part of the schematic is for the built in ferrite rod antenna, it works as in any other portable device: tune and turn the radio body for better reception.

SSB Reception
This is somethnig that is really annoying me: I see this also in the first versions of the ATS20/25 receivers based on the SI 4732.

For example I need to tune DSC 8414.5 khz and decode the signal with YaDD: tuning upward from 8413 kHz I get the 1000 Hz tone at 8413.9, tuning downward from 8414.5 I get the 1000 Hz tone at 8413.6 kHz. And on top of this the postion of the 1000 Hz tone is even influenced by the chosen bandwith.

However: if they could eliminate the muting while tuning and extend  SSB reception modes to all bands, this would be a very cool receiver.

SDRplay on PowerSDR

 Before entering the point of the post, I like to share my last purchase. Past week I've been in Malaysia for working purposes and I found this nice bluetooth speaker/FM radio from the brand Muzen, It's called Wild Jeep Radiooo - Series 1. The case is fully metallic and despite the small dimensions the set is very heavy. Wonderful Sound! I use it for connecting the audio of one of the laptop.

That said: I finally managed to use PowerSDR IF stage with SDR Uno and SDRPlay RSP DX.

I've always liked the graphics of Power SDR but never been able to use it. I finally found a video on youtube with explanations and managed in one afternoon to have it working. Like this:

it has also a waterfall option but here I made the snapshot while I was using just the spectrum.

The background of the spectrum can be whatever picture you like (here an old Hallicrafters model S38) as long as is in PNG format and is 1000 x 550. There's a tutorial from KE9NS on how to do this.

First the SDRUno has to be set in IQ out mode and the sampling rate of the Virtual Audio Cable has to be 192000, this will allow to see more or less 200 kHz spectrum on the powerSDR.

here below the setting in VAC and in Power SDR.

Every time one is changing the "slice" of frequency on SDRUno, the center frequency of the "new slice" has to be input also in Power SDR in the box "Center frequency" of the first settings picture above (where is written 16.750000 MHz) this will allow us to read the right tuned frequency also in PowerSDR dial.

Nooelec LANA HF amplifier

 I am using a chinese build RF LNA model RF AMP 03A 0.1MHz - 60 MHz, despite this description, it works up to 150 MHz @11dB declared gain. As written elsewhere is powered with a battery pack of 3A, when this is exhausted the recharging to full takes various hours.

The Nooelec LANA is powered with 5V DC with a miniusb which I connect to the USB charger of the laptop external screen.

I got the Nooelec today, paid 43 Euros on Amazon, the performances between the two are quite similar, both LNA are good in terms of noise, could be the Nooelec is slightly less noisy and shows some better SNR...but it's a matter of peanuts.

The disadvantage of the Nooelec is that swutching it off the signal doesn't pass aymore, while the chinese LNA lets the signal passing through without amplificaton, which is a quite comfortable feature, listening with amplification is not always better than without.

Willing to suggest one or the other, I could not figure out what to say. Surely the Chinese is less expansive.

More experiments with Youloop + HF LNA

 I have just bought on the web a rotating stand-display for the Youloop, with a remote control.

It's quite an improvement while using the youloop, since I do not need anymore to stand from the chair to rotate the loop. I paid it 26 euros.

After getting the "rotor" and after putting the loop into a ridging plastic pipe, I decided to paint it with a solid army-green spray paint, it provides all the thing with a nice "rugged" aspect. I have been working with this set up quite a lot from MW to SW.

It's coupled wih a HF LNA working with a rechargable battery pack of 3 Amp, this way it feeds the Airspy HF+. I have noticed that the HF LNA on some bands brings in FM broadcasting noise, no issue: I still have a notch filter for FM band which I bought for few euros on the web. With this all the spurious signals from FM broadcasting have disappeared.

Here the notch filter connected to the HF LNA, the brand is not visible but the label just says: "Band reject 88-108 MHz"

However: what is surprising me, which is the reason to make this post, is the deep null of the Loop on every band ad the ability it has to reduce man made noise from neighbours.

Here the effect of rotation showing null and noise reduction on WRMI 9395 kHz eralier this morning (around 8 UTC):

Beaming the loop NW - SE the reception is stunningly clear with a SNR of 38, having the noise floor lowered down to -95dBFS

Beaming the loop E-W, WRMI signal gets burried in the noise with a SNR of 25, the noise floor rises to - 75 dBFS.

This Youloop is is becoming more and more interesting. One just needs to give it more attention and a chance. The LNA helps a lot.

posts comments from readers

I have realised few days ago that I have hundreds of comments from readers that I never moderated and never read/published before. I have to honestly admit that I never went into the comments box to make a check simply because I have never seen that option in the menu of the blog.

I really apologise with everyone, many interesting comments some date back to 2016, I am not going to publish all of them, but I have just released the most recent ones.

Sorry gain for this, I will check with more attention in the future.

Anello per Youloop

Mi è sempre sembrato complicato lavorare con la Youloop dal momento che è un antenna costruita con semplice cavo coassiale.

Ho pertanto deciso di inserirla in un tubo in polietilene rigido da irrigazione con diametro 1 pollice, Il tubo è fissato in una scatola per usi elettrici. Questo assemblaggio lo tenevo in garage ed era una vecchia loop per onde medie he avevo costruito anni fa e che non utilizzavo più.

Per darle un po' di "sprint" l'ho collegata ad un amplificatore alimentato da un powerbank da 3A; è un amplificatore low noise e ad ampio spettro da 0,1 a 60 MHz che avevo acquistato in rete un paio di anni fa.

il risultato finale, visibile nella foto qua sotto, permette ora di manovrare e direzionare la loop in interno con maggiore facilità. Attualmente è collegata con il Malahit SDR V3 in DSC su 8414.5 kHz in contemporanea con un ATS25 a 8414.5 kHz collegato alla end fed esterna da 25m. E' un confronto un po' impari, ma fra qualche ora vedremo su anche la Youloop amplificata si comporta con onore.