Tag Archives: Georges (F6DFZ)

Georges creates an IARU S meter scale for his Belka-DX

Many thanks to SWLing Post contributor, Georges Ringotte (F6DFZ), who writes:

When I did tests on my Belka-DX, I noticed that the signal level scale was extremely accurate, each mark is 10 dB

I regretted that the manufacturer didn’t use the IARU S meter scale. So I decided to make my own. With RF Gain to the maximum sensitivity, -73 dBm, or S9, is at the 45 mark. I used Front Designer software to make a scale, with 10 dB graduations above S9, and 6db graduations below S9.

Then this scale was printed on water based transfer, 40 mm by 26 mm, when applied on the existing display.

The result is great, and now I have precise readings of signals reports.

That’s brilliant, Georges! Golly..it looks stock when applied to the screen! Thank you for sharing this!

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Georges repairs and enjoys this vintage Hallicrafters SX-130

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Many thanks to SWLing Post contributor, Georges Ringotte (F6DFZ), who writes:

Recently my “radio brother” Bruno F6CRN gave me a vintage Hallicrafters SX-130 from the mid seventies. The receiver was extremely nice for a 55 years old rig, had never seen a soldering iron for repair and had original Hallicrafters tubes but was not performing very well.

After some research , I found a solder joint between 2 pins of a tube support, and this solder joint was done during manufacture!

After alignment, the receiver performed relatively well for that kind of somewhat low cost receiver.

These low to mid cost receivers, made by Hallicrafters, Hammarlund and National are single conversion design, with a low frequency IF near 455 kHz or 1.6 MHz. Their frequency calibration is rather poor, they drift, and have poor image rejection, but can perform reasonably well on AM, and also on SSB and CW on the lower bands. Generally, these American receivers are powered on 117 VAC, have no built in speaker, and the crystal calibrator was optional or an outboard accessory.

To use it, I decided to built a small console with an isolation transformer to reduce the European mains from 230 to 117 VAC, a good quality 4 ohms speaker, and a 1 MHz calibrator Manhattan style.

With this console, the receiver looks great, give a taste of the few remaining broadcast stations and warm the shack.

Oh wow! What a beautiful SX-130, Georges! What a great friend you have in Bruno.

Thank you for sharing!

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The new Belka-DX: Georges’ short review and tests

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Many thanks to SWLing Post contributor, Georges Ringotte (F6DFZ), who writes:

I received the Belka-DX a few days ago, and it appears to be an outstanding receiver considering its price, its size, and quality of construction.

AGC and audio reproduction are way better than any Chinese SW receiver giving some superb receptions in CW, SSB and AM.

I shall not repeat that other have said, but I must add that the AM2 pseudo synchronous reception seems good to my ears and a bonus with weak signals.

I made some measures :

MDS is about -127 dBm in SSB mode, slightly better in CW mode

Sensitivity is constant from 1.5 to 30 MHz

Image rejection is over 70 dB, better than a KX3 that I tested a few years ago

I couldn’t measure selectivity because my HP generator is somewhat noisy, but the Belka-DX is very good, and also way better than Chinese receivers

“S meter” is calibrated as follows: -107 dBm = 10 and -37 dBm = 80, and on this range a 10 change equal a 10 dB change, very accurately. Over -37 dBm, S meter doesn’t move any more.

Even on my 2x18m center fed or my Hexbeam, I didn’t notice any signs of overload, but as you know the propagation is not outstanding, and BCL stations are not as bothersome as 40 years ago!

there are a few birdies, but if you move your frequency 100 Hz away, they disappear

In my opinion, considering the superb quality of reception, this receiver is outstanding.

Best regards.

Georges

Thank you for sharing this, Georges! Sounds like the Belka-DX is a performer!

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Georges’ review of the XHDATA D-808

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Many thanks to SWLing Post contributor, Georges (F6DFZ), who writes:

After the first information from your wonderful website, I immediately ordered the XHDATA D-808 receiver from Aliexpress for €62 including shipment to France.

