Glad it arrived on time :)
@Peter_Mundy, great service with fast delivery. Ordering from within Sweden would have taken longer to deliver.
Done, thanks!
@Dimme – many thanks – please email your (mobile) telephone number to peter @ pilotshop.nl – DHL insist on having it and we do not get it from PayPal.
Just ordered from the Dutch shop, @Peter_Mundy feel free to ship faster if you can 
This should work great with a USB-C sound card. Does anyone know a reseller in Europe?
https://www.sportys.com/nflightcam-iphone-intercom-audio-interface-cable.html
EDIT: Found: https://thepilotshop.nl/contents/en-us/p1891_NFlightcam_Smartphone_Audio_Cable.html
See post #3 here.
The output needs to drive a passive headset speaker. Bose don’t publish specs but here is another and my guess would be a few volts max. You can always drop it down with two resistors, as required.
From PM7000 IM:
and that works out in the ballpark of 2V rms. This is a bit more than a standard “line” level (up to 1V pk) but it will either work or you can drop it with resistors.
I find a piece of wire a lot more reliable than bluetooth, which tends to work on Mondays and Wednesdays 
But yes you want a BT device which presents the phone with a “mike” profile – or at least a “headset” profile which would also work because when flying you aren’t really interested in hearing the phone’s output audio.
Also, the Bluetooth device has to act as a “Bluetooth mic” on the phone side. The ones I find on Amazon are for transmitting audio to a headset, not to a phone. I doubt they will be recognized by the phone as a mic.
Malibuflyer wrote:
You can buy bluetooth audio transmitters with 3.5mm jackplugs at less than 10 EUR at amazon.
Can those handle the voltage output of the intercom, or will it saturate?
If I’m not mistaken, audio signals for 3.5mm jack plugs are limited to ~1 volt peak-to-peak. Maybe it can be solved with a resistor in series…
@Peter, do you have any specs for the kind of voltage output of intercoms?
You can buy bluetooth audio transmitters with 3.5mm jackplugs at less than 10 EUR at amazon.
PJ-055 to 3.5mm adaptor cable seems to be more of an investment but the PJ-Plug should be about 15 EUR so that with 20EUR total you can put together the cable by yourself (or buy the adapter at about 40 EUR).
