I am trying to find out whether the encoder ordered does not exactly match the one mentioned here.
The ALPS EC12E2424407 often mentioned here differs from my ordered, if at all, only a little bit from the mechanical properties
and dimensions but it should be the same from the electrical side (I hope ...)
It is an Alps STEC12E08 rotary encoder, 24 pulses / 24 detents, vertical.
Find only a very bad datasheet of this STEC12E08 ...
And I already had doubts because the STEC12E08 is funny to buy only from a single dealer across the country
and this type does not even appear in the manufacturer list on the Alps website ...
Not even Mouser or Farnell think of this type.
Reichelt is using an extremely old part number.
It looks like the part was originally STEC12E08. Sometime in the 2000s, Alps renumbered its encoders, and it became the EC12E2424407. Later, it was discontinued, which is why it's not found on any modern Alps datasheets for the EC12 series.
I've attached below an older EC12 series datasheet that includes the EC12E2424407, as well as a 20 year old Alps catalog that lists the STEC12E08.
I am trying to find out whether the encoder ordered does not exactly match the one mentioned here.
The ALPS EC12E2424407 often mentioned here differs from my ordered, if at all, only a little bit from the mechanical properties
and dimensions but it should be the same from the electrical side (I hope ...)
It is an Alps STEC12E08 rotary encoder, 24 pulses / 24 detents, vertical.
Find only a very bad datasheet of this STEC12E08 ...
At the moment it is not quite sure whether I might have caught a defective encoder when ordering.
As it is now, I cannot leave it. 50% of menu items can only be selected between two stop points ...
No, it's not broken, it's just the wrong part for your scope.
But why do I have the problem that two menu items are jumped per click?
Unfortunately I had not tried the encoder with the older firmware.
Since the update to 04.04.04.03 I have not come back to the previous 00.04.04.04.02 to test the encoder.
For whatever reason, it looks like Alps used to make lots of 1:1 detent-to-pulse ratio encoders, but little by little moved entirely to 2:1.
It appears that Rigol changed from 1:1 THT encoders in older boards to modern, probably 2:1 SMD encoders in newer boards. If you put a 1:1 encoder in a circuit expecting a 2:1, you get twice as many pulses per detent, causing the software to move twice as fast as you wanted.
For the original THT board: I'm a bit puzzled by the fact everyone is using EC12 series encoders in a board that clearly uses EC11 series originally. For a given shaft length, the EC12 is 0.5mm taller than the EC11, which explains why the knobs sit proud when using an EC12.
---- Edit ---
From what I can tell, for everyone with a board using the 1:1 THT encoders, the optimal Alps part number is STEC11B13 (EC11, 20mm shaft, with button, 20 detents, 20 pulses; AKA EC11B20244), and the equivalent Bourns (which is an active part) is PEC11L-4120F-S0020 (PEC11L, 20mm shaft, with switch, 20 detents, 20 pulses).
For those with a 2:1 SMD encoder board, it'd be one of the following Alps models:
EC11J0924411
EC11J1524413 <-- probably this one
EC11J0925403
EC11J1525402
Those differ in number of detents/pulses (# of pulses in red) and button travel (in green, 4=0.5mm, 5=1.5mm travel). My guess is that 0.5mm travel is probably the right one, but I don't know whether 9 or 15 pulses is better. AFAIK, either will work, just at different speeds obviously. Given that Bourns only makes this in a 30-detent/15-pulse version, my hunch is that the second one (in bold) is likely what Rigol is using, insofar as the Chinese clones will also probably be of the most widely available type. The equivalent Bourns part is PEC11S-9220F-S0015.
As detailed in a reply below, it turns out that they measure the shaft length differently on the plastic-shaft encoders vs. metal-shaft ones.
The plastic ones include the body, the metal ones do not, adding 5mm length. Bourns carries both the THT and SMD metal ones in the needed 15mm height, but the SMD one doesn't seem to be in stock anywhere. Alps doesn't even have part numbers for them.
So here's the updated info.
From what I can tell, for everyone with a board using the 1:1 THT encoders, the optimal encoder is the Bourns
PEC11L-4115F-S0020 (PEC11L,
15mm shaft,
with switch,
20 detents,
20 pulses).
For those with a 2:1 SMD encoder board, it'd be Bourns part
PEC11S-9215F-S0015, which nobody seems to have in stock.
--- /Edit ---
I've attached the current Alps and Bourns datasheets, too.