One point could not reveal the curve. Scaling 207 = 100 W straight down read
30 W where the radio showed 10, and 75 where it showed 50 — wrong everywhere
except at the single point it was fitted to.
Three readings taken against the rig's own display give the shape:
raw 62 → 10 W
raw 155 → 50 W
raw 207 → 100 W
Interpolating between them reproduces the radio exactly at those points and stays
close in between. I did not fit a formula: three samples can be made to support
several curves, and the operator can check a table against their own meter.
Above the top the last segment's slope continues rather than clamping, so a rig
driving an amplifier does not sit pinned at 100 W. A test pins the measured pairs
and the monotonicity, so a later change that breaks them fails against the radio
rather than against taste.
A quarter-per-poll decay covers the milliseconds between CW elements but not the
gaps that matter on the air: between the words of a CQ, in CW as in SSB, the
meters genuinely read 0 for most of a second and the bars fell with them.
A peak now stands for 1.5 s before it starts to fall, and still rises instantly —
a needle goes up fast and comes down slow. The SWR RATIO is not updated at all
from a zero reading: showing 1.0 during a word gap is worse than showing a stale
figure, because it looks like good news.
A test caught a real defect on the way: the proportional decay stalls on
integers. With the needle at 13 and the truth at 10, a quarter of the gap rounds
to zero and the meter sat three units high for ever. It now always steps down by
at least one, so it converges.
A second measurement at a known mismatch settled both the index and the scale.
At SWR 1.1: RM6=0. At SWR 1.5: RM6=52, while RM4 kept tracking the power.
52/255 = 0.204, which is the reflection coefficient of a 1.5 SWR to three
decimals. So the raw value is rho scaled to 255, and the ratio is
(1+rho)/(1-rho) — physics, not a curve fitted through two points, which is why
2.0 and 3.0 fall out of it correctly without ever having been measured.
The panel now shows that ratio, the number the operator reads on the rig, rather
than a percentage of meter travel — and a dash while receiving, since a stale SWR
from the last transmission reads as a live one.
Both measurements are recorded in the code and in a test, so the mapping is
evidence rather than a table borrowed from another model — which is exactly how
it came to read 81 in the first place.
Reported on the FTDX10: listening on 14.244 with VFO B still holding 18.115 from
an earlier session, pressing SPLIT threw the transmitter onto another band. The
button only flipped the rig's split flag, and the other VFO is stale by nature —
the only transmit frequency that makes sense is one derived from where the
operator is listening NOW. SPLIT therefore places the TX VFO too: up 1 kHz on CW
and the data modes, up 5 kHz on phone, the offsets operators actually call. The
+1k / +5k buttons remain for anything else, and a test pins the mapping.
The panel also drew its own flat meters while the Flex and Icom consoles use the
shared LED-segment MeterBar. Two instrument styles in one application is just
inconsistency — it now uses the shared component, and the local one is gone.
And the three consoles are named alike: "Flex Console", "Icom Console", "Yaesu
Console", in the tabs and in the Main-view pane list, in both languages.
rouggy