Replacing the fuse F1002 in the FT-817ND

On last Saturday’s V-UHF contest I observed reduced output power on the 70cm band in my FT-817ND. I spent the next day poking inside the radio with the oscilloscope trying to see where the problem was. While doing this, at some point I completely lost output power in all bands. I found that the problem was that F1002, an SMD fuse, had gone open. Here I describe said fuse and the replacement procedure, which I found much easier than I thought.

Continue reading “Replacing the fuse F1002 in the FT-817ND”

Concurso Costa del Sol V-UHF 2016

Yesterday, my father and I hiked to Cerro de San Pedro, SOTA summit EA4/MD-020 (1425m), to work QRP in this month’s national V-UHF contest: Concurso Costa del Sol. Since the forecast for Sunday was rainy, I decided to go up on Saturday’s afternoon. The summit is a short hike from a nearby road. We arrived to the summit around 14:25UTC, so I could work in the contest for a bit more than two hours until we started packing at 17:00UTC before it got too dark.

Activity seemed a little low, although this is not surprising, given that the national RTTY contest was also running at the same time. I also get the impression that there is more activity on Sunday mornings. Nevertheless, my results have been better than in March’s contest. I did fewer QSOs, but got more points and worked more DX. In fact, I could work almost everybody I heard. In the map below, as always, my location is marked in red, the stations in blue are those worked only in 144MHz and the ones in green where worked both in 144MHz and 432MHz.

Continue reading “Concurso Costa del Sol V-UHF 2016”

Scanning Ku band satellites with the FUNCube Dongle

I’ve recently installed my satellite dish and modified LNBF in my garden. This equipment will be used to receive Es’hail 2, the first geostationary satellite carrying an amateur radio transponder. Here I’ll look at the hardware I’m using, how I did the alignment to the 25.5ºE geostationary orbital position where Es’hail 2 will be located, and how to have some fun scanning the direct broadcast satellites in the Ku band with a FUNCube Dongle Pro+.

Continue reading “Scanning Ku band satellites with the FUNCube Dongle”

Concurso Combinado V-UHF 2016

This weekend, being the first weekend in March, marks the start of the Spanish V-UHF contest season for this year. In previous years, I’ve been operating casually in some of these contests as a portable station. Sometimes I’ve worked on the countryside just outside my town, Tres Cantos, and on other occasions I’ve being enjoying the contest from a summit while doing a SOTA activation. My plan for this year is to participate in all (or almost all) of the contests and try to work from a summit as many times as I can. I pretend to work QRP (5 Watts) always and enter the 6-hour category, which allows working for a maximum of 6 consecutive hours.

Today, I’ve worked in the Concurso Combinado V-UHF. The weather forecast was too windy and cold to stay for several hours on a summit, so I decided to work from the countryside near town. I’ve worked this morning from 09:00UTC to 12:00UTC more or less. The equipment was, as usual, an FT-817ND and an Arrow satellite yagi antenna (3 elements on 144MHz and 7 elements on 432MHz). See below for a map of the stations worked. My position is marked in red, the stations worked in 144MHz only are marked in blue and the stations worked in both 144MHz and 432MHz are marked in green.

Continue reading “Concurso Combinado V-UHF 2016”

Calibrating the S-meter in Linrad

In a previous post, I talked about the GALI-39 amplifier kit from Minikits. Here I will describe the procedure to calibrate the S-meter in Linrad (or another SDR) using this amplifier or any other amplifier with a known NF and an uncalibrated signal source. Leif Åsbrink has a youtube video where he speaks about the calibration of the S-meter in Linrad. However, he doesn’t use an amplifier, so I will be following a slightly different procedure.

Continue reading “Calibrating the S-meter in Linrad”

Building the GALI-39 amplifier kit from Minikits

The GALI-39 is a DC-7GHz MMIC amplifier from Minicircuits. This device has a gain around 20dB and a NF of about 2.4dB. The nice thing about MMICs is that their input and output impedances are matched to 50Ω, so it’s quite easy to work with them. Minicircuits makes many MMIC amplifiers suiting different needs, but unfortunately their products are not so easy to get in small quantities.

