ic705suite: tuning the antenna from the rooftop with a phone

Goal achieved

Go up to the antenna just once and, with nothing but the phone in my hand, get the SWR right with nobody's help: sweep and adjust until it is as good as it gets.

The suite, in a nutshell

ic705suite brings what I use with the Icom IC-705 into a single console program. One connection to the radio and, on top of it, the applications, each on its own function key:

Rig view (F2): the whole front panel, the meters and the band scope with its waterfall.
CW (F3): decoder, skimmer and keyer.
Antenna (F5): SWR and noise sweeps, and a page for the phone.
Logbook (F6) and Packet (F7): hamrlog and hamrpkt.

The ic705suite dashboard in the terminal, in English and with the simulated radio: on the left the applications with their function keys, from F2 IC-705 View to F7 Packet, and under them the quick log with today's contacts; on the right the radio (7.030 MHz, 40 m, CW, S6, receive only), a small band scope with its waterfall, the basic settings (frequency, band, mode, power, AF, RF, SQL, AGC, preamp, attenuator and filter) and the station; at the bottom, the messages. Top right, what the suite takes: CPU 9 %, RAM 112 MB. — The dashboard, with the simulated radio. Each application opens on its key and, without leaving it, you see the radio with a small band scope, change the basic settings and log a contact. All from the keyboard: `Tab` goes from one window to the next.

A minute through the suite, keyboard only: a contact in the quick log, CW with its skimmer, the rig view and the logbook, and back to the dashboard.

Like hamrlog, it is driven by the keyboard alone and runs even on the plain Linux console, with no desktop. The applications share the connection, so the CW decoder can keep listening while a sweep runs. But what I want to talk about is the antenna.

Before: up, down, up again

The HF antenna is on the rooftop and the radio is downstairs. The antenna is tuned by moving its coil, and the SWR can only be seen on the radio. So tuning was a walk: go up, move the coil a little, go down, transmit, read the SWR, go back up, move it a little more… until it was right or until I had had enough of the stairs.

And every trip down only brought back one number: the SWR on whatever frequency the radio was on. Whether the resonance was below or above, and how far, I could not tell, so the next adjustment was guesswork again.

Now: the phone in my hand

The suite serves a web page on port 8705. I open it on the phone, go up to the rooftop and from there:

What happens on each sweep. The numbers in the drawing are the steps:

From the phone, at the top of the ladder, I ask for an SWR sweep. The request goes over WiFi to the PC.
The PC drives the IC-705, also over WiFi, one frequency at a time: it tunes it, keys the PTT and reads the SWR.
At each point the IC-705 transmits a short, low-power carrier that goes up the coax to the antenna.
The PC finds the dip of the curve and sends the phone the resonance and the verdict: raise or lower the coil, and by how much.
I move the coil with my other hand and go back to step 1 until the SWR is right. Then I save the setting and go down.

I choose the band with a button. Each band comes with its target frequency (the FT8 one; on 40 m, 7.074 MHz) and a sweep step.
I start the SWR sweep. Downstairs, the radio steps across the band with a low-power RTTY carrier and measures the SWR at each point. The curve builds up on the phone's screen.
I read the verdict. The suite finds the dip of the curve, says where the resonance is, how far it is from the target and whether to raise or lower the coil. With the band's history it also works out how much, to a quarter of a division on the scale.
I move the coil and sweep again. Without going down. A 40 m sweep takes a few seconds.
I save the setting once the SWR is right: the coil position, the resonance and the SWR are kept for that band and that antenna. Next time I know where to leave it, and the suite uses those settings to refine how many kHz each division moves the resonance.

The Antenna application in the terminal, connected to the IC-705 over WiFi: on the left the bands, with the setting saved on 40 m (position 12.2, resonance 7.095 MHz, SWR 1.17); on the right an SWR sweep from 7.000 to 7.200 MHz as coloured bars, with the resonance at 7.105 MHz, lowest SWR 1.97 and the verdict “Raise the coil”, about 0.25 divisions. — **Antenna** (`F5`) in the terminal, with the real radio over WiFi. On the left, the setting I saved this morning on 40 m; on the right, a sweep from this afternoon: resonance 31 kHz above the target and the advice to raise the coil a quarter of a division.

The same afternoon sweep, on the phone (in Spanish). This is the page in dark mode:

The antenna page on the phone, in Spanish and in dark mode: the active antenna, Komunica HF-PRO-2-PLUS-T; the band buttons with 40 m chosen; the 7.074 MHz target; the SWR sweep and noise sweep buttons, and the verdict “Raise the coil” with the resonance at 7.105 MHz, lowest SWR 1.97, +31 kHz off target, SWR 2.09 on the target and 150 kHz per division. — Top: the antenna, the band and the target, both sweeps and the verdict.

Further down the same page: the verdict, the sweep curve from 7.000 to 7.200 MHz with the target and resonance lines, and the table of settings saved on 40 m: 10-10 12:04, coil 12.2, resonance 7.095, lowest SWR 1.17. — Further down: the curve and the settings saved on the band, with this morning's.

There is also a noise sweep, which does not transmit: it looks for where the noise floor rises, which is where the antenna resonates. It gives an idea without putting out any RF, although the SWR shows it much better.

This morning

A Komunica HF-PRO-2-PLUS-T on 40 m, aiming at 7.074 MHz. All of it from the rooftop: 31 sweeps between 11:06 and 12:04, without going down once.

Some of the morning's sweeps, from the suite's history
Time	Lowest SWR	Resonance
11:06	5.22	below 7.000 MHz, outside the sweep
11:22	2.20	7.011 MHz
11:43	2.25	7.171 MHz, now above
12:03	1.17	7.095 MHz

At first the resonance was below the band and the sweep only saw the slope: the suite says so, "at the edge", and gives the direction but not the distance. From there it was a matter of closing in, overshooting and coming back. At 12:03 the curve had its dip at 7.095 MHz with an SWR of 1.17, and below 1.5 on 7.074, which is what counts. I saved the coil at 12.2 and went down. Once.

The antenna page on the phone, in Spanish: SWR sweep and noise sweep buttons, the verdict “Raise the coil” with the resonance at 7.095 MHz, lowest SWR 1.17, +21 kHz off target, SWR below 1.5 from 7.027 to 7.174 MHz, and the sweep curve. — The page on the phone, on the rooftop, at 12:04 this morning (in Spanish). It still suggested another quarter of a division, but with the SWR below 1.5 from 7.027 to 7.174 MHz the FT8 frequency was already inside.

Carefully

Letting a web page make the radio transmit calls for a few precautions, and the suite has them:

Receive only by default. Unless the suite is started with --tx, no command able to key the radio leaves the computer. Without --tx there is only the noise sweep.
Low power. The SWR sweep transmits at the power percentage set in the configuration (30 % by default).
PTT watchdog. Each point of the sweep is a short transmission, and if anything hangs the radio stops transmitting after 2 seconds.
Everything goes back. When the sweep ends, the radio gets back the frequency, mode and power it had.

And each antenna keeps its own history and saved settings, so there can be more than one, and the active one can be chosen from the phone.

ic705suite on GitHub hamrlog, without a mouse