IC-7300: more antenna connectors with Arduino!

Posted in Electronics, VHF with tags , , , , on 12 April 2017 by iw0ffk

I wish to use the IC-7300 on all my bands, but the problem with this rig it’s always the same: too much frequencies for a single antenna connector and I don’t want to swap the coax all the time. On the market there are manual coax switches, but there are not so handy for a remote use…and this one is cheaper.

So, in a rainy Sunday I have built this 1×3 antenna switch controlled by Arduino. I already done something similar in 2009 with a PIC, this time I choose Arduino because it does not need of any programmer to write the code on it, just the USB cable. In the past several OMs have sent their empty PICs to me and I have sent them back programmed. A single project usually don’t worth the cost of a PIC programmer.

This should stops the foot traffic, everyone can load the code in the IDE and write it into the chip with a click.

This 1×3 ant switch is made with few generic electronic components around a “Nano” (ATMEGA328), but the code can be adapted to any ucontroller. It is powered by the transceiver (pins 2 and 8 of the ACC connector) and reads the frequency from the “Remote” jack. It can be fixed directly on the antenna’s connector by using a male-male PL259 adapter. Into the RF box there are three Finder relays model 41.52.9.012.5010 with gold plated contacts. The values of attenuation and isolation between the ports are good:

28 MHz – att. 0.11 dB – isol. 40 dB
50 MHz – att. 0.11 dB – isol.35 dB
70 MHz – att. 0.12 dB – isol. 32 dB

The microcontroller and the rest of the parts are in a separate box to avoid interferences.

The IC-7300’s range of frequency 30-74800 kHz is divided in 24 sub-bands, every sub-band can have associated one of the three antennas output. The right antenna is selected automatically. Simply it remembers the last selection.

IC-7300_CI-V_ANT_Multiplexer

Ask me the source code to my qrz.com address.
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Icom IC-7300 RX Antenna mod

Posted in Electronics with tags on 11 March 2017 by iw0ffk

I like this transceiver, good receiver, fantastic DSP filtering and NR, excellent GUI and many goodies like the automatic record of QSOs triggered by ptt/key or the RS-BA1 software that shows the waterfall on the PC screen (it works ok also in Linux wine).

Probably Icom has decided to limit some capability of this model for market reasons. The IC-7300 has only one TXRX antenna connector and no RX input, but it’s easy to add a connector on the back and, inside, there is enough room to place a coax relay.

The relay can be mounted on a shaped aluminium bracket fixed to the transceiver by two screws that fix the RF-UNIT board to the chassis.

The adapter has been made with a female TMP connector and a SMA-M to SMA-F transition (used as a wear protection for the connectors of the instruments).

The external ATU supply connector can be moved away, like on the IC-756, and replaced by two pieces of copper pcb board that holds the switch and the coaxial connector.
The orange wire of the ATU is used to energize the relay.

This mod is fully reversible and the transceiver can return in his original status in few minutes.

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Now the IC-7300 can be used also as a second receiver for the 6m or for monitoring the IF of the FT-817, connected to the 3cm transverter.

Remote station update

Posted in VHF on 5 February 2017 by iw0ffk

A brief report of the changes in the remote station system.

The relays to control the mains of the whole station and the PSU of the linear amplifier have been replaced with solid state relays like this one:

ssr

The relays are controlled via WiFi by an ESP8266, I added a small display just to monitor the temperature of the amplifier and to read the IP address.

esp

Some update has been made also on the web interface:

Hacking the Spectrum Analyzer Siglent SSA 3021X

Posted in Electronics on 29 January 2017 by iw0ffk

ssa3021Last year  in the laboratory where I work we bought two Siglent SSA 3021X 2.1 GHz Spectrum Analyzer for generic/every day use. It’s a nice cheap object with all the functions of a modern digital instrument: colors, memory and math for traces, ethernet access, usb drive support etc.
After a while I found some bug in the software (v 7.03), as example if a screenshot image is saved in the internal memory with spaces in the filename, then it’s impossible to delete….
So I googled for a firmware update and casually found a thread on EEVBlog’s Forum where a guy shared the root’s user/password to log in the instrument with a telnet client. :-)

The big brother of the SSA3021X is the SSA3032X 3.2 GHz SA that has the same hardware of the SSA3021X. The instrument works on Linux, Busybox is running, and it’s an easy job to edit a configuration file and upgrade the SSA3021X to SS3032X with all the options enabled (tracking generator included) and extra BW filters 1Hz and 3MHz (!!!)

This works with installed firmware version 7.07, probably Siglent has corrected this bug on the newer firmware releases, but for sure I don’t need further updates on these units…

ssa3021x_to_3032x

10GHz update + first “DX”

Posted in VHF on 15 December 2016 by iw0ffk

The annoying difference of frequency between TX and RX has been solved by stabilizing the supply of the local oscillator with a DC-DC converter. There was a small voltage drop due to the high current of the TX-RX coaxial relays (600 mA…)

First test with Silvano I0LVA, QRB about 50 km easily worked in SSB also with minimum power (50mW).

The surprise was during the Vecchiacchi Memorial Day of 4 December, Cesare I6XCK in JN63QO QRB  of about 215 km with the mountains in the middle, worked in CW directly, no RS. I received I6XCK with a clear 529 for the whole duration of the sked, but I had to wait a bit and repeat the report/number/locator several times to complete the QSO probably due to about 10dB of difference of RF pwr. I think a PA is needed…

jn61fs_jn63qo

I’m always free for any reasonable sked on 3cm.

10 GHz, state of play

Posted in VHF with tags on 17 November 2016 by iw0ffk

Over the past few months I acquired some parts needed to complete the Eyal Gal transverter. I had to build the filter placed just after the TX mixer that has been done by using 15mm pipe caps.  The local oscillator feeds the two mixers (TX and RX) with a 6dB directional coupler and a buffer amplifier.

The sequencer has been made with a simple circuit (IK5ZWU) and adapted to the Eyal Gal. The signal “TX Inhibit” is used to avoid any RF coming from the FT-817 during the changeover. In RX the Eyal Gal’s amplifier is disabled and his gain is set to the minimum.

txrx_seq_pcb_01

20161112_164036_hdr

The “ALC” level sets the gain of the output amplifier. With the FT817 set to maximum output power on 432 MHz, about 4 Watts (total input attenuation is 37dB), the trimmer R11 is regulated to obtain little more than 1 Watt on 10G. By lowering the FT817 driving power to 2W, 1W, 500mW, the 10G power will be lowered to 600, 250 and 50 mW

Up to now I had only one SSB QSO, with IK0EQJ, and I discovered an annoying difference of some kHz between the RX and TX frequency. Probably I have to separate the power supply of the local oscillator from the transverter.

First steps on 3cm band

Posted in VHF on 16 September 2016 by iw0ffk

Two years ago in 2014 I bought from an Israeli surplus store an Eyal-Gal unit, model 6075 with range 10.0 – 10.85 GHz. This module has a LNA and a mixer for the RX path and an amplifier with huge gain and discrete power for the TX. It needs few other parts to become a complete transverter: local oscillator, mixer, bp filter and two relays for the TX/RX changeover. For the local oscillator I used a 100 MHz OCXO with a crystal at 99.36 MHz, manufactured by Eisch-Kafka Electronics, as a reference for a PLL-DRO to obtain 9936 MHz. This permits to convert 10368 MHz to 432 MHz and use the FT817 as IF.

Here the module tested in RX and TX in the LTG lab:

 

Finally this summer I had the time to install the dish on the roof, an old tv-sat 85cm dish and a feedhorn.

20160905_19_55_01
I still need some parts to complete the TX section, but at least I can receive and testing the band.

For now I received 4 beacons directly IQ0RM/B JN61fw, IW0REF/B JN62hj, IQ0AH/B JN40qw, IT9CIT/B JM67lx and IQ5FI/B in rain scatter.