Minikits.com.au is an Australian store that sells Minicircuits parts in small quantities as well as many interesting RF kits. I needed some RF amplifier having a known NF to do some signal level calibrations, so I ended up ordering the GALI-39 amplifier kit from Minikits. This kit includes just the GALI-39, a PCB and the handful of SMD components you need to bias the amplifier. At 22AUD, the price of the kit is about right and buying the kit instead of just the GALI-39 saves me to do the shopping for the assorted SMD components and using the PCB instead of botching some circuit is always nice, because the PCB uses microstrip transmission line (but the substrate is regular FR-4). Here I have a look at what is included in the kit (I’ve been unable to find a complete list on Minikit’s web).

Continue reading “Building the GALI-39 amplifier kit from Minikits”

An idea for a low cost stable 10GHz receiver

The satellite Es’Hail-2 is expected to be launched by the end of 2016. This will be the first geostationary satellite carrying an amateur radio transponder. As the launch date comes nearer, it becomes interesting to find a low cost solution to receive its 10GHz downlink.

Several amateurs have been experimenting with low cost LNBFs designed to receive satellite TV. These operate in the Ku band and usually cover the frequencies 10.7GHz-12.75GHz. However, many of these LNBFs have also good performance in the X band, and particularly in the amateur 10GHz band (10GHz-10.5GHz). In fact, the ASTRA-type LNBFs have a local oscillator which can be setted to either 9.75GHz or 10.6GHz. The 9.75GHz local oscillator mixes 10.386GHz (the narrowband terrestrial subband) to 618MHz, which is a frequency covered by most SDRs and conventional scanners. The satellite subband, which is 10.45GHz-10.5GHz gets mixed down to 700MHz-750MHz, a frequency which is also easy to deal with.

Continue reading “An idea for a low cost stable 10GHz receiver”

Building the G0MRF comb generator

A comb generator is essentially an RF oscillator whose output is amplified in a non-linear fashion, so that plenty of harmonics are produced. This is an easy way of producing microwave signals. The G0MRF comb generator was originally designed as a 2.4GHz signal source, to help in the alignment of receivers for the amateur radio satellite S-band. It has a 96.013MHz crystal oscillator, so its 25th harmonic falls at 2400.325MHz, right in the satellite allocation of the 13cm amateur band. Its harmonics are usable up to at least 10GHz, so this can be an useful tool when working with microwave equipment.

In fact, several other harmonics fall on the amateur bands: The 13th harmonic is 1248.169MHz. This is inside the 23cm amateur band, but quite far from the narrow-band segment, which is at 1296MHz. The 24th harmonic is 2304.312MHz. This falls inside the 13cm band. Indeed, 2302MHz is used for EME in some parts of the world. The 36th harmonic is 3456.468MHz, in the 9cm band, but far from the narrow-band segment. The 59th harmonic is 5664.767MHz, in the 6cm band. This is in the satellite uplink segment and quite near the first narrow-band segment, which is at 5668MHz. The 60th harmonic is 5760.780MHz, right in the second narrow-band segment of the 6cm band. The 105th-109th harmonics all fall in the 3cm band. In particular, the 108th harmonic is 10369.404MHz, which is in the narrow-band segment of the 3cm band.

This is a nice kit which is quite easy to build. Most of the components are through-hole, and it can be put together fairly quickly. I built my kit during the Christmas holidays, but I’ve had the PCB lying around until I installed it in a project box yesterday. Here I describe the kit briefly and show the extruded aluminium case I’ve used.

Continue reading “Building the G0MRF comb generator”

Band switching with the Hardrock-50 HF amplifier and the FT-817

The Hardrock-50 HF is a very nice kit for a 50W amateur HF amplifier covering the 160m through 6m bands. It supports interfacing with the FT-817. With the proper cable, the amplifier can be connected to the ACC jack on the FT-817 in order to do PTT keying and read the BAND DATA signal from the FT-817 to select the proper band in the amplifier’s low pass filter automatically. The connections required are shown in the Hardrock-50 Tech Site. Yesterday, I prepared the cable to interface my amplifier to my FT-817ND. However, I have found a problem in my amplifier that prevents automatic band switching from working properly. Apparently, this problem has been fixed in the newest units and can be fixed with an easy modification in the units which are affected.

Continue reading “Band switching with the Hardrock-50 HF amplifier and the FT-817”