I got it very quickly, shipped from Amazon UK!

I did a few tests on SSB. MDS is outstanding, the minimum signal from my HP generator at -127 dBm (0,1uV), is strong even on 28 MHz. Selectivity is also good, and the opposite sideband rejection is audibly also good. However I was unable to measure it because the S meter give the same indication over a few kHz around the signal of the generator. I suspect the opposite sideband rejection to be done by the DSP chip at AF, but I cannot confirm this.

Reception is very good on FM, and the AF from the loudspeaker is reasonable. On headphones, it’s very good. RDS works as it should and sets the clock of the receiver.

I did only a few minutes test on LW and MW, and it seemed OK, even if I don’t have a lot of experience on these bands.

SW AM listening was very good; good audio, great selectivity. I suspect that the bandwidths given are AF bandwidths as even the most selective were not too much muffled. If it was IF selectivity, the AF bandwidths would have been half the values and much muffled.

SSB and CW reception are also very good even if the DSP chip has a long attack time and hence gives distortion during the beginning of each message.

About SSB: I think that this receiver is better than the [Tecsun] PL-880 and comparable to the PL-660.

Reception is good on the short but sturdy telescopic antenna.

If you connect the receiver to a large external antenna, you will encounter many IMD signals. As there is no built-in attenuator, you will need an external one.

The manual is correct, but very short about the memories.

ATS logs its findings into the first pages, so if you want to keep some memories, log them a few pages away.

The available pages are different with bands, FM has its pages, SW its pages etc…

Unfortunately, memories don’t keep the mode on SW–only the frequency and selectivity. After calling a memory, you will have to choose between AM, USB and LSB.

I was totally unable to light the “Preset” label on the display ?!?

Display and backlighting are very nice.

Somewhat odd, but the squelch seems to work sometimes on other bands than Air band !

Ergonomics are reasonable, quality of construction is good for the price.

Overall, for the price, this receiver is quite outstanding.

Best regards from France .

Georges F6DFZ

Thank you, Georges! Excellent thoughts on the D-808. Your note about squelch control working outside the AIR band reflects what the Digitech AR-1780 does as well–hinting that firmware is very similar.

I fully suspect the D-808 is on the path to being one of the best radio values under $100 US.

Merci bien, Georges!

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George demonstrates the Tecsun PL-880 tuning bug

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PL-880-Tuning-Bug

[19 January 2016: Please read this updated post.]

In response to Pawel’s post about a tuning bug affecting a recent batch of Tecsun PL-880s, SWLing Post contributor Georges (F6DFZ) comments:

I have posted a new video about this important bug of the PL-880.

I did so because it seems some people don’t understand this very important issue.

This video shows the Tecsun PL-880 tuning bug which is present on SSB when using the Fine Tuning knob.

The PL-880 is tuned to the Shannon Volmet on 5,505 MHz USB.

At the beginning, I use the coarse Tuning knob to shows the effect of tuning 1 kHz down ; the pitch of the voice increases as we are on USB.

Then, I tune down 1 kHz using the Fine Tuning knob, and now the pitch of the voice decreases, indicating the bug with the reverse tuning using the Fine Tuning knob on SSB.
At the end, I use the coarse Tuning knob to hear the voice with a normal pitch, and you can see that the displayed frequency is 5,503.01 MHz, a difference of nearly 2 kHz versus the true frequency.

Best regards, and a Happy New Year

Georges F6DFZ

Thank you, Georges. Since I have an early PL-880 model that doesn’t have this bug, your video and explanation does clarify the situation.

That is frustrating. Until this bug is fixed, I couldn’t recommend purchasing a new Tecsun PL-880. I hope someone can confirm when the bug is fixed and the production run is once again free of this tuning issue.

Many thanks to Pawel and Georges for bringing this to our attention.

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