Författare: Lars Thunberg

Kategorier
Amateur Radio

RTL-SDR v3 vs IC-705 FT8 RX

With an antenna RX splitter I did some fast compare between a simple RTL-SDR v3 SDR dongle and my IC-705 on 21 MHz and 14 MHz FT8. The RTL-SDR v3 is not original designed to run on HF, but with HF Quadrature mode it is possible to use it on HF.

And I was very surprised that this very cheap SDR could decode a lot of the stations that the far more expensive IC-705 did. The spectrum was cleaner from the IC-705 and more stations was decoded, but the results from the SDR was impressive because it is such a cheap and simple device.

Used equipment:

Cable mess
Cable mess during testing

All images below:

  • Left – RTL-SDR v3
  • Right – IC-705

PSKReporter map compare – 15 minutes RX on 14 MHz.

14 MHz

WSJT-X window. Cleaner spectrum from the IC-705.

WSJT-X screendump

Logbook from PSKReporter.

PSKReporter

Signals in dB from WSJT-X. The yellow reports are from the same station. I could notices some difference and RTL-SDR via SDR Console would often give higher dB values, but I have no idea why.

dB
Kategorier
Amateur Radio

New installation 50 MHz Oblong Januari 2025

New installation of the 50 MHz Oblong in Januari 2025.

Kategorier
Amateur Radio

432 MHz EME QSO

Some time ago now – but I made two EME QSOs with DL7APV (now SK) in February 2023. I used my 2* 15 el LFA X-yagi and 40 watt output from IC-9700.

See also my Tweet from this event:

Kategorier
Övrigt

2.2 GHz Helix

Some construction notes of my two 2.2 GHz Helix antennas I now using for my SatNOGS station and manual satellite RX.

The print scaffold set is from Dereksgc and i friend of mine did the printing https://www.thingiverse.com/thing:4980180

Construction notes from UHF-Satcom:
https://uhf-satcom.com/satellite-reception/s-band

The wire is from a RFC-400 coax cable center conductor – I just stripped one meter.

First set the wire to the printed support frame:

Then drill a hole in the reflector and mount a connector – I used both N-type and SMA-type.

In order to get good 50 ohm match I needed to solder a piece of copper tape according to the image below:

Then a lot of hot glue and UV protection spray to get it a little bit more water proof:

Finally mounted at the mast:

This is the SWR plot after mounting:

I can recommend Dereksgc Youtube channel for lot of videos about S-band antennas and RX:

https://www.youtube.com/@dereksgc

Kategorier
Amateur Radio

Internal and external LNA tests IC-9700

Some test with the internal LNA (P.AMP) of the IC-9700 and external LNA. What combinations will give the best SNR? Note that all tests are done without any type of professional equipment – only by looking at the waterfall and listening with my ears.

I have used my VHF and UHF yagis and external LNAs Mini-2 and Mini-70 mounted just below the antennas. I have aprox. 16 meters of high quality LMR-400 cables between the IC-9700 and antennas/LNAs.

VHF – beacon SK1VHF at 144.447 MHz

Without internal P.AMP and external LNANot possible to hear beacon
With only internal P.AMPPossible to hear beacon
With both internal P.AMP and external LNABetter SNR but needed to reduce RFGain to get good SNR
With only external LNABest SNR! No need to reduce RFGain.

Note on VHF: The difference between using both internal P.AMP + external LNA and only external LNA is not huge, but is clearly audible.

UHF – beacon SK1UHF at 432.405 MHz

Without internal P.AMP and external LNANot possible to hear beacon
With only internal P.AMPPossible to hear beacon
With both internal P.AMP and external LNABetter SNR but needed to reduce RFGain to get good SNR
With only external LNABest SNR! No need to reduce RFGain.

Note on UHF: Almost the same result as VHF, but the external LNA gives better result and SNR compared to VHF.

Summary:

If you do not have an external LNA it is mandatory to use the internal P.AMP on the IC-9700 for very weak signals.
If you have a good external LNA mounted close to the antenna it is best to turn off the internal P.AMP to get best SNR.

Kategorier
Amateur Radio

QO-100 SatRover fixed setup

Final fixed dish setup

This is my final QO-100 fixed setup with the SatRover:

  • SatRover Mk 1 from PE1CKK
  • 2.4 GHz Helix (as a part of SatRover)
  • LNB a part of the SatRover, feed with normal 75 ohms TV cable coax
  • 60 cm dish from Triax (TD64) branded as Canal Digital
  • IC-705 as TRX
  • 10 dB attenuator and a number of meters of Hyperflex 5 coax cable to make the output on 2.4 GHz at the Helix to aprox 100 mW (legal power limit in Sweden)
The SatRover combined 2.4 GHz TX Helix and LNB for 10 GHz RX
First test of fixed installation
Rear connections of the SatRover

SatRover and the IC-705
Frequency stability test with an web SDR receiver for full duplex and FT8. Very good!
Kategorier
Amateur Radio

50 MHz Oblong

April 2024 I made a 50 MHz Oblong according to this.

Some pictures from building and mounting on roof: