FLIGHT LINE FL-760A Instruction Manual

DISTRIBUTORS, INC.
FL-760A FREQUENTLY ASKED QUESTIONS
Q: My radio works fine but people receiving my transmissions say my voice volume is weak.
A: You may need to go into the Setup Mode (power the radio up while holding down the MOD
button) and toggle to the Mic Sensitivity screen and adjust the mic bias level up. The Mic
Sensitivity control range is 0 – 80 and is defaulted at the factory to approximately 60 as a starting
level, because there is no way of knowing what kind of headset and mic will be used by the radio
owner.
Electret mics are probably most common these days, but for louder aircraft cabins a headset with
dynamic mic may be a better match. These mics require different levels of bias and different
usage techniques. Electret mics are for quieter cockpits and can usually be whispered into and be
heard, while Dynamic mics are typically in louder aircraft (helicopters, open cockpit and fabric
aircraft) and require the user to speak louder to generate the best mic audio level.
We would advise adjusting the Mic Sensitivity level up or down initially by a factor of 10 to start
with (if voice is weak at a level of 60, try boosting to 70 and transmit to someone listening on
another radio). If further adjustment is needed, it may take several hit-n-miss attempts with
smaller adjustments to land on the optimum level for your headset/mic and airplane. A headset
with an amplified dynamic mic is preferred and a windsock on the mic is also advised.
Q: The sidetone level is too low so I am not hearing my voice loud enough in my own headset
when I transmit. The intercom volume is also low.
A: Like practically all aircraft ATC radios, the FL-760A incorporates a Sidetone Amplifier that is
activated when you press the PTT switch. At that point, your voice signal from the Mic Audio line
that is feeding the radio transmitter is also routed through the Sidetone Amplifier and then back
into your headset so you can hear what you are saying in the high noise environment.
The built in two-place intercom system (ICS) that is featured in the FL-760A is simply using that
Sidetone Amplifier as an intercom and giving you the option of turning it on via a voice activated
trigger circuit (VOX) or a dedicated ICS PTT (not to be confused with your radio PTT). The
Sidetone Amp is pulling “double duty” essentially - it always activates to provide Sidetone when
you press the radio transmit PTT, but when you are not transmitting on the radio, it acts as a VOX
activated ICS or a PTT activated ICS.
_________________________________
12830 E. Mirabeau Parkway, Spokane, WA 99216●[phone]
●LOCAL [phone]●FAX [phone]

DISTRIBUTORS, INC.
The ICS PTT could be a secondary button on a yoke or stick to activate ICS only, or a momentary
button on the panel that is pushed in to speak on the ICS and then released. PTT ICS works well in
louder aircraft (open cockpit for instance) and VOX ICS is tailored for quieter environments.
Bottomline – the Sidetone and ICS volume levels are one and the same. To adjust them, enter the
Setup Mode (hold down the MOD button while powering up the radio) and toggle to the “Audio
Level of Intercom” screen (Page 11 of the Operations Manual) and increase the value there. The
scale again is 0 – 80 and factory default is approximately 60.
Q: My FL-760A powers up and receives ATIS but will not transmit.
A: Check the connections/continuity between “Pilot PTT” Pin 7 on the radio connector harness
and the tab on the Pilot Mic Jack that corresponds to the Tip, as well as “Electret, Amplified
Dynamic (Pilot)” Pin 1 on the radio connector and the tab on the Pilot Mic Jack that corresponds
to the Ring of the Mic Plug. The tip is the PTT segment that gets grounded when you push the
radio PTT button. This triggers the transmitter to activate; the ring is what the headset mic audio
comes in on and that is sent to the transmitter to modulate it and allow your voice to be
broadcast over the radio.
If you sourced a prewired harness from a third party such as Aircraft Spruce & Specialty, we’ve
discovered that there may have been a number of harnesses sold in the Mid 2019 (estimate July-
Sept 2019)timeframe that had the tip and ring wires on both the Pilot and Co-Pilot Mic Jacks
swapped. PTT was tied to the Ring and Mic Audio was running through the Tip. This was wrong
and will result in no transmitting of the radio. If you investigate and find you have a mis-wired
harness sourced from Aircraft Spruce, please contact them for a replacement. They have assured
us any mis-wirings have been rare and they are anxious to make it right and make sure you are
satisfied as a customer.
In some circumstances, you can send in your harness for evaluation. The cost for the wire harness
evaluation is $35 USD.
_________________________________
12830 E. Mirabeau Parkway, Spokane, WA 99216●[phone]
●LOCAL [phone]●FAX [phone]

DISTRIBUTORS, INC.
Q: My FL-760A powers up and transmits but I have no sidetone, no ICS audio and no radio
receive audio.
A: Again, if you happened to source a pre-wired harness from Aircraft Spruce and Specialty
(estimate July-Sept 2019) we have seen at least a couple instances where they used Stereo
Headphone Jacks for both Pilot and Co-Pilot headphone connections. Check these jacks – if they
look very similar to Mic Jacks (they have tabs for Tip and Ring + Base) these are Stereo Jacks.
There is no Stereo aspect to the FL-760A. The correct headphone jacks should simply be mono
with a single tab for the Tip (+ Base). We found the defective harnesses had the headphone audio
line soldered to the Ring on the incorrect Stereo Jack and this was grounding the headset audio
when a Mono Headset was plugged in. Contact Aircraft Spruce if you confirm you have stereo
headphone jacks on your prewired FL-760A harness, as they will correct this issue and get you
flying.
Q: What is the “TOT” acronym in the Setup instructions on Page 11 of the Operations Manual
referring to??
A: TOT is essentially a “Timed Out Transmit” feature of the radio or sometimes known as a “Stuck
Mic” feature. The setting selections are OFF, 1 min, 3 mins, or 5 mins. If the transmitter is
activated and stays on due to a stuck mic situation, the radio will automatically release the
transmitter when it reaches the TOT time. Factory default setting is 5 mins.
Q: What is the “BLO” acronym in the Setup instructions on Page 11 of the Operations Manual
referring to??
A: BLO stands for “Busy Lock Out” and if turned on will not allow you to transmit if there is receive
audio detected in the radio. In other words, if someone is talking on the frequency already you
will be precluded from stepping on them because the FL-760A transmitter will be Locked Out until
the channel is clear and no receive audio is heard. We have all flown and monitored a CTAF
channel like 122.8 and are constantly hearing whistles and squeals from pilots stepping on each
other. The BLO feature of the FL-760A helps minimize and mitigate this. Factory default for BLO
is OFF.
_________________________________
12830 E. Mirabeau Parkway, Spokane, WA 99216●[phone]
●LOCAL [phone]●FAX [phone]

DISTRIBUTORS, INC.
Q: When using the internal intercom (ICS) for flight instruction, our ICS conversation is muted
each time there is radio chatter on the FL-760A. Is there a way to turn this muting off, or
reverse the priority so that radio chatter is muted when ICS audio is detected?
A: The short answer is no. Right now, the FL-760A is programmed to give ATC radio calls priority
over intercom communication inside the aircraft. We understand that in a flight instructing
environment, the opposite would be desirable. We are working with FlightLine engineering to see
if a feature enhancement is possible to make that priority selectable – either ATC Priority or ICS
Priority. We will keep you posted.
Q: The internal two place intercom (ICS) is turned on and creates noise when the cabin noise
level increases on takeoff or cruise. I turn the Squelch knob on the face of the radio but that
doesn’t fix it.
A: First of all, the concentric Squelch and Volume knobs on the face of the radio control the
loudness and the squelch threshold for the radio receiver and have no control at all over the ICS
squelch or volume.
What is happening in this case is your internal ICS is set for VOX (voice) activation and the
threshold is set too low. The VOX ICS is being triggered by the rise in ambient cabin noise when
you increase power for takeoff or cruise. This opens the ICS squelch, activating the intercom; that
makes the headset mics go “live” and the background cabin noise is amplified and heard in your
headset.
Both the volume and the VOX threshold for the ICS are adjusted in the Setup Mode and this is
covered in Section 6.6 User Settings on Pages 10 & 11 of the Operations Manual. The fix here is
to go into Setup Mode and find the screen that pertains to the VOX setting. The control range is 0
– 24 and factory default is 12. This will be another trial and error adjustment. Try setting it at 20.
If the ICS squelch still opens at takeoff or in cruise, take the setting higher. If the squelch remains
closed, but when you try to speak over the intercom, the first syllable of the first word is cut off,
or you find yourself speaking louder to trigger the squelch to open, roll it back a couple of
numbers. You need to find the ICS VOX Squelch “sweet spot” for your aircraft.
The volume adjustment for the ICS/Sidetone level was covered in an earlier question.
_________________________________
12830 E. Mirabeau Parkway, Spokane, WA 99216●[phone]
●LOCAL [phone]●FAX [phone]

DISTRIBUTORS, INC.
Q: I fly a single seat airplane and don’t need the internal intercom function. Can I deactivate it?
A: YES. Go to the Setup Mode (hold down the MOD button while powering on the radio) and find
the VOX adjustment screen. The adjustment range is 0-24 or OFF. Select OFF. This will
deactivate the ICS that is not needed in a single seat aircraft.
Q: I fly a two seat, open cockpit aircraft and it is too noisy for the VOX ICS to be used effectively.
A: You will probably want to activate the intercom via a PTT method rather than using VOX. To do
this, follow the Setup steps in the FAQ above to turn the VOX function OFF. Then wire a
momentary switch in a convenient place in the cockpit (yoke, stick or on the panel near the radio).
This will be your ICS activation button. You simply connect one side of the switch to Pin 5 labeled
“Intercom (Ground to Activate)” and the other side to Ground. When the button is pushed, it
provides a ground trigger to Pin 5 that activates the Sidetone/ICS amplifier in the radio and
provides intercom audio as long as the button is pushed. In a side-by-side, two place aircraft, a
single momentary switch on the panel labeled “ICS TALK” would work. In a tandem aircraft you
would need a switch at each seat location with both switches wired to Pin 5 on one side and the
other side to aircraft ground.
Q: I have a 4plc airplane and don’t plan to use the built in 2plc Intercom in the FL-760A. Instead,
I am going to wire in a third party, stand-alone, 4plc ICS or use the 4plc ICS that is integrated
into my chosen audio panel. Is the FL-760A compatible with this scenario??
A: Yes – simply follow the Setup steps in one of the FAQ’s above to turn the VOX function OFF and
don’t wire anything up to Pin 5 on the FL-760A and then just follow the MFR’s instructions for
wiring a standard COM radio into the third party intercom of your choice. If you need additional
insight, contact us at EDMO and we can send you an interconnect drawing we have on file of an
FL-760A wired to a Sigtronics SPA-400 intercom as an example.
Q: I don’t see my issue in the FAQ topics, can I call for more support?
A: Yes – please call EDMO Distributors at 800-235-3300 for tech support
_________________________________
12830 E. Mirabeau Parkway, Spokane, WA 99216●[phone]
●LOCAL [phone]●FAX [phone]