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121.5 auto select

Started by Magoo, Sat, 3 Jun 2023 13:09

Magoo

Hi Hardy,
I've noticed that when I tune 121.5 on STBY on the left radio panel, and the left radio volume switch is turned off, as I switch to activate 121.5, the left radio volume switch turns itself on as you would expect by design, but when you deselect it, the left radio volume switch stays on, which it doesn't in real life as far as I can tell. I realise this is some serious nit picking but I know your work is of such high standard I would think you'd be happy to know.
I'm very great-full for you hard work!

Hardy Heinlin

Hi Magoo,

I didn't know that it should return to the previous volume switch.

So the real box remembers the previous setting as long as you don't change it while 121.5 is active?


|-|ardy

John H Watson

The automatic function is to select all receivers
Quote from: Magoo on Sat,  3 Jun 2023 13:09the left radio volume switch stays on, which it doesn't in real life as far as I can tell.

It's been 10 years since I played with this stuff on the real aircraft, so I'm not going to rely on memory. I found some details in a workshop manual in relation to the emergency frequency, but it doesn't really clarify the issue.

The selection of the emergency frequency to the Active Window sends out a constant signal (earth) to the other panels to turn on the rxr lights when the emergency frequency is selected, so it may be true that in the absence of the signal, the panels return to their normal (previous) states. Is it considered to be a state held in "memory" or is it more a case of the removal of an "override" signal"? In the latter case, perhaps a logic "OR" gate?

Quote"M. Transfer Button/Emergency Frequency Command Test
(1) Energize the panel.
(2) Push VHF1 button.
(3) Set the STANDBY frequency to "121.50".
(4) Push Transfer button:
(a) Make sure frequency value previously shown in ACTIVE display is now shown
in STANDBY display.
(b) Make sure "121.50" frequency value selected in STANDBY display is now
shown in ACTIVE display.
(c) [Referring to bench test equipment:]Make sure lamp connected to J1-16 (Emergency Frequency Command) comes
"ON". [I think this refers to the data sent to the other panels]
(5) Push Transfer button.
(a) Make sure "121.50" frequency value shown in ACTIVE display is now shown in
STANDBY display.
(b) Make sure lamp connected to J1-16 (Emergency Frequency Command) goes
"OFF".
(6) De-energize the panel.

(12) EMERGENCY FREQUENCY COMMAND (J1-16): OUTPUT
RTP drives and maintains in a LO state for this discrete output while 121.50(0) is the active frequency for the on-side VHF radio. During Panel Off mode, OPEN/GND
status of this discrete is maintained in the last prevailing state.

C. Emergency Frequency Command (121.500 MHz)
(1) While an RTP is tuning its on-side VHF radio to 121.500 MHz (121.50 in the ACTIVE
window), the RTP puts and maintains a LO to EMERGENCY FREQUENCY
COMMAND output discrete. Otherwise, this output discrete is OPEN.
(2) Even though an active frequency of 121.505 MHz causes the same tuning data to be
encoded (into the ARINC 429 output of the RTP) as would be for 121.500 MHz, an
active frequency of 121.505 MHz will not put a low on the EMERGENCY
FREQUENCY COMMAND output.

Even the workshop manual doesn't show the schematics for this system. It just says replace an internal circuit board if this function fails.

Do any cockpit simmers have some real Gables panels with this feature? Energising one panel should should at least tell us if the onside panel behaves one way or another.


Hardy Heinlin

Is it all possible to select a "non-121.5" listen-channel while 121.5 is active?

If it is possible, this will probably terminate the auto-select status.

John H Watson

Quote from: Hardy Heinlin on Sun,  4 Jun 2023 05:57Is it all possible to select a "non-121.5" listen-channel while 121.5 is active?

The receiver light will always be lit on all 3 RCPs if any RCP has 121.5 as an active frequency. All crew stations must listen to the frequency if it is active. I don't think, however, that the volume is locked. You could, if you didn't want to listen to it, turn down the volume. You would be still be free to transmit and receive on any frequency (on the other two VHF radios) and on HF, Int, PA, CAB). 

All RCP receiver buttons can be pushed (at the same time). It just gets a bit noisy.

Do flight crews ever (normally) make the emergency frequency active and not just leave it in the Standby window? I have found myself in a cockpit at the gate on a foreign aircraft where it was active, but I don't know if that was a special circumstance.



Hardy Heinlin

I see. As you wrote above, it must be a logic OR function.

Green = "User-selected" OR "121.5"

Magoo

We always have 121.5 tuned in the right radio with the local ATIS on STBY as SOP's.
Yes you can turn the volume down on 121.5 and not listen to it if you want but as long as it is an active frequency the volume rotating switch will always light up, even if not selected on, once you switch to another frequency, if that switch was not selected, it will go back to off.

Hardy Heinlin


Magoo

Hi Hardy, I've just tried the new version but now the volume button doesn't light up when selecting 121.5 if it was off.

Hardy Heinlin

Can you be more specific? I see no problems.

Magoo

Yes you are right Hardy, it's working great now, many thanks.

Avi

Hi,
I set 121.500 as the active frequency but I don't see any green light in any audio control panel (v10.171 of course).
What am I missing here? What do you mean by "auto select"?
Avi Adin
LLBG

Hardy Heinlin

Hi,

"autoselect" green light.

Is the related option selected on your Models > Equipment page?


|-|ardy

Avi

No   ;D

(I asked what I'm missing here  :) )

Thanks,
Avi Adin
LLBG